A Large-Scale Cholera Outbreak in Kassala State, Sudan from 2024-2025: Risk Factors Associated with Mortality Rate in a Conflict-Affected Setting

A Large-Scale Cholera Outbreak in Kassala State, Sudan from 2024-2025: Risk Factors Associated with Mortality Rate in a Conflict-Affected Setting | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article A Large-Scale Cholera Outbreak in Kassala State, Sudan from 2024-2025: Risk Factors Associated with Mortality Rate in a Conflict-Affected Setting Ahmed Ali Mustafa, Ahmed Saeed Kabbashi, Wala Yahia Osman, Malaz Abbas Degail, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9579768/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Cholera remains a significant public health threat in regions lacking sufficient water, sanitation, and hygiene (WASH) infrastructure, particularly in conflict zones. This study aimed to investigate the epidemiological and clinical characteristics of cholera, as well as the factors associated with mortality, during an outbreak in Kassala, Sudan. Methods We conducted an analytical cross-sectional study of 8,858 patients with confirmed or suspected cholera who were admitted with watery diarrhea, dehydration, and vomiting between July 22, 2024, and January 26, 2025, using data from the National Cholera Surveillance System in Kassala State. Stool examination was performed. Sociodemographic characteristics, clinical presentation, vaccination status, and outcomes were analyzed. Chi-square analysis was used to evaluate the association between categorical risk factors and mortality. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined for each variable. Results The outbreak primarily affected women (53.2%). Children were the most affected group (41.5%), followed by adults (25.3%), adolescents (20.0%), and older adults (13.2%). Urban residents accounted for (60.1%). Vaccination coverage was critically low (3.5%). The positivity rate for Vibrio cholerae among the cases was (97.25%). The overall case fatality rate (CFR) was 2.8% (28/1000). Adults (OR = 1.60, 95% CI: 1.16–2.20, p = 0.003), older individuals (OR = 2.51, 95% CI: 1.78–3.54, p = 0.001), non-vaccinated individuals (OR = 3.02, 95% CI: 1.03–9.12, p = 0.046), and patients with severe symptoms (OR = 2.59, 95% CI: 1.66–4.06, p = 0.001) had a higher risk of mortality. Conclusion The cholera fatality rate is 28 per 1,000. Older adults, unvaccinated individuals, and those with severe symptoms are at a higher risk of mortality. Expanding oral cholera vaccine use, improving urban water hygiene and infrastructure, and implementing protective measures for children in conflict regions in Sudan are imperative to prevent future outbreaks. Bacteriology Cholera outbreak Sudan Kassala case fatality rate oral cholera vaccine children conflict Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1. Introduction Cholera is a significant global public health threat and an indicator of inequity and insufficient social development ( 1 ). The World Health Organization (WHO) estimates 1.3–4.0 million cases and 21,000–143,000 deaths annually worldwide ( 2 ). In 2024, the crisis intensified, with over 560,000 cases and 6,028 deaths across 60 countries, a 50% increase in fatalities compared to 2023. The average fatality rate, recorded from 2000 to 2023, was 2.3% across 44 African nations ( 3 ). Children under five years of age comprise 20% of cases, with Africa accounting for 46% of cases and nearly 83% of deaths ( 2 , 4 ). Cholera is endemic in Sudan, with outbreaks exacerbated by seasonal rains, flooding, conflict, and fragile health infrastructure ( 5 ). The civil war, which erupted in April 2023, brought the health system to the verge of collapse. Over 70% of hospitals in conflict zones are non-operational, with facilities either damaged or destroyed, supplies looted, and staff displaced ( 6 , 7 ). Vaccination coverage has plummeted to its lowest level in 40 years, leaving millions of children at risk ( 8 , 9 ). The disruption of water and electricity infrastructure forces families to rely on unsafe, contaminated water, thereby facilitating the transmission of waterborne diseases ( 9 ). By mid-2024, a cholera outbreak was reported across several Sudanese states, with Kassala State being particularly hard hit. Beginning in July 2024, the outbreak in Kassala spread to all 18 states in Sudan. By September 2025, over 113,600 cases and more than 3,000 deaths were recorded, resulting in a case fatality rate of 2.7% ( 9 ). Cholera remains a persistent challenge in the region, underscoring the importance of epidemiological and clinical data to understand transmission dynamics, identify high-risk groups, and assess control measures in conflict-affected areas. Unfortunately, timely analyses of the 2024–2025 outbreak in Kassala are lacking. This study aimed to examine the mortality rate in relation to sociodemographic and clinical risk factors associated with cholera outbreaks in Kassala State and to identify strategies and allocate resources effectively during this and future outbreaks in conflict-affected regions. 2. Methods 2.1. Study Design and Setting We conducted an analytical cross-sectional study using data from the National Cholera Surveillance System in Kassala State, located in eastern Sudan ( Fig. 1 ) . The study included 8,858 confirmed diagnoses and suspected cholera patients admitted with watery diarrhea, dehydration, and vomiting. This study covered the first six months of the outbreak, from July 22, 2024, to January 26, 2025. Kassala State, bordering Eritrea, has faced population displacement due to conflict, straining its limited water and sanitation infrastructure. 2.2. Case Definitions and Laboratory Testing Laboratory confirmation involves stool culture or rapid diagnostic testing (RDT) for Vibrio cholerae serogroups. Confirmed cases are suspected cases verified by laboratory testing using culture, RDTs, or PCR, in accordance with WHO guidelines, which define a suspected cholera case as any individual aged ≥ 2 years with acute watery diarrhea, with or without vomiting ( 10 ). For children under 2 years of age, clinical judgment and local epidemiology are considered. A total of 4,330 stool samples were collected and tested using culture, rapid diagnostic tests (RDTs), and polymerase chain reaction (PCR). The results were recorded as positive, negative, or inconclusive. The ongoing conflict in Sudan has led to shortages of laboratory resources, medical staff, and infrastructure, significantly constraining the study’s capacity to diagnose all suspected cases. 2.3. Data Sources and Variables De-identified, line-listed data were obtained from the Sudan Federal Ministry of Health's national surveillance database. The analysis focused on the following variables: The variables analyzed included sex, age group (children: 1–18 years; adolescents: 19–30 years; adults: 31–55 years; elderly: 56 years and older), and residence (urban/rural). Clinical data: symptoms, dehydration level (mild, moderate, or severe) per WHO classification, and clinical outcome (survival or death). Preventive status: cholera vaccination history (self-reported or documented). 2.4. Data Analysis Statistical analyses were conducted using SPSS version 21.0 (SPSS Inc., Chicago, IL, USA) and GraphPad Prism 8. Descriptive statistics are reported as frequencies and percentages (%), with the case fatality rate (CFR) expressed as the number of deaths per 1,000 cases. Associations between categorical variables were evaluated using the chi-square test, and results are reported as odds ratios (ORs) with 95% confidence intervals (CIs). Statistical significance was defined as a p-value less than 0.05. 2.5. Ethical Considerations This study utilized anonymized secondary surveillance data collected by the Ministry of Health for public health purposes. Ethical approval was obtained from the Sudan Federal Ministry of Health’s Ethical Review Board. All data were managed confidentially and analyzed anonymously. 