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Monday 21st February, 2005
Physicians found that symptoms and risk factors
are absent in more than half of the mothers of infants with congenital
Physicians found that signs, symptoms and identifiable
risk factors are absent in more than half of the mothers of
infants with congenital toxoplasmosis in a national study of
children with this disease.
More than half of the pregnant women who were at risk for acute
infection with Toxoplasma gondii could not be identified by history
or routine examination. Therefore, the physicians recommend that
systematic screening for acute acquired toxoplasmosis for all
pregnant women in the United States during prenatal visits, as well
as screening for congenital toxoplasmosis in all newborns, become
standard medical practice. The group also emphasizes that
confirmation of test results in reference laboratories and informed
counseling are essential parts of the process.
An infection caused by the parasite Toxoplasma gondii,
toxoplasmosis can be harmful and potentially lethal to the children
of women who acquire the infection during pregnancy.
In the February issue of the The American Journal of Obstetrics
and Gynecology, the researchers report that current clinical
practice -- taking a careful history and performing a physical
examination -- would identify only half of the at-risk mothers who
have acquired the infection during pregnancy and have had infants
with congenital toxoplasmosis. Screening through blood tests could
have identified the rest, the researchers said.
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"We have medicines that can help if we catch the infection and
improve outcomes if we detect the infection early, but by only
taking a careful history and examination we are missing many
pregnant women and their infants who may benefit from treatment,"
said study co-author Rima McLeod, M.D., professor of ophthalmology
and medical director of the Toxoplasmosis Center at the University
According to the Centers for Disease Control and Prevention, more
than 60 million people in the United States probably carry the T.
gondii parasite, but few have symptoms. The immune system usually
keeps the parasite from causing illness. However, pregnant women
should be cautious. If the infection is acquired for the first time
while a woman is pregnant, it can cause serious problems. Infection
of the fetus may cause severe eye and brain damage, and may result
in crippling diseases in the newborn or later in life.
"Early detection and treatment of the T. gondii infection in the
mother, fetus and infant can prevent or reduce the risks of
ophthalmologic and/or neurologic damage," said Kenneth Boyer, M.D.,
chairman of pediatrics at Rush University Medical Center and a
co-author of the study.
T. gondii infects humans through three principal routes: eating
undercooked, infected meat; ingesting T. gondii oocysts that cats
pass in their feces, with exposure occurring through cat litter or
soil (examples include gardening, eating unwashed fruits and
vegetables, water contamination); and a newly infected pregnant
woman passing the infection to her fetus.
The physicians questioned the mothers of 131 children with
confirmed congenital toxoplasmosis who were referred to the National
Collaborative Treatment Trial. This is a study sponsored by the
National Institutes of Health and is based in Chicago, but involves
children throughout the United States.
The physicians gathered demographic data, including place of
residence, age, race and socioeconomic status, and information about
the mothers' exposures to undercooked meats, cat litter, raw eggs
and more. The physicians also asked the mothers if they experienced
any illnesses, such as flulike symptoms including headaches, night
sweats and swollen lymph nodes, which can be symptoms and signs of
this infection in older children and adults.
Only 8 percent of the mothers in the study were screened by
serologic testing for toxoplasmosis during pregnancy. The physicians
said the finding is consistent with the infrequent screening of
pregnant women in the United States for this infection.
The group found that 52 percent of mothers couldn't recall an
illness of any kind during pregnancy or identify risk factors,
including ingestion of undercooked meats and or exposure to cat
The physicians also found that demographics play no role in the
occurrence of infections. "Acute toxoplasmosis and transmission to
the fetus can affect individuals of any background and socioeconomic
status," McLeod said.
In France and Austria, education about toxoplasmosis and
screening for T. gondii is part of routine obstetrical care.
Infection rates have been reduced by about 50 percent as a result of
education. But this shows that other measures, such as blood tests
during each month of pregnancy, are necessary so that doctors can
identify the infection early. Treatment of the mother may help
prevent the harmful consequences of the infection in the fetus.
Although most states require screening for a number of genetic
and metabolic diseases in the newborn, including phenylketonuria,
congenital hypothyroidism and congenital adrenal hyperplasia in the
newborn, each of these genetic diseases is less common than
toxoplasmosis. But there is no systematic program for screening for
toxoplasmosis during pregnancy in the United States.
More than 10 years ago, Jack Remington, a co-author of the study
and a professor of medicine at Stanford University School of
Medicine and Marcus Krupp research chair and chairman of the
department of immunology and infectious diseases at the Research
Institute, Palo Alto Medical Foundation, wrote "the time has come"
to better address the problem of this significant and treatable
cause of loss of sight, hearing and cognition. This study indicates
again that to detect this infection so it can be treated, systematic
obstetrical and newborn screening for toxoplasmosis are needed. The
authors suggest that this is long overdue in the United States.
"Clearly, we need to be doing more than we currently are doing to
prevent this congenital infection and adverse consequences of the
infection in the fetus and infant," McLeod said. "Education is
important, but it is not sufficient."
University of Chicago Medical Center