A Worldwide Systematic Review and Meta-Analysis of the Prevalence and Subtype Distribution of Blastocystis Sp. in Water Sources: A Public Health Concern.

Contaminated water sources can result in outbreaks of parasitic infections such as Blastocystis sp. in communities, creating a substantial strain on healthcare systems and affecting the general health of the population. To ascertain the prevalence and subtype distribution of Blastocystis sp. in water sources globally, a systematic review and meta-analysis of published papers up to May 19, 2024 were carried out. A thorough search of multiple electronic databases (PubMed, Scopus, Google Scholar, and Web of Science) identified 24 studies/28 datasets meeting the inclusion criteria, encompassing 2,451 water samples from 15 countries worldwide. Water samples comprised wastewater (six datasets, 285 samples), tap/drinking water (10 datasets, 253 samples), surface water (eight datasets, 1013 samples), and uncategorized water (four datasets, 900 samples). Total estimates and 95% confidence intervals (CIs) were computed using a random-effects model. This review found that 18.8% (95% CI: 12.8-26.9%) of examined water samples contained Blastocystis sp. Wastewater showed the highest Blastocystis sp. infection rate at 35.5% (95% CI: 13.5-66.1%), followed by tap/drinking water at 19.1% (95% CI: 9.5-34.5%), surface water at 17.6% (95% CI: 7.2-36.8%), and uncategorized water at 9.9% (95% CI: 4.1-21.8%). Sensitivity analysis assessed weighted prevalence variations following the exclusion of individual studies. Subgroup analysis of Blastocystis sp. prevalence was performed based on publication years, countries, continents, WHO regions, sample sizes, and diagnostic methods. Water samples can be the source of infection for nine Blastocystis sp. subtypes (STs) (ST1-ST4, ST6, ST8, ST10, ST21, and ST24), with seven STs (ST1-ST4, ST6, ST8, and ST10) capable of infecting humans. It is important to take preventative and control measures, improve the cleanliness and quality of water sources, and promote public health awareness due to the presence of different parasites such as Blastocystis sp. in water sources.