Incidence and risk factors of Blastocystis infection in an orphanage in Bangkok, Thailand

BACKGROUND: Blastocystis sp. is one of the most common intestinal protozoa in humans. Unlike other intestinal parasitic infections such as giardiasis and cryptosporidiosis, the epidemiology of blastocystosis in children who live in crowded settings such as day-care centers and orphanages has been rarely explored. METHODS: A retrospective cohort study was conducted to evaluate incidence and risk factors of Blastocystis infection in an orphanage every two consecutive months during April 2003 to April 2004, in Bangkok, Thailand. Blastocystis sp. was identified using direct simple smear, and in vitro cultivation in Jones' medium. RESULTS: The incidence rate was 1.8/100 person-months and the independent risk factors associated with Blastocystis infection were age, nutritional status and orphans living in the room where their childcare workers were infected. CONCLUSIONS: Person-to-person transmission was most likely to occur either from orphans to childcare workers or from childcare workers to orphans living in the same room. Universal precautions such as regular hand washing and careful handling of fecally contaminated materials are indicated.