A brain-damaged baby girl born last month in upstate New York was
infected with West Nile virus while in her mother's womb, marking the
first known instance of West Nile transmission in the uterus, and
raising fears that the virus can cause lasting neurological problems in
newborns.
Officials with the Centers for Disease Control and Prevention said
they are not certain the newborn's severe nervous system problems were
caused by the infection -- though they ruled out the other most likely
potential sources. They held out hope that mother-to-fetus transmission
may ultimately prove to be rare, noting that the only other pregnant
woman carefully tracked after being diagnosed with West Nile gave birth
to a healthy baby with no evidence of the virus.
Nonetheless, the case adds a new and frightening avenue of infection
for West Nile, the mosquito-borne virus that has spread dramatically
across the nation since it first appeared the United States in late
1999. Yesterday the CDC issued a special warning encouraging pregnant
women to wear protective clothing and use insect repellent during
mosquito season to reduce the risk of infection.
That was just the latest warning triggered by the West Nile epidemic,
which has killed record numbers of people and animals this year. Health
officials have already warned that the virus can be transmitted via
organ transplants, blood products and probably breast milk. The agency
yesterday also presented the first two cases of workplace transmission
of West Nile in laboratory workers who accidentally infected themselves.
Additional routes of infection and unexpected medical complications
often pop up as more and more people succumb to a newly arrived virus,
said Anthony Fauci, chief of the National Institute of Allergy and
Infectious Diseases. "When you have the thousands of cases like
we've had this season, then you start to see the rare components, or at
least unusual components, that you might not otherwise see," he
said.
Nonetheless, the growing list of problems attributed to West Nile --
including the newborn's brain damage, which Fauci suspects was indeed
caused by the virus -- should energize the quest to develop a vaccine
for people, Fauci said. The only West Nile vaccine now licensed by the
Food and Drug Administration is for horses.
West Nile outbreaks have occurred in several European and Middle
Eastern nations in recent decades, but this year's U.S. epidemic was the
largest ever, according to a wrap-up of the outbreak as of Nov. 30
published in the CDC's Morbidity and Mortality Weekly Report. Today's
issue also reports on the fetal and laboratory cases.
The virus was detected in 44 states and the District, a 17-state
increase since last year. It caused 3,389 cases of disease -- about 70
percent of them in the most serious form, known as West Nile
meningoencephalitis -- compared with a total of only 149 cases from 1999
through 2001. The disease had killed about 232 people as of this week,
and scientists suspect that tens or hundreds of thousands of others have
been infected without showing symptoms.
The two cases of occupational transmission both occurred in
microbiologists. One got infected from an accidental needle puncture in
the finger while working with live virus and suffered few symptoms. The
other, who got infected through an accidental scalpel cut while
performing a necropsy on a dead blue jay, was sick for a week with
chills, fever and a body rash.
With a growing number of laboratories handling West Nile specimens,
careful laboratory practices are more important than ever, the CDC
report warns.
The case of the newborn girl with West Nile arose in late August in
the vicinity of Syracuse, N.Y., when a 20-year-old woman in the third
trimester of pregnancy came down with fever, elevated heart rate and
weakness of the legs. Two weeks and two hospitalizations later she was
diagnosed with West Nile, and about five weeks after that she delivered
a full-term baby girl.
The girl was outwardly normal, but her blood contained a type of West
Nile antibody that cannot pass through the placenta from mother to
fetus, indicating that she'd been infected while a fetus. A careful eye
exam after birth showed abnormalities of the retina, which prompted a
brain exam with magnetic resonance imaging.
That revealed "severe neurological abnormalities,"
including a large-scale loss of the delicate branches that extend from
the brain's neurons, said CDC epidemiologist Daniel O'Leary, who helped
investigate the case. Tests for other viruses or conditions that might
cause such abnormalities were negative, and there was nothing in the
woman's medical history that might explain the child's problems.
Doctors said it's too soon to say what effect the damage will have on
the girl, but several agreed that cognitive and motor problems are
likely. Lloyd F. Novick, Onondaga County's Commissioner of Health, who
oversaw the case locally, said the girl went home soon after delivery
but recently was readmitted to a hospital with respiratory problems. He
said he did not know if the new problems were related to the brain
abnormalities.
The CDC has asked public health departments nationwide to be on the
lookout for additional cases of West Nile in pregnant women. Meanwhile,
the agency is recommending that pregnant women use insect repellants
containing DEET, which has no known harmful effects on fetuses.
Officials do not recommend routine testing for West Nile in pregnant
women, since the telltale antibodies can persist in a woman's blood for
more than a year and so may simply indicate a past infection.
Despite the growing number of documented routes of infection, CDC
officials said there was no evidence that the virus can be transmitted
by sexual intercourse. A Colorado woman recently claimed that she
contracted West Nile through sex with her husband, but the evidence
"was extremely inconclusive," said CDC epidemiologist Lyle
Petersen.