INTESTINAL UPSET - GIARDIA
Is It a Parasite?
By Jennifer L. Schori, VMD
Diarrhea is common in pets. Often, it is a temporary disorder that resolves on its own with the passing of time and, perhaps, a bland diet or medicine to control the symptoms. Other times, however, it can be a sign of something more serious. Infection with the Giardia parasite is one such example.
How does my pet become infected?
Giardiasis (JEE-ahr-DYEah-sis) occurs when an animal is infected with a microscopic, one- celled organism known as Giardia. Infection in dogs and cats is common: in symptomatic animals,rates of 19% of dogs and 11% of cats in the U.S. have been reported, and rates may be even higher in specific populations (up to 50% in puppies and 100% ii) some shelters and kennels). A pet becomes infected when it ingests parasite cysts (parasites enclosed within a protective wall) from food, water, or other objects that have been contaminated with fecal matter from infected animals or humans. Once ingested, the cyst opens and releases the active form of the parasite, known as a trophozoite.
Trophozoites attach themselves to the cells lining the small intestine. It is at this stage that diarrhea occurs. Later, the trophozoites form a wall around themselves, forming cysts again. Within 5 to 7 days of ingestion, the infected pet sheds the cysts in its feces, thus completing the cycle Cysts are immediately infectious to other animals and to the same
animal, which can ingest them while grooming itself
What are the signs?
Signs of giardiasis develop 1 to 2 weeks after infection and include diarrhea, greasy stools, and gas. Severe symptoms can occasionally result in weight loss and dehydration. Some infected pets, however, may not show any signs but can still be a source of infection. Unfortunately, this makes diagnosing giardiasis tricl In addition, sometimes cysts are only shed intermittently in the feces and the parasite can be difficult to identify under a microscope. Your veterinarian may therefore use several different types of fecal tests to diagnose giardiasis and may need to repeat the testing if infection is suspected despite initial negative tests. In addition, a newer type of test, called an ELISA (enzymelinked immunosorbent assay), can help identify pets that have the disease but show no symptoms.
How do you treat giardiasis?
Several medications have been used to treat Giardia infection, although none has been approved for use in dogs and cats. The effectiveness of some of these drugs can vary, and safety concerns may limit their use. Your veterinarian can develop a treatment strategy based on your pet's individual needs. In addition to medication, measures to rid the environment of the cysts are very important. After treatment, your veterinarian may want to test the pets to see if therapy was successful.
Can I get Giardia from my pet?
The number of Giardia strains that exist and what species they might infect is not known but most strains do not infect humans. Transmission of Giardia from animals to humans appears to be rare, but caution must still be exercised if your pet is infected to protect yourself and family as well as other pets. Good hygiene is critically important, including wearing gloves when handling infective feces and washing hands thoroughly with soap and water after handling an infected animal.People with underlying disease, or who have compromised immune systems should limit exposure to infected pets. Any person in the household who has been exposed to an infected pet or other sources of infection and develops gastroin testinal signs should consult his or her physician. If both human and animal family members arc infected at the same time, it is very difficult to determine where the infection came from.Infected humans can infect their pets. While it is not known how often this occurs, infected people should be sure to wash their hands with soap after using the toilet and before feeding or handling their pets.Pets should also be prevented from drinking from toilet bowls to prevent transmission from this potential source.
People at Highest Risk for Intestinal Parasites
*Plumbers
*Gardeners
*Infants and children
*Anyone who might eat dirt or animal feces (usually children and the mentally disabled)
*Those with immunosuppressive disease (eg, AIDs, liver disease, diabetes)
*Those on immunosuppressive drugs or undergoing radiation treatment (eg, those with auto- immune disease or cancer)
Treatment & Prevention of Giardiasis
In addition to medication, these are things you can do for pets with giardiasis:
Bathe your pet with shampoo to remove feces and associated parasite cysts after medication is finished.
Remove feces daily, wearing gloves to protect your hands. In addition, be sure to wash your hands thoroughly after handling an infected animal.
Decontaminate surfaces with commercially available disinfectants or by steam cleaning;
allow surfaces to dry thorougi1y atterward to dry up any remaining cysts. Giardia cysts arc tough and can survive for several months, especially in cool water. This makes decontamination difficult in grass, soil, or standing water.
Treat all pets in the home at one time.
There is a vaccine against Giardia; however, there does not seem to be enough evidence to support its use in the prevention or treatment of infection.
For more information on giardiasis in pets and humans, visit the Companion Animal Parasite Council \Veb site at www.capcvet. org or the \Veb site for the Centers for Disease Control and Prevention at www.cdc.gov.I
References
Diarrhea caused by Giardia and Clostridium perfringens enterotoxicosis. Tamrns TR, AVC Proceedings, 2001
Giardia (Giarciia canis, Gierciia cati). Fnsby H. peteducation.com, 2000.
Giardia in dogs and cats: More common than you think. Marks SL Veterinary Forum, 2004.
Prevalence of Giardia in symptomatic dogs and cats throughout the United States as
determined by the IDEXX SNAP Giardia Test Bowman DD, Scarlett JM, Garrett J. Lorentzen L
AAVP Annual Meeting, 2005.
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