Toxoplasmosis
Toxoplasmosis: Excerpt from Handbook of Diseases
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
T. gondii existsin 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. (See Avoidingtoxoplasmosis.)
Congenital toxoplasmosis follows transplacental transmission from a chronically infected mother or one who acquired toxoplasmosis shortly before or during pregnancy.
Signs and symptoms
The following signs and symptoms characterize congenital toxoplasmosis and acquired toxoplasmosis.
Congenital toxoplasmosis
Toxoplasmosis acquired in the first trimester of pregnancy often results in stillbirth. About one-third of neonates who survive have congenital toxoplasmosis. The later in pregnancy maternal infection occurs, the greater the risk of congenital infection in the neonate.
Obvious signs of congenital toxoplasmosis include retinochoroiditis, 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
Acquired toxoplasmosis may cause 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.
CLINICAL TIP: Approximately 80% to 90% of primary infections produce no symptoms.
Diagnosis
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
Acute disease is treated with sulfonamides and pyrimethamine for about 4 weeks and, possibly, folinic acid to control adverse effects. Asymptomatic individuals aren’t usually treated; however, children may be treated to prevent retinal inflammation. In patients who also have acquired immunodeficiency syndrome, treatment continues indefinitely.
CLINICAL TIP: No safe, effective treatment exists for chronic toxoplasmosis or toxoplasmosis occurring in the first trimester of pregnancy.
gender influence If the patient is pregnant, she should have a friend or a family member change her cat’s litter box daily. If this isn’t possible and she must do it on her own, she should wear gloves and wash her hands immediately afterward. Diligent hand washing is important because the parasite found in cat feces can infect a person a few days after being passed.
Special considerations
❑ When caring for patients with toxoplasmosis, monitor drug therapy carefully and emphasize thorough patient teaching to prevent complications and control spread of the disease.
❑ Because sulfonamides cause blood dyscrasias and pyrimethamine depresses bone marrow, closely monitor the patient’s hematologic values.
❑ Report all cases of toxoplasmosis to your local public health department.
Pictures
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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