All pregnant women and newborns should be screened for a serious infection called toxoplasmosis (search), says one group of researchers.

They say that the majority of women with the infection have no symptoms. Many don't realize they have been exposed to a parasite that can cause serious health risks or death to their baby.

Toxoplasmosis develops when a pregnant woman is exposed to the parasite Toxoplasmosis gondii in cat litter, undercooked meat, or garden soil, writes lead researcher Kenneth M. Boyer, MD, of Rush University Medical Center (search) in Chicago.

A pregnant woman has about a 40 percent chance of passing the infection to her unborn child, according to the March of Dimes (search). Only about 10 percent of infants with severe infections show signs of toxoplasmosis at birth. Many infected infants may not show signs until months or years later.

Boyer's study appears in the February issue of The American Journal of Obstetrics and Gynecology.

Toxoplasmosis is devastating for families. The majority of infected infants have no deformities at birth, but without treatment, most will develop serious eye and brain damage and die from massive infection by the end of adolescence, he writes.

"We have medicines that can help if we catch the infection and improve outcomes if we detect the infection early," says co-researcher Rima McLeod, MD, professor of ophthalmology and medical director of the Toxoplasmosis Center at the University of Chicago (search), in a news release.

Are You a Carrier of Toxoplasmosis?

The CDC reports that more than 60 million people in the U.S. probably carry the T. gondii parasite but few have symptoms. The immune system usually keeps the parasite from causing illness. However, if the infection is acquired for the first time while a woman is pregnant, it can cause crippling diseases in the newborn or later in life.

In their study, researchers interviewed the mothers of 131 infants with toxoplasmosis. They asked about the mothers' exposure to undercooked meats, cat litter, raw eggs, and more.

They also asked mothers about symptoms of infection, such as flu-like symptoms that include headaches, night sweats, fever, muscle aches, and swollen lymph nodes.

In their study, only 8 percent of mothers were tested for toxoplasmosis during pregnancy, Boyer notes.

Researchers found that 75 percent of women who delivered an infant with toxoplasmosis could recall a conceivable exposure. Only 39 percent could specifically recall exposure to cat litter, while 25 percent could not recall any possible exposure to cat litter or uncooked meats.

Researchers also say 48 percent reported symptoms that might have included toxoplasmosis as a cause during pregnancy.

They call for more education of pregnant women on toxoplasmosis. Doctors should watch carefully for symptoms. Mothers should get blood tests with the first prenatal visit in the first trimester and monthly afterward. Newborns should also be tested, writes Boyer.

According to the March of Dimes, pregnant women can take steps to reduce the chances of becoming infected:

— Don't eat raw or undercooked meats.

— Wash hands after handling raw meats.

— Don't empty or clean the cat litter box — have someone else do it.

— Keep cats indoors to prevent them from being exposed.

— Wear gloves when gardening to avoid contact with soil that may be infected.

By Jeanie Lerche Davis, reviewed by Brunilda Nazario, MD

SOURCES: News release, The University of Chicago. Boyer, K. The American Journal of Obstetrics & Gynecology, February 2005. March of Dimes.