Sarcocystis

Question 1

Sarcocystis

Answer 1

• Apiocomplexan
• ubiqitous in nature
• hosts include herbivours and humans/ other primates (sometimes birds, reptiles, and fish can be hosts)

Question 2

Describe the 2 hosts in the sarcocyst lifecycle?

Answer 2

Intermediate host: muscles become infected with cycsts containing infecious zoites (non-human hosts)

Definitive host: they ingest the cysts and become infected with intestinal stage and excrete oocysts/ sporocysts into the enviroment (humans/ primates)

Question 3

Describe the morphology of sarcocysts.

Answer 3

Asexual phase: seen in intermediate hosts, trophozoites in muscle tissue cyst; cysts are large enolgated ovals, that has components (trabeculae) filled with merozoites and has a complex wall

Sexual phase: sporozoites in the sporocysts which then turn to oocysts in the intestinal lumen of the definitive host

Question 4

Describe the lifecycle of Sporocysts.

Answer 4

1. Sporocysts and thin-walled oocysts are passed in the feces
2. Sexual Cycle occurs in definitive host where…
   a) brodyzoites are released from the ruptured cyst and enter intestinal wall
   b) gametes are formed (microgametocyte and macrogametocyte) which fertalize and make a immature oocyst which exists host to repeat cycle
3. Asexual cycle occurs in intermediate host when…
   a) sporocysts are ingested by cows/ pigs
   b) sporocysts rupture and release sporozoites that enter the endothelial cells of blood vessels and undergo schizogany
   c) schizonts rupture and release merozoites which penetrate muscle cells and develop into cysts with bradyzoites which can be ingested in undercooked meat,repeating the cycle

Question 5

Describe the pathogenesis of Sporocystis.

Answer 5

• Gut proliferation stages have little to no reaction unless there is a large infective dose
• Muscle cysts have no inflammation when intact, tissue damage occurs when cysts disintegrate (muscle inflammation, necrosis, and vasculitis)

Question 6

How long do humans shed oocysts for?

Answer 6

10 days-6 months

Question 7

What are the symptoms for sporocystsis?

Answer 7

Muscle invasion: occurs weeks to months after exposure and has painful swellings with fever (sometimes a rash and difficulty breathing)

Intestinal invasion: occurs 3-6 hours after exposure. From eating encysted beef, mild nausea, diarrhea, and stomach discomfort. From eating encysted pork, acute diarrhea, vomiting, stomach ache, and cramps

Question 8

How is sporocystis diagnosed?

Answer 8

Microscopy of cysts in feces and muscle biopsy

Question 9

Hoe do you prevent sporocystis?

Answer 9

Freeze meat at -20 degrees celcius for 1 day and cook until the colour changes