3. Results 3.1. Laboratory Confirmation and Epidemiological Trends During the outbreak period, laboratory testing was performed on 4,330 stool samples collected from patients with suspected cholera. Of these, 4,210 (97.25%) were positive for Vibrio cholerae by culture and rapid diagnostic testing (RDT), 115 (2.66%) tested negative, and five (0.08%) had no recorded results (Fig. 2 ). The outbreak's temporal progression, captured in epidemiological curves, showed a rapid escalation following initial detection in July 2024, peaking within subsequent weeks before declining markedly toward year-end (Figs. 3 , 4 , and 5 ). In most cases (99.5%) and all reported deaths, the outbreak occurred in 2024, indicating its peak intensity in the latter half of that year. 3.2. Sociodemographic Distribution and Vaccination Status Analysis of demographic characteristics revealed a predominance of female patients (53.2%) and a strikingly high proportion of children (41.5%), who constitute the most affected age cohort, followed by adults (25.3%), adolescents (20.0%), and the elderly (13.2%). Geographically, urban residences accounted for 60.1% of cases. Critical gaps in prevention were evident, with exceptionally low vaccination coverage: only 3.5% of cases had received cholera vaccination (Table 1 ). Table 1 Sociodemographic characteristics of cholera cases in Kassala State, Sudan, July 22, 2024, to January 26, 2025 (n = 8858) Characteristic Category Frequency Percentage (%) Sex Male 4147 46.8 Female 4711 53.2 Age group (in years) Children 3679 41.5 Adolescents 1773 20.0 Adults 2240 25.3 Elderly 1168 13.2 Residence Rural 3534 39.9 Urban 5324 60.1 Vaccination status Yes 310 3.5 No 8548 96.5 Dehydration level Medium 8489 95.8 Mild 36 0.4 Severe 332 3.7 Unknown 1 0.0 Years 2024 8811 99.5 2025 47 0.5 Mortality assessment Died 248 2.8% = 28* Survived 8610 97.2 * Rate/1000 3.3. Clinical Manifestations and Case Outcomes Clinical presentation consistently featured the hallmark symptoms of cholera: watery diarrhea (100%), dehydration (100%), and vomiting (99.9%). The distribution of clinical characteristics (Fig. 6 ) further emphasizes this pattern, with moderate dehydration documented in 95.8% of the cases and severe dehydration in 3.7%. Other symptoms, including nausea (1.9%), fever (0.7%), and headache (0.03%), were reported less frequently. 3.4. Factors Associated with Mortality Chi-square analysis revealed several factors significantly associated with increased mortality risk during the outbreak (Table 2 ), compared to children (the reference group), adults aged 31–55 years had a 1.60-fold higher risk of death (OR = 1.60, 95% CI: 1.16–2.20, p = 0.003), while the elderly (> 56 years) faced the highest risk with a 2.51-fold greater likelihood of death (OR = 2.51, 95% CI: 1.78–3.54, p = 0.001). Lack of cholera vaccination was a major risk factor, as unvaccinated individuals had three times the odds of dying compared to those who received the oral cholera vaccine (OR = 3.02, 95% CI: 1.03–9.12, p = 0.046). Severe disease was also strongly associated with mortality, with patients experiencing severe illness having 2.59 times higher odds of death than those with mild or moderate symptoms (OR = 2.59, 95% CI: 1.66–4.06, p = 0.001). In contrast, sex and residence were not statistically significant predictors of mortality (p = 0.250 and p = 0.262, respectively). Table 2 Univariate Analysis of Factors Associated with Mortality During the Major Cholera Outbreak in Kassala State, Sudan (2024–2025) Characteristics Death, F(%) Survive, F(%) OR CI P value Sex Females 123(2.61%) 4584(97.39%) 0.86 0.67–1.10 0.250 Males 125 (2.02%) 4018(97.98%) Age groups Children 79(1.81%) 3600(98.19%) Adolescent 32(2.15%) 1739(97.85%) 0.83 0.54–1.26 0.404 Adults 76(3.39%) 2164(96.61%) 1.60 1.16–2.20 0.003 Elderly 61(5.23%) 1106(94.77%) 2.51 1.78–3.54 0.001 Residence Rural 101(3.06%) 3205(96.94%) Urban 147(2.65%) 5403(97.36%) 1.15 0.89–1.49 0.262 Vaccination No 245(2.87%) 8303(97.13%) 3.02 1.03–9.12 0.046 Yes 3(0.97%) 307(99.03%) Severity Mild 0(0.00%) 36(0.43%) Moderate 126(2.66%) 8263(97.34%) Severe 22(6.63%) 310(93.77%) 2.59 1.66–4.06 0.001 F = Frequency, OD = Odds ratio, CI = Confidence intervals. 4. Discussion This study presents a comprehensive analysis of the major cholera outbreak in Kassala State, Sudan, between July 2024 and January 2025. The outbreak included 8,858 reported cases. The cholera outbreak was marked by a high impact on children and mostly urban transmission. Vaccination coverage was low. These factors led to a case-fatality rate above the World Health Organization's emergency threshold. The study underscores the severe consequences of the outbreak, which are tightly linked to Sudan’s ongoing humanitarian crisis. Prolonged conflict has caused massive displacement and the collapse of health infrastructure, worsening the outbreak’s impact ( 11 – 13 ). The outbreak showed an unusually high proportion of cholera cases among children (41.5%). This is a notable deviation from typical patterns, where adults and older people are more often affected. Older people had the lowest proportion of cases (13.2%) ( 14 ). The high burden of cholera among children was primarily due to missed passive immunity in infants, disrupted health services, lack of prior exposure, or vaccination ( 2 ), and widespread malnutrition, which weakened immune defenses and increased the risk of severe disease ( 15 , 16 ). Displacement contributed to unsafe feeding practices and to exposure to contaminated food, thereby heightening infection risk ( 17 ). These patterns match those seen in other conflict-affected African regions ( 9 , 18 ). Being young was not an independent risk factor for severe outcomes in multivariate analysis, but it was significant in bivariate analysis ( 19 ). The urban predominance of cases (60.1%) challenges the conventional perception of cholera as a predominantly rural phenomenon and reflects the specific vulnerabilities of Sudan's urban centers during conflict. Kassala has experienced massive population displacement from active conflict zones, with internally displaced persons (IDPs) seeking refuge in urban areas, where they often reside in overcrowded settlements with limited access to safe water and sanitation ( 20 , 21 ). The disruption of urban water infrastructure due to attacks on power and water systems has forced families to rely on contaminated sources ( 22 ). This finding aligns with recent data showing that urban areas across Sudan, including Khartoum, White Nile, and Gadarif states, have experienced significant cholera transmission ( 23 ). The urban concentration of cases mandates a critical re-evaluation of WASH priorities, emphasizing the need for secure municipal water systems and targeted hygiene promotion in urban and peri-urban areas. The fatality rate was found to be 2.8%, which remains unacceptably high and is consistent with the national CFR of 2.7% reported across Sudan during this period ( 9 ). This rate exceeds the WHO target of < 1% and the CFR across 44 African countries of 2.3% ( 3 ), indicating likely delays in seeking care, overwhelmed healthcare facilities at the peak of the outbreak, and a high proportion of severe cases upon presentation ( 24 ). In some localities of West Darfur, the CFRs reached 11.8%, reflecting the extreme challenges of accessing care in active conflict zones ( 25 ). Univariate analysis revealed that older age, lack of vaccination, and severe symptoms were significant risk factors for mortality. This may indicate higher comorbidities in older populations and age-related susceptibility to developing dehydration. A previous study identified older age, younger age, and sex as the most common CFR risk factors, with mortality being more prevalent in men than in women ( 26 ). Unvaccinated individuals have a mortality risk three times higher than vaccinated ones, showing the vaccine's strong protective effect and matching evidence of OCV effectiveness in conflict settings. OCV campaigns reduce cholera incidence by up to 80%, especially when coverage is high (70–90%) ( 27 ). Sudan's 3.5% coverage is much lower than neighboring Ethiopia, which, from 2019 to 2023, vaccinated over 1.8 million people and reached 70–90% coverage in targeted districts ( 28 ). This low coverage in Sudan highlights a failure of prevention and points to the challenges vaccination campaigns face in conflict zones, including access, logistics, vaccine shortages, and cold-chain maintenance ( 9 , 27 ). Security conditions severely limit Sudan's access to vaccines, and WHO and partners face 'severe access constraints' when delivering vaccines to affected areas, especially Darfur ( 29 , 30 ). The campaign in Darfur, which started in September 2025 after weeks of preparation, aimed to protect 1.86 million people but encountered major challenges in 'getting the vaccines there' ( 30 ). To close these gaps, improve infrastructure, and run preventive OCV campaigns in high-risk areas, especially urban centers with high IDP concentrations. The study has several limitations. First, case underreporting may have occurred due to passive surveillance. Second, the possibility of misclassification, as case identification relied on clinical diagnoses, which may affect its accuracy. Recall bias may have affected self-reported vaccination status, potentially leading to erroneous estimates of vaccine coverage. Additionally, the absence of detailed environmental and behavioral information limits understanding of transmission routes and risk factors. Since only univariate analysis was performed, confounding factors were not controlled. Furthermore, missing data on vaccination timing prevented evaluation of vaccine effectiveness. Finally, generalizability is limited because of differences in conflict, displacement, and healthcare access across Sudanese regions. 