Blastocystis colonization among inland and forest periphery Negritos in Malaysia: The crucial role of sanitation and hygiene practices

Abstract

There has been an increasing trend in the study of Blastocystis due to its ubiquitous nature, and potential impact on human health. In Malaysia, its prevalence among the undeserved indigenous Orang Asli (OA) population varies widely from 1.7 %- 80.0 %. These huge differences were suggested to be attributed to disparities in living standards, including sanitation and access to treated water status. We investigated the prevalence, risk factors, and subtypes of Blastocystis among the OA Negritos residing in forest periphery villages and the inland jungle settings. A cross-sectional study was conducted involving 259 participants and their stool samples were screened microscopically for intestinal parasites and molecular techniques for Blastocystis. Risk factors including the type of village category and Blastocystis subtypes were identified. Of the 259 participants, 40 (15.4 %) were found to be colonized with Blastocystis. Prevalence was higher in the inland (17/81; 21.0 %) than in forest periphery villages (23/178; 12.9 %), but the difference was not statistically significant (P = 0.096). Among the 40 positive individuals, 31 (77.5 %) were co-infected with soil-transmitted helminths (STH). Multivariate analysis identified the unavailability of a household latrine (P < 0.001), infrequent washing hands after defecation (P = 0.005), having other household members positive with Blastocystis (P = 0.003), individuals from the Bateq subtribe (P = 0.011), and living in inland villages (P = 0.033) as significant predictors of Blastocystis colonization. Three subtypes were identified: ST1, ST2 and ST3 (the most predominant). We highlighted the critical role of hygiene and sanitation practices in the transmission dynamics of Blastocystis rather than type of village category or development status among OA. Continuous health practices, particularly on proper hygienic practices, should be emphasized especially concerning parasites transmitted via the fecal-oral route.