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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Publications at this Location » Publication #383431

Research Project: Detection and Control of Foodborne Parasites for Food Safety

Location: Animal Parasitic Diseases Laboratory

Title: Sarcocystosis

item SYKES, JANE - University Of California
item Dubey, Jitender

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/30/2021
Publication Date: 3/15/2022
Citation: Sykes, J.P., Dubey, J.P. 2022. Sarcocystosis. In: Sykes, J.E., editor. Greene's Infectious Diseases of the Dog and Cat. 5th Edition. St. Louis, MO: Elsevier. p.1172-1178.

Interpretive Summary: Members of the genus Sarcocystis are single-celled organisms, comprising of more than 200 species. Some species of the genus are zoonotic and some species cause serious illness in livestock and humans. Sarcocystis species have 2-host cycle. Carnivores are the definitive hosts (reservoirs) and become infected by eating tissues of intermediate herbivorous hosts. An environmentally resistant stage of the parasite (oocyst/sporocyst) is excreted in feces of carnivores. Hervivorous hosts become infected by consumption of feed or water contaminated with carnivore feces. Dogs and cats can act as both intermediate and definitive hosts for Sarcocystis species. In the present paper the authors summarizes information on biology , clinical signs, epidemiology, diagnosis, and treatment of sarcocystosis in dogs and cats. This paper will be of interest to biologists, veterinarians, and parasitologists.

Technical Abstract: Cause: Protozoan parasites belonging to Order Apicomplexa, Family Sarcocystidae. There are more than 200 named species of Sarcocystis.1 Disease in dogs and cats results from infection with Sarcocystis neurona or Sarcocystis neurona-like organisms, Sarcocystis felis ,Sarcocystis canis, and Sarcocystis caninum. First Described: The encysted stage of the parasite (sarcocyst-in Greek, Sarkos=flesh, kystis=bladder) was first found in muscle of a house mouse in 18432 but its life cycle remained unknown until 1970. Natural sarcocyst infection in dogs was reported in 19663 and in cats in 1986.4 Affected Hosts: Most warm-blooded animals, humans, and some cold-blooded animals. Intermediate and Definitive Hosts: These vary with each Sarcocystis species. Geographic distribution: Worldwide. Some species may be confined to geographic locations defined by the distribution of definitive or intermediate hosts. For example, Sarcocystis neurona is confined to Americas, dependent on the geographic location of its definitive host, the opossum (Didelphis spp.). Route of Transmission: Definitive hosts become infected by ingestion of muscles of an infected intermediate host. Intermediate hosts are infected by ingestion of food or water that has been contaminated with sporocysts. Major Clinical Signs: These depend on the Sarcocystis species and the specific intermediate hosts infected, but include fever, lethargy, neurological signs (Sarcocystis neurona), muscle pain, weakness (myositis due to sarcocysts), and icterus as a result of hepatitis (Sarcocystis canis, Sarcocystis caninum). Differential Diagnosis: Toxoplasmosis, neosporosis, hepatozoonosis, rabies, canine distemper virus infection, infectious canine hepatitis, West Nile virus infection, canine monocytic ehrlichiosis, Rocky Mountain Spotted fever, deep mycoses, migrating ascarid infections, neuronal storage diseases, granulomatous or eosinophilic meningoencephalitis, immune-mediated neuromuscular diseases, primary or metastatic neoplasia. Human Health Significance: Humans can be definitive and intermediate hosts for certain species of Sarcocystis. However, Sarcocystis species of dogs and cats do not infect humans.