Coccidiosis Flashcards
which coccidia species are we concerned about in cattle? how does the prevalence of coccidia species differ geographically?
- Eimeria zuernii & Eimeria bovis - cause severe clinical disease
- To a lesser extent, Eimeria alabamensis also can cause clinical disease
- Prevalence of the different species of coccidia can vary considerably between farms, regions, seasons and age groups
what age group is most susceptible to coccidiosis? how does infection occur?
- Coccidiosis is a common parasitic protozoan disease of cattle - particularly weaned calves
- Calves: 3 weeks to 6 months of age
- Infection occurs from contaminated pastures or lots by older cattle or other infected calves
- Mature cattle may become infected when place in crowded feedlots or barns
Life Cycle of Coccidia
- Bovine coccidia have stages within and outside host
- Microscopic eggs (oocysts) are passed out in the manure
- Oocyst develops within three to seven days and is now capable of infecting cattle
> Affected by temperature, moisture and oxygen - Oocyst contains eight bodies (sporozoites), each capable of invading an intestinal cell
<><> - Sporozoite enters a cell > changes into a meront and divides many times (up to 100,000 offspring called merozoites)
> The numbers produced depend on the species of coccidia involved - Each offspring, in turn, may enter another intestinal cell
> This cycle is repeated several times - Large numbers of intestinal cells are destroyed during the multiplication of parasite stages
<><> - Eventually, the cycle stops and sex cells (macro & microgametocytes) are produced
- Then they produce the next generation of oocysts, which rupture from the intestinal cell and are passed in the manure
- Thousands of oocysts, each containing eight sporozoites when mature, can be passed in the manure of an infected animal
coccidia pethogenesis
- Destruction of intestinal epithelial cells
- Second-generation schizonts/gamonts maturation
- Loss of large bowel epithelium
<><> - Exposes capillaries of lamina propria
- Rupture of capillaries
- Loss of red blood cells
- Loss of plasma
- Non-absorption of water, Na+, K+
coccidiosis patient profile for dairy
- Mainly young cattle (<1 year)
- Dairy calves:
– Young calves (3 weeks - 6 months)
– Older than 17-18 days
– Massive, rapid exposure
– Crowding
– Small, heavily contaminated yards
coccidiosis patient profile for beef
- Beef calves:
– 5-10 months old
– Yearling cattle
– Feedlots
– Stress: overcrowding, early weaning, diet changes, cold wet weather, poor sanitation
coccidiosis disease severity factors
- Number of oocysts eaten
- Species of coccidia present
- Age of the animal
- Animal immunity due to previous infection
Cattle Susceptibility
* Are they all equal?
- Coccidia occur in all breeds of cattle
- Calves may acquire infection as soon as they begin grazing or eating food other than milk
- Common in calves 3 weeks to 6 months of age
- May occur in yearlings & adults
coccidiosis seasonal incidence and where they are relevant
“Summer coccidiosis”
- High humidity, warm weather
- Ontario, Maritimes
- Young, highly susceptible calves
- Sporadic cases
- Unsanitary barns and pastures
- High mortality
<><>
“Winter coccidiosis”
* Calves 5-10 months old
* Feedlots, beef ranches
* Alberta, B.C., Manitoba, Sask, Quebec
* High incidence: January-March
- Stress, confinement
- Lower mortality
- Effects on weight gain
- Up to 25-50% of group affected
clinical signs of coccidiosis?
- Not specific to coccidiosis
- Common signs:
- Profuse diarrhea that may contain blood
- Dehydration, weight loss and death in severe cases
- Loss of appetite regardless of the Eimeria spp. involved
- Feed intake can be reduced as much as 60% during peak infection and can remain low subsequently
forms of coccidiosis?
- Enteric form
> Intestinal coccidiosis - Enteric + nervous form
> Nervous coccidiosis
enteric form of coccidiosis signs
Diarrhea/dysentery
* Watery feces to profuse diarrhea
* Frank blood 2-3 days after diarrhea (hematochezia)
* Mucus 2-3 days after diarrhea
<><>
* Tenesmus
> Rectal prolapse in some cattle
* Depression
* Weakness
* Rough hair coat
* Dehydration
<><>
* Anorexia
* Poor weight gain
* Anemia, pale mucous membranes
* Death in acute, severe cases
* Up to 3% mortality
nervous form of coccidiosis prevalence and timing? signs? mortality?
- Small % of cases affected
- Up to 20-30% in western Canada
- January to March
<><> - Muscle tremors
- Loss of balance
- Recumbency
- Convulsions
- Hyperexcitable
- Paddling
- Frothing at mouth
- Opisthotonus
- Nystagmus
- Strabismus
- Blindness
<><> - Up to 50% mortality
- Die on first day or live 3-5 days
clinical pathology of coccidiosis?
- Hemoconcentration - due to dehydration
- Anemia - due to large intestinal damage
- Hyponatremia/hypochloremia - due to lesions in cecum, proximal colon
- Hyperglycemia - due to convulsive episodes in nervous coccidiosis
diagnosis of bovine coccidiosis?
Combination of:
- Herd history
- Season
- Clinical signs
- Physical examination
- Microscopic examination of manure taken from the rectum
- Fecal flotation for oocysts: > 5,000 egg E. zuernii, E. bovis
<><>
* Diarrhea usually precedes heavy oocyst discharge by one or two days
> May continue after oocyst discharge has returned to low levels
necropsy findings for coccidiosis
Necropsy findings:
* Intestinal mucosal scrapings
* Oocysts/schizonts/merozoites
* No neurological lesions on histopathology
Treatment of Affected Animals for coccidiosis
- Several anticoccidial drugs available
- Outbreaks of coccidiosis in calves and feeder
cattle:
> mass medication added to feed or water
therapeutic plan for coccidiosis - what do we do based on disease progression and what should we keep in mind?
- May be self-limiting disease
- Spontaneous recovery
- Adults usually immune
- No clinical signs until life cycle of Eimeria almost complete
- Gut severely damaged by that stage
<><> - Drugs effective against merozoites and schizonts
- Prevent disease in animals at risk !!
- Fluids (parenteral/oral)
- Tranquilizers (nervous form)
drugs for coccidia
- Amprolium
- Sulfamethazine
- Benzene acetonitrile compounds
> Toltrazuril
> Diclazuril
how does amprolium work for coccidiosis?
- Thiamine antagonist
- Retards generation of 1st-generation schizonts in intestinal epithelium
- Dose: 10 mg/kg for 5 days
