Giardia is a common intestinal infection that affects cats, dogs, and humans. It is caused by a single-celled parasite and can result in diarrhea and weight loss; if untreated or chronic, Giardia infection can lead to a decrease in nutrient absorption, damage to the intestinal lining, dehydration, and failure to thrive in children. Infection usually is not life-threatening in developed countries, but infants and people who are already immunocompromised are more susceptible to complications. Giardia is found in every region of the US, as well as in other regions around the world.

While Giardia is technically a zoonotic parasite, meaning it can be transferred from animals to humans, most cases of Giardia in people are of human origin. In other words, your chances of contracting Giardia from your cat or dog are quite low.

Here are a few basic facts about Giardia:

  1. How can I get Giardia? Giardia is passed through the feces of an infected animal or person. Infection in humans most often occurs from drinking contaminated water or eating contaminated food. People living in areas without access to safe drinking water are particularly susceptible. Infection can also occur if your hands become contaminated with fecal matter; this makes parents and caretakers of young children particularly at risk. One of the challenges of Giardia is that the parasite can survive outside of a host for weeks or months by forming a hard cyst. This means that the parasite can still spread even if there is no sign of active infection.
  2. How do I know if I have Giardia? In many people, Giardia is asymptomatic, meaning there are no obvious signs of infection. When symptoms do occur, it is typically within one to three weeks of infection. The most common symptoms are diarrhea, fatigue, abdominal cramps, bloating and gas, and nausea. Because these symptoms are often chalked up to other causes, however, many people do not suspect a Giardia elisa infection. If left untreated, Giardia will eventually lead to more acute symptoms, including bloody diarrhea, weight loss, and dehydration. If you or your child experience a bout of diarrhea lasting more than a day or two, contact your doctor immediately. Your doctor will collect a stool sample and perform either a fecal flotation test to look for Giardia cysts in the sample or an antigen test to more precisely detect the presence of antigens in the sample. Some versions of these antigen tests need to be sent out to labs for analysis, while others produce rapid results and can be read by your doctor within 10-15 minutes.
  3. How is Giardia typically treated? For people who do not present with symptoms of Giardia, treatment for Giardia infection is often not necessary unless the infected person is likely to spread the disease to other people (for example, if the infected person is a young child or works in a child care center). If symptoms do persist or progress, your doctor will most likely prescribe a course of anti-protozoal and/or antibiotic medication to clear the Giardia infection from your system. For severe cases, people may also need to be treated for dehydration.
  4. How can I protect myself and my family against Giardia? As with most other common parasitic infections, prevention of Giardia infection is key. The easiest way to prevent Giardia infection is to wash your hands thoroughly and ensure proper hand-washing techniques in children. Avoid drinking untreated water, and use clean water to wash any foods that are to be eaten raw. In areas with poor sanitation, use bottled water or water filters to reduce your risk of infection. In addition, always pick up your pet’s feces immediately using gloves or a bag over your hand. If infection does occur, it is also important to disinfect household objects that may have come into contact with Giardia cysts. A combination of 1-2 cups of bleach in 1 gallon of water should be used on bleach-safe surfaces such as toilets and countertops.
  5. What types of Giardia test are there? Giardia is tested using a fecal flotation test or an antigen test. The different types of antigen tests include lateral flow tests, such as the IVD Giardia Stool Antigen Detection Lateral Flow test kit, which can be done at your doctor’s office; ELISA tests, such as the IVD Giardia and Giardia/Cryptosporidium Stool Antigen Detection Microwell ELISA test kits; and direct immunofluorescence assays, like the IVD Cryptosporidium/Giardia Human Fecal Direct Immunofluorescence Antigen Detection Kit. Both of these latter kits require fecal samples to be sent to a reference laboratory.

While typically not life-threatening, Giardia infection is certainly uncomfortable and inconvenient. Maintaining a clean environment and ensuring good hygiene practices among your family are the only ways to truly prevent you or your family from contracting Giardia.


Centers for Disease Control and Prevention (CDC). 2015. “Parasites – Giardia.” Available at

Mayo Clinic. 2017. “Giardia Infection (Giardiasis).” Available at