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Coccidiosis (Eimeria and Isospora)


Coccidia is a protozoan parasite. It can cause diarrhea in many species and generally affects the young animals.  Most often it affects those that are in large populations in rather confined areas such as feedlots, weaner lots or corrals. Severity of problems and signs are dependent on the parasite load of the animal. Signs can vary from rough, dull hair coats and slow growth (mild infection) to loose diarrhea to neurologic and recumbent animals (severe case). If left untreated it can lead to death.


 Pathogenesis: The route of infection is fecal-oral. Oocysts dwell in the small intestines where they sporulate and enter the enterocytes for further maturation. These effected cells often go through necrosis and as more coccidia mature more cells are damaged. This destroys both the epithelium and in severe cases the entire mucosa. Immature oocysts are then shed into feces where they may be transmitted to susceptible animals.


Problems associated with coccidian infections.

     1. Diarrhea - acute  

     2. Dehydration

     3. Anorexia

     4. Depression

     5. Weight loss

     6. Mild Fever



Diarrhea: Due to damaged intestinal epithelium and mucosa have malabsorption of fluid and as mucosa erodes have hemorrhage into the lumen.

Dehydration: Due to malabsorption of fluid and water loss in diarrhea.   




Acute vs. Chronic: coccidiosis can be either depending on severity

Localization: The diarrhea normally involves the cecum, ileum and colon.

Epidemiology: Coccidiosis is an infectious disease that often occurs in stressed or overcrowded animals. It can affect large numbers or just individual animals. It is often present in low concentrations in most herds, but may flare up dependent on parasite load in either feces or the herd.

Mucosal Damage: This disease can be characterized by significant mucosal damage, but it is not always the case as it may be a mild infection.

Diagnosis: Coccidiosis normally is diagnosed using a fecal float, and correlating it with clinical signs.  Small numbers of coccidia are normal on fecals.


Treatment and prevention:  Management is the best and most important tool for minimizing coccidial infections.  Coccidia are normal inhabitants of the intestinal tract and overgrow and lead to clinical signs if the immune system is suppressed.  Avoid stress such as overcrowding pens and keep animal housing areas clean.  Adequate nutrition and mineral nutrition are needed to keep the immune system functioning adequately.  These steps will greatly reduce the parasite problem and help minimize infections of other animals.  If coccidiosis is a problem there are feed supplements available that will limit coccidia proliferation.  Also coccidian infections can be treated with sulfa drugs. (Always follow drug label directions and check with your veterinarian before using).  5 days or therapy is required to break the life cycle of the organism but often 3 days therapy such as with sustain released sulfa boluses usually  reduces numbers adequately to alleviate clinical signs.  When dealing with coccidian infections look for underlying causes that may be suppressing the immune system.