Epidemiology and subtype distribution of Blastocystis in humans: A review

• Published in: Infection, genetics and evolution Vol. 95; p. 105085
• Main Authors: Popruk, Supaluk, Adao, Davin Edric V., Rivera, Windell L.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.11.2021
• Subjects: Blastocystis; Blastocystis - genetics; Blastocystis - physiology; Blastocystis Infections - epidemiology; Blastocystis Infections - parasitology; cross-sectional studies; Distribution; drug resistance; enzyme activity; Epidemiology; evolution; gastrointestinal system; Genetic diversity; genetics; Humans; hygiene; infection; intestinal microorganisms; pathogenicity; Prevalence; Protozoa; public health; sanitation; Subtypes; Subtypes; Genetic diversity; Blastocystis; Epidemiology; Distribution
• ISSN: 1567-1348; 1567-7257; 1567-7257
• DOI: 10.1016/j.meegid.2021.105085

Blastocystis is a commonly encountered gastrointestinal protozoan in humans and animals with uncertain pathogenicity. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype (ST) distribution of Blastocystis have been rarely reported. Among Blastocystis STs, ST1–ST4 are common in humans, including healthy and immunodeficient populations. According to the Chi-squared (χ2) association based on the data compiled for this cross-sectional study, the presence of ST1 is associated with asymptomatic infection, whereas the presence of ST4 is associated with symptomatic infection. However, cross-sectional studies cannot clarify the potential pathogenicity of Blastocystis, unlike in vivo and in vitro studies. Poor hygiene, poor sanitation and zoonotic transmission are possible factors associated with high Blastocystis prevalence, although this protozoan may be part of the normal healthy human gastrointestinal microbiota. This review covers the prevalence, STs and distribution of Blastocystis infection in humans. Thus, future epidemiological and subtyping studies could reveal new STs in humans as well as possible associations of STs with disease, drug resistance and related mechanisms such as protease activity. These associations with proper ST identification may facilitate the control of potential threats to host health, including the direct pathogenic effects of Blastocystis or alterations of the gastrointestinal microbiome. •The prevalence of Blastocystis sp. in humans is as high as 100%.•ST1–ST4 comprise 91.65% of all STs identified in humans globally.•The association between Blastocystis sp. and gastrointestinal disease is uncertain.•Blastocystis sp. has global significance because it can colonize several hosts.