5. Conclusion In summary, the 2024–2025 cholera outbreak in Kassala State is a significant public health event characterized by a high attack rate among children, who represented the largest affected age group. This pattern deviates from typical cholera epidemiology. This was accompanied by a predominant spread in urban areas and a critically low oral cholera vaccine coverage, exacerbated by the ongoing conflict that crippled Sudan's health system. The near-universal presentation of watery diarrhea, dehydration, and vomiting confirmed the classical clinical pattern of the disease. At the same time, the CFR is 2.8% exceeded the WHO emergency threshold, underscoring the persistent challenges in timely case management in conflict-affected settings. Older age, severe disease, and non-vaccination are significant risk factors for mortality, with non-vaccinated individuals having threefold higher odds of death. These findings collectively highlight the urgent need for targeted interventions, including. Strengthened child protection strategies through the promotion of safe breastfeeding and weaning practices in displacement settings, with special attention to infants who rely on passive immunity Rapid scaling up of preventive OCV campaigns in high-risk populations, particularly in urban areas with high IDP concentrations. Sustained investment in climate-resilient and conflict-proof WASH infrastructure. Enhanced community-based surveillance and early warning systems. Ensuring the functionality of cholera treatment centers with adequate supplies of rehydration solutions and trained staff. Abbreviations CATI Case-Area Targeted Intervention CFR Case Fatality Rate CI Confidence Interval IDP Internally Displaced Person OCV Oral Cholera Vaccine OR Odds Ratio PCR Polymerase Chain Reaction RDT Rapid Diagnostic Test WASH Water, Sanitation, and Hygiene WHO World Health Organization Declarations Ethics approval and consent to participate This study used anonymized secondary surveillance data routinely collected by the Ministry of Health for public health purposes. Institutional approval was obtained from the Sudan Federal Ministry of Health’s Ethical Review Board. All data were handled with confidence and analyzed anonymously. Consent for publication Not applicable. This manuscript does not contain any individual data. Availability of data and materials The datasets generated and/or analyzed during the current study are available from the Sudan Federal Ministry of Health. Still, their availability is limited, as they were used under license for the current study and are not publicly available. However, the data are available from the corresponding author upon reasonable request, with permission from the Sudanese Federal Ministry of Health. Competing interests The authors declare that they have no competing interests. Funding No funding was received for this study. Authors' contributions WYO, MAD, and AAM conceived and designed the study. AAM, ASK, WYO, MAD, AAE, and AYM collected and cleaned the data. AAM, AAE, AMI, and ASK performed statistical analyses. AAM, WYO, AAE, and MAD drafted the manuscript. ASK, AYM, AAE, D R Z and AMI critically revised the manuscript for intellectual content. All authors have read and approved the final manuscript. Acknowledgements The authors thank the Sudan Federal Ministry of Health and the health authorities in Kassala State for providing access to surveillance data. We also thank the healthcare workers who managed the patients during this outbreak and contributed to data collection. Authors' information Ahmed Ali Mustafa: Department of Botany and Microbiology, Faculty of Science, University of Gezira, Sudan. Ahmed Saeed Kabbashi: Department of Biomedical Science, Faculty of Pharmacy, Omar Al-Mukhtar University, Al-Bayda, Libya; Department of Microbiology and Parasitology, Medicinal and Aromatic Plants and Traditional Medicine Research Institute, National Center for Research, Khartoum, Sudan; Department of Microbiology, Faculty of Medical Laboratory Sciences, International University of Africa, Khartoum, Sudan. Wala Yahia Osman: Department of Botany and Microbiology, Faculty of Science, University of Gezira, Sudan. Malaz Abbas Degail: Department of Botany and Microbiology, Faculty of Science, University of Gezira, Sudan. Ahmed A. Elshikh: Department of Biotechnology, Faculty of Science and Technology, Omdurman Islamic University, Omdurman, Sudan. Amna Yousif Mohamed: Department of Biotechnology, Faculty of Science and Technology, Omdurman Islamic University, Omdurman, Sudan. Doaa Rafaat Zahran: Department of Botany and Microbiology, Faculty of Science, University of Cairo, Egypt. Amar Mohamed Ismail: Department of Biomedical Science, Faculty of Pharmacy, Omar Al-Mukhtar University, Al-Bayda, Libya; Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, Al Neelain University, Khartoum, Sudan. References Ali M, Nelson AR, Lopez AL, Sack DA. Updated global burden of cholera in endemic countries. PLoS neglected tropical diseases. 2015;9(6):e0003832. Mohamed MG, Dabou EAA, Abdelsamad S, Elsalous SH. Cholera outbreaks: Public health implications, economic burden, and preventive strategies. AIMS Public Health. 2025;12(3):767. Koua EL, Moussana FH, Sodjinou VD, Kambale F, Kimenyi JP, Diallo S, et al. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9579768","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":632617414,"identity":"9ba6c750-825d-4753-b419-835100c3a9d0","order_by":0,"name":"Ahmed Ali Mustafa","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBklEQVRIiWNgGAWjYDACCSDmYWCQYWNmbP/wocIGyGVsPECMFh42duY2xhln0kBaGojTwsDP3sbM23IYLIhXC//s7sQPbxjsePiYGdse8Dact1vbfhhoS41NNE5L7pzdLDmHIZkH5BcDyR23k7edSQRqOZaW24BLz43cDdI8DMwgLQ0ShmduJ5sdAGphbDiMU4v8jdzNv3kY6iFaEtvOJZudf4hfi8GN3G1AWw6DtLRJHGw7YGd2g4AthkAtlnMMjoO0NBs2nElOMLsBtCUBj1/kgA678aaiWk6+//jDx38q7OzNzqc/fPChxga39yHOQzATwSoT8CpHA/akKB4Fo2AUjIKRAQAnAGCR6L4T1QAAAABJRU5ErkJggg==","orcid":"","institution":"Department of Botany and Microbiology, Faculty of Science, University of Gezira, Sudan.","correspondingAuthor":true,"prefix":"","firstName":"Ahmed","middleName":"Ali","lastName":"Mustafa","suffix":""},{"id":632627523,"identity":"27145b9e-ef7e-4c82-a3fd-802705f4b30b","order_by":1,"name":"Ahmed Saeed Kabbashi","email":"","orcid":"","institution":"Department of Biomedical Science, Faculty of Pharmacy, Omar Al-Mukhtar University, Al-Bayda, Libya.Department of Microbiology and Parasitology, Medicinal and Aromatic Plants and Traditional Medicine Research Institute, National Centre for Research, Khartoum, Sudan. Department of Parasitology, Faculty of Medical Laboratory Sciences, International University of Africa, Khartoum, Sudan.","correspondingAuthor":false,"prefix":"","firstName":"Ahmed","middleName":"Saeed","lastName":"Kabbashi","suffix":""},{"id":632627524,"identity":"909b32ef-ad9a-4f52-b9e6-f09a418442cc","order_by":2,"name":"Wala Yahia Osman","email":"","orcid":"","institution":"Department of Botany and Microbiology, Faculty of Science, University of Gezira, Sudan.","correspondingAuthor":false,"prefix":"","firstName":"Wala","middleName":"Yahia","lastName":"Osman","suffix":""},{"id":632627525,"identity":"14babc33-d66b-48b6-8c0c-e5a02ecbcfc4","order_by":3,"name":"Malaz Abbas Degail","email":"","orcid":"","institution":"Department of Botany and Microbiology, Faculty of Science, University of Gezira, Sudan.","correspondingAuthor":false,"prefix":"","firstName":"Malaz","middleName":"Abbas","lastName":"Degail","suffix":""},{"id":632627526,"identity":"f7bcbc7e-5afa-4b44-a833-2946642416a8","order_by":4,"name":"Ahmed A. Elshikh","email":"","orcid":"","institution":"Department of Biology, Center for Human and Biological Sciences, Federal University of São Carlos (UFSCar), Rodovia João Leme dos Santos, Km 110, SP 264, Sorocaba, SP, ZIP 18052-780, Brazil. Department of Botany, Faculty of Science and Technology, Omdurman Islamic University, Omdurman, Sudan","correspondingAuthor":false,"prefix":"","firstName":"Ahmed","middleName":"A.","lastName":"Elshikh","suffix":""},{"id":632627527,"identity":"c9c93fbb-d772-4caa-bac5-1ee5b92f220e","order_by":5,"name":"Amna Yousif Mohamed","email":"","orcid":"","institution":"Department of Biotechnology, Faculty of Science and Technology, Omdurman Islamic University, Omdurman, Sudan.","correspondingAuthor":false,"prefix":"","firstName":"Amna","middleName":"Yousif","lastName":"Mohamed","suffix":""},{"id":632627528,"identity":"8076c8be-320a-4bc7-89c9-1ac62683f32a","order_by":6,"name":"Doaa Rafaat Zahran","email":"","orcid":"","institution":"Department of Botany and Microbiology, Faculty of Science, University of Cairo, Egypt.","correspondingAuthor":false,"prefix":"","firstName":"Doaa","middleName":"Rafaat","lastName":"Zahran","suffix":""},{"id":632627529,"identity":"b09c8c8a-4cf3-4726-8fba-b0a67b30a5ec","order_by":7,"name":"Amar Mohamed Ismail","email":"","orcid":"","institution":"Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, Al Neelain University, Khartoum, Sudan","correspondingAuthor":false,"prefix":"","firstName":"Amar","middleName":"Mohamed","lastName":"Ismail","suffix":""}],"badges":[],"createdAt":"2026-04-30 16:49:44","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-9579768/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9579768/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108839386,"identity":"d158ea5c-e3b4-4757-b198-ae2ec745998a","added_by":"auto","created_at":"2026-05-09 00:45:08","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":233183,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical representation of the study area and a map showing the different districts in Kassala State, Sudan.