Toxoplasmosis is caused by a parasite that lives inside cells. Toxoplasmosis is a zoonotic disease, which means that people can acquire the infection from animals. Any mammal can be infected, but only cats can produce the infective form of the organism, called an oocyst. Many cats, dogs, and people have evidence of exposure to the toxoplasma organism, but clinical disease is very rare. Contrary to popular belief, owning a cat is not a common way to acquire toxoplasmosis. In fact, the primary risk factors in the United States for acquiring toxoplasma infection are eating undercooked meat or ingesting contaminated water or soil. Animals become infected by ingesting tissue cysts (eating contaminated meat), ingesting oocysts (fecal-oral infection, like drinking contaminated water), or by congenital infection (infection across the placenta). Most cats are infected congenitally or by hunting behavior soon after weaning.
Scientific name:Toxoplasma gondii infection
In cats, illness is most common and most severe in kittens who are infected across the placenta or by nursing. Many are stillborn, and others die shortly after birth. Surviving kittens can show signs of inflammation in the liver, lungs, and brain. Infections in adult cats are rare. Exceptions include an overwhelming infection in a cat never before exposed to the organism, or an exposed cat who becomes immuno-suppressed for some reason (like a virus or immuno-suppressive medication).
Studies have shown that 30% of U.S. cats and dogs show evidence of exposure (not infection) to the toxoplasma organism. Twenty five to 50% of Americans show evidence of exposure to toxoplasma. Actual infection and disease caused by Toxoplasma gondii is very rare.
Animals and people living in rural areas are more likely to be exposed to toxoplasma.
Clinical signs (primary,most to least frequent, scientific term, synonyms)
Clinical signs are fairly non-specific, meaning that they could be caused by many other things besides toxoplasmosis, depression, lethargy (tiredness), dyspnea (difficulty breathing), fever, weight loss, muscle pain, central nervous system abnormalities, icterus (yellow coloring to skin, whites of eyes, etc.), ocular abnormalities (uveitis, chorioretinitis), vomiting and diarrhea.
Clinical signs (secondary,most to least frequent, scientific term, synonyms)
Ascites (fluid build-up in the abdomen), enlarged spleen or lymph nodes, joint pain.
Cause (scientific, common term)
Organ system affected (most to least affected)
Lungs, central nervous, system/brain, liver, pancreas, heart, eyes.
Baseline bloodwork, including complete blood count, chemistry panel, and urinalysis. IgM and IgG titers for Toxoplasma, Toxoplasma organisms are rarely seen in tissue or fluid samples, no diagnostic test is 100% accurate, and sometimes a diagnosis of toxoplasmosis is one of exclusion.
Many diseases mimic the signs and symptoms of toxoplasmosis, and most are more common than toxoplasma infection.
Toxoplasma gondii is a parasite that lives inside mammalian cells. Any mammal can be infected, but only cats are capable of excreting infective organisms in their feces. Cats only shed organisms in their feces 3-21 days after initial infection, and repeated shedding of organisms is rare. Toxoplasmosis is a public health concern because human beings can be infected.
Infection in cats severe enough to cause illness is rare, with most cases of death reported in kittens that were infected across the placenta during pregnancy or by nursing from an infected mother. There have been cases of adult cats becoming ill with toxoplasmosis. Cats who are immunosupressed are at increased risk, but even so, the risk is very low. Clinical signs are vague and often not directly attributable to toxoplasma infection. These signs could include fever, depression, tiredness, and signs related to dysfunction in the lungs, muscles, brain, eyes, liver, and pancreas
Toxoplasma is a public health concern. Otherwise healthy people infected with toxoplasma may only experience flu-like symptoms. However, in AIDS patients, infection with toxoplasmosis is very severe, and causes many deaths. Congenital infection in people (infection to the fetus through the placenta) can lead to stillbirths, problems with the eyes and brain, deafness, respiratory disease, and liver disease.
Even though toxoplasmosis is a dangerous and serious disease in people, it is important to understand that owning a cat is not a common way to become infected with toxoplasmosis. In fact, no direct correlation has been found between owning a cat and infection with toxoplasmosis. The majority of people who are infected with Toxoplasma gondii are infected by eating undercooked meat (especially lamb and pork), or by ingesting contaminated water or soil. Accidental ingestion takes places when people garden without gloves, play in contaminated sandboxes, or eat root vegetables that are unwashed. These areas can be contaminated with feces from free-roaming cats.
There is absolutely no need to give up a cat because of fear of infection with toxoplasmosis. Simple steps to avoid exposure include:cook meats thoroughly, wear gloves when gardening, thoroughly wash root vegetables, cover sandboxes, keeping cats indoors, feeding cats commercial diets (no raw meat), scooping litter boxes daily. Oocysts take 1-5 days to sporulate, or to become infective. Removing feces the day they are deposited in the box greatly decreases the unlikely possibility that any present oocysts could become infective.
Home care for a cat infected with toxoplasmosis in not recommended. Veterinary care is recommended.
The mainstays of treatment for toxoplasmosis are antibiotics with anti-protozoal effects. Supportive care for any organ systems affected is also important.
Consultation with a veterinarian is key feline toxoplasmosis is suspected.
The prognosis for congenitally affected kittens is grave. Most infected adults will recover. Affected adults who are immuno-compromised may have difficulty fighting the disease and have a much poorer prognosis. Luckily, toxoplasmosis infection in cats causing clinical disease is very rare.
Bernsteen, L., et al. Acute toxoplasmosis following renal transplantation in three cats and a dog. Journal of the American Veterinary Medical Association 1999; 215:1123-1126.
Toxoplasmosis in Cats, available at: http://www.vet.cornell.edu/fhc/resources/
Ettinger, S.J. & Feldman, E.C. Textbook of Veterinary Internal Medicine (6th ed.). Elsevier Saunders, 2005; 638-42.
Dubey JP. And Lapin MR. Toxoplasmosis and Neosporosis. In: Greene, Craig E., ed. Infectious Diseases of the Dog and Cat, 3rd edition. St. Louis: Elsevier, 2006; 754-68.
Jones, J.L., et al. Toxoplasmosis-related knowledge and practices among pregnant women in the United States. Infectious Disease in Obstetetrics and Gynecology 2003; 9:1999-2000.
Kravetz, J.D. & Federman, D.G. Prevention of toxoplasmosis in pregnancy: knowledge of risk factors. Infectious Disease in Obstetetrics and Gynecology 2005; 13:161-165.
Emmy Pointer, DVM
Sharon Gwaltney-Brant DVM, PhD