Coccidia and other Protozoa of Food Animals

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Coccidia and other Protozoa of Food Animals
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Coccidia or Ruminants
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Common coccidian oocysts of cattle.
E bovis 28 x 20u
E zuernii 18 x 15 u

• Coccidiosis Eimeria in ruminants, poultry
  Isospora in dog, cat, pig
• Species specific
• Self limiting
• Contagious, especially crowding, moist
  transmission foci (water holes, leaky troughs)
• Non-immune, young animals Multipier effect at
  exposure

Only E bovis, E zuernii are definite pathogens in
cattle
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Coccidian Life Cycle
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Eimeria oocyst
Eimeria has four sporocysts with two
sporozoites Isospora has two sporocysts with four
sporozoites
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Eimeria bovis has characteristic, 1st generation
giant schizonts in small intestine
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Gross pathology giant schizonts of E. bovis
are grossly visible
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The major pathogenesis of both Eimeria bovis and
E zuernii is due to the sexual stages that occur
deep in the mucosa of the caecum, large intestine
and rectum
Developing Oocyst
Oocyst
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Feedlot Clinical coccidiosis is a major problem
in the dairy and feedlot industries
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E. bovis - clinical signs in young dairy heifer
Bloody, mucoid diarrhea is often seen 1-3 days
before 1st oocysts are shed. Prepatent period
16-17 days, peak oocyst production at 3 weeks.
Patent period is 2-3 weeks, then self limits.
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Clinical Signs

• Bloody, mucoid diarrhea /- epithelial mucosal
  tags, dehydration, depression, tenesmus,
  occasional rectal prolapse
• Seasonality Disease most common in fall, least
  summer a highly pathogenic form of the disease
  winter coccidiosis of unclear epidemiology
  occurs, especially in feedlots above the 40th
  parallel
• Acute death by 5-7 days Others develop
  secondary enteritis, pneumonia, a few linger in
  poor condition and are culled
• Nervous coccidiosis Seen in a variable of
  animals in outbreaks - high mortality, diarrhea,
  tremors, convulsions, nystagmus, blind,
  aggressiveness. Seen especially with some strains
  of E zuernii

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Diagnosis
Gross pathology findings in colon and rectum.
Evidence of hemorrhagic enteritis with frank
blood, mucous
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Fresh mucosal impression smear with coccidian
developmental stages. Necropsy touch preparations
or rectal scrapings can be used to diagnose
prepatent infections
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Treatment
Drug Dosage
Class Amprolium
Pv 5 mg/kg for 21 days
Thiamine Rx
10 mg/kg for 5 days antagonist Decoquinate
Pv 0.5 mg/kg for 28 days
Quarternary Ammonium
Sulfaquinoxaline Rx 8-70 mg/kg per day
Sulfonamide Monensin Pv
3 mg/kg/day Ionophore
antibiotic Lasalocid Pv 3
mg/kg/day Ionophore
antibiotic
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Control

• Treat to prevent incubating new cases and reduce
  oocyst shedding multiplier effect clinical
  signs are seen after damage is done
• Treat until infections self-limit and/or immunity
  builds
• Oocysts live 1 year at 4o C, resist mild
  freezes sunlight and dry heat kills oocysts in 4
  hours
• Provide clean dry conditions, reduce stress,
  crowding (eg. portable calf sheds, fix leaks)
  
• Do not feed off ground or follow probable heavy
  contamination

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Coccidia of sheep and goats

• Most transmission in spring at lambing
• 2-8 week-old lambs in confinement, 2-3 weeks post
  weaning or stress (eg. shipping, change of feed)
• Heavily stocked irrigated pastures, contaminated
  wet areas, feedlot
• Sheep and goats tend to have watery diarrhea,
  seldom bloody
• Diagnosis Several thousand oocysts/gm most shed
  high oocyst background

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Coccidia of sheep and goats
Species Prepatent period
Clinical Effects E. ahsata Sh
18-21 days Sh , G
E. christenseni G
(28 x
18u) E ovina - Sh 19-29 days
Sh , G E arloingi - G

(28 x 20u) E ovinoidalis -
Sh 9-15 days Sh , G
E ninakohlyakimovae - G
(23 x 18u)

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Toxoplasma gondii

• Ruminant-cat cycle oocysts can survive 18
  months if cool, wet
• Sheep and goats - Seldom acute disease, outbreaks
  of late abortion, weak lambs, pyometra,
• Cattle minor more resistant
• Immunity no additional abortions or clinical
  signs if re-exposed

Sporulated oocysts
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Toxoplasma gondii late abortion
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• Diagnosis
• Placental lesions - cotyledons inflammed,
  greyish white foci 1-3mm (below). Impression
  smears reveal typical banana-shaped organisms
• Paired titers IFA, IHA, CF, ELISA, Sabin-Feldman
  dye test, mouse inoculation ? intraperitoneal
  organisms

