Infants born in North America are more likely to suffer the severe effects of the parasitic infection toxoplasmosis than infants in Europe, a new study says.
In the study, 84 percent of U.S. infants had the most severe symptoms of toxoplasmosis, including eye disease, calcium deposits in the brain and hydrocephalus, a condition where fluid builds in the brain, possibly causing brain damage.
Similar studies looking at toxoplasmosis in European newborns found much lower rates, around 15 percent, the study said.
The researchers said differences in prenatal care might explain the differences in the infections. In European countries such as France, Italy and Austria, pregnant women are routinely screened and treated for toxoplasmosis infections, but the United States has no such policy.
For the sake of the babies in the U.S., something needs to be done at the national level so that women can be tested, and infants can get the benefit of prenatal treatments, said Dr. Jose Montoya, an associate professor of infectious diseases at Stanford University and lead author of the new study.
Congenital toxoplasmosis: from mothers to babies
Toxoplasmosis is an infectious disease caused by the parasite Toxoplasmoa gondii, which is usually contracted by eating raw or undercooked meat, or coming in contact with the feces of an infected cat. The U.S. Centers for Disease Control and Prevention estimates that more than 60 million people in the country harbor the parasite, but few show symptoms because the immune system usually prevents illness.
An infant can get congenital (present from birth) toxoplasmosis if his mother is infected for the first time in her life during her pregnancy. If a mother is infected early on in her pregnancy, the risk of her child getting the infection is relatively low about 1 or 2 percent but this risk rises to 80 percent in later stages of pregnancy, Montoya said.
If infected, infants can suffer severe health problems such as brain damage, blindness and epilepsy.
In Europe, doctors give the antibiotic spiramycin to pregnant women infected with toxoplasmosis to try to reduce the likelihood a serious infection will be passed to their developing babies.
In the U.S., however, spiramycin is considered an experimental drug, though doctors can request it from the Food and Drug Administration.
For the new study, the researchers identified 155 U.S. and nine Canadian babies in a medical database who were treated for congenital toxoplasmosis between 1991 and 2005. Their mothers had not been screened or treated for toxoplasmosis during pregnancy.
And that's where the shock came in we were startled to see how many of the babies were severely damaged, Montoya said.
Of the 138 infants for whom there was clinical information available, 92 percent had eye disease, 80 percent had brain calcification legions, 68 percent had hydrocephalus and 62 percent had all three conditions concurrently, the researchers found.
By comparison, a 2007 study found that 15 percent of European infants had eye disease, and 6 percent had brain calcification; the mothers of these infants were all treated during pregnancy.
A question of routine screening?
Montoya said the differences in toxoplasmosis infections between North America and Europe is due to a number of factors. Different strains of the Toxoplasmoa parasite could be to blame, as could genetic differences between people.
But the explanation Montoya said he sees as most likely is that there are major differences in prenatal care between Europe and the U.S., and this, he said, needs to change.
Screening for the infection could be as cheap as $5 to $10 for each test, Montoya said.
Dr. Kimberly Lee, an associate professor of pediatrics at the Medical University of South Carolina, who was not involved in the study, said the research was well thought-out. And if universal prenatal screening and treatment are as effective in Europe as they seem to be, then they should be seriously considered as part of U.S. obstetric care.
However, Dr. Bill Schaffner, chairman of the Department of Preventive Medicine at the Vanderbilt University School of Medicine, said he is not convinced that universal screening is necessary.
Schaffner pointed to previous studies in France showing that 70 percent of all pregnant women have had some contact with the parasite before getting pregnant previous exposure is thought to provide some protection against passing severe toxoplasmosis to developing babies. Depending on the region of the U.S., only 3 to 30 percent of pregnant women have been previously exposed to T. gondii, he said.
It's probably not nearly as big of a problem as the researchers suggest, Schaffner said. The organism seems to be less frequently present in the environment here than it is in Europe.
Still, there's no doubt from the research that congenital toxoplasmosis can be serious," he said. The study may open the door for more discussion on the issue.
The study was published online on Wednesday (Oct. 5) in the Pediatric Infectious Disease Journal.
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