Zoonoses from Carnivores Flashcards
What type of parasite is Toxoplasma gondii?
apicomplexan protozoan parasite.
When are cats usually infected with T. gondii? How long do they shed for?
Usually infected early in life, and excrete the oocysts for 1-3 weeks.
Which immature stage of T. gondii replicates fast? Which replicates slow?
Fast = tachyzoites. Slow: bradyzoites.
What behavioral change are you likely to see in mice infected with T. gondii?
They lose their fear of cats.
How do humans become exposed to T. gondii?
by coming in contact with oocysts in soil, or by ingesting tissue with bradyzoites (undercooked meat for example)
How long do oocysts remain stable in the environment?
18 days.
How can you render tissue cysts noninfectious?
freezing for >7 days, or by cooking.
Most human infections of T. gondii in the states come from what?
cumulative lifetime exposure to undercooked meat – NOT soil exposure.
What does T. gondii cause in early pregnancy? What about in late pregnancy?
early - abortion/stillbirth. Late - baby born w/ toxoplasmosis. Will see hydroencephalis, blindness, etc.
Does it matter when mom is infected with T. gondii while pregnant?
YES. The earlier she is infected, the more severe the symptoms for the baby when born.
If a pregnant woman was infected with T. gondii prior to being pregnant, and becomes reinfected while pregnant, is this a problem?
No. Only a problem when infected for the first time when pregnant.
How can a pregnant woman prevent exposure to T. gondii if she has a cat?
Clean the box every single day.
What are some common roundworms of pet animals?
T. canis, T. cati, T. vitulorum
What disease is considered a “neglected tropical disease”?
Human toxacariasis.
Who is most at risk for human toxocariasis?
Children between the ages of 1-4 years, due to pica and geophagia (kids are gross, basically).
What percentage of raccoons have Baylisascaris procyonis? Why is this of concern?
70-90% have it. Concerning because they shed a lot when they have it and it is very zoonotic (dogs can be definitive hosts or intermediate hosts).
What is the most common form of larval migrans of Baylisascaris?
ocular or neurologic.
For what cestodes do humans serve as the definitive host?
T. saginata and T. solium, Diphyllobothrium, Dipylidium caninum (rare).
For what cestodes are humans an intermediate host?
Echinococcus granulosus and multilocularis, T. solium, and a few others that are rare.
What are the symptoms usually like when a human is the intermediate host for a cestode infection?
symptoms are caused by the cyst, and clinical signs depend on where the cyst is (liver, lungs, brain, etc.). Can get anaphylactic symptoms if the cyst ruptures.
What is the difference between hydatid cyst disease and alveolar cyst disease?
Hydatid cyst disease is caused by E. granulosus, and it is individual, large, fluid filled cysts in multiple tissues. Alveolar disease is made of multilocular small, and solid cysts.
Who is the reservoir for all echinococcus species?
canids.
How do humans get Echinococcus granulosus?
by ingesting the eggs, NOT MEAT.
Cystic echinococcosis is associated with what industry in the US?
The sheep industry.
Why is alveolar echinococcosis very destructive and often fatal?
because the cysts aren’t encapsulated and are very infiltrative, so they are often not operable once diagnosed.
