West Nile, A Pregnancy Danger?
If a woman becomes ill with West Nile fever while she is
pregnant, can her baby be damaged by the West Nile virus (WNV)? In 2002, there
were 4 confirmed cases of WNV infection involving pregnant women and one baby
was born with not only detectable WNV infection but also with brain damage
possibly caused by the virus.
The CDC is now gathering outcome data for pregnancies of
WNV-infected mothers. The CDC Guidelines include -- how to screen for WNV during
pregnancy, how to diagnose WNV infection during pregnancy, evaluation of the
fetus with ultrasound and possibly, tissue biopsy or amniotic fluid, and evaluation of
babies after birth. The report concludes with recommendations as to how women
can avoid being infected with the WNV in the first place. These same
recommendations are applicable to everyone, pregnant or not.
Barbara K. Hecht,
Ph.D.
Frederick Hecht, M.D.
Medical Editors, MedicineNet.com
West Nile Related Links
Pregnancy Related Links
Interim Guidelines for the Evaluation of Infants Born to Mothers Infected
with West Nile Virus During Pregnancy
West Nile virus (WNV) is a single-stranded RNA flavivirus with antigenic
similarities to Japanese encephalitis and St. Louis encephalitis viruses. It is
transmitted to humans primarily through the bites of infected mosquitoes.
Flavivirus infection during pregnancy has been associated rarely with both
spontaneous abortion and neonatal illness but has not been
known to cause birth defects in humans (1--4). During 2002, a total of 4,156
cases of WNV illness in humans, including 2,946 cases of neuroinvasive disease,
were reported to CDC by state health departments. In 2002, a woman who had WNV
encephalitis during the 27th week of her pregnancy delivered a full-term infant
with chorioretinitis,
cystic destruction of cerebral
tissue, and laboratory evidence of congenitally
acquired WNV infection (5,6). Although this case demonstrated intrauterine WNV
infection in an infant with congenital
abnormalities, it did not prove a causal relation between WNV infection and
these abnormalities. During 2002, CDC investigated three other instances of
maternal WNV infection. In all three
cases, the infants were born at full term with normal appearance and negative
laboratory tests for WNV infection; cranial imaging studies and ophthalmologic
examinations were not performed. During 2003, CDC received reports of
approximately 9,100 cases of WNV illness, including approximately 2,600 cases of
neuroinvasive disease*. CDC is gathering data on pregnancy outcomes for
approximately 70 women with WNV illness during pregnancy (CDC, unpublished data,
2003).
To develop guidelines for evaluating infants born to mothers who acquire WNV
infection during pregnancy, on December 2, 2003, CDC convened a meeting of
specialists in the evaluation of congenital infections. This report summarizes
the interim guidelines established during that meeting.
Screening for WNV During Pregnancy
No specific treatment for WNV infection exists, and the consequences of WNV
infection during pregnancy have not been well defined. For these reasons,
screening of asymptomatic pregnant women for WNV infection is not recommended.
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