Cryptosporidium infection in Zambian adults: prevalence, risk factors and molecular characterization

BACKGROUND: Cryptosporidium is an important enteric parasite causing diarrhoea in humans and animals worldwide. Data on the molecular epidemiology of Cryptosporidium infection in adults in Zambia are limited. METHODS: A total of 566 stool samples from adults (18-50 years) were examined for Cryptosporidium oocysts by light microscopy following modified Ziehl-Neelsen staining. Molecular analysis of positive samples targeted the 60-kDa glycoprotein and heat shock protein 70-kDa genes. Demographic and potential risk factor information was obtained by semi-structured closed questionnaires. RESULTS: The prevalence of Cryptosporidium infection was 3.0% (17/566), affecting a higher proportion of people living with human immunodeficiency virus (HIV) compared with HIV-negative participants, with a significantly higher prevalence among people living with HIV not using antiretroviral therapy (ART) (p=0.001). Additional associated factors included the use of municipal water (p=0.016), moderate monthly income (p=0.01), watery stool and frequent diarrhoea (p=0.001) and haemoglobin levels <10 g/dl (p=0.001). Both Cryptosporidium parvum and Cryptosporidium hominis were identified and all C. parvum subtypes were associated with anthroponotic transmission (IIiA9 [n=4], IIiA6 [n=2], IIeA11G1 [n=1] and IIcA5G3 [n=2]). For C. hominis subtypes, IeA11G3T3 (n=2), IaA26R3 (n=1) and IdA13 (n=1) were identified. CONCLUSION: Cryptosporidium infection continues to be a significant issue among individuals living with HIV. Health education focusing on reducing anthroponotic transmission routes should be a priority.