http://ens.lycos.com/ens/jun2001/2001L-06-22-06.html

 

Pesticides Cause More Bird Deaths Than West Nile Virus

By Cat Lazaroff

NEW YORK, New York, June 22, 2001 (ENS) - A New York State wildlife official has discovered that of birds collected for a study on West Nile Virus, more died from pesticide poisoning than from the virus itself. In response to this early data, the National Audubon Society is calling upon Connecticut, Delaware, Maryland, New Jersey, Pennsylvania and Virginia to begin testing dead birds for pesticide poisoning.

Pathologists examine crows suspected of being infected with West Nile Virus (Photo courtesy U.S. Geological Survey)

Many bird species are susceptible to West Nile Virus. American crows, in particular, have been shown to suffer close to 100 percent mortality after being exposed to the virus.

But new data suggest that spraying pesticides to control the mosquitoes that carry the virus may cause more problems than it solves.

"This data is very troubling," said John Flicker, president of National Audubon Society. "States owe it to their residents to get to the bottom of this."

Last year, prompted by concern about the spread of West Nile Virus, New York State asked counties to report dead birds to its wildlife pathology laboratory. After receiving more than 80,000 birds, Dr. Ward Stone discovered that while the virus was a factor in some of the deaths, the leading cause was pesticide poisoning. Common lawn care chemicals were among the most common toxins.

"Millions of us use pesticides like Diaznon and Dursban at home," said Frank Gill, Audubon's senior vice president of science. "We deserve to know as much as possible about their effect on us. Like canaries in a coalmine, birds warn of danger in our environment. If these chemicals kill birds, what are they doing to our kids?"

Biologists once thought that West Nile Virus could only be transmitted through bites by mosquitoes like this treehole mosquito, but now believe the disease may also spread directly from one bird to another (Two photos courtesy Centers for Disease Control and Prevention)

Audubon and other environmental groups, including the American Bird Conservancy, warned last year that spraying pesticides to control mosquitoes might do more harm than good.

West Nile Virus has had a far greater impact on birds than humans in North America with at least 60 bird species, including merlins, great horned owls, catbirds, warblers, gulls, swans and at least one bald eagle, amounting to thousands of individual birds, testing positive for the virus. By contrast, there have been just eight human deaths from West Nile in the U.S. in two years, points out the American Bird Conservancy.

"The response to West Nile is a typical example of how pesticides are used to control perceived risk … risks they often end up compounding," said Kelley Tucker, director of American Bird Conservancy's Pesticides and Birds Campaign. "As the outbreak of West Nile Virus has shown, birds are important sentinels of environmental health. We can't afford to ignore them."

Some evidence suggests that mosquito spraying actually increases infection rates in the birds that carry the virus by compromising their immune response, making them more susceptible to infection. Mosquitoes that survive insecticide exposure may be affected in ways that make them more efficient transmitters of the infectious virus, some scientists believe.

"State governments are responsible for protecting the public's health," said Audubon president John Flicker. "We think it's important for them to find out what these bird deaths [from pesticides] mean."

House mosquitoes like this have been found to carry the virus

In addition to threatening wildlife, pesticides are believed to harm humans. According to Pesticide Watch, pesticides have been linked to a wide range of human health hazards, from short term impacts such as headaches and nausea to chronic conditions like cancer, reproductive harm, and endocrine disruption.

The American Bird Conservancy suggests measures for containing West Nile Virus should mirror preventive measures currently taken by public health and mosquito abatement officials for St. Louis Encephalitis - a similar virus, as outlined by the Centers for Disease Control. These measures generally do not entail the spraying of adult mosquitoes in residential or suburban areas.

Instead, controlling mosquitoes at the larval stage using less toxic methods is advocated and remains the most effective and least environmentally harmful methodology available, the group says.

Last summer, several groups launched ad campaigns and filed lawsuits challenging the safety and legality of mosquito spraying campaigns in the New York City area, where the first known human cases of West Nile Virus occurred two years ago.

American crows seem particulary susceptible to West Nile Virus (Photo by Peter S. Weber, courtesy USGS)

"People are calling on their public officials at the local, state and national level to stop unnecessary pesticide use that can result in widespread poisoning and contamination. If people knew the truth about the dangers of pesticides, they would not tolerate their use," said Pam Hadad Hurst, executive director of the New York Coalition for Alternatives to Pesticides.

Jay Feldman, executive director of Beyond Pesticides, called aerial spraying "a cure that is worse than the disease, especially given the availability of alternative approaches and materials."

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