Parasite Life Cycles

Question 1

What is this life cycle?

Answer 1

Toxoplasma gondii - Unsporulated oocysts are shed in the cat’s feces
Oocysts: Usually only shed for 1-2 weeks, large numbers may be shed (>100,000/g
Take 1-5 days to sporulate in the environment and become infective.
Intermediate hosts in nature (including birds and rodents) become infected after ingesting soil, water or plant material contaminated with oocysts (2).
Oocysts transform into tachyzoites shortly after ingestion
Localize in neural and muscle tissue and develop into tissue cyst bradyzoites (3).
Cats become infected after consuming intermediate hosts harboring tissue cysts (4).
May also become infected directly by ingestion of sporulated oocysts.
Animals bred for human consumption and wild game may also become infected with tissue cysts after ingestion of sporulated oocysts in the environment (5).

Humans can become infected by any of several routes:
Eating undercooked meat of animals harboring tissue cysts (6)
Consuming food or water contam with cat feces or by contaminated environmental samples (such as fecal-contaminated soil or changing the litter box of a pet cat) (7)
Blood transfusion or organ transplantation (8)
Transplacentally from mother to fetus (9)

Question 2

What is this life cycle? Name the vector

Answer 2

Leishmaniasis
Lutzomyia sandfly - Old World
Phlebotomus sandfly - New World

Question 3

What is the infective stage?

Answer 3

metacyclic trypomastigotes

Question 4

What is the infective stage? Where does T. brucei gambiense vs. T. brucei rhodesiense occur?

Answer 4

metacyclic trypomastigotes
WAG/EAR - Western African Trypanosomiasis (T. brucei gambiense), Eastern African Trypanosomiasis (T. brucei rhodesiense)