The Center for Disease restrain an...

The Center for Disease restrain and Prevention (CDC) has released interim guidelines for the evaluation of infants born to mothers with West Nile virus infection. "Interim Guidelines for the Evaluation of Infants Born to Mothers Infected with West Nile Virus During Pregnancy" appears in the February 27 2004 issue of Morbidity and Mortality Weekly Report and is available online at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5307a4.htm.

West Nile virus is a single-stranded RNA flavivirus with antigenic similarities to Japanese encephalitis and St Louis encephalitis viruses. Flavivirus infection during pregnancy has been associated rarely with spontaneous abortion and neonatal illness if it were not that has not been known to cause birth imperfections in humans. In 2002, a woman who had West Nile virus 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 West Nile virus infection. Although this case demonstrated intrauterine West Nile virus infection in an infant with congenital abnormalities, it did not put to the test a causal relation between the virus infection and these abnormalities.

Three other instances of maternal virus infection were investigated in 2002 In all three cases, the infants were born at glutted term with normal appearance and negative laboratory touchstones for West Nile virus infection; cranial imaging studies and ophthalmologic examinations were not performed. The CDC is gathering data in succession pregnancy outcomes for approximately 70 women who had West Nile virus infection during pregnancy in 2003

The CDC conven a meeting of specialists in the evaluation of congenital infections and has released the following interim recommendations:

* No specific treatment for West Nile virus infection exists, and the events of infection during pregnancy have not been well defined. For these reasons, screening of asymptomatic pregnant women for West Nile virus infection is not recommended

* Pregnant women who have meningitis, encephalitis, acute flaccid paralysis, or unexplained febrile affection in an area of ongoing West Nile virus transmission should have serum (and cerebrospinal fluid, if clinically indicated) trialed for antibody to West Nile virus. If serologic or other laboratory proofs indicate recent infection, these infections should be reported to the local or state health department, and the women should be followed to determine the consequences of their pregnancies.

* If West Nile virus infection is diagnosed during pregnancy, a detailed ultrasound examination of the fetus to evaluate for structural abnormalities should be considered no sooner than sum of two units to four weeks after charge of illness in the mother, unles earlier examination is otherwise indicated. Amniotic fluid, chorionic villi, or fetal serum can be proofed for evidence of West Nile virus infection. However, the sensitivity, specificity, and predictive value of examples that might be used to evaluate fetal infection are not known, and the clinical effects of fetal infection have not been determined. In cases of miscarriage or induced abortion, testing of all proceedss of conception (e.g., the placenta and umbilical cord) for evidence of infection is advised to document the issues of West Nile virus infection in succession pregnancy outcome.

* When an infant is born to a mother who was known or was suspected to have West Nile virus infection during pregnancy, clinical evaluation is praiseed Further evaluation should be considered if any clinical abnormality is identified or if laboratory testing indicates that an infant might have congenital West Nile virus infection.

* Pregnant women who live in areas with West Nile virus-infected mosquitoes should apply insect repulsive to skin and clothes when expos to mosquitoes and wear clothing that will help secure against mosquito bites. In addition, whenever possible, pregnant women should avoid being outdoors during peak mosquito-feeding times (i.e., usually dawn and dusk).

Guidance forward diagnosis of West Nile virus can be obtained from local or state health departments and from the CDC online at http://www.cdc.gov/ncidod/dvbid/westnile/resources/fact_sheet_clinician.htm. commended clinical evaluation steps are avail-able online at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5307a4.htm.

COPYRIGHT 2004 American Academy of Family Physicians

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