There is one documented case of trans-placental (mother-to-child) transmission of WNV in humans. Although the newborn in this case was infected with WNV at birth and had severe medical problems, it is unknown whether the WNV infection itself caused these problems or whether they were coincidental. More research will be needed to improve our understanding of the relationship-if any-between WNV infection and adverse birth outcomes.
Nevertheless, pregnant women should take precautions to reduce their risk for WMV and other arboviral infections by avoiding mosquitoes, using protective clothing and repellents containing DEET. When WNV transmission is occurring in an area, pregnant women who become ill should see their health care provider. Those whose illness is consistent with acute WNV infection should undergo appropriate diagnostic testing. For more details regarding the case described above, please see Centers for Disease Control and Prevention (CDC) MMWR Dec. 20, 2002.