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Parasitology #2 > protozoa-cattle and sheep > Flashcards

protozoa-cattle and sheep Flashcards

1
Q

Giardia

A

-high prevalence in cattle, mostly dairy
-worldwide distribution, mainly young

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2
Q

Impact of Giardia spp

A

-clinical disease is uncommon, but can cause acute, intermittent or chronic diarrhea

-reduced gain, feed efficiency, and carcass weight

**may be further influenced by concomitant infections

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3
Q

Diagnosis of Giardia

A

Daily fecal samples (3 days)
1. Zinc sulphate flotation
2. direct saline smear
3. Coproantigen/PCR

**Remember trophozoites are fragile

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4
Q

Management of giardia

A

-Fenbendazole

-Address contaminated environment/water
*chlorination not usually effective, usually need ozonation/filtration

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5
Q

Giardia species

A
  1. G. duodenalis (A)
    *humans, livestock, cats, dogs,
  2. G. duodenalis (E)= G. bovis
    *cattle and hoofed livestock
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6
Q

Subclassifications of G. duodenalis (A)

A

A-I= humans and animals

A-II= humans

A-III and A-IV = animals only
**not all species of giardia are zoonotic

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7
Q

Tritrichomonas sp

A

-No free living or cyst stage therefore need direct transmission

-cattle and cat strains differ genetically

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8
Q

Tritrichomonas blagburni

A

-Cats
-causes intestinal, chronic diarrhea, flatulence, tenesmus, fecal incontinence

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9
Q

Tritrichomonas foetus

A

-cattle

-causes venereal, pyometra, embryonic death, late-term abortions

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10
Q

Transmission of Tritrichomonas foetus

A

Live in genital mucosa, and transmitted sexually (both natural and artificial insemination)

Bulls- asymptomatic carriers; infected for life in the crypts of the prepuce (even deeper in older bulls)

Infected cows- return to estrus after early embryonic death. Pyometras decreases pregnancy rates
*most clear infections and cycle again but some may remain carriers
*re infection possible

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11
Q

Diagnosis of Tritrichomonas foetus

A
  1. will see decreased pregnancy rates and increased open cows in newly infected herds
  2. can look at cows cervical mucous and uterine fluids for parasite or DNA
  3. Can look at stomach fluid of abortus
  4. Can examine bulls (preputial scrapings/washes, and repeated sampling (3x at weekly intervals)
    *no chilling or freezing
  5. Direct observation, culture, PCR
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12
Q

PCR for giardia

A

Higher sensitivity than cultures

Higher specificity (differentiates from other trichomonads, rumen contaminants and free living organisms)

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13
Q

Control of Tritrichomonas in cattle

A
  1. no effect treatment or vaccine
  2. Test and cull bulls
    -use only young bulls on pastures or AI from clean bulls
  3. Do not breed cows for 3 months after infection
  4. Quarantine new animals
  5. Report to provincial chief vet if suspected or confirmed cases… CFIA reportable
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14
Q

Apicomplexa

A

-mostly intracellular parasites
-ubiquitous and host specific
-can have direct life cycles in intestines OR tissue cyst forming indirect life cycles

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15
Q

Intestinal direct life cycle apicomplexa

A
  • Eimeria= coccidiosis = cattle and sheep have own species
  • Cryptosporidium
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16
Q

Tissue cyst forming indirect life cycle apicomplexa

A

-sarcocysts

-neospora (cattle)

-toxoplasma (sheep)

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17
Q

Eimeria- Coccidia

A

-obligate intracellular parasites
-parasitize gut epithelium
-worldwide distribution/high prevalence
-complex life cycles
-infective stage= sporulated oocyst (resistant to cleaning)

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18
Q

Coccidiosis risk factors

A

-stocking density
-poor hygiene
-stress
-history of coccidiosis

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19
Q

Relevance of coccidiosis

A

-high cost to livestock industry
-clinical disease most often with intensive production systems and subclinical disease impacts production

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20
Q

Eimeria life cycle

A
  1. Cattle: merogony (unique multiple fission, resulting in merozoites that when host cells rupture, are released for further infection; repeats 2-5x) and gametogony in enterocytes
    PPP:2-3wks
  2. unsporulated oocysts released into environment
  3. Sporulate in environment
  4. Sporulated oocysts (8 sporozoites in 4 sporocysts) ingested by host. Sporozoites exit and infect epithelial cells of intestine
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21
Q

How are sporozoites of eimeria contained in the cytoplasm?

