Is Your Cat Giving You Giardia? The Surprising Truth About This Parasite

What is Giardia?

Giardia is a microscopic parasite that causes an intestinal infection called giardiasis [1]. The parasite is called Giardia intestinalis or Giardia lamblia. It most commonly infects the small intestine and causes symptoms like diarrhea, gas, greasy stools, and stomach cramps in humans [2]. Giardia is one of the most common parasites found in cats, dogs and humans.

Giardia parasites have a teardrop shape and exist in two forms: trophozoites and cysts. Trophozoites are the active, reproducing form that lives in the small intestine and causes infection. They produce cysts which are the infective form of the parasite. These hardy cysts are shed in the infected animal’s feces and can contaminate food, water and surfaces. If ingested by another animal or human, the cysts transform back into active trophozoites in the small intestine to cause infection [1].

Giardia infection is more common in places with poor sanitation and unsafe drinking water. Good hygiene and proper cleaning can help prevent spread of this intestinal parasite [2].


How do cats get infected with Giardia?

Cats become infected with Giardia when they ingest the parasite from contaminated sources. Giardia spreads through the ingestion of cysts that are shed in the feces of infected cats or other animals. The three main ways cats can become infected with Giardia include:

Ingesting contaminated soil or water – Giardia cysts can survive for weeks to months in the environment, especially in wet and damp areas. When cats drink from puddles, lakes, streams or other outdoor water sources contaminated with feces from an infected animal, they risk ingesting the parasite. Cysts can also be spread from playing in contaminated dirt or using a contaminated litter box.

Eating infected rodents – Rodents and other small animals can carry Giardia. When cats hunt and eat infected prey, they can become infected through ingesting cysts present in the animal’s intestines.

From mother cat before birth – Kittens can contract Giardia while still in the womb if their mother is infected. They can also become infected from contact with the mother’s feces after birth.

Can humans get giardia from cats?

Yes, but it is uncommon for humans to contract giardia from cats. According to the CDC, the chances of people getting a Giardia infection from dogs or cats are low. The type of Giardia that infects humans is usually not the same type that infects cats [1].

However, giardia transmission from cats to humans is possible if a person ingests infected cat feces containing the parasite. A cat becomes infected with giardia by consuming contaminated food or water or through contact with infected feces [2].

The greatest risk of contracting giardia from cats is for people with weakened immune systems, such as those with HIV/AIDS, cancer patients undergoing chemotherapy, and transplant recipients taking immunosuppressant drugs. Healthy people are less likely to become infected with giardia from cats [3].

Ways to prevent spreading giardia from cats

There are several steps you can take to reduce the risk of your cat spreading giardia in your home:

Practice good hygiene like washing your hands frequently, especially after cleaning the litter box or touching contaminated surfaces. The CDC recommends scrubbing your hands with soap and water for at least 20 seconds after coming into contact with animal feces to prevent disease spread (CDC).

Scoop and clean litter boxes daily to remove feces before giardia cysts can sporulate and become infectious. Disinfect the litter box weekly with boiling water or a bleach solution to kill any lingering cysts (VCA).

Treat any infected cats with medications prescribed by your veterinarian, like metronidazole or fenbendazole. Completing the full course of treatment is important to fully clear giardia infections in your cat and prevent reinfection (Texas A&M).

By staying vigilant with hygiene and proper sanitation, as well as promptly treating infected cats, you can minimize the spread of giardia from your feline companions.

Signs your cat may have giardia

Common signs that your cat may have a giardia infection include:

  • Loose stools or diarrhea – Giardia infections irritate the intestinal tract causing increased mucus production and poorly formed stools. Diarrhea from giardia is often pale, greasy, and foul smelling.
  • Excessive licking back end – The inflammation and itchiness around the anus caused by giardia may cause a cat to lick their bottom more than usual.
  • Loss of appetite – The intestinal upset caused by giardia can make cats lose their appetite. An infected cat may eat less food or refuse to eat at all.
  • Vomiting – Some cats with giardia will vomit in addition to having diarrhea. The irritation from the infection can cause nausea and vomiting.

