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Coccidiosis refers to the condition in which a host harbors coccidian parasites. Coccidia are intestinal parasites of mammals, birds, reptiles, and amphibians. They infect the epithelial cells lining the intestinal wall. The infection begins by the ingestion of sporulated oocyst of a coccidian parasite. The sporozoites are then released, and in the presence of trypsin or bile of the host, they become active and invade epithelial cells as trophozoites. Upon further development, the trophozoites give rise to merozoites that can reproduce either asexually or sexually. The most typical symptom is diarrhea. Coccidiosis in humans is caused by Cystoisospora belli, Cyclospora and Cryptosporidium species. In dogs and cats, the common species causing coccidiosis is Isospora. In young dogs and cats, coccidiosis can lead to serious symptoms and may even lead to death. Common treatment is by administering coccidiostats that disrupt the reproduction of the coccidian parasite.

See also


  1. Coccidia Life Cycle - WikiVet English. (2012). Retrieved from website:
  2. MediRabbit. (2019). Retrieved from website:
  3. CDC - Cystoisosporiasis - Biology. (2019). Retrieved from
  4. Cryptosporidium infection - Symptoms and causes. (2016). Retrieved from Mayo Clinic website:

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