Toxoplasmosis is an infection caused by a tiny organism called a protozoon. Many people are infected with this protozoon. However, few people have any symptoms or problems from it.


Toxoplasmosis is passed from animals to humans. People can contract it by:

  • Touching infected cat feces or something that has had contact with cat feces, such as soil or insects
  • Eating undercooked, infected meat, or by touching your mouth after touching the meat
  • In rare cases, receiving a blood transfusion]]> or an organ transplant

A pregnant woman who gets toxoplasmosis for the first time has a 15% to 60% chance of passing it to her unborn child. Active infection usually occurs only once in a person’s life, although the protozoon remains inactive in the body. If a woman has become immune to the infection before getting pregnant, she will not pass the condition to her baby.


Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. People at risk for having symptoms from toxoplasmosis are:

  • Babies born to mothers who are first exposed to toxoplasmosis just before becoming pregnant or during pregnancy
  • People with very weakened immune systems from causes such as:



Most people do not have symptoms. Those who do have symptoms may experience the following:

  • Swollen lymph nodes
  • Fever
  • Fatigue
  • Sore throat]]>
  • Muscle aches and pains
  • Rash

People with weakened immune systems may develop toxoplasmosis infections in multiple organs. Infection is most common in the brain ( ]]>encephalitis]]> ), eye ( ]]>chorioretinitis]]> ), and lung (pneumonitis). Symptoms may include:

  • Fever
  • ]]>Seizures]]>
  • Headache
  • Visual defects
  • Problems with speech, movement, or thinking
  • Mental illness
  • Shortness of breath


Swollen brain
© 2009 Nucleus Medical Art, Inc.

In babies, the severity of symptoms depends on when during pregnancy the mother became infected. If infection occurs during the first three months of pregnancy, babies are less likely to become infected, but if they do, their symptoms are much more severe. During the last six months, babies are more likely to become infected, but their symptoms are less serious. Toxoplasmosis can also cause miscarriage or stillbirth.

About one in 10 babies born with toxoplasmosis has severe symptoms. These include:

Many babies infected with toxoplasmosis who seem healthy at birth may develop problems months or years later. These include:

  • Visual defects
  • ]]>Hearing loss]]>
  • Learning disabilities
  • Seizures



The doctor will ask about symptoms and medical history, and perform a physical exam. Blood tests are done to look for antibodies produced by the body to fight the toxoplasmosis. Other lab tests are done to look for the protozoon itself.

If a pregnant woman is infected, prenatal tests, including ultrasound]]> and ]]>amniocentesis]]> , are performed to determine if the fetus is infected.


People who are healthy and not pregnant do not need treatment. Symptoms usually go away within a few weeks to months. People with a weakened immune system are treated with antitoxoplasmosis medicines for several months.

If a pregnant woman is infected but the fetus is not, the mother is usually given the antibiotic spiramycin. This medicine can decrease the chance of the fetus becoming infected by about 60%.

Fetuses with confirmed toxoplasmosis infections are treated by giving the mother the following combination of three medications:

  • Spiramycin
  • Pyrimethamine
  • Sulfadiazine
  • Folinic acid

These drugs can reduce the severity of, but not eliminate, a newborn's symptoms. Once born, the infant will be given different combinations of medicines.


Women who are pregnant or considering becoming pregnant should talk to their physician about taking a blood test to determine if they are immune to toxoplasmosis (which would indicate a previous exposure). If they are not, they should take the following steps to avoid sources of toxoplasmosis:

  • Do not eat raw or undercooked meat. If you touch raw meat, do not touch your eyes, mouth, or nose. Wash your hands, cutting boards, knives, and sink with soap and warm water.
  • Wash all raw vegetables and fruits.
  • Do not empty a cat’s litter box. Have someone else do it.
  • Avoid children’s sandboxes. Cats may use them for a litter box.
  • Do not feed your cat raw or undercooked meat.
  • Keep your cat inside to prevent it from hunting rodents or birds that could be infected.
  • Wear gloves when gardening. Keep your hands away from your eyes, mouth, and nose. Wash your hands when done.

These steps also apply to people with weakened immune systems.