Epidemiology of HIV and Schistosoma mansoni infections among sugar-estate residents in Ethiopia

Few studies have examined the interaction between schistosomiasis and infec tion with human immunodeficiency virus (HIV). The overlap between the two i nfections, and the effect of HIV infection on the egg output and worm load of individuals co-infected with Schistosoma mansoni, were therefore investi gated in a sugar estate in central Ethiopia. The 1239 subjects were selecte d by stratified sampling of residents aged 15-54 years. The intensities of infection with S. mansoni were measured as egg output in stools (all subjec ts) and as the concentration of circulating cathodic antigen (CCA) in urine (a proxy for worm load, measured in 287 subjects). Schistosome infection was detected in 358 subjects [adjusted prevalence (AP ) = 31.4%] and HIV infection in 52 (AP = 3.1%). The two infections clustere d into different populations of the estate: the schistosome infections were predominantly found in the camps, and primarily affected young people (age d < 20 years) and those working in the field, whereas the HIV epidemic was found in the main village, primarily affecting those aged > 20 years and th ose who had recently arrived on the estate. Schistosome infection was detec ted in 348 of the 1187 HIV-negatives (AP = 31.6%) and 10 of the 52 HIV-posi tives (AP = 25.1%; P > 0.05). Schistosoma mansoni egg output was significan tly lower in the HIV-positives than in the HIV-negatives (Mann-Whitney test ; P = 0.03; ratio of geometric means = 0.74), and remained so after control ling for potential confounders (gender, age, and residence). However, CCA c oncentrations (i.e. worm loads) were found to be similar for these two grou ps, after controlling for potential confounders (age, gender, residence, an d duration of residence).