Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2014
Publication Date: 5/15/2014
Citation: Fayer, R., Elsasser, T.H., Gould, R., Solano Aguilar, G., Santin, M., Urban Jr, J.F. 2014. Blastocystis tropism in the pig intestine. Parasitology Research. 113:1465-1472. Interpretive Summary: Blastocystis is an intestinal parasite found worldwide in human and non-human animal hosts and is often the most frequently detected parasite in epidemiological surveys. Its high prevalence in humans has been associated with poor hygiene, exposure to animals, and consumption of contaminated food or water. Despite its high prevalence and ubiquitous presence, reports of Blastocystis detected in feces of large animals, domesticated or wild are rare, and there are no reports of Blastocystis found in any specific location within the gastrointestinal tract of such animals. Because pigs are infected with Blastocystis of the same subtypes found in humans the present study was undertaken to determine where this parasite is found within the gastrointestinal tract, with the intention that such information will be helpful in understanding how and where this parasite causes disease and how best to provide treatment. Forms of the parasite were detected in portions of the small intestine and throughout the large intestine, mostly mixed with intestinal contents, sometimes closely associated with cells lining the intestine, but never invading or disrupting the tissues. The new detection methods developed in this study are useful for physicians, veterinarians and epidemiologists concerned with this widespread group of parasites.
Technical Abstract: Blastocystis subtype 5, a subtype known to infect humans, was detected by molecular methods in the feces of 36 naturally infected market age pigs. At necropsy, 6 heavily infected pigs were selected to determine the tropism of the infection within the gastrointestinal tract. Because so little is known of the location and invasiveness of this parasite in humans and animals, such data can provide insight into the underlying mechanism of disease and possible treatment protocols. Tissue segments from the duodenum, jejunum, ileum, cecum and colon were isolated, prepared as histologic sections, and stained with monoclonal and polyclonal antibodies against Blastocystis. Forms of the parasite were detected in the jejunum, cecum, and the proximal and distal colon, mostly in luminal contents, but some forms closely adherent to the luminal surface of epithelial cells. Invasion of tissues was not observed. The findings provide a useful new protocol for detection of Blastocystis in patients by clinicians, in animals by veterinarians, and in foodborne or waterborne outbreaks investigated by epidemiologists.