Toxoplasmosis

10. Toxoplasmosis

Toxoplasmosis passes from animals to humans, sometimes without causing any symptoms. When kids do have symptoms, they vary depending on the child's age and the immune system's response to the infection. (As with humans, infected cats often don't show any signs of a toxoplasmosis infection.)

Toxoplasmosis infections in people fall into three basic patterns:

• congenital toxoplasmosis, in which the child becomes infected before birth
• toxoplasmosis in an otherwise healthy child (these are the same symptoms a pregnant woman may experience)
• toxoplasmosis in a child with a weakened immune system

Congenital toxoplasmosis

When a pregnant woman (even one who has no symptoms) catches toxoplasmosis during pregnancy and remains untreated, there's a chance that she could pass the infection on to her developing fetus. Babies who become infected during their mother's first trimester tend to have the most severe symptoms.

However, it's rare that a woman who got toxoplasmosis before getting pregnant will pass the infection on to her unborn baby because she (and, therefore, her baby) will have built up immunity to the infection. It can occur, though, if a pregnant woman who's had a previous infection becomes immunocompromised and her infection is reactivated. Generally, it's probably a good idea to wait to try to get pregnant until at least 6 months after a toxoplasmosis infection.

Up to 90% of children born with congenital toxoplasmosis have no symptoms early in infancy, but a large percentage will show signs of infection months to years later. Others show clear signs of infection either at birth or within the first month of life. Some are born prematurely or are unusually small at birth. Other signs and symptoms, if there are any at all, may include:

• fever
• swollen glands (lymph nodes)
• jaundice (yellowed skin and eyes caused by abnormal levels of a liver chemical called bilirubin)
• an unusually large or small head
• rash
• bruises or bleeding under the skin
• anemia
• enlarged liver or spleen

Some babies with congenital toxoplasmosis have brain and nervous system abnormalities that cause:

• seizures
• limp muscle tone
• feeding difficulties
• hearing loss
• mental retardation
• They're also at high risk for eye damage involving the retina (the light-sensitive lining at the back of the eye responsible for sight), resulting in severe vision problems.

If a child is born with congenital toxoplasmosis and remains untreated during infancy, there's almost always some sign of the infection (often eye damage) by early childhood to adolescence.

Toxoplasmosis in an otherwise healthy child

A healthy child who becomes infected with toxoplasmosis may have no symptoms of infection or only a few swollen glands that:

• usually appear in the child's neck
• are sometimes tender to the touch
• may become larger and smaller over several months
• A child typically will not experience any long-term problems if he or she goes undiagnosed and untreated.

Toxoplasmosis in a child with a weakened immune system

Kids whose immune systems are weakened (for example, by AIDS, cancer, or medications taken after organ transplants) are at special risk for severe toxoplasmosis infections. Especially in children with AIDS, toxoplasmosis can attack the brain and nervous system, causing toxoplasmic encephalitis (an inflammation of the brain) with symptoms including:

• fever
• seizures
• headache
• psychosis (a type of severe mental illness)
• problems with vision, speech, movement, or thinking