A

Parasitophorous vacuole

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22
Q

Bovine coccidiosis and severity

A

Multiple species cause this in cattle but they have different disease potential
*most severe to least= E. bovis, E. zuernii, E. alabamensis, E. auburnesis , E. ellipsoidalis

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23
Q

Disease of bovine coccidiosis

A

*host specific

-can occur indoors (common!), yards, or pasture
-common in calves (2-12 mths of age); older cattle rare but are a source of infection

-acute or chronic diarrhea or sub clinical impacts such as growth
-high oocyst numbers can present without clinical signs, and clinical signs may present without oocysts in feces

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24
Q

Clinical coccidiosis

A

-diarrhea (may be bloody)
-anorexia
-abdominal pain

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25
Q

Coccidiosis signs at necropsy

A

-intestinal mucosa thickened and congested
-hemorrhage often present
-mucosal sloughing in extreme cases
-Hypertrophic jejunum!

26
Q

Acute coccidiosis

A

-obvious
-young animals 2-6mths, typically in summer in young but anytime
-infected from dams, triggered by stress
-high morbidity, low mortality

-“winter coccidiosis”

27
Q

Signs of acute coccidiosis

A

-abdominal pain
-diarrhea, dysentery
-tenesmus
-dehydration
-weakness
-inappetence

28
Q

Chronic coccidiosis

A

-diagnostic challenge
-chronic diarrhea
-results in reduced growth rates and delayed puberty/fertility

29
Q

Nervous coccidiosis

A

-muscle tremours
-hyperesthesia
-convulsions with ventroflexion of head and neck
-nystagmus
-high mortality

*increasing in occurrence in North USA and Canada

30
Q

Diagnosis of Eimeria

A
  1. clinical signs
  2. oocysts in feces
    -based on sporulated oocysts features
    -flotation technique
31
Q

Prevention of coccidiosis

A

-impossible to be Eimeria free so aim to minimize build up of sporulated oocysts in environment and all gradual acquisition of immunity to reduce disease risk

-oocysts survive long periods, over winter and are spread in feed, water, coats, fomites

-Hygiene and avoid overcrowding
>clean water tanks, feeders, bedding
>10% bleach for at least 2 hrs

32
Q

Monitoring coccidiosis

A

-fecal oocyst count testing allows risk assessment
-10 animals
-provide evidence base for intervention strategies including chemotherapy

33
Q

Therapeutic chemotherapy for coccidiosis

A

-sulfonamides/ inophores in feed, water or oral doses
-provide during period of risk
-treat all exposed calves and lambs
-Toltrazuril, ponazuril (coccidiocidal)

34
Q

Cryptosporidium

A

-worldwide distribution
-zoonotic
-infections can be subclinical or cause diarrhea
-morphology and life cycle similar to coccidia (intracellular) BUT

  1. infects microvilli brush border
  2. Oocysts are immediately infective and very resistant to environmental conditions (sporogony happens inside the host)
35
Q

Transmission of cryptosporidiosis in humans

A

From ingestion or contaminated water and food

or direct contact with animals (vets)

36
Q

What does Cryptosporidiosis commonly infect

A

**linked with neonatal diarrhea! 100% prevalence

c. parvum= calves as early as 2 days old

C. andersoni= post-weaned calves, adults

37
Q

Transmission of cryptosporidiosis in cattle

A

-acquired through ingestion of contaminated feed, water, grooming

-auto infection is possible, can be serious in immunocompromised individuals

38
Q

infectious dose of Cryptosporidiosis

A

Low infectious dose (1 oocyst)

39
Q

Malabsorptive diarrhea or cryptosporidiosis

A

-yellow, pasty and profuse
-usually self limiting but can have high mortality in naive herds
-epithelial ell damage affects nutrient absorption and fluid transport in gut

40
Q

Depression, anorexia, and abdominal pain in cryptosporidiosis

A

Linked with C. andersoni
-gastroenteritis, production losses (reduced milk production), present in about 10% of adult cattle abomasal glands

41
Q

Diagnosis of cryptosporidium

A

-detection of oocysts in feces
(multiple samples over 2-3 days intervals)
>centrifugal flotation, fecal smears (acid fast), immunofluorescent staining (TEST OF CHOICE), molecular analysis for species ID

42
Q

Treatment, sanitation, and care for cryptosporidium

A

-steam clean, disinfect (remember resistant to chlorine)

