15. Cattle Protozoa Flashcards
What is the transmission and pathogenesis of tritrichomonas foetus?
parasite lives in genital mucosa
Sexually transmitted - mostly natural service (pastured animals, but survives artificial insemination)
In Bulls: asymp carriers and infected for life - lives in crypsts of prepuce epithelium (therefore culled pos)
infected cows: early embryonic death In first few months of gestation
most clear infections nd cycle again; some may stay infected as carried
re-infection is possible
How do we diagnos T. foetus in cattle/
InPouch Tf test, culture and PCR or direct PCR - higher sensitivity that culture alone. Higher specific: differentiates from other trichomonads, rumen contaminants and free living organisms
Epidemiological clues: 50-60% open cows in newly infected herds
Graully lengthening of calving interval (age spread of calves)
abortus: organism can be observed in stomach fluid
Bulls: preputial scrapings or washes
Repeated sampling (1 test/3 wks)
How do we control T. foetus in cattle?
test and quarantine new anims to herd - make sure cows successfully calved last season
test and cull bulls (no tx once infected)
use only young bulls (<4yrs) on pastures, or use AI from reliable sources
Cows: do not breed for at least 3 mo, or cull (carriers)
No effective tx or vx
annually notifiable to OIE, provincially notifiable in AB
What are the flagellates of cattle?
giardia
What is giardia in calves?
30% prevalence in calves
often asymp, can cause acute, intermittent or chronic diarrhea
dx - daily fecal samples over 3 days
direct smear, zinc sulphate floatation, fecal Ag/PCR
Mgmt: fenbendazole (10-20mg/kg per os for 3 f)
address contaminated enviro
What is the common apicomplexa protozoa of cattle?
intestinal, direct life cycle: eimeria spp - coccidiosis, cryptosporidium
Tissue cyst forming, indirect life cycle: sarcocystis, neospora
What is the life cycle of eimeria?
PPP: 2-3wks
Unsporulated oocysts in feces > sporulate in enviro > spurlated oocysts w/ 8 sporozoites in 4 sporocysts > ingested by cattle > Merogony and gametogony in enterocytes
What does an infection of emeria called in cattle?
coccidiosis
12 speces found in cattle
infection more common than dz
What are the 2 significant spp of emieria?
eimeria zuernii
E. bovis
What are the two clinical syndromes of emeria
ordinary, winter/nervous
What is ordinary coccidiousis?
probably infected from cows, who excrete oocysts around calving
yg anims (2-6mos), any time of year
Most common when other stressors are present - crowding, weaning, etc
severity linked to intensity (Can be really high numbers of oocysts)
clinical signs include diarrhea +/- blood, tenesmus, dehydration, weakness, loss of appetite and condition
High morbidity, low mortality
reasonably good immunity develops
What is winter/nervous coccidiosis?
associated w/ stretch of extreme cold weather or cold snap - often other stressors like weaning, shift from pasture to feedlot, transport, crowding
often no oocysts in feces
clinical signs as per ordinary, but more severe
nervous signs (ex. muscle tremors, hyperesthesia, convulsions w/ ventroflexion of head/neck, nystagmus) associated w/ high mortality rate (80-90%)
How is coccidiosis dx and controlled?
dx: clinical appearance, # of oocysts (size and shape for species) on fecal float
Control: spread via fecal contamination of feed, water, coats, fomites
isolate calves w/ diarrhea
tx: all exposed calves, ASAP w/ toltrazuril, ponazueril (coccidiocidal)
support therapy
prevent w/ ionophores in feed
What si the life cycle of cryptosporidium?
PPP: 4-6 days
Shed for 1-2 wks
Oocystes immediately infecting when leave host
Sporozoite >trophozoite > 1st gen meronts > merozoite >2nd gen meronts > Merozoite> Macrogametocyte > micrygametocyte > unsporulated oocysts > sporulated oocyst> exit from body/ingested or autoinfection
What is the pathogenesis of cryptosporidium?
calves <3mo old most commonly infected
important cause of neonatal diarrhea - millions of oocyst/g of feces
oocysts immediately infective, highly resistant and viable for mo in winter
malabsorptive diarrhea, yellow pasty and produce
+/- anorexia, dehydration, acidosis, fever, depression, can be fatal
Concurrent infections common - toavirus, coronavirus, e. coli
