Symptoms and Complications
For most of us, the immune system never reaches a state where toxoplasmosis
can get enough of a foothold to cause symptoms. However, a few healthy people
suffer mild symptoms from toxoplasmosis infection.
About 80% to 90% of us show no symptoms when we first get toxoplasmosis. About
10% to 20% of us will develop symptoms that are similar to infectious mononucleosis
("mono"). There may be a low-grade fever, muscle aches, sore throat,
and swollen glands. There may also be a mild anemia. Usually the only symptom
is slightly swollen glands. These symptoms can last for a long time - in
some cases, up to a year.
People with weak immune systems feel much worse, with high fever, chills and
sweating, rashes, and possible inflammation of the brain (encephalitis),
its lining (meningitis), the heart (myocarditis), the lungs (pneumonitis),
and various other organs. Even people with strong immune systems very occasionally
get severe disease.
Of people with AIDS, about 40% develop disease from toxoplasmosis, usually
because of the reactivation of an old infection. Most of these infections
involve the central nervous system. They cause conditions such as:
- coma
- loss of vision or other senses
- meningoencephalitis (inflammation of the brain and its lining)
- partial paralysis
- tremors
In about 60% to 90% of AIDS-related cases of toxoplasmosis, the onset of the
disease is quite slow and subtle. There may be changes in emotions, behavior,
or cleanliness. Later, there may be numbness or weakness in the arm a leg. Eventually
the person will drift off into a coma. About 15% to 25% of AIDS-related cases
of toxoplasmosis are first noticed when the person has a seizure or bleeding
in the brain.
People with AIDS need immediate treatment or the disease may be fatal. Even
if they recover, they must usually stay on preventive medication indefinitely
because the parasite is likely to reappear.
Women who already have toxoplasmosis infection and become pregnant have
little to worry about. But if a woman becomes infected while pregnant, there's
a risk the fetus will be infected. The risk is about 15% in the first trimester.
Fetuses infected at this stage often miscarry. The risk of infection of the
fetus rises to 30% if infection occurs in the second trimester and rises up
to 60% if infection occurs in the third trimester.
Babies infected late in pregnancy rarely miscarry but instead have symptoms
such as:
- brain damage
- enlarged spleen and liver
- eye damage
- jaundice
- poor motor coordination
- unusually small head
- rash
Early blindness and death are all too likely in these cases. Less severe infections
may not be obvious at birth. The baby often grows up into a healthy young adult.
But around age 20 or 30, the eyesight starts to degenerate as toxoplasma attacks
the retina, the light-sensitive membrane at the back of the eye. Ocular toxoplasmosis
can cause pain, blurred vision, and permanent damage, including blindness.
Recent evidence suggests that healthy people who catch toxoplasmosis as adults
can also occasionally suffer ocular damage.