Young male fisher Exhibited abnormal behavior and ataxia in hind limbs Necropsy revealed pale organs and hemorrhages on heart, lung, skeletal muscle, brain, and under the skin Believed fisher suffered from Sarcocystis

Concluded that the disease was Apicomplexa due to the presence of sporozoites, merozoites, and bradyzoites. Literature search of Apicomplexa and mammals yielded five potential culprits Neospora Toxoplasma Sarcocystis Cryptosporidium Eimeria

Ruled out because both of these infections of the intestinal tract will shed protozoa in the feces and both will cause characteristic diarrhea. This fisher did not exhibit either of these. Cryptosporidium and Eimeria

They all can have very similar symptoms such as pelvic ataxia. Neospora and Toxoplasma have often been confused especially in canids. Neospora, Toxoplasma, and Sarcocystis

Sarcocystis The key to narrowing it down to Sarcocystis was the life cycle and structures of the protozoans themselves. The case study talks about the zoites having an oval to elongated shape, which was the first clue to it being identified as Sarcocystis. Neospora and Toxoplasma zoites are generally more round to oval.

Secondly the case study talks about merozoites, which form from the schiozonts and subsequently invade the muscle fibers and develop into the typical sarcocysts. This type of life cycle is not present in Toxo and Neo. Sarcocystis

Authors of the paper concluded the infection was caused by Sarcocystis neurona by using immunohistochemistry as well as looking at the protozoan itself. Protozoal features of the schizonts and merozoites were consistent with those typical of Sarcocystis neurona seen in previous studies. Source of the infection in this fisher was unknown and no pre-existing virus was found.

Name the daughter cell that invades the muscle fiber and develops into sarcocysts

o Gerhold, Richard W., Elizabeth W. Howerth and David S. Lindsay. Sarcocystis neurona-associated Meningoencephalitis and Description of Intramuscular Sarcocysts in a Fisher (Martes pennanti). Journal of Wildlife Diseases, 41(1), 2005, pp © Wildlife Disease Association 2005 o Field Manual of Wildlife Diseases : Birds. Sarcocystis. Pg 219 – 222. Online