Prenatal Toxoplasmosis Tests: Medical Advances, Backward Policy?
Weisburd, Stefi, Science News
Prenatal toxoplasmosis tests: Medical advances, backward policy?
Toxoplasma gondii is a widespread parasite infecting, among others, about 35 percent of the U.S. population and up to 80 percent of Parisians. Most of these people are unaware of their infection because they have healthy immune systems to keep the parasite at bay. But fetuses, with their underdeveloped immune systems, are not so lucky. Of women who first become infected with the parasite during pregnancy, 50 percent pass it on to the fetus. And depending on the time of infection, congenital toxoplasmosis can cause death, mental retardation, epilepsy or blindness. In most cases the infected child appears healthy at birth; the first symptoms may arise anytime from a few months to nine years later.
In light of these serious repercussions, France and Austria have mandated prenatal testing for T. gondii. And as evidenced by a recent study of 746 infected pregnant women, French researchers in particular have come far in developing accurate prenatal toxoplasmosis test- including blood and amniotic fluid tests and ultrasound examination of the fetal brain-for both mother and fetus. Such tests enable patients to make more informed decisions about whether or not to terminate a pregnancy, Fernard Daffos of the Hopital Notre Dame de Bon Secours in Paris and his colleagues write in the Feb. 4 NEW ENGLAND JOURNAL OF MEDICINE.
Prenatal tests also give physicians a chance not only to minimize the parasite's effects but also to protect the fetus from infection in the first place. Daffos's group reports some success in treating infected fetuses with antibiotics while in the womb and concludes that "prenatal therapy in women who wish to continue their pregnancies reduces the severity of the manifestations of the disease."
In addition, Daffos's group discovered that the percentage of fetuses that became infected with the parasite was considerably lower than what was found in their previous studies. The researchers attribute this difference to immediately treating the infected women in the recent study with the antibiotic spiramycin. This finding, they say, is indirect evidence that spiramycin can limit placental infection by the parasite (which can take weeks to move from mother to fetus) and can reduce the chances of congenital transmission. (In the United States, physicians treating infected pregnant women must get permission from the Food and Drug Administration to use spiramycin, which is also used in other countries to treat strep throat and the like.)
Uninfected French women are tested monthly for T. …