Causative Agent: Toxoplasmosis is caused by the parasite Toxoplasma gondii, which is ingested by cats when they eat raw meat or birds and mice. Domestic cats are the host species where the parasite reaches full maturity. This parasite lives in the small intestine of the host animal and its eggs are shed in the feces. Once shed, the eggs are hardy, and have been known to live in the environment for over 1 year. Once the eggs have hatched, they are able to infect almost all vertebrates, including humans.

Clinical Signs: Most cats infected with toxoplasmosis do not show signs of infection, unless they are young or stressed. In young animals, particularly kittens, the infection involves the whole body and symptoms include fever, anorexia, cough, difficulty breathing (dyspnea), diarrhea, and a yellow coloration commonly seen in the white of the eye and gums (jaundice).

Diagnosis: Toxoplasma antibodies can be identified using several available blood (serologic) tests. Among these tests are the indirect fluorescent antibody (IFA) test, and the enzyme-linked immunosorbent assay (ELISA). See page D135 for more information on serologic tests and testing.

Treatment: Once a diagnosis has been made, the cat can be treated with clindamycin (Antirobe). See page G33 for more information on clindamycin. If the cat is suffering severe clinical signs, supportive care (fluids and nutrition support) is required.

Prevention: There is no vaccine currently available for toxoplasmosis. To minimize egg transmission, cats should not be fed raw meat, or allowed to catch birds or rodents. Soiled litter should be disposed of daily, since this will minimize the chance for the toxoplasma eggs to hatch.

Public Health Concerns: Because toxoplasmosis is transmissible to humans, anyone who has contact with cats or cat feces should wear rubber gloves, and take caution to not contaminate benches, tables, or countertops. Humans become infected with toxoplasmosis when they eat undercooked meat or accidentally ingest cat feces contaminated with parasite eggs. A human can be infected with toxoplasmosis for a period of time and not show any symptoms. Women who are considering pregnancy and think they may have come in contact with toxoplasmosis in the past, should see their physician before becoming pregnant. This disease can cause miscarriage, stillbirth, and serious birth defects in a human fetus. Pregnant women should avoid handling any cat feces or cat litter.