Coccidiosis

What is coccidiosis?

Coccidia oocysts (eggs)

Coccidiosis is an infection with a one-celled organism; these organisms are classified as protozoa and are called coccidia. Coccidia are not worms; they are microscopic parasites which live within the cells of the gut lining. Because they live in the intestinal tract they can be associated with diarrhoea problems especially in puppies. Diarrhoea due to coccidiosis is occasionally a problem in young puppies and kittens but the coccidia are usually associated with another causal organism such as worms, or the stress of being rehoused or even a change of diet.

How did my dog or cat become infected with coccidia?

Oocysts (immature coccidia) are passed in the faeces of the dog or cat. They remain in the environment and eventually sporulate (mature) into a more developed oocyst which can infect the dog or cat again. Other dogs, cats, or mice may also become infected. This process can occur in as little as 6 hours, but it usually takes 7-10 days. If the sporulated oocysts are swallowed, they mature in the animal's intestine to complete the life cycle. If the oocysts should be swallowed by a mouse, the dog may also become infected by eating the mouse.

What kinds of problems are caused by coccidial infection?

Most dogs that are infected with coccidia do not have diarrhoea or any other clinical signs. When the eggs (oocysts) are found in the faeces of a dog without diarrhoea, they are generally considered a transient, insignificant finding. However, in puppies and debilitated adult dogs, they may cause mucoid diarrhoea often with blood, dehydration, abdominal distress, and vomiting. Most puppies and kittens infected with coccidia are still well in themselves and eat well.

How is coccidial infection diagnosed?

Coccidiosis is diagnosed by performing a microscopic examination of a stool sample. Since the oocysts are much smaller than the eggs of the intestinal worms, a very careful study must be made.

How is the coccidial infection treated?

The drug we use most commonly to treat coccidia is Baycox (toltrazuril). Baycox is only registered for use in chickens so should only be supplied and dispensed by your veterinarian. Other treatments are also used if diarrhoea and dehydration occur. Reinfection of the animal is common so environmental disinfection is important. The use of chlorine bleach, 500ml in 4 litres, is effective if the surfaces and premises can be safely treated with it.

Are the coccidial parasites of my dog infectious to humans?

The most common coccidia found in dogs do not have any affect on humans. However, less common types of coccidia are potentially infectious to humans. Coccidial parasites pose a health risk for immuno-suppressed humans (i.e., AIDS patients, those taking immune suppressing drugs, cancer patients, the elderly). Good hygiene and proper disposal of dog faeces are important in minimising risk of transmission of all canine parasites to humans. Although there is risk of the dog transmitting parasites to humans it does not warrant removing the dog from the household except in very rare circumstances.