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GIARDIA LAMBIA protozoa, an amoeba, causes Giardiasis. It is a common cause of diarrhea.

Giardia (gee-ar-dee-ah) is a microscopic parasite that can infect all warm-blooded animals, including humans. Giardia was discovered in the 19th century, but was not classified as a pathogen (an organism capable of causing disease) until 1981 by the World Health Organization.

In the United States, Giardia is the most commonly identified pathogen in waterborne disease outbreaks. Contamination of a water supply by Giardia can occur in two ways, by the activity of animals (especially rodents such as beavers and muskrats defecting in the water) in the watershed area of the water supply or by the introduction of untreated sewage into the water supply. Wild and domestic animals have been shown to be a major contributor in contaminating water supplies. Studies have also shown that, unlike many other pathogens, Giardia is not host specific. This means that Giardia cysts excreted by animals can infect and cause illness in humans. Additionally, several major outbreaks of waterborne Giardia have been found to be caused by sewage contaminated water supplies.

Treating the water supply, however, can effectively control waterborne Giardia. Chlorine and ozone are examples of two disinfectants known to effectively kill Giardia cysts. Filtration of the water is also effective by trapping and removing the parasite from the water supply. The combination of disinfecting and filtration is the most effective water treatment process available today. The contamination can also come from contaminated ground water. The amoeba can survive in boiling water.

As part of Giardia’s life cycle, the organism forms a cyst, which can be very resilient. The outer shell (cyst) protects the organism and allows it to survive outside the body for long periods of time. The infection is spread in the cyst form. It is passed from the intestine of an infected animal (in the cyst form) through feces into the water supply, contaminating it. If an animal drinking the contaminated water ingests viable cysts, the cyst transforms in the intestine of the new host, and begins to multiply causing Giardiasis.

Giardiasis, is an intestinal illness that can cause nausea, fever, and severe diarrhea. The symptoms can last for several days to a week. The body can usually naturally rid itself of the parasite in one to two months. However, individuals with a weakened immune system often cannot rid itself of the parasite without medical treatment and medications.

When in its normal state in the intestine, Giardia can multiply to high populations, causing extreme distress with symptoms including diarrhea, bloody stool. It can also cause great discomfort and extreme pain.

Usual treatment for Giardia infestation is a course of strong antibiotics, including Metroniadazole (Flagyl) at 66mg/kg-body weight per day for five to ten days. Flagyl will usually suppress the Giardia infestation. Repeat treatments may be necessary, as the protozoa can be very resistant to treatment. Increasing the percentage of protein in the dog’s diet can also be beneficial in aiding recovery from Giardia protozoan infestation, especially in puppies and older dogs. The most efficient method of maintaining a dog’s health is to administer the Giardia vaccination as part of the regular annual inoculations. There is a high rate of re-infestation from the parasite even after conventional treatment is administered. Some veterinarians believe there is some variability in tolerance to Giardia amongst dogs.

Diagnosis is usually established by microscopic laboratory diagnoses. The disease can range in severity from violent diarrhea to a slow indolent wasting disease resembling cancer symptoms. Treatment with Flagyl is usually successful, but mild relapses are frequent and re-treatment is common. Besides being difficult to diagnose because of the small number of protozoa’s in the stool, it is essential that the stool be extremely fresh, preferably being delivered within half an hour of defecation. Also, conventional centrifuge/flotation methods will not produce quality laboratory results in isolating the Giardia protozoan, therefore a saline dilution must be used.

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