Toxoplasma Flashcards
What is special about Toxoplasma and felines?
Toxoplasma can only undergo sexual reproduction in felines (only asexual in every other species)
Prevalence of Toxoplasma?
high, it’s everywhere, infects ~1/3 of human population and also present in dogs, cats, pigs, sheep, and more
Toxoplasma is a leading cause of abortion in what two species?
sheep and goats
Toxoplasma gondii sources of infection
cat feces, contaminated water/veggies, raw or undercooked meat
How do cats pick up toxo?
hunting birds and rodents (ingesting sporulated cysts)
Where in the cat does toxo undergo sexual reproduction?
enterocytes
Asexual Reproduction of Toxoplasma
oocysts rupture, transform into tachyzoites, these multiply in ANY nucleated cell in the body, will encyst to avoid the immune system and these cysts can be found in CNS, muscles, and visceral tissue
Why is the cat the best host for Toxoplasma gondii?
cats have a lot of linoleic acid (a fatty acid) because, surprise surprise, they lack the enzyme required to break it down
Three Forms of Toxoplasma
- Oocyst
- Tachyzoites
- Bradyzoites/Cysts
Which form of toxoplasma is infectious?
trick question, they all are
only non infectious when it’s a non-sporulated oocyst in the environment
endodyogeny
a form of asexual reproduction, forms two daughter cells within the mother cell
“toxo”
bow
apicoblast
a plant-like organelle which makes a good drug target
Are bradyzoites indicative of acute or chronic infection?
chronic
What species are asymptomatic when infected with Toxoplasma?
horses, cattle, chicken (and most cats) (and some humans)
Can cats transmit toxo transplacentally?
RARELY
Ocular Toxoplasma
result of congenital infection
severe retinochorditis and can get keratic precipitates in the cornea
Effect of Toxoplasma gondii on sheep
ABORTION, with twins one will be normal and the other is mummified; small areas of focal necrosis on the placenta (specifically the cotyledons)
With humans, who is most at risk from Toxoplasma?
pregnant women, AIDS patients, chemotherapy patients
Can toxoplasma alter behavior?
yes - schizophrenia, some psychotic symptoms
mice aren’t afraid of cats
Direct Toxo Detection Methods
look at blood, body fluids, tissue
Indirect Toxo Detection Methods
ELISA, IFA, Sabin-Feldman
Sabin-Feldman Test
tachyzoites react with complement factor and methylene blue
Is there a vaccine for Toxo?
for sheep! but not here in the US
Main treatment for toxo?
clindamycin (and SDDS); no way to kill the tissue cysts though