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9579768/v1/4bf2ca2dace85bac8daa689b.png"},{"id":108977530,"identity":"edd9c6af-0123-488f-bcb0-420912f5fe7f","added_by":"auto","created_at":"2026-05-11 11:31:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":18356,"visible":true,"origin":"","legend":"\u003cp\u003eLaboratory results of stool samples tested for \u003cem\u003eVibrio cholerae\u003c/em\u003e during the cholera outbreak in Kassala State, Sudan, July 22, 2024, to January 26, 2025 (n=4,330 samples tested). Positive: 4,210 (97.25%); Negative: 115 (2.66%); No results: 5 (0.08%).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9579768/v1/d7d81322c9a458e81c833c28.png"},{"id":108976825,"identity":"3f13dc04-6f6c-45e3-a3c5-c263c0915881","added_by":"auto","created_at":"2026-05-11 11:28:59","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":94173,"visible":true,"origin":"","legend":"\u003cp\u003eEpidemiological curve of cholera cases according to entry by epidemiological week in Kassala State, Sudan, July 22, 2024, to January 26, 2025 (n=8,858).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9579768/v1/bbf5f617915b00788430febb.png"},{"id":108977402,"identity":"62eb070a-4e4f-46c6-b1a1-940fb3116d06","added_by":"auto","created_at":"2026-05-11 11:31:38","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":109940,"visible":true,"origin":"","legend":"\u003cp\u003eEpidemiological curve of cholera cases by date of symptom onset by epidemiological week in Kassala State, Sudan, July 22, 2024, to January 26, 2025 (n=8,858).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9579768/v1/f2d7ef13e3d5148c4a3c3c82.png"},{"id":108977094,"identity":"baa79758-724a-4679-9326-e4a179f925b9","added_by":"auto","created_at":"2026-05-11 11:30:22","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":196182,"visible":true,"origin":"","legend":"\u003cp\u003eEpidemiological curve of cholera cases by date of onset and admission, from July 22, 2024, to January 26, 2025.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-9579768/v1/8ea02da23f2acb3c58993991.png"},{"id":108977174,"identity":"066ad912-c0bd-4cc1-bd40-07697d148266","added_by":"auto","created_at":"2026-05-11 11:30:43","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":62763,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of cholera cases by clinical characteristics in Kassala State, Sudan.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-9579768/v1/35666de1d063a9d0134f6740.png"},{"id":108979735,"identity":"4dbe0a37-8ef6-45f1-b248-46d52d92d92a","added_by":"auto","created_at":"2026-05-11 12:00:57","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":921266,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9579768/v1/44eab425-a364-4e39-9240-302c765c147d.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eA Large-Scale Cholera Outbreak in Kassala State, Sudan from 2024-2025: Risk Factors Associated with Mortality Rate in a Conflict-Affected Setting\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eCholera is a significant global public health threat and an indicator of inequity and insufficient social development (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). The World Health Organization (WHO) estimates 1.3\u0026ndash;4.0\u0026nbsp;million cases and 21,000\u0026ndash;143,000 deaths annually worldwide (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). In 2024, the crisis intensified, with over 560,000 cases and 6,028 deaths across 60 countries, a 50% increase in fatalities compared to 2023. The average fatality rate, recorded from 2000 to 2023, was 2.3% across 44 African nations (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Children under five years of age comprise 20% of cases, with Africa accounting for 46% of cases and nearly 83% of deaths (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCholera is endemic in Sudan, with outbreaks exacerbated by seasonal rains, flooding, conflict, and fragile health infrastructure (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). The civil war, which erupted in April 2023, brought the health system to the verge of collapse. Over 70% of hospitals in conflict zones are non-operational, with facilities either damaged or destroyed, supplies looted, and staff displaced (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). Vaccination coverage has plummeted to its lowest level in 40 years, leaving millions of children at risk (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). The disruption of water and electricity infrastructure forces families to rely on unsafe, contaminated water, thereby facilitating the transmission of waterborne diseases (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eBy mid-2024, a cholera outbreak was reported across several Sudanese states, with Kassala State being particularly hard hit. Beginning in July 2024, the outbreak in Kassala spread to all 18 states in Sudan. By September 2025, over 113,600 cases and more than 3,000 deaths were recorded, resulting in a case fatality rate of 2.7% (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Cholera remains a persistent challenge in the region, underscoring the importance of epidemiological and clinical data to understand transmission dynamics, identify high-risk groups, and assess control measures in conflict-affected areas. Unfortunately, timely analyses of the 2024\u0026ndash;2025 outbreak in Kassala are lacking.\u003c/p\u003e \u003cp\u003eThis study aimed to examine the mortality rate in relation to sociodemographic and clinical risk factors associated with cholera outbreaks in Kassala State and to identify strategies and allocate resources effectively during this and future outbreaks in conflict-affected regions.\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Study Design and Setting\u003c/h2\u003e \u003cp\u003eWe conducted an analytical cross-sectional study using data from the National Cholera Surveillance System in Kassala State, located in eastern Sudan \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. The study included 8,858 confirmed diagnoses and suspected cholera patients admitted with watery diarrhea, dehydration, and vomiting. This study covered the first six months of the outbreak, from July 22, 2024, to January 26, 2025. Kassala State, bordering Eritrea, has faced population displacement due to conflict, straining its limited water and sanitation infrastructure.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Case Definitions and Laboratory Testing\u003c/h2\u003e \u003cp\u003eLaboratory confirmation involves stool culture or rapid diagnostic testing (RDT) for \u003cem\u003eVibrio cholerae\u003c/em\u003e serogroups. Confirmed cases are suspected cases verified by laboratory testing using culture, RDTs, or PCR, in accordance with WHO guidelines, which define a suspected cholera case as any individual aged\u0026thinsp;\u0026ge;\u0026thinsp;2 years with acute watery diarrhea, with or without vomiting (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). For children under 2 years of age, clinical judgment and local epidemiology are considered. A total of 4,330 stool samples were collected and tested using culture, rapid diagnostic tests (RDTs), and polymerase chain reaction (PCR). The results were recorded as positive, negative, or inconclusive. The ongoing conflict in Sudan has led to shortages of laboratory resources, medical staff, and infrastructure, significantly constraining the study\u0026rsquo;s capacity to diagnose all suspected cases.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Data Sources and Variables\u003c/h2\u003e \u003cp\u003eDe-identified, line-listed data were obtained from the Sudan Federal Ministry of Health's national surveillance database. The analysis focused on the following variables:\u003c/p\u003e \u003cp\u003eThe variables analyzed included sex, age group (children: 1\u0026ndash;18 years; adolescents: 19\u0026ndash;30 years; adults: 31\u0026ndash;55 years; elderly: 56 years and older), and residence (urban/rural).\u003c/p\u003e \u003cp\u003eClinical data: symptoms, dehydration level (mild, moderate, or severe) per WHO classification, and clinical outcome (survival or death).\u003c/p\u003e \u003cp\u003ePreventive status: cholera vaccination history (self-reported or documented).