High prevalence of Enterocytozoon bieneusi (Microsporidia) in asymptomatic schoolchildren, Zambia

Authors: MUTENGO, MABLE - Levy Mwanawasa Medical University; DASHTI, ALEJANDRO - National Center For Microbiology, The Institute Of Health Carlos Iii; LIPTAKOVA, MICHAELA - National Center For Microbiology, The Institute Of Health Carlos Iii; MULUNDA, NAMWIINGA - Levy Mwanawasa Medical University; CHABALA, FREEMAN - Levy Mwanawasa Medical University; KYOKO, HAYASHIDA - Hokkaido University; CHINYANTA, STANLEY - Levy Mwanawasa Medical University; CHISANGA, KELLY - Levy Mwanawasa Medical University; MWANSA, JOAMES - Levy Mwanawasa Medical University; KOSTER, PAMELA - National Center For Microbiology, The Institute Of Health Carlos Iii; Santin, Monica; SOTILLO, JAVIER - National Center For Microbiology, The Institute Of Health Carlos Iii; SANCHEZ, SERGIO - National Center For Microbiology, The Institute Of Health Carlos Iii; CARMENA, DAVID - National Center For Microbiology, The Institute Of Health Carlos Iii

Submitted to: Medical Mycology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2025
Publication Date: 7/22/2025
Citation: Mutengo, M., Dashti, A., Liptakova, M., Mulunda, N.R., Chabala, F.W., Kyoko, H., Chinyanta, S., Chisanga, K., Mwansa, J., Koster, P., Santin, M., Sotillo, J., Sanchez, S., Carmena, D. 2025. High prevalence of Enterocytozoon bieneusi (Microsporidia) in asymptomatic schoolchildren, Zambia. Medical Mycology. 63(7). Article emyaf065. https://doi.org/10.1093/mmy/myaf065.
DOI: https://doi.org/10.1093/mmy/myaf065

Interpretive Summary: Microsporidia are single-celled parasites related to fungi that can infect a wide range of animals, including humans. They can cause diseases in people with weakened immune systems, like those with HIV/AIDS or organ transplants. However, it seems that many people might have these infections without showing any symptoms, which could be a hidden public health issue. This study provides new data on the occurrence and genetic diversity of microsporidial infections in stool samples from healthy schoolchildren. Our findings suggest that many children might have infections without showing any symptoms. These children could unknowingly spread the infection to others, which could be a public health concern. This information will be useful to scientists, physicians, and public health agencies to better understand transmission and public health importance of Microsporidia.

Technical Abstract: Microsporidia are single-celled, fungi-related eukaryotic intracellular parasites able to infect a wide diversity of invertebrate and vertebrate hosts. Among them, Enterocytozoon bieneusi and Encephalitozoon spp. (including Enc. cuniculi, Enc. hellem, and Enc. intestinalis) are known causative agents of infectious diseases in immunocompromised individuals including HIV/AIDS patients and organ transplant recipients. Additionally, asymptomatic microsporidial infections seem more frequent than initially anticipated and might represent an overlooked public health threat. Here we provide novel data on the occurrence and genetic diversity of microsporidial infections in individual stool samples (n = 247) collected from apparently healthy schoolchildren (age range: 5–18 years; male/female ratio: 1.1) in Lusaka, Zambia. Stool DNA samples were analysed by PCR and Sanger sequencing methods. A basic epidemiological questionnaire was used to retrieve data on variables potentially linked with higher odds of harbouring E. bieneusi infections. A high prevalence rate was found for E. bieneusi (9.3%, 23/247; 95% CI: 6.0–13.6) whereas Enc. intestinalis was much less frequent (0.4%, 1/247; 95% CI: 0.01–2.2). Four known (D, S2, S6, and Type IV) and three novel (HhZbEb1, HhZbEb2, and HhZbEb3) genotypes were identified within E. bieneusi. Genotype D was the predominant genotype found (30.8%, 4/13), followed by genotypes Type IV, HhZbEb2, and HhZbEb3 (15.4%, 2/13, each), and genotypes S2, S6, and HhZbEb1 (7.7%, 1/13, each). The only Encephalitozoon-positive sample was identified as Enc. intestinalis. Subclinical infections by E. bieneusi were common in the investigated paediatric population. Infected children could act as disregarded spreaders of microsporidial pathogens at the community level, representing a potential public health concern.