Toxoplasmosis

Toxoplasmosis (tok-so-plaz-MO-sis), often called toxo, is an infection caused by the Toxoplasma gondii parasite that animals can transmit to people. It usually causes no symptoms in healthy people, but it can be serious in people with weak immune systems and in unborn babies.

What Is Toxoplasmosis?

Toxoplasmosis is a disease caused by the microscopic parasite Toxoplasma gondii. This parasite lives in the soil and can infect humans and many species of animals. It is particularly common in cats, and the parasite's eggs pass from their bodies in their feces (FEE-seez, or bowel movements). Touching dirty litter from a car's litter box is one common way that people contract the parasite. The eggs can stick to a person's hands and may eventually end up in the mouth, where the person can inadvertently swallow them. People also become infected by accidentally eating contaminated soil or by eating raw or undercooked meat, especially pork, lamb, and venison, containing the parasite's cysts. Thorough cooking kills the parasite.

In addition, pregnant women can pass the disease to their unborn babies, leading to congenital toxoplasmosis, a condition that can range from mild to severe, and may involve developmental problems and mental retardation, seizures, and vision problems.

In rare cases, blood transfusions, organ transplants, and laboratory accidents also can cause toxoplasmosis.

Toxoplasmosis is a life-long infection, although usually it is latent (inactive). Most people with toxoplasmosis have no symptoms or symptoms that are very mild. The disease can be life-threatening, however, for people with weakened immune systems and for babies born with the disease. Toxoplasmosis also may cause miscarriage or stillbirth.

How Common Is Toxoplasmosis?

The Centers for Disease Control estimates that T. gondii infects more than 60 million Americans, but cases of actual disease are much less common. Most people who carry the parasite have no symptoms of illness.

What Are the Symptoms of Toxoplasmosis?

Most people with toxoplasmosis, including pregnant women, have no symptoms. When symptoms do appear, they usually appear within 10 days of exposure, and they vary with the person's age and the response of his or her immune system. Children with toxoplasmosis fall into three groups:

* Babies born with toxoplasmosis: Congenital infection occurs when babies get toxoplasmosis before birth from their mothers. Most of these babies (85 percent) appear normal at birth but later have learning disabilities, movement disorders, mental retardation, and loss of vision.

* Healthy children who become infected: These children may have no symptoms, or they may have swollen glands, fever, general tiredness, and weakness.

* Children with immune disorders such as AIDS or cancer: These children may have severe infections, which attack the central nervous system, brain, lungs, and heart. Symptoms may include fever, seizures, headache, psychosis (severe mental disturbance), and problems in vision, speech, movement, or thinking.

For most people who get toxoplasmosis after birth, symptoms may include:

* fever

* night sweats

* weight loss

* general tiredness

* sore throat

* muscle pain

* swollen lymph nodes

* calcium deposits in the brain