Epidemiology and aetiology of moderate to severe diarrhoea in hospitalised HIV-infected patients ≥5 years old in South Africa, 2018-2021: a case-control analysis

Diarrhoea is a recognised complication of HIV-infection, yet there are limited local aetiological data in this high-risk group. These data are important for informing public health interventions and updating diagnostic and treatment guidelines. This study aimed to determine the pathogenic causes for diarrhoeal admissions in HIV-infected patients compared to hospital controls between July 2018 and November 2021. Admitted diarrhoeal cases (n=243) and non-diarrhoeal hospital controls (n=101) ≥5 years of age were enrolled at Kalafong, Mapulaneng and Matikwana hospitals. Stool specimens/rectal swabs were collected and pathogen screening performed on multiple platforms. Differences in pathogen detections between cases and controls, stratified by HIV status, were investigated. The majority (n=164, 67.5%) of diarrhoeal cases with known HIV status were HIV-infected. Pathogens could be detected in 66.3% (n=228) of specimens, with significantly higher detection in cases compared to controls (72.8% versus 50.5%, p <0.001). Amongst HIV-infected participants, prevalence of Cystoisospora spp. was significantly higher in cases than controls (17.7% versus 0.0%, p =0.028), while Schistosoma was detected more often in controls than cases (17.4% versus 2.4%, p =0.009). Amongst the HIV-uninfected participants, prevalence of Shigella spp., Salmonella spp. and Helicobacter pylori was significantly higher in cases compared to controls (36.7% versus 12.0%, p =0.002; 11.4% versus 0.0%, p =0.012; 10.1% versus 0.0%, p =0.023). Diarrhoeal aetiology differed by HIV status, with Shigella spp. (36.7%) and Salmonella spp. (11.4%) having the highest prevalence amongst HIV-uninfected cases and Shigella spp. (18.3%), Cystoisospora (17.7%), and Cryptosporidium spp. (15.9%) having the highest prevalence amongst HIV-infected cases. These differences should be considered for the development of diagnostic and treatment guidelines.