Blastocystis sp., Parasite Associated with Gastrointestinal Disorders: An Overview of its Pathogenesis, Immune Modulation and Therapeutic Strategies

Abstract

Blastocystis sp. is a unicellular parasitic microorganism commonly found in the gastrointestinal tracts of humans and animals. It causes symptomatic or asymptomatic infection and its route of transmission is via fecal-oral. High prevalence of Blastocystis infection in developing countries is usually due to poor hygiene practices, exposure to animals infected with the parasite and intake of contaminated water or food. Blastocystis infected individuals often suffer from diarrhea, abdominal pain, nausea, and stomach bloating. Even though pathogenecity of Blastocystis is unclear, it is commonly associated with irritable bowel syndrome. In this review we have analysed the evidences that shows the association between this microorganism and gastrointestinal disorders. There have been a number of studies which showed that the pathogenicity of Blastocystis is related to its different STs. The pathogenicity is speculated to be due to cysteine proteases formation which stimulates mucosal cells to release interleukin-8 which has been associated with extreme dehydration and gut inflammation. In vitro studies on human colonic epithelial cells revealed that incubation of Blastocystis modulated the host immune response by stimulating the formation of pro-inflammatory cytokines and granulocyte macrophage colony-stimulating factor. Metronidazole is found to be the first-line drug of choice. Other treatment option is the combination therapy with trimethoprim/sulfamethoxazole.

Occurrence and genotypes of Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. in household, shelter, breeding, and pet market dogs in Guangzhou, southern China

“…This could be related to the fact that the anthelminthic ingredients used for dogs in China mainly include ivermectin, pyrantel, praziquantel, pyrantel pamoate, febantel, nitazoxanide, metronidazole, and fenbendazole, most of which are also effective against protozoan infections, such as Giardia spp., Cryptosporidium spp., and Blastocystis sp. 46 – 48 . Thus, pet hygiene management is suggested to be a major risk factor for contracting these pathogens in dogs.…”

<p>Molecular Epidemiology and Risk Factors of Blastocystis sp. Infections Among General Populations in Yunnan Province, Southwestern China</p>

“…continues to be debated, this parasite is widely accepted as a pathogenic contributor to diarrhea and abdominal pain in humans. 2,7 Notably, Blastocystis sp. infections may induce obvious diarrhea in immunocompromised patients, such as HIV/AIDS and cancer patients.…”

“… 6 Although the pathogenic role of Blastocystis sp. remains controversial, 5 this intestinal pathogen is linked to gastrointestinal disorders, 7 – 10 urticaria 11 – 14 and Steven Johnson’s syndrome. 15 In addition, Blastocystis sp.…”

Prevalence of Blastocystis and its Association with Intestinal Dysbiosis in Clinically Healthy and Metabolically Ill Subjects.

“…The high prevalence of Blastocystis infection in developing countries is usually due to poor hygiene practices, exposure to animals infected with parasites, and intake of water or food contaminated (17).…”