Blastocystis hominis infection in Southeast Asia: A systematic review of prevalence and risk factors

Background: Intestinal protozoan infection is a global health problem caused by several protozoans including Blastocystis hominis. Southeast Asia is a region with diverse demographic conditions, both in lifestyle and socio-economic conditions. Therefore, studying the prevalence and risk factors of Blastocystis sp. in this region is very interesting in order to gather precise data on this protozoan. The purpose of this study is to determine the prevalence and risk factors of Blastocystis sp. infections in Southeast Asian countries. Methods: This systematic review synthesized findings from 28 studies published between 2014 and 2024 to assess the prevalence and risk factors of these infections across Southeast Asia. Relevant articles were selected using PRISMA guidelines from databases including PubMed, Scopus, and Web of Science, focusing on observational studies that reported on human infections. Results: The analysis revealed high variability in Blastocystis sp. infection rates, ranging from 3.35% to 83.7%. Identified risk factors included sanitation, water source, personal hygiene, animal contact, demographic, health condition, and transmission. Conclusion: This study found that Blastocystis sp. prevalence in Southeast Asia varies widely and is driven by poor sanitation, unsafe water, inadequate hygiene, demographic and socioeconomic factors, and possible zoonotic transmission. These findings highlight the need for a one health approach integrating human, environmental, and pathogen factors.