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Data Analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were conducted using SPSS version 21.0 (SPSS Inc., Chicago, IL, USA) and GraphPad Prism 8. Descriptive statistics are reported as frequencies and percentages (%), with the case fatality rate (CFR) expressed as the number of deaths per 1,000 cases. Associations between categorical variables were evaluated using the chi-square test, and results are reported as odds ratios (ORs) with 95% confidence intervals (CIs). Statistical significance was defined as a p-value less than 0.05.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Ethical Considerations\u003c/h2\u003e \u003cp\u003eThis study utilized anonymized secondary surveillance data collected by the Ministry of Health for public health purposes. Ethical approval was obtained from the Sudan Federal Ministry of Health\u0026rsquo;s Ethical Review Board. All data were managed confidentially and analyzed anonymously.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Laboratory Confirmation and Epidemiological Trends\u003c/h2\u003e \u003cp\u003eDuring the outbreak period, laboratory testing was performed on 4,330 stool samples collected from patients with suspected cholera. Of these, 4,210 (97.25%) were positive for \u003cem\u003eVibrio cholerae\u003c/em\u003e by culture and rapid diagnostic testing (RDT), 115 (2.66%) tested negative, and five (0.08%) had no recorded results (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe outbreak's temporal progression, captured in epidemiological curves, showed a rapid escalation following initial detection in July 2024, peaking within subsequent weeks before declining markedly toward year-end (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, and \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). In most cases (99.5%) and all reported deaths, the outbreak occurred in 2024, indicating its peak intensity in the latter half of that year.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Sociodemographic Distribution and Vaccination Status\u003c/h2\u003e \u003cp\u003eAnalysis of demographic characteristics revealed a predominance of female patients (53.2%) and a strikingly high proportion of children (41.5%), who constitute the most affected age cohort, followed by adults (25.3%), adolescents (20.0%), and the elderly (13.2%). Geographically, urban residences accounted for 60.1% of cases. Critical gaps in prevention were evident, with exceptionally low vaccination coverage: only 3.5% of cases had received cholera vaccination (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSociodemographic characteristics of cholera cases in Kassala State, Sudan, July 22, 2024, to January 26, 2025 (n\u0026thinsp;=\u0026thinsp;8858)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCategory\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFrequency\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePercentage (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eMale\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4147\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e46.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eFemale\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4711\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e53.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eAge group (in years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eChildren\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3679\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e41.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eAdolescents\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1773\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e20.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eAdults\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e25.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eElderly\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1168\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e13.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eResidence\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eRural\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3534\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e39.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eUrban\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5324\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e60.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eVaccination status\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eYes\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e310\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eNo\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8548\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eDehydration level\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eMedium\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8489\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e95.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eMild\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eSevere\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e332\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eUnknown\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eYears\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e2024\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8811\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e2025\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eMortality assessment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eDied\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e248\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.8% = 28*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eSurvived\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8610\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003cb\u003e* Rate/1000\u003c/b\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Clinical Manifestations and Case Outcomes\u003c/h2\u003e \u003cp\u003eClinical presentation consistently featured the hallmark symptoms of cholera: watery diarrhea (100%), dehydration (100%), and vomiting (99.9%). The distribution of clinical characteristics (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e) further emphasizes this pattern, with moderate dehydration documented in 95.8% of the cases and severe dehydration in 3.7%. Other symptoms, including nausea (1.9%), fever (0.7%), and headache (0.03%), were reported less frequently.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.4. Factors Associated with Mortality\u003c/h2\u003e \u003cp\u003eChi-square analysis revealed several factors significantly associated with increased mortality risk during the outbreak (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), compared to children (the reference group), adults aged 31\u0026ndash;55 years had a 1.60-fold higher risk of death (OR\u0026thinsp;=\u0026thinsp;1.60, 95% CI: 1.16\u0026ndash;2.20, p\u0026thinsp;=\u0026thinsp;0.003), while the elderly (\u0026gt;\u0026thinsp;56 years) faced the highest risk with a 2.51-fold greater likelihood of death (OR\u0026thinsp;=\u0026thinsp;2.51, 95% CI: 1.78\u0026ndash;3.54, p\u0026thinsp;=\u0026thinsp;0.001). Lack of cholera vaccination was a major risk factor, as unvaccinated individuals had three times the odds of dying compared to those who received the oral cholera vaccine (OR\u0026thinsp;=\u0026thinsp;3.02, 95% CI: 1.03\u0026ndash;9.12, p\u0026thinsp;=\u0026thinsp;0.046). Severe disease was also strongly associated with mortality, with patients experiencing severe illness having 2.59 times higher odds of death than those with mild or moderate symptoms (OR\u0026thinsp;=\u0026thinsp;2.59, 95% CI: 1.66\u0026ndash;4.06, p\u0026thinsp;=\u0026thinsp;0.001). In contrast, sex and residence were not statistically significant predictors of mortality (p\u0026thinsp;=\u0026thinsp;0.250 and p\u0026thinsp;=\u0026thinsp;0.262, respectively).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eUnivariate Analysis of Factors Associated with Mortality During the Major Cholera Outbreak in Kassala State, Sudan (2024\u0026ndash;2025)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDeath, F(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSurvive, F(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eOR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemales\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e123(2.61%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4584(97.39%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.67\u0026ndash;1.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.250\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMales\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e125 (2.02%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4018(97.98%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChildren\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e79(1.81%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3600(98.19%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdolescent\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e32(2.15%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1739(97.85%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.54\u0026ndash;1.