Mosquito-borne disease in N.Y. may be rare virus; Officials first thought fatalities were caused by St. Louis encephalitis


NEW YORK -- In a new effort to identify the mosquito-borne disease that has killed three people in New York City, health officials sent dozens of staff members through city streets yesterday to retrieve dead birds for testing.

The search for dead birds comes one day after experts discovered that a disease they believed to be St. Louis encephalitis -- which killed dozens of birds at the Bronx Zoo and has infected at least 14 people in New York City and four in Westchester County -- may be the rare West Nile virus, which has not been diagnosed in the Western Hemisphere, government scientists said.

The federal Centers for Disease Control and Prevention said Friday night that they had identified a West Nile-like virus in four birds from New York that they had tested in Fort Collins, Colo.

The birds included two flamingos and an Asian pheasant from the Bronx Zoo, and a crow reported to be from Scarsdale, said Kristine Smith, a spokeswoman for the New York State Health Department.

In starting the bird hunt Friday night, city health officials opened special telephone lines and asked residents to report dead birds. By noon yesterday, the City Health Department had received a dozen reports of dead birds and sent staff from its pest-control division to retrieve specimens, said a spokeswoman, Sandra Mullen.

"The birds will be kept on dry ice and brought to our Bureau of Laboratories," she said, adding that most of the dead birds reported were crows, which have been dying in large numbers since the beginning of the outbreak.

In Manhattan, a team from the Parks Department swept through Central Park on Friday night searching for dead birds but found none, said Parks Commissioner Henry Stern. He said more teams would be dispatched, but that all park staff had been notified and were on the lookout.

News that the infection might be West Nile virus has deepened an epidemiological mystery that began in July with the deaths of numerous crows around the Bronx Zoo.

A pathologist at the zoo, Tracey McNamara, first noticed that large numbers of crows were dying, reaching 40 by August. Then birds at the zoo, including a guanay cormorant, three Chilean flamingos, a pheasant and a bald eagle, died.

Though the symptoms of the two diseases are similar and the steps to combat them are the same, the mosquitoes that carry them can differ, officials said.

Smith of the state Health Department said the mosquitoes that carry St. Louis encephalitis and West Nile viruses, the Culex pipiens, are generally active from dusk to dawn. Another type of mosquito known to carry the West Nile virus, the Aedes vexans, is also active during the day, she said. Both illnesses usually produce mild symptoms, but in some cases can cause neurological disorders and death.

The identification of a West Nile-like virus stunned health officials. "It is totally unprecedented," said Duane Gubler, director of the division of vector-born infectious disease at the Centers for Disease Control. He said the "movement of people and the jet airplane" have increased the movement of pathogens.

While the implications of the suspected virus are unknown, he said, "We could expect to see it move north and south in the Western Hemisphere."

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