Coccidia and other Protozoa of Food Animals. Coccidia or Ruminants. 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
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E bovis 28 x 20u
E zuernii 18 x 15 u
Only E bovis, E zuernii are definite pathogens in cattle
Eimeria has four sporocysts with two sporozoites
Isospora has two sporocysts with four sporozoites
Eimeria bovis has characteristic, 1st generation ‘giant schizonts’ in small intestine
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
Feedlot– Clinical coccidiosis is a major problem in the dairy and feedlot industries
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.
Gross pathology findings in colon and rectum. Evidence of hemorrhagic enteritis with frank blood, mucous
Fresh mucosal impression smear with coccidian developmental stages. Necropsy touch preparations or rectal scrapings can be used to diagnose prepatent infections
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
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)
Treatment: Sulfadiazine+Pyrimethimine seldom given, impractical
Vaccine in New Zealand
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.
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.
Autogenous re-infection cycle by Type1 thin walled cysts (20%); Thick walled Type two cysts pass in feces to the environment.
Causes villous atrophy; mononuclear infiltrate in lamina propria, especially in the ileum; mucofibrinous exudate in severe cases.
Cysts appear to be on cells, but are just under cell membrane at microvillous border. Immediate fixation or lose by autolysis.
Cryptosporidium –Oocysts, Phase Contrast Microscopy after Sheather’s sugar flotation. Note the typical ‘dot’ (residual body). Up to millions per gram of feces are shed.
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.
Cysts 12 x 8u Trophozoite
Note the 3 anterior flagellae and an undulating membrane
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 Diamond’s 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 <1% 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.
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+ Lugol’s iodine), scanning electron microscopy, and PCR may be done in questionable cases on valuable animals, especially young bulls.
Note the three anterior flagellae and the flagellae associated with the undulating membrane running posteriorly