Toxoplasmosis is an infection due to the parasite Toxoplasma gondii.

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
• 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

Most primary infections produce no symptoms. The time between exposure to the infection and symptom development is 1 - 2 weeks. 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
• Mild illness with fever, similar to mononucleosis
• Muscle pain
• Sore throat

Symptoms in immunosuppressed persons:

• Confusion
• Fever
• Headache
• Retinal inflammation that causes blurred vision
• Seizures

For symptoms in babies born with the condition, see congenital toxoplasmosis.

Tests to determine infection or to find cysts:

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

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.

Acute infection in children may cause swelling of the retina in the eye.

Toxoplasmosis in adults has a good outcome in people with a healthy immune system.

• Permanent disability, such as blindness or learning disorders, in infants with congenital toxoplasmosis
• Return of the disease
• Spread of infection in a person with a weakened immune system (can be deadly)

Call for an appointment with your health care provider if you develop symptoms of toxoplasmosis. This disorder requires urgent or emergency care if it occurs in an immunosuppressed person or in a baby, or if confusion, seizures, or other severe symptoms develop.

Tips for preventing this condition:

• Avoid undercooked meats.
• Freeze meat to minus 20 degrees Celsius for 2 days.
• Wash hands after handling raw meat.
• Protect children's play areas from cat and dog feces.
• Wash your hands thoroughly after contact with soil that may be contaminated with animal feces.
• Pregnant women should avoid cleaning cat litter boxes and materials that are potentially infected with cat feces. They should also avoid materials that could be contaminated by insects exposed to cat feces (cockroaches, flies, etc.).
• Pregnant women should have a blood test for toxoplasmosis.
• Patients with HIV disease should have their toxoplasma antibody titers checked. Those with positive blood test results and a CD4 count of less than 100 should take preventive antibiotics with antiretroviral therapy until the CD4 cell count has risen.

Cohen J, Powderly WG. Infectious Diseases. 2nd ed. New York, NY: Elsevier; 2004.

Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases. 6th ed. London: Churchill Livingstone; 2005.