Other symptoms of giardia may include gas, abdominal pain, dehydration, and weight loss. Giardia infections are not always obvious so it’s a good idea to have a stool sample tested if chronic digestive issues arise. (Source)

Getting your cat tested and treated

If you suspect your cat may have giardia, the best thing to do is take your cat to the veterinarian. The vet can test a stool sample to check for the presence of giardia parasites and confirm a diagnosis.

There are several medications that can be prescribed to kill the giardia parasites in cats. Fenbendazole is one commonly used medication. According to the VCA Animal Hospitals, fenbendazole is given orally for 3-5 days to treat giardia in cats [1]. Fenbendazole works to disrupt the microtubules in giardia parasites, which effectively kills the parasites. Other potential medications include metronidazole or tinidazole.

It’s important to finish the full course of medication as prescribed by your vet to fully eliminate the giardia infection. Even after treatment, your vet may recommend follow-up stool tests to confirm the parasites have been cleared.

In addition to medication, your vet can provide guidance on environmental disinfection and stopping the spread of infection to other pets.

Disinfecting your home

If your cat has been diagnosed with giardia, it’s important to thoroughly disinfect your home to prevent reinfection and reduce the chances of spreading the parasite. Bleach is an effective disinfectant that kills giardia cysts. The CDC recommends using 1 part bleach to 9 parts water to disinfect surfaces.

Be sure to wear gloves when using bleach and do not mix it with other chemicals. Focus on disinfecting areas your cat frequents such as their litter box, food and water bowls, bedding, and anywhere they like to sleep. Scrub litter boxes with the bleach solution and allow them to air dry.

For carpets and rugs, use a carpet steamer to heat the fibers to a high temperature that will kill giardia cysts. Wash any cat beds, blankets, sheets, and towels your cat uses in hot water and dry thoroughly. Continue disinfecting your home until your cat’s infection has fully cleared.

Here are some helpful CDC guidelines on disinfection when dealing with giardia:

Risk factors for humans

Although anyone can become infected with Giardia, certain groups have a higher risk of contracting the parasite:

Young children – Children are at a much higher risk of Giardia infection than adults. Children under the age of 10 have infection rates that are 2-3 times higher than adults. This is likely due to poorer hygiene habits and higher exposure from contaminated sources like water or surfaces.

Elderly – Older adults also have an increased risk of acquiring giardiasis. Their weaker immune systems make it harder to fight off the parasite once infected. Additionally, medications and health conditions common in the elderly can make symptoms worse.

Those with weakened immune systems – Anyone with a compromised immune system is more susceptible to getting sick from Giardia. This includes people with HIV/AIDS, cancer patients undergoing chemotherapy, and those taking immunosuppressant medications like steroids or drugs for autoimmune disorders.

Proper handwashing and avoiding potentially contaminated food and water sources are important preventative measures, especially for high risk groups. Seeking prompt treatment when symptoms appear can help reduce the duration and severity of illness.

Treating giardia in humans

The most common prescription antibiotic used to treat giardia is metronidazole, according to the CDC ( Metronidazole is taken orally for 5-7 days. Tinidazole is another antibiotic that can be prescribed and only needs to be taken for 1-2 days.

These antibiotics work by stopping the growth of the giardia parasite. It is important to take the full course as prescribed, even if symptoms improve, in order to fully eliminate the infection.

Over-the-counter medications like loperamide or bismuth subsalicylate can help manage diarrhea symptoms. Staying hydrated with fluids and electrolytes is also important. Probiotics may help restore healthy gut bacteria after antibiotic treatment.

See a doctor if symptoms persist after treatment, as further testing may be needed. Recurrent infections can occur after treatment.

When to see a doctor

If your diarrhea, stomach cramping, bloating, and nausea persist for more than 1 week without improvement, it’s important to see your doctor for an evaluation (source). Giardia usually resolves on its own within a few weeks, but a lingering infection can lead to dehydration and malnutrition. Getting tested can confirm if Giardia is the cause of your symptoms.

Signs of dehydration include dry mouth, decreased urine output, dizziness, and dark yellow urine. Severe dehydration requires urgent medical care to prevent complications. Your doctor can assess for dehydration and may recommend IV fluids if necessary.

To test for Giardia, your doctor will likely collect a stool sample and send it to a lab for microscopic examination or antigen testing. This is the most accurate way to diagnose a Giardia infection (source). Your doctor can provide proper treatment if Giardia is confirmed.

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