Mosquito virus survived winter

N.Y. study finds traces of deadly disease in hibernating insects

March 19, 2000|By Eric Lipton | Eric Lipton,New York Times News Service

NEW YORK -- Federal health investigators have found genetic evidence in hibernating mosquitoes collected recently in northeastern Queens that suggests the West Nile virus that killed seven people in the New York region last year survived the winter.

Mosquitoes extracted from bunkers at the historic Fort Totten -- in three of 69 samples examined -- had low but detectable levels of a genetic material associated with the mosquito-borne virus, the Centers for Disease Control and Prevention has reported. Another 22 samples collected from spots including the Whitestone Bridge in Queens and storm sewers next to the Bronx Zoo found no hint of the virus.

"This does not necessarily mean the disease is coming back when it warms up in the New York area," said Dr. Stephen M. Ostroff, associate director at the National Center for Infectious Diseases in Atlanta, a division of the CDC. "But this raises the possibility that it might. There is at least some evidence that it is still present in the area."

Findings no surprise

City and state health officials said they were not surprised by the findings, given the first confirmation last summer that the virus -- prevalent in Africa, West Asia and the Middle East -- had somehow been carried to the United States. But the latest findings added urgency to a campaign scheduled to begin soon in New York City to kill mosquito larva and reduce mosquito breeding sites, and they raised the possibility the city might return to widespread aerial pesticide spraying this summer.

"We have got to kill as many of those critters as possible," Mayor Rudolph W. Giuliani of New York City said.

The New York City Department of Health has issued an alert to medical professionals citywide warning them of the latest findings and urging them, beginning May 1 when mosquitoes become more prevalent, to immediately report to the city any suspected cases of viral encephalitis, a brain infection that can result after a person is bitten by an infected mosquito.

Seven deaths reported

Last year, in addition to seven deaths, 62 serious illnesses were attributed to the virus in the New York area, with the largest number confirmed in Queens and the Bronx. Its symptoms resemble a severe flu, with fever, as well as poor muscle control or mental disorientation. The federal government, as previously planned, is also distributing $2.9 million in special grants to Middle-Atlantic states to enhance testing this summer of mosquitoes, as well as birds, which can spread the disease.

Medical experts were somewhat split on the significance of the CDC findings, which were published in a recent issue of the Morbidity and Mortality Weekly Report. Dr. John Edman, director of the Center for Vector Borne Disease Research at the University of California in Davis, cautioned against overreacting, given that the tests found no evidence of live virus, only genetic traces, meaning the virus may not reproduce and cause infection.

'A cause for concern'

But Dr. W. Ian Lipkin, a scientist at the University of California in Irvine who helped diagnose West Nile virus as the cause of deaths in New York last year, said the findings were "definitely a cause for concern."

And Dr. Andrew Spielman, a professor of tropical public health at Harvard School of Public Health, said he was now more concerned that the virus might be on its way to establishing itself as a permanent health threat in the United States.

"The big biological question was would the mosquitoes become infected before going into hibernation? It looks like the answer is yes," Dr. Spielman said. "Now the question is, have enough of them gone into hibernation with the infection so that the cycle will continue."

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