Information

 

Blastocystis is one of the most common parasites found in gastrointestinal system of human and animals (Cian et al. 2017). The pathogenesis of Blastocystis is not yet clearified and may vary depending on the subtype (ST) of parasite, and the immune status of the cases (Elwakil and Hewedi 2010). There are many controversial topics such as pathogenicity, relation with intestinal microbiota, life cycle and genetic diversity. Blastocystis may cause various intestinal pathologies especially irritable bowel syndrome (Wawrzyniak et al. 2013), and heavier infections in immune compromised and cancer patients (Lepczynska et al. 2017).

Transmission of infection occurs through fecal-oral route, by ingestion of food and water contaminated by Blastocystis cysts from infected patients (Leelayoova et al. 2008). Human in contact with animals have higher risk of getting Blastocystis infection (Parkar et al. 2010). Recently the presence of Blastocystis among domestic farm animals like bovine, pigs and pets like cats and dogs and wild animals such as pheasants, ducks, and primates in Japan as well as UK and European countries (Abe et al. 2002; Cian et al. 2017; Osman et al. 2015).

Recently, PCR-based molecular diagnostic methods have been successfully used to determine Blastocystis in feces, and SSU rRNA gene-based subtyping is the preferred method for diagnosis (Wawrzyniak et al. 2013). High genetic diversity is observed within Blastocystis isolates. There has been discussion about the subtypes of Blastocystis which has been detected so far. Currently, a total of 26 subtypes have been identified and submitted to Genbank (Maloney et al. 2018). Blastocystis subtypes from ST1 to ST9 and ST12 have been reported in humans at varying prevalence levels (Ramírez et al. 2016; Stensvold and Clark 2016). Microsatellites are 2-6 bp length genetic markers that can be inherited in both male and female individuals. They are found abundantly in the genomes of eukaryotic organisms. It is possible to identify the causative agents precisely in populations of different genotypes with the help of microsatellite markers, because they contain high amounts of genetic diversity (Havryliuk et al., 2009). Microsatellite markers are generally regarded as neutral alleles that do not evolve under selection print, making it an ideal tool for determining the history of populations.

References

  • Cian A, El Safadi D, Osman M et al (2017) Molecular epidemiology of Blastocystis sp: in various animal groups from two French zoosandevaluation of potential zoonotic risk. PLoSOne 12:e0169659.                                                                         
  • Elwakil HS, Hewedi IH (2010) Pathogenic potential of Blastocystis hominis in laboratory mice. Parasitol. Res. 107:685–689. 
  • Wawrzyniak I, Poirier P, Viscogliosi E, Dionigia M, Texier C, Delbac F, Alaoui HE (2013) Blastocystis, an unrecognized parasite: an overview of pathogenesis and diagnosis. Ther. Adv. Infect. Dis. 1:167–178.                                               
  • Lepczyńska M, Białkowska J, Dzika E, Piskorz-Ogórek K, Korycińska J (2017) Blastocystis: how do specific diets and human gut microbiota affect its development and pathogenicity? Eur J Clin Microbiol Infect Dis. 36(9):1531–1540.             
  • Leelayoova S, Siripattanapipong S, Thathaisong U et al (2008) Drinking water: a possible source of Blastocystis spp. subtype1 infection in school children of a rural community incentral Thailand. Am. J. Trop. Med. Hyg. 79(73):401–406.         
  • Parkar U, Traub RJ, Vitali S et al (2010) Molecular characterization of Blastocystis isolates from zoo animals and their animal-keepers. Vet. Parasitol. 169:8–17.                                                                       
  • Osman M, Bories J, El Safadi D et al (2015) Prevalence and genetic diversity of the intestinal parasites Blastocystis sp. and Cryptosporidium spp. in house hold dogs in France and evaluation of zoonotic transmission risk. Vet. Parasitol. 214:167–170.
  • Maloney JG, Lombard JE, Urie NJ, Shivley CB, Santin M. Zoonotic and genetically diverse subtypes of Blastocystis in US pre-weaned dairy heifer calves. Parasitol Res. 2019 Feb;118(2):575-582.              
  • Havryliuk, T. ve Ferreira, M.U. (2009) “A closer look at multiple-clone Plasmodium vivax infections: detection methods, prevalence and consequences”, Mem Inst Oswaldo Cruz, 104(1), 67–73.