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Infectious Diseases

Exposed to toxoplasmosis in pregnancy



Hi, I tested negative for toxoplasmosis (IgG & IgM) at the beginning of my pregnancy and I had an exposure in my last trimester (week 35). My baby is now 7 weeks old and I got tested again for peace of mind. It came out positive (IgG positive, IgM negative). So, the baby was exposed in utero. She has no symptoms but I was told that babies exposed in last trimester show no symptoms usually until childhood or even adulthood. What are the chances she got it from me in the womb, and is it too late to treat her now? Will treating her do any good? Give me the worst case scenario on what effects this will have on her, please. Will she go blind and have eye lesions, hearing loss, etc? Please help! Thanks.


It is unusual for a person to become IgG positive for Toxoplasma (seroconvert) and remain IgM negative. There are occasional problems with results provided by non-specialized laboratories. The first thing that needs to be done is determine whether indeed you seroconverted which would indicate that you were recently infected with Toxoplasma. In order to do that, the blood sample drawn during pregnancy AND the one drawn after your baby was born need to be run IN PARALLEL. In your case, it is advisable to send the samples to a specialized laboratory. The national referral center for diagnosis of toxoplasmosis is the Research Institute of the Palo Alto Medical Foundation (Ph 650-326-8120). They run additional tests not available in the usual commercial laboratories. In addition, it may be a good idea to send them a sample of blood from your baby since the tests that they perform will help determine if she is infected with Toxoplasma. You are correct that babies born with congenital toxoplasmosis can be normal at birth. The later in pregnancy that the infection is transmitted to the baby, the more likely that the infection will be subclinical (no evidence of disease). Babies who acquire toxoplasmosis in the third trimester may develop inflammation of the choroid and retina of the eye which usually manifests during adulthood. This late infection tends to be more benign than those acquired in early stages of pregnancy. It is too premature to talk about treatment of your baby since the diagnosis of toxoplasmosis needs to be made first. Even when the mother becomes acutely infected during the third trimester, babies have a 40% chance of not being infected.

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Response by:

Carlos   Subauste, MD Carlos Subauste, MD
Assistant Professor
College of Medicine
University of Cincinnati