Toxoplasmosis in Cats

Toxoplasmosis is caused by a microscopic protozoan Toxoplasma gondii. The organism exist in in the intestinal tract of cats and in the tissues of many rodents and animals raised for human food. Although cats are the only domesticated animal that can shed the parasite’s eggs (also known as oocysts) in their feces, Toxplasma gondii also resides in animals’ tissues and is released when other animals or humans consume that meat.

Toxoplasma infection in the feline:

Most cats are asymptomatic, meaning they do not show signs of disease, even when they are carriers of the parasite. When symptoms are apparent, the cat may have diarrhea, weight loss, and transient fever, and rarely can have neurological signs.

Transmission to people:

People are most commonly infected as a result of eating raw or undercooked meat (the most common route, as noted on the US Center for Disease Control website), but also can contract Toxoplasmosis by ingesting food or water contaminated with cat feces. This includes if the person has fecal matter on their hands, as in cleaning a litter box, or cleaning any area where an infected cat has defecated, and then puts their uncleaned hands into their mouth.

Clinical signs noted to occur in people (Note: if you have any concerns, please see your primary care physician):

Most commonly, people whom have been exposed to toxoplasmosis, are asymptomatic and have no health concerns associated with exposure.
In the symptomatic person, signs resemble the common flu (fever, malaise, enlarged lymph nodes, fatigue, headache, and discomfort when swallowing.) In the most severe cases, the parasite can invade the central nervous system, including brain tissue, and cause significant morbidity and in extreme cases, can be fatal.

Who is at risk?

The most likely subset of patients to actually develop illness from toxoplasmosis are those individuals that are immunocompromised. This includes the elderly, young children, or any patient on immunosuppressive medications or on chemotherapy, or those patients with Human Immunodeficiency Virus (HIV).
For many years, there was a significant fear related to pregnancy and toxoplasmosis infection. After years of research and data retrieval, it was found that those women at the highest risk were those that became infected or exposed for the first time whilst pregnant. In that population, the risks include infecting the fetus, stillbirths, spontaneous abortions, and birth defects.

It is important to also know, that once you are found to be sero-positive (meaning a blood test shows that you have been exposed to the parasite) you will always have a positive test result. This does not mean, however, that you will ever become sick or have any ill effects from the disease.

Do you need to get rid of your cat or have it tested if you are an “at risk” individual?

According to the CDC: “Cats only spread Toxoplasma in their feces for a few weeks following infection with the parasite. The Toxoplasma shedding in feces will go away on its own; therefore it does not help to have your cat or your cat’s feces tested for Toxoplasma.”

We would recommend that if you are concerned and/or you are an at-risk individual, that you take universal precautions with your cat:
– Always change your cat litter, or outdoor sandboxes daily – If you are at risk, either wear examining gloves (latex or nitrile) when cleaning these areas – If possible, have a person that is not “at risk” do this cleaning for you – ALWAYS WASH YOUR HANDS after handling fecal material.

For more information associated with humans and Toxoplasmosis, please see the Center for Disease Control’s website:

Works Cited:

Dubey, JP and Lappin, MR. Toxoplasmosis and Neosporosis. Greene Infectious Diseases of the Dog and Cat. Third edition. Chapter 80. Pp 754-775. Saunders Elsevier. 2006.
Montoya JG, Liesenfeld. Toxoplasmosis. Lancet. 2004 Jun 12;363:1965-1976.

Steven Berkowitz, DVM
Dr. Steven Berkowitz attended St. Georges University and did his clinical year at the University of Illinois. Berkowitz joined NorthStar VETS after serving as the Chief of Emergency and Critical Care at another specialty hospital. Prior to that, he completed a three-year residency in Emergency and Critical Care medicine at the Oradell Animal Hospital in Paramus, NJ. His residency was completed at one of only a few recognized veterinary trauma centers in the United States. Prior to his residency, he was a staff Emergency Veterinarian at Animal Specialty Center in Yonkers, NY as well as serving as an emergency doctor at Animal Emergency and Referral Associates in Fairfield, NJ for 3 years. Dr. Berkowitz can be seen on seasons 5 and 6 of “Animal Precinct” on Animal Planet, which was filmed during his internship at The Bergh Memorial Animal Hospital of the ASPCA in New York City.
Dr. Berkowitz has special interest in the management of metabolic and endocrine derangements, trauma, as well as management of the septic patient.

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