For people with weakened immune systems (especially those with AIDS), toxoplasmosis can cause major infections of the brain or, less commonly, the lungs or heart. Severe disease can be fatal.

How Is Toxoplasmosis Diagnosed?

If toxoplasmosis is suspected, the doctor draws a blood sample and tests it for evidence of the parasite. For people who have weakened immune systems and are therefore more likely to develop a severe infection, a doctor may order a magnetic resonance imaging* (MRI), a computerized tomography (CT) scan of the head, or rarely, a brain biopsy (removing a small sample of brain tissue to examine) to look for signs of damage caused by the parasite.

The doctor may also suggest a visit to an ophthalmologist for an eye exam, which may include the use of a special lamp called a slit lamp to check for signs of the disease in the eyes. These signs may include reduced, hazy, or blurred vision; pain when looking into bright light; eye redness; tearing; inflammation in the back of the eye; swelling in part of the retina; and lesions (injuries) in the retina and/or an adjacent membrane called the chorioid. Ophthalmologists sometimes prescribe medicine to treat an active disease. Occasionally, an eye doctor may find signs of a prior infection with the Toxoplasma gondii parasite during a routine eye exam, even though the patient never experienced or noticed any symptoms. This is not a cause for alarm, but pregnant women and those with weakened immune systems should discuss the findings with their regular doctor to determine whether they should take any additional precautions to prevent repeat infection.

What is the Treatment for Toxoplasmosis?

People who have symptoms from toxoplasmosis but are otherwise healthy do not need any treatment, and their symptoms will likely only last a few days. Doctors treat with medication pregnant women, newborns with the congenital infection, and people with weak immune systems. Patients with AIDS often continue taking the medicine even after the infection clears up to keep it from returning. In newborns and patients with unhealthy immune systems, the illness can last for weeks or months, and it can cause permanent disability.

How Is Toxoplasmosis Prevented?

Toxoplasmosis can be prevented by careful attention to hygiene and sanitation. Preventive steps include:

* Thoroughly cooking meat, which means heating it to an internal temperature of 160 degrees Fahrenheit, and until it is no longer pink in the center or until the juices run clear.

* Washing hands, utensils, and food preparation surfaces after handling meats.

* Washing fruits and vegetables before eating them

* Keeping flies and cockroaches away from food

* Washing hands after petting cats and changing litter boxes

* Wearing gloves when working in the garden or cleaning sandboxes.

* Keeping outdoor sandboxes covered when not in use so that they will not be used as litter boxes by cats who roam outdoors

In addition, pregnant women and people whose immune systems are weak can take additional precautionary measures, including being tested for the parasite. This allows the doctor to discover the infection and begin treatment even if the individual does not have any symptoms. Even if people in these groups do not have an infection, they should be especially

careful to avoid contact with soil, uncooked meat, and strange or stray cats. In addition, they should keep their own cats indoors and on a diet of canned or dried cat food because cats can pick up the parasite from cating raw meat.

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