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.404\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdults\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e76(3.39%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2164(96.61%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.16\u0026ndash;2.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eElderly\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e61(5.23%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1106(94.77%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.78\u0026ndash;3.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResidence\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRural\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e101(3.06%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3205(96.94%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUrban\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e147(2.65%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5403(97.36%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.89\u0026ndash;1.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.262\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVaccination\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e245(2.87%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8303(97.13%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.03\u0026ndash;9.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.046\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3(0.97%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e307(99.03%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSeverity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMild\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0(0.00%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e36(0.43%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModerate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e126(2.66%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8263(97.34%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSevere\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e22(6.63%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e310(93.77%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.66\u0026ndash;4.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eF\u0026thinsp;=\u003c/b\u003e\u0026thinsp;Frequency, \u003cb\u003eOD\u0026thinsp;=\u003c/b\u003e\u0026thinsp;Odds ratio, \u003cb\u003eCI\u0026thinsp;=\u003c/b\u003e\u0026thinsp;Confidence intervals.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThis study presents a comprehensive analysis of the major cholera outbreak in Kassala State, Sudan, between July 2024 and January 2025. The outbreak included 8,858 reported cases. The cholera outbreak was marked by a high impact on children and mostly urban transmission. Vaccination coverage was low. These factors led to a case-fatality rate above the World Health Organization's emergency threshold. The study underscores the severe consequences of the outbreak, which are tightly linked to Sudan\u0026rsquo;s ongoing humanitarian crisis. Prolonged conflict has caused massive displacement and the collapse of health infrastructure, worsening the outbreak\u0026rsquo;s impact (\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe outbreak showed an unusually high proportion of cholera cases among children (41.5%). This is a notable deviation from typical patterns, where adults and older people are more often affected. Older people had the lowest proportion of cases (13.2%) (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). The high burden of cholera among children was primarily due to missed passive immunity in infants, disrupted health services, lack of prior exposure, or vaccination (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e), and widespread malnutrition, which weakened immune defenses and increased the risk of severe disease (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). Displacement contributed to unsafe feeding practices and to exposure to contaminated food, thereby heightening infection risk (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). These patterns match those seen in other conflict-affected African regions (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Being young was not an independent risk factor for severe outcomes in multivariate analysis, but it was significant in bivariate analysis (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe urban predominance of cases (60.1%) challenges the conventional perception of cholera as a predominantly rural phenomenon and reflects the specific vulnerabilities of Sudan's urban centers during conflict. Kassala has experienced massive population displacement from active conflict zones, with internally displaced persons (IDPs) seeking refuge in urban areas, where they often reside in overcrowded settlements with limited access to safe water and sanitation (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). The disruption of urban water infrastructure due to attacks on power and water systems has forced families to rely on contaminated sources (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). This finding aligns with recent data showing that urban areas across Sudan, including Khartoum, White Nile, and Gadarif states, have experienced significant cholera transmission (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). The urban concentration of cases mandates a critical re-evaluation of WASH priorities, emphasizing the need for secure municipal water systems and targeted hygiene promotion in urban and peri-urban areas.\u003c/p\u003e \u003cp\u003eThe fatality rate was found to be 2.8%, which remains unacceptably high and is consistent with the national CFR of 2.7% reported across Sudan during this period (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). This rate exceeds the WHO target of \u0026lt;\u0026thinsp;1% and the CFR across 44 African countries of 2.3% (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e), indicating likely delays in seeking care, overwhelmed healthcare facilities at the peak of the outbreak, and a high proportion of severe cases upon presentation (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). In some localities of West Darfur, the CFRs reached 11.8%, reflecting the extreme challenges of accessing care in active conflict zones (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eUnivariate analysis revealed that older age, lack of vaccination, and severe symptoms were significant risk factors for mortality. This may indicate higher comorbidities in older populations and age-related susceptibility to developing dehydration. A previous study identified older age, younger age, and sex as the most common CFR risk factors, with mortality being more prevalent in men than in women (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eUnvaccinated individuals have a mortality risk three times higher than vaccinated ones, showing the vaccine's strong protective effect and matching evidence of OCV effectiveness in conflict settings. OCV campaigns reduce cholera incidence by up to 80%, especially when coverage is high (70\u0026ndash;90%) (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). Sudan's 3.5% coverage is much lower than neighboring Ethiopia, which, from 2019 to 2023, vaccinated over 1.8\u0026nbsp;million people and reached 70\u0026ndash;90% coverage in targeted districts (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e). This low coverage in Sudan highlights a failure of prevention and points to the challenges vaccination campaigns face in conflict zones, including access, logistics, vaccine shortages, and cold-chain maintenance (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). Security conditions severely limit Sudan's access to vaccines, and WHO and partners face 'severe access constraints' when delivering vaccines to affected areas, especially Darfur (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). The campaign in Darfur, which started in September 2025 after weeks of preparation, aimed to protect 1.86\u0026nbsp;million people but encountered major challenges in 'getting the vaccines there' (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). To close these gaps, improve infrastructure, and run preventive OCV campaigns in high-risk areas, especially urban centers with high IDP concentrations.\u003c/p\u003e \u003cp\u003eThe study has several limitations. First, case underreporting may have occurred due to passive surveillance. Second, the possibility of misclassification, as case identification relied on clinical diagnoses, which may affect its accuracy. Recall bias may have affected self-reported vaccination status, potentially leading to erroneous estimates of vaccine coverage. Additionally, the absence of detailed environmental and behavioral information limits understanding of transmission routes and risk factors. Since only univariate analysis was performed, confounding factors were not controlled. Furthermore, missing data on vaccination timing prevented evaluation of vaccine effectiveness. Finally, generalizability is limited because of differences in conflict, displacement, and healthcare access across Sudanese regions.