Parasites ugh

Question 1

small parasitic ruminant abortion

Answer 1

toxoplasma gondii (neospora also possible, but less common)

Question 2

cattle parasitic abortion

Answer 2

neospora caninum (toxoplasma and tritrichomonas)

Question 3

pig parasitic abortion

Answer 3

toxoplasma gondii

Question 4

horse and dog parasitic abortion

Answer 4

none!

Question 5

what aspects of reproduction can parasites affect?

Answer 5

• puberty
• mating
• testicular function
• number of ovulation and conception
• pregnancy

Question 6

how do animals become infected with toxoplasma gondii?

Answer 6

ingestion of oocysts shed in the feces of cats (usually young kittens)

Question 7

pathogenic stage of toxoplasma gondii

Answer 7

tachyzoites

Question 8

how does T. gondii cause abortion?

Answer 8

1. pregnant sheep/goat ingests T. gondii oocysts
2. oocysts become tachyzoites once ingested
3. tachyzoites infect cross the placental barrier and infect the fetus

Question 9

clinical importance of T. gondii infection in small ruminants

Answer 9

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

Question 10

is T. gondii transmissible between individual sheep/goats?

Answer 10

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

Question 11

outcomes of T. gondii infection based on stages of pregnancy

Answer 11

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

Question 12

diagnosing T. gondii

Answer 12

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

Question 13

controlling T. gondii

Answer 13

• 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

Question 14

public health concerns of T. gondii

Answer 14

• 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

Question 15

how do animals become infected with neospora caninum?

Answer 15

Exogenous Transmission: cow ingests oocysts shed in canid feces, oocysts develop into tachyzoites

or

endogenous transmission: tachyzoites cross the placenta and infect the fetus

Question 16

what 3 outcomes are possible with cows that become infected with N Neospora during pregnancy based on gestation period?

Answer 16

1. birth of healthy, uninfected calf (first trimester)
2. abortion of calf (second trimester)
3. birth of the calf with latent infection that reactivates with pregnancy (third trimester)

Question 17

epidemic vs endemic pattern of neospora infection

Answer 17

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

Question 18

clinical importance of neospora infection in cattle

Answer 18

if a cow aborts the first pregnancy once infected, they have a high risk of further abortion -> so infected cows should be culled

Question 19

diagnosing neospora

Answer 19

• histology of fresh fetus or placenta
• PCR (fetal brain, heart, muscel, liver, lung – check which sample the individual lab wants)
• serology of the dam

Question 20

treating neospora

Answer 20

no tx available - cull affected animals

Question 21

controlling neospora

Answer 21

• 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

Question 22

where in the body does tritrichomonas foetus live?

Answer 22

extracellularly on the mucosa of the reproductive tract

cows: entire tract, vulva to uterus

bulls: epithelial lining of the penis, prepuce, and distal urethra

Question 23

how is tritrichomonas spread?

Answer 23

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)

Question 24

diagnosing tritrichomonas

Answer 24

• 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)

Question 25

controlling tritrichomonas

Answer 25

• infected bulls should be culled
• infected cows should be rested from breeding for at least 90 days
• reduce breeding season 120 days