Location: Animal Parasitic Diseases
Title: Life cycle of Cystoisospora felis (Coccidia: Apicomplexa) in cats and mice Author
Submitted to: Journal of Eukaryotic Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 20, 2014
Publication Date: N/A
Interpretive Summary: Toxoplasmosis continues to be a public health problem. Cats (domestic and wild) are the main reservoirs of Toxoplasma gondii infection because they are the only hosts that can excrete the environmentally resistant stage of the parasite, the oocyst. Cats that have once excreted oocysts in feces become immune and seldom re-excrete oocysts. Cats are also hosts to several other coccidian parasites, one of which, Cystoisospora felis, can affect the immune status of the cat. Cats that have shed toxoplasma oocysts can restart shedding Toxoplasma oocysts after infection with Cystoisospora felis. I studied the life cycle of C. felis in cats in order to better understand the biology and interaction of these parasites in the cat. These results will be of interest to biologists, parasitologists, and epidemiologists.
Technical Abstract: Cystoisospora felis is a ubiquitous apicomplexan protozoon of cats. The endogenous development of C. felis was studied in cats after feeding them infected mice. For this, 5 newborn cats were killed at 24, 48, 72, 96, and 120 h after having been fed mesenteric lymph nodes and spleens of mice that were inoculated with C. felis sporulated sporocysts. Asexual and sexual development occurred in enterocytes throughout the villi of the small intestine. The number of asexual generations was not determined with certainty, but there were different sized merozoites. At 24 h, merogony was seen only in the duodenum and the jejunum. Beginning at 48 h the entire small intestine was parasitized. At 24 h, meronts contained 1-4 zoites, and at 48 h up to 12 zoites. Beginning with 72 h, the ileum was more heavily parasitized than the jejunum. At 96 and 120 h, meronts contained many zoites in various stages of development; some divided by endodyogeny. The multiplication was asynchronous, thus both immature multinucleated meronts and mature merozoites were seen in the same parasitophorous vacuole. Gametogony occurred between 96 and 120 h, and oocysts were present at 120 h. For the study of the development of C. felis in murine tissues, mice were killed from day 1 to 720 days after having been fed 105 sporocysts, and their tissues were examined for the parasites microscopically, and by bioassay in cats. The following conclusions were drawn. (1) Cystoisospora felis most frequently invaded the mesenteric lymph nodes of mice and remained there for 23 months at least. (2) It also invaded the spleen, liver, brain, lung, and skeletal muscle of mice, but division was not seen based on microscopical examination. (3) This species could not be passed from mouse to mouse.