Sarcocystis spp. (1) Flashcards
What are the final hosts?
Dogs
Cats
Humans
Other carnivores
Birds
What are the intermediate hosts?
Cattle
Herbivores
Omnivores
Birds
How do you identify?
Sporulated Oocysts contain 2 Sporocysts each with 4 sporozoites
- 18 micro m
Sporocysts Sporulate inside the intestine
Individual Sporocysts often observed
Muscle tissue of intermediate hosts, bradyzoites observed
Explain the life cycle
Include Gametogony in final host
Schizogony and sarcocyst formation in IH
Final host (Gametogony)
- By ingestion of mature Sarcocysts with bradyzoites
- Bradyzoites liberated in intestine
- Freed zoites pass to the subepithelial Lamina propria
- Differentiate into micro- and macrogametocytes
- Conjugation and fertilization of gametes take place forming thin-
walled Oocysts
- Sporulate within body
- Fragile oocyst wall ruptures
- Free Sporocysts found in feces
- Oocysts or free Sporocysts are immediately infectious upon
discharge from final host
Intermediate Host (schizogony)
- By ingestion of Sporocysts from infected final host
- Followed by 3 asexual generations (at least)
- Sporozoites released from Sporocysts
- Invade intestinal wall
- Enter capillaries
- Locate in endothelial cells
- 2 schizogonous cycles
- 3rd asexual cycle occurs in circulating lymphocytes
- Merozoites penetrating muscle cells
- Encyst and divide by budding/endodyogeny
- Broad banana shaped bradyzoites contained within
cyst - Mature sarcocyst (Infective)
PPP in carnivores: 7-14 days
Patent Period (period during which Sporocysts are passed in feces by carnivores: 1 week - several months
From ingestion of Sporocysts to presence of infective bradyzoites in muscles of intermediate hosts is usually 2-3 months but may extend to 12 months
Complete life cycle: 2 1/2 - 6 months
What are the sites of infection?
Muscles in IH
Oocysts or Sporocysts in gastrointestinal tract of FH
Describe the Pathogenesis
No illness in FH
Schizogony in endothelium of herbivore may result in serious or fatal disease
Cattle - Clinical signs (release of 2nd wave of Merozoites about 4-6
weeks after infection)
- Protracted Fever
- Anemia
- Lymphadenopathy
- Anorexia
- Diarrhea
- Hypersalivation
- Weakness
- Hair loss about the eye, neck and tail switch
- Last trimester of pregnancy may abort
How do you diagnose?
Sporocysts or Oocysts in FH
Bradyzoites in muscle tissue of IH
How do you treat and prevent?
Cycle of infection can be interrupted either by cooking meat
Preventing fecal contamination from FH
What is important about Sarcocystis spp.?
It’s ZOONOTIC (several species)
