Toxoplasmosis - Human

T gondii is an important zoonotic agent. In some areas of the world, up to 60% of the human population have serum IgG titers to T gondii and are likely to be persistently infected. Toxoplasmosis is a major concern for people with immune system dysfunction (eg, people infected with human immunodeficiency virus). In these individuals, toxoplasmosis usually presents as meningoencephalitis and results from the emergence of T gondii from tissue cysts located in the brain as immunity wanes rather than from primary T gondii infection. Toxoplasmosis is also a major concern for pregnant women because tachyzoites can migrate transplacentally and cause birth defects in human fetuses. Infection of women with T gondii may occur after ingestion of undercooked meat or accidental ingestion of oocysts from cat feces. To prevent infection, the hands of people handling meat should be washed thoroughly with soap and water after contact, as should all cutting boards, sink tops, knives, and other materials. The stages of T gondii in meat are killed by contact with soap and water. T gondii organisms in meat can also be killed by exposure to extreme cold or heat. Tissue cysts in meat are killed by heating the meat throughout to 67°C or by cooling to -13°C. Toxoplasma in tissue cysts are also killed by exposure to 0.5 kilorads of gamma irradiation. Meat of any animal should be cooked to 67°C before consumption, and tasting meat while cooking or while seasoning should be avoided. Pregnant women should avoid contact with cat litter, soil, and raw meat. Pet cats should be fed only dry, canned, or cooked food. The cat litter box should be emptied daily, preferably not by a pregnant woman. Gloves should be worn while gardening. Vegetables should be washed thoroughly before eating because they may have been contaminated with cat feces. At present there is no vaccine to prevent toxoplasmosis in humans.