What is Giardia?
Giardia is a microscopic protozoan that lives in the intestinal tract of many animals worldwide. Unlike other common parasites, it is not considered a worm. Rather, it is a single-celled organism that can cause gastrointestinal upset (i.e. diarrhea and vomiting) in some animals.
How is it Transmitted?
Infected animals spread giardia cysts through their feces. These cysts are designed to withstand many environmental conditions and can survive for months in the right conditions. Animals then come into contact with the cysts through drinking contaminated water or walking over contaminated ground. Cysts that make it to the gastrointestinal tract transform into trophozoites, also known as the feeding form of giardia. This form can cause gastrointestinal disease, typically in young or immune-compromised animals. Healthy adult animals can carry giardia without being symptomatic which leads to increased transmission.
Symptoms of Giardia
As mentioned, giardia can cause gastrointestinal symptoms in affected animals. Patients often will present with sudden onset of diarrhea that sometimes contains blood and/or mucous. As the infection progresses, animals may develop vomiting and weight loss. Other times, animals have no symptoms at all. Testing fecal samples regularly (annually in adult dogs, more frequently in puppies and kittens) is recommended to screen for giardia and other intestinal parasites in otherwise healthy animals. (Learn more: Know Your Parasites.)
How is it Diagnosed?
Microscopic examination of the stool (also called a fecal flotation) can detect the presence of giardia cysts, but the cysts are difficult to find and can be missed. Because of this, giardia is typically diagnosed through a special test that checks for giardia antigens in the stool. These antigens are found in animals that have giardia trophozoites in their intestinal tract.
Giardia can be tricky to treat due to animals easily reinfecting themselves with the organism. Because of this, it is recommended to pick up stool immediately after an infected animal has a bowel movement. This allows for minimal environmental contamination. Wiping off the paws and rear end after going outside to remove any possible cysts on the fur can also reduce reinfection rates.
Veterinarians can treat giardia with a few different medications and diet changes depending on the severity of symptoms and number of cysts seen on the fecal test. It is not uncommon for animals to go through multiple rounds of treatment before being cleared of giardia entirely.
Two to four weeks after treatment, animal’s stool should be rechecked for the presence of giardia cysts. To be considered cleared of giardia, animals need two consecutive negative fecal checks, spaced two to four weeks apart. Some animals consistently have cysts present in their stool and are considered carriers of giardia. If they are not symptomatic, many do not require continual treatment.
Can I Get Giardia From my Pet?
While humans can get giardia, the type that typically affects them is different than the ones that dogs and cats get which means the risk is minimal. It is still recommended to wear gloves while handling feces from animals and to wash hands afterwards. Cleaning toys, bedding, bowls, furniture, and flooring in the house regularly can also reduce exposure risk to people. Washing at high temperatures or cleaning with quaternary ammonium compound products will help to disinfect the areas.