N.Y. Newborn Was Infected With West Nile While in Womb

A brain-damaged baby girl born last month in upstate New York was infected with West Nile virus while in the 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.

In a weekly health update, the U.S. Centers for Disease Control and Prevention said the baby tested positive for the virus after her birth. The infant’s mother, a 20-year-old resident of Syracuse, had suffered from fever, headaches and other symptoms of West Nile two months earlier and later tested positive for the virus, officials said.

CDC officials said the baby was born with birth defects, including loss of brain matter. They said they could not be sure that the presence of the virus led to the abnormalities.

The CDC officials 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 in the United States in late 1999. On Thursday, 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 transplated organs, blood products and probably breast milk.

The CDC on Thursday 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 people succumb to a newly arrived virus, said Anthony Fauci, head 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, he 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 CDC report.

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.