Treatment SulfadiazinePyrimethimine seldom
given, impractical Vaccine in New Zealand
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Neospora caninum
A transplacentally transmitted protozoan parasite
of livestock and dogs that was until 1988 often
misdiagnosed as T gondii. Dogs were shown to be a
definitive host in 1998.
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Neospora caninum is a major problem in dairies
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Abortion in dairy cattle

• Retrospective studies in California specimen
  archives show Neospora was the cause of 18-19 of
  all aborted fetus tissues, with 24.4 of those
  from the dairy industry. It is now known to be
  the most common cause of bovine abortion in
  California, the Netherlands and New Zealand and
  has a worldwide distribution.
• It was first recognized in dogs in Norway (1984)
  in association with encephalitis and myositis.
  Infections have been demonstrated in cattle,
  sheep, goats, horses, deer, dogs (which serve an
  intermediate and definitive host), cats and mice.
• Abortion is also reported naturally for goats,
  experimentally for sheep.

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Clinical signs and pathogenesis

• Year-round abortion in heifers and cows, mainly
  at 3-6 months
• Intensive management favors transmission.
  Contamination of feedstuffs with dog feces
  apparently quite common Sarcocystis bovicanis is
  ubiquitous in cattle. Dairy and beef equally
  susceptible
• Repeat abortions can occur repeatedly in the same
  herd (5, up to 30) and the same animal,
  unknown it re-infection or reactivation
• Congenitally infected calves have CNS damage
  ranging from proprioceptor deficits to paralysis
  or no signs but high pre-colostral antibody
  titers. Vertical congenital transmission, with
  abortion in offspring is documented. This broad
  range of effects is possibly related to infective
  dose or to strain of parasite.

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Diagnosis and control

• Submit aborted calf, placenta and serum from dam
• Histopathology shows non-suppurative multifocal
  protozoal encephalomyelitis, especially in spinal
  grey matter, and myocarditis, portal hepatitis
  and lesions in cardiac and skeletal muscles.
  Neospora has thicker walled cysts than Toxoplasma
• Immunohistochemistry (IFAT) of tissue sections,
  ultrastructure or species specific PCR
  differentiates Neospora from Toxoplasma or
  Sarcocystis
• ELISA and IFAT (gt1640) is useful for
  sero-epidemiology evaluations. Risk of
  seropositive cows aborting is twice that of
  negative titer, possibly by congenital exposure
  from dam.
• Limit access of young dogs. Litters may develop
  fatal ascending paralysis, myocarditis with
  dermal lesions. Variable treatment success with
  sulfadiazine/pyrimethemine, clindamycin.

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Sarcocystis

• A Predator-Prey life cycle. Many highly
  host-specific species occur
• A large number of fully sporulated sporocysts are
  shed by predators

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Sarcocystis in muscle
Sarcocystis bovicanis Cause of uncommon acute
outbreaks of abortion storm (Dalmeny disease).
Signs are fever, anorhexia, cachexia, abortion,
some deaths, characteristic rat tail associated
with 2 asexual reproduction generations in
endothelial cells of highly vascular organs.
Muscle sarcocysts seen above are 3rd generation
schizonts, a frequent gross pathological finding
in cardiac, esophageal muscles of slaughter
cattle.
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Sarcocystis in esophagus of a goat
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Cryptosporidium
Autogenous re-infection cycle by Type1 thin
walled cysts (20) Thick walled Type two cysts
pass in feces to the environment.
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Cryptosporidium in superficial mucosa
Causes villous atrophy mononuclear infiltrate in
lamina propria, especially in the ileum
mucofibrinous exudate in severe cases.
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Cryptospridium histopathology section, HE
Cysts appear to be on cells, but are just under
cell membrane at microvillous border. Immediate
fixation or lose by autolysis.
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Clinical signs and epidemiology

• C. parvum (6 x 4u) occurs mainly in neonatal to
  lt4 week-old calves as a part of the calf scours
  complex, in most cases concurrent with rotavirus,
  coronavirus and/or E. coli.
• Yellow, loose diarrhea of 2 weeks duration, 4-day
  prepatent period
• Immunity limits life cycle, but autoinfection
  persists if immuno-suppressed. No treatment,
  nitazoxinide effective experimentally.
• Low host specificity. Calf-human transmission is
  well documented and can be fatal in AIDS
  patients. Recent evidence from CDC community
  outbreaks in water supplies and use of PCR
  reveals two strains that infect humans, Genotype
  1 (human-human) and Genotype 2 (calf-human).
  Most outbreaks were due to sewage contamination
  vs agricultural waste runoff. Cryptosporidium
  can be found in most natural waters, but much may
  be strains or species (eg C. muris (rodents), C.
  agilis (birds) of questionable infectivity.

