Researchers call for prenatal screening for parasitic infection
The Associated Press
Feb. 8, 2005
CHICAGO - Janet Morel doesn't know whether it was the undercooked eggs she ate while she was pregnant or parasites from the pet cat that caused her daughter's blindness and brain damage.
Her daughter, Dana, is now 17, and Morel and her husband face a lifetime of caring for her. Doctors determined toxoplasmosis caused Dana's brain damage, which is why Morel supports a call for routine testing of pregnant women and infants for the parasitic infection.
"If you could see my daughter, you would understand why it is I feel so strongly about this," the Scottsdale, Ariz., resident said Monday.
Few pregnant women or infants are routinely tested for toxoplasmosis, which can cause blindness and brain damage in babies, and can be contracted during pregnancy if a woman cleans a cat litter box or eats raw eggs or meat.
A group of researchers is now calling for routine screening of pregnant women and infants.
"What it takes is a little push to get this going," said Dr. Kenneth Boyer, pediatrics chairman at Rush University Medical Center, and lead author of a new study that investigated risk factors for toxoplasmosis. "I believe our paper ought to be a push in that direction."
The study, published in the February American Journal of Obstetrics and Gynecology, found that even if doctors ask all the right questions to find known risk factors, they miss about half of mothers who go on to give birth to babies with toxoplasmosis.
About 500 to 5,000 babies are born each year in the United States with toxoplasmosis, previous studies have estimated, a rate of around 1 per 1,000 births.
Some are born with no obvious symptoms and damage becomes apparent only later. Others, like Dana Morel, have severe and obvious symptoms at birth.
"Dana does not walk or talk or sit by herself or feed herself," Morel said. "She cannot toilet herself. She fortunately does hear. But she doesn't see."
Treatment with oral drugs during an infected baby's first year of life can prevent some children from developing serious symptoms, Boyer said. Though the treatment, which involves daily oral medication to kill the parasites and weekly blood tests to prevent side effects of the medication, is not 100 percent effective, he said.
One problem with universal screening is false positive tests, which could raise parents' anxiety needlessly, Boyer said. But, he said, routine blood tests could also get more babies treated and prevent blindness and mental retardation.
The study looked at 131 children who were referred from across the country to the Chicago Collaborative Treatment Trial, a project funded by the National Institutes of Health. The children all were diagnosed with toxoplasmosis and most were referred during their first two months of life.
Researchers interviewed the children's mothers, asking whether they owned cats, cleaned litter boxes, gardened or ate uncooked meat while pregnant. The parasite Toxoplasma gondii, which causes toxoplasmosis, can live in soil, so gardening is another possible source of infection.
The researchers also asked the women if they had flu-like symptoms or swollen lymph nodes during pregnancy.
Half the women recalled no symptoms or risk factors, the researchers found.
Boyer said that shows that normal prenatal care, which involves such interview questions but no blood test, potentially misses about half the cases of toxoplasmosis during pregnancy. The parasite can be passed from mother to fetus.
Boyer does not consider the potential for faulty memory to be a limitation of the study. In fact, he said, mothers of babies with birth defects tend to "spend day and night racking their brains for answers to what went wrong."
Only about 8 percent of women in the study had a blood test for toxoplasmosis during pregnancy. The American College of Obstetrics and Gynecology currently does not recommend routine prenatal testing for toxoplasmosis.
Standard advice for pregnant women includes a warning to let someone else clean the cat litter box since cats can host the parasite and shed it in their feces. Pregnant women also should wear gloves while gardening and avoid eating raw or undercooked food, another source of infection. Shellfish and untreated water are new suspected culprits, according to the study.
Massachusetts and New Hampshire are the only states now requiring newborn screening for toxoplasmosis, according to the National Newborn Screening and Genetics Resource Center.
"It works quite well here," said Roger B. Eaton, director of the New England Newborn Screening Program at the University of Massachusetts Medical School, which conducts the tests for both states.
The blood test currently finds infection in 1 in 15,000 births in Massachusetts, Eaton said. It is combined with other newborn screening tests at a total cost of about $55 per baby, he said.
Eaton recommended that states considering toxoplasmosis screening make it part of a program that also involves treatment.
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