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eIn summary, the 2024\u0026ndash;2025 cholera outbreak in Kassala State is a significant public health event characterized by a high attack rate among children, who represented the largest affected age group. This pattern deviates from typical cholera epidemiology. This was accompanied by a predominant spread in urban areas and a critically low oral cholera vaccine coverage, exacerbated by the ongoing conflict that crippled Sudan's health system. The near-universal presentation of watery diarrhea, dehydration, and vomiting confirmed the classical clinical pattern of the disease. At the same time, the CFR is 2.8% exceeded the WHO emergency threshold, underscoring the persistent challenges in timely case management in conflict-affected settings. Older age, severe disease, and non-vaccination are significant risk factors for mortality, with non-vaccinated individuals having threefold higher odds of death. These findings collectively highlight the urgent need for targeted interventions, including.\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eStrengthened child protection strategies through the promotion of safe breastfeeding and weaning practices in displacement settings, with special attention to infants who rely on passive immunity\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eRapid scaling up of preventive OCV campaigns in high-risk populations, particularly in urban areas with high IDP concentrations.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eSustained investment in climate-resilient and conflict-proof WASH infrastructure.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eEnhanced community-based surveillance and early warning systems.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eEnsuring the functionality of cholera treatment centers with adequate supplies of rehydration solutions and trained staff.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eCATI\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCase-Area Targeted Intervention\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eCFR\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCase Fatality Rate\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eCI\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eConfidence Interval\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eIDP\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInternally Displaced Person\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eOCV\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eOral Cholera Vaccine\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eOR\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eOdds Ratio\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003ePCR\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePolymerase Chain Reaction\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eRDT\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRapid Diagnostic Test\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eWASH\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eWater, Sanitation, and Hygiene\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eWHO\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eWorld Health Organization\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study used anonymized secondary surveillance data routinely collected by the Ministry of Health for public health purposes. Institutional approval was obtained from the Sudan Federal Ministry of Health\u0026rsquo;s Ethical Review Board. All data were handled with confidence and analyzed anonymously.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. This manuscript does not contain any individual data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed during the current study are available from the Sudan Federal Ministry of Health. Still, their availability is limited, as they were used under license for the current study and are not publicly available. However, the data are available from the corresponding author upon reasonable request, with permission from the Sudanese Federal Ministry of Health.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was received for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWYO, MAD, and AAM conceived and designed the study. AAM, ASK, WYO, MAD, AAE, and AYM collected and cleaned the data. AAM, AAE, AMI, and ASK performed statistical analyses. AAM, WYO, AAE, and MAD drafted the manuscript. ASK, AYM, AAE,\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003eD R\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003eZ\u003cstrong\u003e\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003e\u003c/strong\u003eand AMI critically revised the manuscript for intellectual content. All authors have read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank the Sudan Federal Ministry of Health and the health authorities in Kassala State for providing access to surveillance data. We also thank the healthcare workers who managed the patients during this outbreak and contributed to data collection.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAhmed Ali Mustafa:\u003c/strong\u003e Department of Botany and Microbiology, Faculty of Science, University of Gezira, Sudan.\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003e\u003cstrong\u003eAhmed Saeed Kabbashi:\u003c/strong\u003e Department of Biomedical Science, Faculty of Pharmacy, Omar Al-Mukhtar University, Al-Bayda, Libya; Department of Microbiology and Parasitology, Medicinal and Aromatic Plants and Traditional Medicine Research Institute, National Center for Research, Khartoum, Sudan; Department of Microbiology, Faculty of Medical Laboratory Sciences, International University of Africa, Khartoum, Sudan.\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003e\u003cstrong\u003eWala Yahia Osman:\u003c/strong\u003e Department of Botany and Microbiology, Faculty of Science, University of Gezira, Sudan.\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003e\u003cstrong\u003e\u0026nbsp;Malaz Abbas Degail:\u003c/strong\u003e Department of Botany and Microbiology, Faculty of Science, University of Gezira, Sudan.\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003e\u003cstrong\u003eAhmed A. Elshikh:\u003c/strong\u003e Department of Biotechnology, Faculty of Science and Technology, Omdurman Islamic University, Omdurman, Sudan.\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003e\u003cstrong\u003eAmna Yousif Mohamed:\u003c/strong\u003e Department of Biotechnology, Faculty of Science and Technology, Omdurman Islamic University, Omdurman, Sudan.\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003e\u003cstrong\u003eDoaa Rafaat Zahran:\u003c/strong\u003e\u003csup\u003e\u0026nbsp;\u003c/sup\u003eDepartment of Botany and Microbiology, Faculty of Science, University of Cairo, Egypt.\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003e\u003cstrong\u003eAmar Mohamed Ismail:\u003c/strong\u003e Department of Biomedical Science, Faculty of Pharmacy, Omar Al-Mukhtar University, Al-Bayda, Libya; Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, Al Neelain University, Khartoum, Sudan.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAli M, Nelson AR, Lopez AL, Sack DA. Updated global burden of cholera in endemic countries. PLoS neglected tropical diseases. 2015;9(6):e0003832.\u003c/li\u003e\n \u003cli\u003eMohamed MG, Dabou EAA, Abdelsamad S, Elsalous SH. Cholera outbreaks: Public health implications, economic burden, and preventive strategies. AIMS Public Health. 2025;12(3):767.\u003c/li\u003e\n \u003cli\u003eKoua EL, Moussana FH, Sodjinou VD, Kambale F, Kimenyi JP, Diallo S, et al. Exploring the burden of cholera in the WHO African region: patterns and trends from 2000 to 2023 cholera outbreak data. BMJ Global Health. 2025;10(1).\u003c/li\u003e\n \u003cli\u003eOrganization WH. Cholera, 2023= Chol\u0026eacute;ra, 2023. Weekly Epidemiological Record= Relev\u0026eacute; \u0026eacute;pid\u0026eacute;miologique hebdomadaire. 2024;99(36):481-95.\u003c/li\u003e\n \u003cli\u003eFederspiel F, Ali M. The cholera outbreak in Yemen: lessons learned and way forward. BMC Public Health. 2018;18(1):1338.\u003c/li\u003e\n \u003cli\u003eAgbo KC, Haruna UA, Oladunni AA, Lucero-Prisno III DE. Addressing gaps in protection of health workers and infrastructures in fragile and conflict-affected states in Africa. Discover Health Systems. 2024;3(1):36.\u003c/li\u003e\n \u003cli\u003eBayet M, Renard C. Logistical and strategic challenges of international humanitarian aid distribution in conflict zones: focus on Mali and Gaza.