One of the most common infectious diseases, toxoplasmosis results from the protozoa Toxoplasma gondii. Distributed worldwide, it's less common in cold or hot arid climates and at high elevations. It usually causes localized infection but may produce significant generalized infection, especially in immunodeficient patients or neonates.
Congenital toxoplasmosis, characterized by lesions in the central nervous system, may result in stillbirth or serious birth defects.
Causes of Toxoplasmosis:
T. gondii exists in trophozoite forms in the acute stages of infection and in cystic forms (tissue cysts and oocysts) in the latent stages. Ingestion of tissue cysts in raw or undercooked meat (heating, drying, or freezing destroys these cysts) or fecal-oral contamination from infected cats transmits toxoplasmosis. However. toxoplasmosis also occurs in vegetarians who aren't exposed to cats, so other means of transmission may exist.
Congenital toxoplasmosis follows transplacental transmission from a chronically infected mother or one who acquired toxoplasmosis shortly before or during pregnancy.
Signs and symptoms of Toxoplasmosis:
The following signs and symptoms characterize congenital toxoplasmosis and acquired toxoplasmosis.
Toxoplasmosis acquired in the first trimester of pregnancy often results in still-birth. About one-third of infants who survive have congenital toxoplasmosis. The later in pregnancy maternal infection occurs, the greater the risk of congenital infection in the infant.
Obvious signs of congenital toxoplasmosis include retinochoroiditis (see Ocular toxoplasmosis), hydrocephalus or microcephalus, cerebral calcification, seizures, lymphadenopathy, fever, hepatosplenomegaly, jaundice, and rash. Other defects, which may become apparent months or years later, include strabismus, blindness, epilepsy, and mental retardation.
Acquired toxoplasmosis may canse localized (mild lymphatic) or generalized (fulminating, disseminated) infection. Localized infection produces fever and a mononucleosis-like syndrome (malaise, myalgia, headache, fatigue, sore throat) and lymphadenopathy.
Generalized infection produces encephalitis, fever, headache, vomiting, delirium, seizures, and a diffuse maculopapular rash (except on the palms, soles, and scalp). Generalized infection may lead to myocarditis, pneumonitis, hepatitis, and polymyositis.
Diagnosis of Toxoplasmosis:
Identification of T. gondii in an appropriate tissue specimen confirms toxoplasmosis. Serologic tests may be useful, and in patients with toxoplasmosis encephalitis, computed tomography and magnetic resonance imaging scans disclose lesions.
Treatment of Toxoplasmosis:
Acute disease is treated with sulfonamides and pyrimethamine for about 4 weeks and, possibly, folinic acid to control side effects. In patients who also have acquired immunodeficiency syndrome, treatment continues indefinitely.
No safe, effective treatment exists for chronic toxoplasmosis or toxoplasmosis occurring in the first trimester of pregnancy.
Special considerations and Prevention tips of Toxoplasmosis:
1. When caring for patients with toxoplasmosis, monitor drug therapy carefully and emphasize thorough patient teaching to prevent complications and control spread of the disease.
2. Because sulfonamides cause blood dyscrasias and pyrimethamine depresses bone marrow, closely monitor the patient's hematologic values.
3. Report all cases of toxoplasmosis to your local public health department.
4. Instruct patients to wash hands after working with soil and to cover children's sandboxes (because soil and sand may be contaminated with cat oocysts).
5. Change cat litter daily because cat oocytes don't become infective until 1 to 4 days after excretion. Cook meat thoroughly and freeze it promptly if it's not for immediate use.
