Epizootiology of Blastocystis spp.: A Parasite with Zoonotic Concern

Abstract

Blastocystosis is an enteric infection caused by globally distributed unicellular Protista Blastocystis. Various animals' species as well as human can be parasitized by Blastocystis species. Due to the existence of genetic diversity between Blastocystis isolates in different hosts recently the organisms were defined as Blastocystis spp. or subtypes, although they are morphologically alike. About 34 valid subtypes have been reported in different hosts. Dissimilarity in Blastocystis genotypes have significant effect on their pathogenicity. The organism is poly morphic, and several distinct morphological forms have been observed including vacuolar, granular, cyst, and amebic forms. Blastocystis spp. are transmit through feco-oral rout via contaminated food and water. The risk for human infection might be higher in the existence of infected animals with Blastocystis, as well as in poor hygienic conditions. Although most of reported cases are asymptomatic, Blastocystis infection can associated with gastrointestinal disorders and appearance of nonspecific symptoms of nausea, abdominal pain, bloating, and diarrhea which might be self-limiting or severe. Blastocystosis also accompany with extra-intestinal urticaria signs such as palmoplantar pruritus. The organism also reported from cases of irritable bowel syndrome. Diagnosis of Blastocystis infection can be done conventionally based on the parasitological methods including microscopic examination of fecal smear. In vitro cultivation of fecal samples in supplemented medium was another detection method. The development of molecular techniques provides a sensitive, and rapid detection procedures for Blastocystis spp., also aid in genotypes differentiation. Metronidazole is the treatment of choice for Blastocystosis. Control measures include improvement in hygiene, and sanitation conditions, increased health awareness also essential in preventing enteric parasites.