Blastocystis subtype

Blastocystis subtype

Blastocystis is an intestinal protozoan that is often found in humans, which can cause symptoms such as diarrhea but  some are asymptomatic (Nofita, Harminarti and Rusjdi, 2014). Blastocystis infection is an intestinal parasitic infection with a higher incidence rate in developing countries by 30-50% (Popruk, Pintong and Radomyos, 2013; Rebolla et al., 2016) compared to developed countries such as in Japan 0.5-1% , in Singapore 3.3%. The prevalence of blastocystis infection in developing countries, such as 27.2% in Argentina , 33.3% in Egypt , 38.5% in Cuba, 40.9% in Brazil, and 60% in Indonesia (Tan, 2008).

    Several studies reported that certain populations may be more susceptible to blastocystis infection. This parasite is most commonly found in Indonesia in patients infected with the HIV / AIDS virus who experienced chronic diarrhea before receiving antiretroviral therapy. Those in close contact with animals also appear to have an increased risk of developing blastocystis, which reinforces the idea that this blastocystis infection may be a zoonotic infection (Kurniawan et al., 2009; Coyle et al., 2012; Popruk, Pintong and Radomyos, 2013).

    Different blastocystis subtypes are believed to have different host reservoirs, geographic distribution, and transmission routes. Subtyping Blastocystis is important for epidemiological studies because it helps to identify potential sources and transmission routes of certain subtypes in certain areas (Popruk, Pintong and Radomyos, 2013). There is no information on the Blastocystis subtype in a specific geographic area, thus limiting our knowledge of the distribution of the Blastocystis subtype. ST1-ST9 was found in human stool samples (Popruk, Pintong and Radomyos, 2013), with ST1-ST4 being the most common subtype in humans. The subtypes of blastocystis commonly found in humans can also be found in animals, suggesting that the animal can act as a reservoir for blastocystis and may be associated with zoonotic transmission.

    The life cycle of Blastocystis cells taking into account recent studies indicates the presence of zoonotic genotypes (subtypes 1 to 7) with various host specificities. Subtype 1 found cross infection between isolates of mammals, chickens, pigs and primates; subtype 2 was found in primates / pigs, subtype 3 was found in humans, subtype 4 was found in rodents, subtype 5 was found in isolates in cattle / pigs; and subtypes 6 and 7 include avian isolates. This shows that humans are potentially infected by seven or more species of blastocystis and certain animals as reservoirs for transmission to humans (Tan, 2008).