Sarcocystis

1. Sarcocystis Sarcocystis is a genus of protozoa. Species in this genus are parasites, the majority infecting mammals, and some infecting reptiles and birds. It was first found in a mouse by Miescher in 1843. Www.RCVetS.com

2. Scientific Classification Kingdom Chromalveolata Phylum Apicomplexa Class Conoidasida Order Eucoccidiorida Family Sarcocystidae Genus Sarcocystis

3. Geographical Distribution These are parasites which live in a number of hosts; therefore their  distribution  is wide, varied and infect animals worldwide. Most prominent cases are observed in: North America South Africa Australia Canada

4. Major Species It has more than 130 recognized species so far. Some of them that are quite important are; Sarcocystis cruzi( Ducks, cattle & birds) Sarcocystis rileyi(   Sheep, Pigs, & waterfowl) Sarcocystis neurona(Equines)   Sarcocystis fusiformis(Humans) The most common species is  Sarcocystis rileyi , which causes the disease known as " rice  breast disease " in waterfowl

5. Hosts It’s hosts are ; Ducks Sheep Cattle Pigs Rats Raccoons Horse Water fowls Humans

6. Transmission in Host The mode of transmission from animal to animal is incompletely understood . For many years it was believed Sarcocystis  was transmitted by ingestion of flesh containing sarcocysts. N ow another indirect method of infection has been proven whereby carnivores and omnivores pass an infective stage of the parasite in their feces. An animal is infected by ingesting material contaminated by the infected feces.

7. Life cycle of Sarcocystis

8. Life Cycle The Sarcocystis sp. parasites have an indirect life cycle that requires a paratentic or transport host animal ( a bird ), in which they live for a time before they are transported to a definitive host animal ( a carnivore ), in which they reach maturity . Birds ingest the eggs or oocysts of the mature parasite in food or water that is contaminated by carnivore feces, which contain the oocysts. The oocysts develop in the intestine of the bird into an intermediate form, the sporozoites, that enter the bird’s bloodstream and infect specific cells of the blood vessels.

9. Multiplication of these cells gives rise to a second intermediate form, merozoites, that are carried by the blood to the voluntary muscles, where elongated cysts or macrocysts are eventually produced. The life cycle is completed when a carnivore ingests the infected muscle tissue of a bird and the parasite reaches maturity and releases oocysts in the intestines of the carnivore. The carnivore is infected only in its intestine. Macrocysts do not develop in the carnivore, and the Sarcocystis sp. parasite rarely causes the carnivore illness or other forms of disease.

10. For some species, humans are the definitive host i.e. the host in which sexual reproduction is completed. In this case there is intestinal sarcocystosis. Humans may also act as accidental dead-end intermediate hosts for several other species and in these cases there is muscular sarcocystosis . In horses infected with  Sarcocystis neurona , the sporozoites enter the  endothelial cells   and replicate asexually, developing into tachyzoites , which then migrate to the animal's central nervous system

11. Signs & Symptoms Sarcocystis is a nonfatal, usually asymptomatic infection. There are no recognizable signs of the infection in most living animals. In heavy infections , Lameness M ild fever Weakness Painful muscular swelling paralysis M uscle pain

12. Diagnosis Diagnosis is usually made by finding the cysts in striated muscle after the animal's death. Further diagnostic methods include; C omplement-fixation D ermal sensitivity tests Frozen muscle tissue M uscle biopsy

13. Treatment No effective treatment is known. Since the disease can be transmitted by the ingestion of feces containing sporocysts. G ood sanitation and hygiene are important in preventing the disease . Cotrimoxazole P rimaquine Both these drugs are appears to be a logical -but unproven-choice till present…. Www.RCVetS.com