Parasites ugh Flashcards
small parasitic ruminant abortion
toxoplasma gondii (neospora also possible, but less common)
cattle parasitic abortion
neospora caninum (toxoplasma and tritrichomonas)
pig parasitic abortion
toxoplasma gondii
horse and dog parasitic abortion
none!
what aspects of reproduction can parasites affect?
- puberty
- mating
- testicular function
- number of ovulation and conception
- pregnancy
how do animals become infected with toxoplasma gondii?
ingestion of oocysts shed in the feces of cats (usually young kittens)
pathogenic stage of toxoplasma gondii
tachyzoites
how does T. gondii cause abortion?
- pregnant sheep/goat ingests T. gondii oocysts
- oocysts become tachyzoites once ingested
- tachyzoites infect cross the placental barrier and infect the fetus
clinical importance of T. gondii infection in small ruminants
small ruminants infected during pregnancy remain infected for life BUT abortion only occurs with the first pregnancy, NOT subsequent/future pregnancies, so culling of the affected doe/ewe is not needed
is T. gondii transmissible between individual sheep/goats?
NO– intermediate hosts of T. gondii are NOT sources of infection for other animals
BUT if humans eat undercooked meat from an infected animal or other animals are exposed to infected placenta/aborted fetus they may be infected
outcomes of T. gondii infection based on stages of pregnancy
before 80 days: embryonic death and resorption or mummification
81-115 days: abortion, still birth, perinatal death
> 115 days: congenitally infected lambs/kids born healthy
diagnosing T. gondii
hx: may affect a few animals or cause abortion storm
lesions: multifocal white necrotic lesions in the cotyledons +/- fetal brain
immunohistochemistry of the fetal brain, muscle, brain
serology: 4x increase in titiers 2-4 weeks apart
PCR
controlling T. gondii
- keep stable population of adult cats and prevent fecal contamination of feed/water
- decoquinate/monesin prevents parasitic reproduction but does not kill
- proper disposal of aborted placenta/fetus
public health concerns of T. gondii
- people can become infected from handling placenta/fetus
- milk from animals with active infection may contain tachyzoites
- pregnant/ immunocompromised people should not handle these materials or congenitally infected lambs
how do animals become infected with neospora caninum?
Exogenous Transmission: cow ingests oocysts shed in canid feces, oocysts develop into tachyzoites
or
endogenous transmission: tachyzoites cross the placenta and infect the fetus
what 3 outcomes are possible with cows that become infected with N Neospora during pregnancy based on gestation period?
- birth of healthy, uninfected calf (first trimester)
- abortion of calf (second trimester)
- birth of the calf with latent infection that reactivates with pregnancy (third trimester)
epidemic vs endemic pattern of neospora infection
epidemic: more than 10% of pregnany cows abort in a 6-8 week period, likely exogenous transmission from contaminated feed/water
endemic: 10% abortion rate in a herd, caused by endogenous transmission when infected cows give birth to infected calves that enter the herd
clinical importance of neospora infection in cattle
if a cow aborts the first pregnancy once infected, they have a high risk of further abortion -> so infected cows should be culled
diagnosing neospora
- histology of fresh fetus or placenta
- PCR (fetal brain, heart, muscel, liver, lung – check which sample the individual lab wants)
- serology of the dam
treating neospora
no tx available - cull affected animals
controlling neospora
- limit puppies on the property (more likely to shed)
- try to protect water and feed from wild canids (foxes, coyotes, wolves)
- proper disposal of aborted fetuses and placenta
where in the body does tritrichomonas foetus live?
extracellularly on the mucosa of the reproductive tract
cows: entire tract, vulva to uterus
bulls: epithelial lining of the penis, prepuce, and distal urethra
how is tritrichomonas spread?
only venereal transmission ( does not live in the bloodstream or intestines so cannot be spread any other way) bull to cow or cow to bull, but can also occur through AI (less common)
diagnosing tritrichomonas
- difficult as it only lives in the repro tract so need a preputial scraping from bulls or reproductive secretions from cows
- PCR
- Culture
(NO serology because it does not live in the bloodstream)
