Wednesday, February 24, 2010

The Truth Behind Coccidia

We all know how important it is to have our pets receive an annual physical by their veterinarian each and every year and as part of their yearly checkup we are often asked to bring in a stool sample. When pressed for a reason why the most common response is to check for parasites or worms. But what exactly is your veterinarian looking for and why is it so important to check for it? How could your “indoor only” pet possible pick up any kind of parasite? Over the next few months we will cover the most commonly seen types of parasites, how your pet can come in contact with them, and what you can do if your pet already has them. Today’s spotlight in our series will be on one of the smallest villains in our series: coccidia.

Coccidia is a one-celled organism that lives within the cells of the intestinal lining. They are not actual worms, but are are often confused with them due to the fact they live in the intestinal tract and commonly cause diarrhea.

Prevalence and Contributing Factors
Coccidia is often found in young kittens and puppies especially if they are strays or have come from a crowded environment with poor hygiene (pet store, puppy “mill,” etc.). The major contributing factors to the spread of coccidia infections are overcrowding, poor sanitation, and stress.

Oocysts (immature coccidia; "eggs") are passed into the environament through the stool of the dog or cat. They lie in the environment and eventually sporulate (mature; hatch) into a more developed oocyst that can then infect the same dog again. This process can occur in as little as 6 hours, but it usually takes 7-10 days. Other dogs, cats, or other animals may also become infected if they come in contact with the contaminated stool. Mature oocysts can be ingested intentially, if your pet eats it’s own stool or the stool of another animal, or accidentally, for example if you pet walks through an infected area and then lickes his or her paws. Once swallowed the mature oocysts will complete it’s life cycle in the animal's intestine. Coccidia can also be spread if your pet eats another infected animal, for example a mouse that is infected with coccidia.

Clinical Signs
Most dogs with an active coccidia infection do not show any clinical signs such as diarrhea. However, the “eggs” (oocysts) can still be found in the stool of a dog or cat with a simple lab test. When found in the stool of a healthy pet that is showing no clinical symptoms they are generally considered a transient, insignificant finding. However, in puppies and debilitated adult dogs, they may cause severe, watery diarrhea, dehydration, abdominal distress, and vomiting. In very severe cases, death may occur.

The presence of coccidia is diagnosed by performing a microscopic examination of a stool sample. Since the oocysts (“eggs”) are much smaller than the eggs of other intestinal parasites, they can be easily missed unless a very careful study is made. An infection with some of the less common coccidial parasites can later be confirmed with additional tests that may require specialized laboratory facilities.

The most common drug used to eliminate coccidia is a sulfa-type antibiotic which is typically given for 10-14 days. The medication is sweet-tasting and most pets will take it with no issue. If the infection persists after giving the sulfa-type drug other medications are also available. If any additional symptoms from the infection such as diarrhea or dehydration occur additional medication may also be needed.

In most cases, a good response to treatment is expected and most pets recover fully. The presence of concurrent diseases or immune suppression can make the prognosis less certain.

Transmission to Humans
The most common form of coccidia found in dogs does not have any affect on humans. However, less common types of coccidia are potentially infectious to humans. One parasite, called Cryptosporidium, may be carried by dogs and may possibly be transmitted to people. This parasite has also been found in public water supplies in some major cites. Another coccidial organism, Toxoplasma, is carried by cats and is of particular concern to pregnant women because of the potential to cause birth defects in newborns. This organism is only able to complete its life cycle in the cat.

These two coccidial parasites pose a health risk for immunosuppressed humans (i.e., AIDS patients, those taking immune suppressant drugs, cancer patients, the elderly). Good hygiene and proper disposal of dog and cat feces are important in minimizing risk of transmission of all parasites to humans. Although there is risk of pets transmitting parasites to humans, it does not warrant removing the pet from the household except in very rare instances.

Reinfection of dogs is very common so sanitizing the environment is very important. The use of chlorine bleach, one cup in a gallon of water, is an effective way to sterilize any surfaces that can be safely treated with it. Because coccidia tends to be a problem in areas of poor sanitation, the need to keep the area as clean and sanitary as possible cannot be emphasized enough.

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