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Cryptosporidium Oocysts, Phase Contrast
Microscopy after Sheathers sugar flotation. Note
the typical dot (residual body). Up to millions
per gram of feces are shed.
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Cryptosporidium - acid fast stain
Cryptosporidium stains bright pink against a
green background. Differentiate from commonly
found yeasts, which are not acid-fast, are
variable in size and occasionally have budding
reproductive forms.
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Giardia duodenalis
Cysts 12 x 8u Trophozoite

• Recently shown to be an underestimated cause of
  diarrhea in calves in dairies, feedlots. Less
  prevalent in lambs.
• Resembles Cryptosporidium clinically. Giardia is
  less age dependent and signs with shedding
  persists for 2-24 weeks
• Rx - Fenbendazole (5 mg/kg) at normal
  anthelminthic dose

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Tritrichomonas foetus
Note the 3 anterior flagellae and an undulating
membrane
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Bovine Trichomoniasis

• Venereally transmitted cause of early silent
  abortion that can lead to a 15 lower calf crop,
  prolonged calving interval (100-day delay in
  conception) and occasional pyometra
• Establishes in crypts of preputial fornix of
  bulls. No effect on semen quality, libido or
  excess preputial discharge. Direct correlation
  between age and infection rates. Bulls lt2-years
  old are somewhat refractory If over 3 years old,
  bulls become and remain infected for life due to
  the development of deeper, more suitable crypts
  in the preputial epithelium.
• Common on shared, open ranges with co-mingled
  herds. In the western USA surveys show 5-8 of
  bulls are infected a 1990 survey in CA revealed
  16 of herds and 27 of bulls infected. Common
  on LA coastal marsh, other southern states.
  Transmission rate high (42) by natural breeding,
  AI possible.

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Pathogenesis

• Colonizes vagina, uterus and oviducts after
  coitus. Pregnancy is established, but fetus
  loses viability via cytotoxic effect on
  placentomal interface by 50-70 days. Since there
  is maternal recognition of pregnancy at 14-18
  days, 21-day estrus cycles are skipped. In
  dairies, cows test pregnant at early palpation,
  then abort or resorb.
• Cows self-cure by 3rd heat cycle, then are immune
  and can be successfully re-bred. Mild vaginitis
  and cervicitis occurs with mild discharge.
• If the fetus is not expelled, the corpus luteum
  is retained and pyometra may develop (up to 10
  of cows) with fluid teeming with organisms. The
  cow becomes a permanent carrier.

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Diagnosis
Bulls Sample and culture smegma from preputial
cavity at fornix level by scraping using an
insemination pipette. Incubate at 37C for up to 4
days, with daily examination for organism with
typical jerky, rotating motility and morphology.
Trypticase-yeast extract-maltose (TYM) or
Diamonds media (1 agar added) used previously.
Commercial InPouch TF kits (Biomed, Diagnostics,
San Jose, CA) has a 2 chamber plastic pouch with
proprietary media. The upper chamber is
inoculated (for immediate exam), then squeezed
into lower chamber for culture. Kit has less
technical error, convenience, longer shelf life
and is 80-90 accurate on a single culture,
96-99 on two and lt1 on three. Multiple bull
examination improves herd diagnosis accuracy of
single samples. Saline lavage less accurate Cows
Culture of females is 50-60 accurate. Pyometra
fluid is teeming with organisms.
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InPouch TF Sampling and Culture
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Pentatrichomonas spp
Fecal contaminant species sometimes colonize the
prepuce. Differentiation is possible by
morphology (4-5 anterior flagellae), slow culture
growth or an experimental PCR test for
Tritrichomonas foetus. Special stains (DifQuik
Lugols iodine), scanning electron microscopy,
and PCR may be done in questionable cases on
valuable animals, especially young bulls.
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Tritrichomonas - Scanning EM
Note the three anterior flagellae and the
flagellae associated with the undulating membrane
running posteriorly
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Treatment and control

• Herd Health Program if risk factors (prior
  diagnosis, old bulls, fences)
• Culture all bulls at pre-season breeding
  soundness examination /- after season 3
  consecutive herd examinations before deem
  individuals uninfected cull infected.
  Metrinidazole, Imidazole IV treatment partly
  effective, but declared ILLEGAL by the FDA.
  Topical Rx ineffective.
• Use young lt2 year-old preferably virgin bulls
  that are culture negative.
• Vaccinate (Trich Guard, Fort Dodge) cow herd
  twice (one month apart) for 2 weeks before
  breeding season. Killed whole organism inhibits
  ability of organism to adhere to vaginal
  epithelium, provide partial cow herd protection
  but no efficacy for bulls.
• Segregate cow herd after palpation Pregnant gt 5
  months (safe), pregnant lt 5 months (cull if
  abort), Open (if pyometra, cull).
• Include neighbor in program or have good fences.