\u003c/li\u003e\n \u003cli\u003eMilton S, Antaby M, Dellai H, Idrees A. Counting the costs of war: A holistic, multi-level assessment of the impact of conflict on Sudan. African Security Review. 2025:1-17.\u003c/li\u003e\n \u003cli\u003eDahab M, AbuKoura R, Checchi F, Ahmed A, Abdalla O, Ibrahim M, et al. War-time mortality in Sudan: a multiple systems estimation analysis. The Lancet Global Health. 2025;13(9):e1583-e90.\u003c/li\u003e\n \u003cli\u003eDerese TN, Koyra ZF, Mario LD, Mideksa HS, Dessie SA, Berihun AA. Exploring barriers and associated factors in the preparedness for cholera outbreak response in Public Health Centres of Addis Ababa, Ethiopia. PLOS Global Public Health. 2025;5(9):e0005087.\u003c/li\u003e\n \u003cli\u003eOrganization WH. Progress report on health issues facing populations affected by disasters and emergencies, including the International Health Regulations (2005)[EM. World Health Organization. Regional Office for the Eastern Mediterranean; 2024.\u003c/li\u003e\n \u003cli\u003eOGBU JT. Examining the impact of protracted conflicts on mortality in humanitarian emergencies: Universit\u0026eacute; catholique de Louvain; 2022.\u003c/li\u003e\n \u003cli\u003eAbuzerr S, Zinszer K, Mahmoud H. Healthcare collapse and disease spread: a qualitative study of challenges in Gaza strip. BMC Public Health. 2025;25(1):589.\u003c/li\u003e\n \u003cli\u003eNoskov A, Kruglikov V, Moskvitina E, Monakhova E, Levchenko D, Yanovich E, et al. Characteristics of the Epidemiological Situation on Cholera in the World and in the Russian Federation in 2020 and Forecast for 2021. Problems of Particularly Dangerous Infections. 2021(1):43-51.\u003c/li\u003e\n \u003cli\u003eSoliman AT, Alaaraj NM, Rogol AD. The link between malnutrition, immunity, infection, inflammation and growth: New pathological mechanisms. Methods. 2022;4(5).\u003c/li\u003e\n \u003cli\u003eMorales F, Montserrat-De la Paz S, Leon MJ, Rivero-Pino F. Effects of malnutrition on the immune system and infection and the role of nutritional strategies regarding improvements in children\u0026rsquo;s health status: a literature review. Nutrients. 2023;16(1):1.\u003c/li\u003e\n \u003cli\u003eBurke RM, Ramani S, Lynch J, Cooper LV, Cho H, Bandyopadhyay AS, et al. Geographic disparities impacting oral vaccine performance: observations and future directions. Clinical and experimental immunology. 2025;219(1):uxae124.\u003c/li\u003e\n \u003cli\u003eLopez AL, Deen J, Azman AS, Luquero FJ, Kanungo S, Dutta S, et al. Immunogenicity and protection from a single dose of internationally available killed oral cholera vaccine: a systematic review and metaanalysis. Clinical Infectious Diseases. 2018;66(12):1960-71.\u003c/li\u003e\n \u003cli\u003eKalima N, Imamura T, Chambah I, Mbewe N, Sinkala A, Chungu C, et al., editors. Clinical characteristics and factors associated with severe outcomes of 1891 pediatric patients admitted to the referral cholera treatment centers in Lusaka, Zambia, December 2023\u0026ndash;March 2024. Open Forum Infectious Diseases; 2025: Oxford University Press US.\u003c/li\u003e\n \u003cli\u003eAmisu BO, Okesanya OJ, Adigun OA, Manirambona E, Ukoaka BM, Lawal OA, et al. Cholera resurgence in Africa: assessing progress, challenges, and public health response towards the 2030 global elimination target. Infez Med. 2024;32(2):148.\u003c/li\u003e\n \u003cli\u003eNunez-Ferrera I, Aubrey D, Earle L, Loose S. IDPs in towns and cities\u0026ndash;working with the realities of internal displacement in an urban world. International Institute for Environment and Development (IIED), Joint IDP Profiling Service (IPS) and UN-Habitat. 2020.\u003c/li\u003e\n \u003cli\u003eGleick PH. Water as a weapon and casualty of armed conflict: A review of recent water‐related violence in Iraq, Syria, and Yemen. Wiley Interdisciplinary Reviews: Water. 2019;6(4):e1351.\u003c/li\u003e\n \u003cli\u003eAzhary A, Hajhamed NM, Mohamed R, Ali ETO, Hamida ME, Muvunyi CM, Siddig EE. Resurgence of multistate cholera in Sudan amidst ongoing conflict. IJID regions. 2025:100798.\u003c/li\u003e\n \u003cli\u003eMwale M, Chipimo PJ, Kalubula P, Hibusu L, Mulima SMC, Kapema K, et al. Building resilience against cholera: lessons from the implementation of integrated community strategy for cholera control in Zambia. BMJ Global Health. 2025;10(1).\u003c/li\u003e\n \u003cli\u003eNatukunda J. Child health in Darfur, Sudan: Addressing the effects of armed conflict on children\u0026apos;s health in Darfur. 2022.\u003c/li\u003e\n \u003cli\u003ePampaka D, Alberti K, Olson D, Ciglenecki I, Barboza P. Risk factors for cholera mortality: A scoping review. Trop Med Int Health. 2025;30(5):332-50.\u003c/li\u003e\n \u003cli\u003eMohamed R, AdamSabi Y, Hassan S, Mahmoud A, Mohammadat D, Abdalla ES, et al. The management of cholera in populations affected by conflict in Africa and the Middle-East: a scoping review. Conflict and Health. 2025.\u003c/li\u003e\n \u003cli\u003eEdosa M, Jeon Y, Gedefaw A, Hailu D, Mesfin Getachew E, Mogeni OD, et al. Comprehensive review on the use of oral cholera vaccine (OCV) in Ethiopia: 2019 to 2023. Clinical Infectious Diseases. 2024;79(Supplement_1):S20-S32.\u003c/li\u003e\n \u003cli\u003eAdeniyi EO. Transmission dynamics and control of cholera in Africa: A mathematical modelling approach. 2024.\u003c/li\u003e\n \u003cli\u003eAyowole DJ, Adebajo GO, Lasisi TO, Bakai JG. Effects of climate change on vaccine storage and cold chain logistics: a qualitative study in Ogun State, Nigeria. BMJ global health. 2025;10(7).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"University of Gezira","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Cholera, outbreak, Sudan, Kassala, case fatality rate, oral cholera vaccine, children, conflict","lastPublishedDoi":"10.21203/rs.3.rs-9579768/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9579768/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eCholera remains a significant public health threat in regions lacking sufficient water, sanitation, and hygiene (WASH) infrastructure, particularly in conflict zones. This study aimed to investigate the epidemiological and clinical characteristics of cholera, as well as the factors associated with mortality, during an outbreak in Kassala, Sudan.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe conducted an analytical cross-sectional study of 8,858 patients with confirmed or suspected cholera who were admitted with watery diarrhea, dehydration, and vomiting between July 22, 2024, and January 26, 2025, using data from the National Cholera Surveillance System in Kassala State. Stool examination was performed. Sociodemographic characteristics, clinical presentation, vaccination status, and outcomes were analyzed. Chi-square analysis was used to evaluate the association between categorical risk factors and mortality. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined for each variable.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe outbreak primarily affected women (53.2%). Children were the most affected group (41.5%), followed by adults (25.3%), adolescents (20.0%), and older adults (13.2%). Urban residents accounted for (60.1%). Vaccination coverage was critically low (3.5%). The positivity rate for \u003cem\u003eVibrio cholerae\u003c/em\u003e among the cases was (97.25%). The overall case fatality rate (CFR) was 2.8% (28/1000). Adults (OR\u0026thinsp;=\u0026thinsp;1.60, 95% CI: 1.16\u0026ndash;2.20, p\u0026thinsp;=\u0026thinsp;0.003), older individuals (OR\u0026thinsp;=\u0026thinsp;2.51, 95% CI: 1.78\u0026ndash;3.54, p\u0026thinsp;=\u0026thinsp;0.001), non-vaccinated individuals (OR\u0026thinsp;=\u0026thinsp;3.02, 95% CI: 1.03\u0026ndash;9.12, p\u0026thinsp;=\u0026thinsp;0.046), and patients with severe symptoms (OR\u0026thinsp;=\u0026thinsp;2.59, 95% CI: 1.66\u0026ndash;4.06, p\u0026thinsp;=\u0026thinsp;0.001) had a higher risk of mortality.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe cholera fatality rate is 28 per 1,000. Older adults, unvaccinated individuals, and those with severe symptoms are at a higher risk of mortality. Expanding oral cholera vaccine use, improving urban water hygiene and infrastructure, and implementing protective measures for children in conflict regions in Sudan are imperative to prevent future outbreaks.\u003c/p\u003e","manuscriptTitle":"A Large-Scale Cholera Outbreak in Kassala State, Sudan from 2024-2025: Risk Factors Associated with Mortality Rate in a Conflict-Affected Setting","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-09 00:45:04","doi":"10.21203/rs.3.rs-9579768/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b776d69d-20e9-471e-8adb-e5bf97a025f1","owner":[],"postedDate":"May 9th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":67341579,"name":"Bacteriology"}],"tags":[],"updatedAt":"2026-05-09T00:45:04+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-09 00:45:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9579768","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9579768","identity":"rs-9579768","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}