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Protozoan enteroparasites species and are major contributors to the burden of gastrointestinal illness in children globally, whereas the stramenopile species has been associated with irritable bowel syndrome and skin disorders.


To investigate the carriage of these parasites in voluntary asymptomatic schoolchildren (4‒14 years) in 12 different primary and secondary schools in Leganés (Madrid, Spain).


In a prospective cross-sectional study, stool samples and epidemiological questionnaires on demographics and potential risk factors were collected from participating schoolchildren. Detection of enteric parasites was conducted by PCR-based methods and confirmed by sequence analysis. We calculated prevalence and odds ratios (OR) with logistic regression.


Stool samples and questionnaires were provided by 1,359 schoolchildren from 12 schools. The individual prevalence for any parasite was 28%; sp. 13%; : 18%; spp.: 1%. Two schoolchildren were infected with all three species and 53 with two species. Multivariable risk factor analysis using logistic regression models indicated that an existing infection with one parasite increased the odds for an additional infection with another parasite. The odds of sp. carriage increased up to the age of 10 years and being female increased the odds of spp. infection. Washing vegetables before preparing a meal was protective for sp. infection.


We detected a larger than expected proportion of asymptomatic cases in the participanting schoolchildren. Further investigation of asymptomatic children should be considered. Good hygiene measures should be encouraged for individuals of all ages to protect from protozoal infections.


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