Toxoplasmosis
Depending on their environment and eating habits, up to 70% of people in North America are infected with Toxoplasma gondii—making toxoplasmosis one of the most common infectious diseases. Occurring worldwide, it’s less common in cold or hot, arid climates and at high elevations.
The disease usually causes localized infection. However, it may produce significant generalized infection, especially in immunodeficient patients, such as acquired immunodeficiency syndrome (AIDS) patients, patients who have recently had an organ transplant, those with lymphoma, and those receiving immunosuppressant therapy.
Once infected, the patient may carry the organism for life. Reactivation of the acute infection can occur. Congenital toxoplasmosis, characterized by lesions in the central nervous system (CNS), may result in stillbirth or serious birth defects.
Causes
Toxoplasmosis is caused by the protozoan T. gondii, which exists in trophozoite forms in the acute stages of infection and in cystic forms (tissue cysts and oocysts) in the latent stages. The infection is transmitted by ingestion of tissue cysts in raw or undercooked meat (heating, drying, or freezing destroys these cysts) or by fecal-oral contamination from infected cats. Because toxoplasmosis has also struck vegetarians who aren’t exposed to cats, other means of transmission may exist.
Pediatric pointerCongenital toxoplasmosis follows transplacental transmission from a mother who acquires primary toxoplasmosis shortly before or during pregnancy. Congenital infection is more severe when acquired early in the pregnancy.
Complications
Toxoplasmosis may cause encephalitis, myocarditis, pneumonitis, hepatitis, or polymyositis. If the disease is acquired in the first trimester of pregnancy, it commonly results in stillbirth. About one-third of infants who survive have congenital toxoplasmosis with CNS involvement and chorioretinitis.
Assessment
The patient’s history may reveal an immunocompromised state, exposure to cat feces, or frequent ingestion of poorly cooked meat.
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