Toxoplasmosis is an infection due to the parasite Toxoplasma gondii.A.D.A.M.

Causes, incidence, and risk factors

Toxoplasmosis is found in humans worldwide, and in many species of animals and birds. Cats are the definitive host of the parasite.

Human infection may result from:

• Blood transfusions or solid organ transplants
• Carelessly handling cat litter, which can lead to accidental consumption of infectious particles
• Eating contaminated soil
• Eating raw or undercooked meat (lamb, pork, and beef)

Toxoplasmosis also affects people who have weakened immune systems.

The infection may also be passed from an infected mother to her baby through the placenta. See: Congenital toxoplasmosis

Symptoms

There may be no symptoms. Symptoms usually occur about 1 to 2 weeks after you come in contact with the parasite. The disease can affect the brain, lung, heart, eyes, or liver.

Symptoms in persons with otherwise healthy immune systems:

• Enlarged lymph nodes in the head and neck
• Headache
• Fever
• Mild illness similar to mononucleosis
• Muscle pain
• Sore throat

Symptoms in people with a weakened immune system:

• Confusion
• Fever
• Headache
• Blurred vision due to inflammation of the retina
• Seizures

For information on babies born with the condition, see: congenital toxoplasmosis

Signs and tests

The doctor or nurse will perform a physical exam. Tests that may be done include:

• Antibody titers for toxoplasmosis
• Cranial CT scan
• MRI of head
• Slit lamp exam
• Brain biopsy

Treatment

Those without symptoms typically do not need treatment.

Medications to treat the infection include an antimalarial drug and antibiotics. AIDS patients should continue treatment for as long as their immune system is weak to prevent the disease from reactivating.

For information regarding treatment of babies and pregnant women, see congenital toxoplasmosis.

Expectations (prognosis)

With treatment, people with a healthy immune system usually recover well.

Complications

The disease may return.

In people with a weakened immune system, the infection may spread throughout the body. This can be deadly.

Calling your health care provider

Call for an appointment with your health care provider if you develop symptoms of toxoplasmosis. Immediate medical care is needed if symptoms occur in:

• Infants or babies
• Someone with a weakened immune system due to certain medications or disease

Immediate medical treatment is also needed if the following symptoms occur:

• Confusion
• Seizures

Prevention

Tips for preventing this condition:

• Do not eat undercooked meat.
• Wash hands after handling raw meat.
• Keep children's play areas free from cat and dog feces.
• Wash your hands thoroughly after touching soil that may be contaminated with animal feces.

Pregnant women and those with weakened immune systems should take the following precautions:

• Do not clean cat litter boxes
• Do not touch anything that may contain cat feces
• Do not touch anything that could be contaminated by insects exposed to cat feces (cockroaches, flies, etc.)

Pregnant women and those with HIV should be screened for toxoplasmosis. A blood test can be done.

References

1. Montoya JG. Toxoplasmosis. In: Goldman L, Schafer AI, eds.Cecil Medicine. 24th ed.Philadelphia,PA: Saunders Elsevier; 2011:chap 357.

Review Date: 12/6/2011.

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.