ASK THE VET (Giardia)

Giardia is a single celled protozoan parasite that can infect birds, people and other animals. Although Giardia can infect any species of bird, it is most often found in cockatiels, lovebirds, budgies, and Grey-cheeked parakeets.

The parasite exists in two forms, a trophozoite, or active form, which moves by means of hair-like structures known as flagella, and a dormant form, known as a cyst. Cysts are shed in the feces from an infected bird and are ingested in contaminated food and water. Certain insects such as flies and cockroaches may serve as mechanical vectors for cyst transmission.

The cyst is digested in the bird's small intestine and releases the active trophozoite form. These attach to the villi, or fingerlike projections in the small intestine, by means of an adhesive disc. The trophozoites undergo multiplication and new cysts are formed which are shed in the feces. Under favorable environmental conditions, the cysts may remain infective for weeks. The cysts are ingested by another bird and the cycle is repeated.

The disease caused by the parasite is known as Giardiosis. Diarrhea may occur and can be acute, chronic or recurrent. A bad odor and lots of mucus may occur with the diarrhea. Depression, lethargy, anorexia and weight loss may occur. The parasite is believed to interfere with absorption of nutrients and fat metabolism. Severely affected birds may die. Skin may become very dry and itchy, and some birds, such as cockatiels and keets may pick out their feathers. Asymptomatic carriers may exist, and serve as sources of infection for other birds.

Diagnosis of Giardia can be difficult. It may be necessary to examine multiple fresh fecal smears to find the motile trophozoites. Zinc sulfate flotation may be used to determine if cysts are present. Elisa tests have been developed to identify trophozoites and cysts. Infected birds may only shed trophozoites and cysts intermittently, rather than continuously.

Giardiosis is thought to have zoonotic potential (transmissable to humans).

The best way to prevent Giardia is to provide clean, dry, uncontaminated food and bedding. Avoid overcrowding. Water should be uncontaminated. Chlorine does not always kill Giardia.

Unfortunately, relapses are common, either as a result of failure to destroy all of the parasites in the bird or as a result of a new infection. Certain medication, such as Flagyl, are sometimes used to treat Giardiosis. There are other treatments used in Europe, but they are not yet available in the U.S.