-supportive care (hydration, ensure colostrum)

43
Q

Sarcocystis life cycle

A
  1. Gametogony and sporogony in carnivore DH 1week
  2. Release of sporulated oocysts (sporocysts with 4 sporozoites)
  3. infect immediately
  4. Merogony in vascular endothelium of IH resulting in sarcocysts with bradyzoites
  5. DH ingests sarcocysts in IH muscle
44
Q

Transmission of sarcocystis

A

-prevent animals from ingesting raw meat
-fecal contamination of cattle feedstuffs

45
Q

Acute sarcocystis

A

*Dalmeny disease

-caused by merogony in vascular endothelium
-fever, emaciation, anemia, abortion, rarely CNS signs
-high morbidity and mortality

46
Q

Chronic sarcocystis

A

-post mortem diagnosis, incidental finding
-greenish focal stripes in skeletal muscles
-breakdown of sarcocysts inducing immune response

47
Q

Diagnosis of sarcocystis

A
  1. post mortem (incidental finding)
  2. abortus: histology and IHC, PCR
48
Q

Control of sarcocystis

A

-prevent dog from eating abortuses, dead stock, raw meat
-keep feed away from wild and domestic canids and felids
-no treatment
-no need to cull aborting cows

**stops after first infection??

49
Q

Neospora caninum

A

**most important cause of bovine abortion in Canadian Cattle

50
Q

Neospora caninum lifecycle

A
  1. Merogony and gametogony in DH
    2.Release unsporulated oocysts into environment
    3.Sporogony in environment
  2. Cattle IH ingests sporulated oocysts
  3. Tissue cysts with bradyzoites in IH, Tachyzoites in abortus and congenitally infected calfs
51
Q

Outcomes of Neospora infection during pregnancy

A

Early preg: fetal death and resorption

Mid preg: Abortion (typical), infected neurological calf (underweight, unable to stand, flexed or hyper extended limbs, lack of coordination, decreased reflexes and sensory perception)

Late preg: infected but clinically normal and might infect their own offspring OR rare uninfected calf

52
Q

Outcomes of Neospora infection for subsequent pregnancies

A
  1. Endemic abortion (endogenous)= recrudescence of chronic infection
  2. Epidemic abortion (exogenous)= acute infection following ingestion of sporulated oocysts= ABORTION STORMS
53
Q

Diagnosis of Neospora

A
  • Clinical and epidemiological
  • Serology: ELISA titres in aborting x non aborting cows
    -Abortus: CNS/muscle histology and IHC, PCR
54
Q

Control of Neospora

A

-prevent dogs from eating abortuses, dead cattle, raw meat

-keep cattle feed and water from wild canids and dogs

-do not breed seropositive cattle (Cull)

55
Q

Toxoplasma gondii

A

-relevant in sheep and goats
-leads to abortion storm in naive animals

56
Q

Outcomes of toxoplasma gondii

A

*depends on time of infection

  1. Early: fetal death and resorption
  2. Mid: abortion or stillborn
  3. Late: weak or normal lambs
57
Q

Toxoplasma tissue cysts

A

common in sheep, goats, pigs

less common in cattle, horses, poultry

58
Q

Toxoplasma lifecycle

A
  1. Cat DH (merogony, gametogony) releases unsporulated oocysts into environment
  2. sporulation in environment (8 sporozoites in 2 sporocysts)
  3. Ingestion of sporulated oocysts by IHs resulting in tachyzoites and tissue cyst bradyzoites
  4. DH (humans and cats) ingest tissue cysts with bradyzoites
59
Q

Diagnosis of toxoplasma

A

-serology, IgG (chronic) and IgM (acute)

-gross pathology (necrosis in cotyledons)

-histology (multifocal necrosis on placentomes and fetal organs)

-microscopy (tachyzoites in brain and placenta)

-isolation from blood of body fluids

-histology/immunohistochemistry

-PCR

60
Q

Control of toxoplasma gondii

A

-note regional variation in seroprevalence in sheep (20-100%)

-prevent access of cats to sheep in feed

-vaccines have been developed but not widespread commercial use (live attenuated strain passaged repeatedly in mice that does not cause tissue cyst administered to sheep to prevent abortion)

-Prevent zoonotic transmission (careful when handling aborted or stillborn fetuses; cook lamb to 70 C or freeze -20C for 3 days)

Parasitology #2 (12 decks)

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