PET-PCR reveals low parasitaemia and submicroscopic malarial infections in Honduran Moskitia

AbstractBackground:Malaria remains the main parasitic disease of humans. Although the largest number of cases is reported in the African region, there are still endemic foci in the Americas. Central America reported 36,000 malaria cases in 2020, which represents 5.5% of cases in the Americas and 0.015% of cases globally. Most malaria infections in Central America are reported in La Moskitia, shared by Honduras and Nicaragua. In the Honduran Moskitia, less than 800 cases were registered in 2020, considering it an area of ​​low endemicity. In low endemicity settings, the number of submicroscopic and asymptomatic infections tends to increase, leaving many cases undetected and untreated. These reservoirs challenge national malaria elimination programs. This study aimed to compare and assess the diagnostic performance of Light Microscopy (LM) with photoinduced electron transfer polymerase chain reaction (PET-PCR) as the gold standard in a population of febrile patients from La Moskitia.Methods:A total of 309 febrile participants were recruited using a passive surveillance approach at the Puerto Lempira hospital. Blood samples were analyzed by LM, nested PCR, and PET-PCR. Diagnostic performance including sensitivity, specificity, negative and positive predictive values, kappa index, accuracy, and ROC analysis was evaluated. The parasitaemia of the positive samples was quantified by both LM and PET-PCR.Results:The overall prevalence of malaria was 19.1% by LM, 27.8% by nPCR, and 31.1% by PET-PCR. The sensitivity of LM and nPCR was 59.6% and 80.8%, respectively. LM showed a kappa index of 0.67, with a moderate level of agreement. Forty positive cases by PET-PCR were not detected by LM.Conclusions:This study demonstrated that LM is unable to detect parasitaemia at low levels and that there is a high degree of submicroscopic infections in the Honduran Moskitia.