Parasitic Protozoa - Apicomplexa (38-39) Flashcards
What is the lifecycle of toxoplasma gondii?
facultative direct/indirect lifecycle
How is one infected with toxoplasma gondii?
ingestion of tissue cysts
2 sporocysts with 4 sporozoites
Who are the hosts for toxoplasma gondii?
cats (domestic and wild)
domestic livestock, birds, grazing wildlife, dogs, people
What is special about cats regarding toxoplasma gondii?
only hosts where sexual multiplication occurs in the small intestine
most are infected by ingestion of tissue cysts
How are domestic livestock, birds, grazing wildlife, dogs, and people infected with toxoplasma gondii?
asexual replication in CNS and edible tissues
What are the phases of clinical signs in cats?
intestinal phase - behaves like other coccidia
tissue phase (asexual replication)
What pathology is associated with the tissue phase i.e. asexual replication regarding toxoplasma gondii in cats?
respiratory disease - sneezing, light cough from intercellular replication of tachyzoites in lungs
lymphadenopathy - tachyzoites in lymph nodes, macrophages
A cat is sneezing with a light cough. Stool sample reveals these eggs (right) and tachyzoites (left). What is the causative agent? What phase is it in?
toxoplasma gondii
tissue phase aka asexual replication - respiratory disease
Findings like these were on necropsy of a domestic livestock animal. They were experiencing lymphadenopathy and abortion storms while alive. How were they infected?
ingestion of sporulated oocysts
2 sporocysts with 4 sporozoites
(this parasite is toxoplasma gondii)
All animals infected by toxoplasma gondii are infected by ______
ingestion of oocysts or tissue cysts
birds, rodents (predator-prey, scavenging)
What is the clinical disease presentation for toxoplasma gondii in canines?
suspect neurologic disease, lymphadenopathy, respiratory complaint, myositis
- congenital
- adult exposure
What is the clinical disease presentation for toxoplasma gondii in sheep and goats?
abortion storms frequent and economically significant in sheep and goat production
ewes at risk at first exposure then protected
goats may abort over multiple pregnancies
Regarding toxoplasma gondii, _______ are a source of tissue cysts for transmission to people
infected livestock
T/F: Toxoplasma gondii is zoonotic
TRUE - unequivocal zoonotic parasite
can cause congenital birth defects, or abortion to fetus when mother acquires primary infection during pregnancy
major cause of mortality for HIV and other immunocompromised persons
Who are the primary source of all infections by infectious oocysts passed in feces regarding toxoplasma gondii?
domestic and wild felidae
What disease is toxoplasma gondii opportunistic in especially?
HIV - caused by a reactivation of a chronic infection
direct correlation with pre-existing antibody titer
risk of toxoplasmic encephalitis decreased with introduction of primary prophylaxis against t. gondii
What is the name of the disease toxoplasma gondii causes in infants?
congenital toxoplasmosis
In what trimester is most at risk of abortion or serious congenital birth defects regarding toxoplasma gondii? What about in the other trimesters?
1st trimester
2nd and 3rd: mild retardation, blindness, etc
How does the baby acquire congenital toxoplasmosis?
foodborne illness in the mother - thought to be responsible for 2000 of the 9,500 infants born
How do you diagnose toxoplasma gondii?
fecal examination
serologic testing
PCR
specimens
What Igs are tested for toxoplasma gondii? When is there an infection with it for probably 1 year of longer?
IgM & IgG
+IgG and - or = IgM
T/F: When IgM is positive but IgG is negative, there is no serological evidence of toxoplasma infection
FALSE - you suspect an early (acute) infection with toxoplasma
testing 2-3 weeks later with a IgG positive test will confirm suspicion
If someone has positive [IgG/IgM]-specific toxoplasma antibodies, they are infected
IgG
T/F: Toxoplasma gondii can cause personality changes
TRUE
Does eating meat increase risk of toxoplasma infection?
maybe
T/F: Owning a cat increases your risk of toxoplasmosis infection
FALSE
What are recommendations for humans and toxoplasma gondii? pt 1
What are recommendations for humans and toxoplasma gondii? pt 2
T/F: Eating well-cooked meat reduces possibility of contracting toxoplasmosis
TRUE
What are some veterinary pharmacologic management for toxoplasma gondii?
arresting (suppressive) rapid proliferation of the tachyzoite stage
trimethoprim-sulfa and pyrimethamine
clindamycin
atovaquone
What is an important drug target of toxoplasma gondii? Why?
apicoplast
important for fatty-acid metabolism
important drug target
For toxoplasma gondii, ____ are the definitive host and ____ are the IH
cats - only definitive host where toxoplasma undergoes sexual reproduction
all endothermic vertebrates - IH
For toxoplasma gondii, all hosts (DH and IH) can be infected from ____ or ______
oocysts
or ingestion of tissue cysts
