Sarcocystosis in animals

Question 1

Sarcocystis spp:

Answer 1

S. bovihominis - Cattle - Human
S. bovicanis - Cattle - Dog
S. bovifelis - Cattle - Cat
S. suihominis - Pig - Human
S. suicanis - Pig - Dog
S. suifelis - Pig - Cat
S. ovicanis - Sheep - Dog
S. ovifelis - Sheep - Cat
S. capracanis - Goat - Dog
S. equicanis - Horse - Dog
S. neurona - raccoon, armadillo, skunk, cat - Opossum (FH), Equine (casual host)

Question 2

What are intermediate hosts of Sarcocystis?

Answer 2

birds & herbivores

asexual stage

Question 3

Egg morphology of sarcocystis

Answer 3

Small, oval, 2 thin shells, sporulated and transparent

Question 4

location of sarcocystis

Answer 4

IH: Muscles
FH: Gastrointestinal tract

Question 5

morphology of sarcocystis

Answer 5

2 sporocysts and 4 sporozoites

Question 6

life cycle of sarcocystis

Answer 6

1) Endogenous sporogony: sporulated oocysts are shed in the feces of final host.
2) Endogenous merogony: intermediate host ingest vegetation with the sporulated oocyst, which then excysts in the intestine. Sporozoites enters the endothelial cells of blood vessels. Inside the cells, they undergo merogony and merozoites are made. Merozoites then travel to lymphocytes where they undergo budding and enter the muscles, where they form cysts. Inside the cysts, bradyzoites are formed.
3) Endogenous gametogony: final host eats the muscles of intermediate hosts containing cysts with bradyzoites. The cysts excyst in the intestine, and bradyzoites enter the intestinal epithelium to become macro- and microgametes. They form a zygote which becomes an oocyst. Oocyst sporulates and is shed in the feces.

Question 7

pathogenesis of sarcocystis

Answer 7

The intermediate host is mostly affected:

• Sporozoites invade intestinal epithelium, then spread via blood to various tissues 20-40 days after infection. Asexual reproduction in blood & internal organs leads to endothelial damage, haemorrhage and inflammation. Formation of cysts in muscle may cause myositis, stiffness or subclinical infection.
• Acute phase: fever, anorexia, anaemia, abortion.
• Acute lesions: edema, hemorrhages, necrosis

Dog:

• Bradyzoites are released and invade intestinal epithelium. Typically asymptomatic, but maybe mild enteritis in some cases.

Question 8

clinical signs of sarcocystis

Answer 8

IH:

• subacute or acute: cattle and pig if they ingest large amount of sporocysts - fever, apathy, anorexia, anaemia, decreased milk yield, weight loss, abortion.
• Chronic: asymptomatic or generalised myositis.

Question 9

diagnosis of sarcocystis

Answer 9

• FH: coprology by flotation (Faust)
• IH: detection of cyst in muscle (digestive method), serology

Question 10

treatment of sarcocystis

Answer 10

none

Question 11

control of sarcocystis

Answer 11

dont allow dogs to feed on raw meat