News Stories

Deadly Mosquitos Spread as Spray Dangers Emerge

One feared effect of a warmer climate has been the northward movement of tropical pests like the Aedes aegypti mosquito. Now the mosquito, which spreads dengue fever and sometimes even the deadly yellow fever appears to have made it to Tempe, Arizona. County health officials caught the mosquito, known as Aedes aegypti, in traps a couple miles away from where an entomologist first spotted the insects and contacted health officials.

The mosquito's appearance marks the first time the species has been identified this far north. Until now, the mosquito was found only as far north as Tucson. It is common in Central and South America.

?It may be more widespread than we believe, and that?s really discouraging,? says Craig Levy, vector-control manager for the Arizona Department of Health Services. Health officials are asking for help in finding the mosquito breeding spots, believed to be small bodies of water. ?If there is any chance of getting rid of this mosquito, it?s getting people to do backyard surveillance,? Levy says.

West Nile virus activity has recently been reported in Florida, including the finding of WNV-positive crows in June. Although mosquitoes have been collected, no WNV-positive pools have been detected. ?We are being faced with a challenge of controlling the mosquitoes that carry this new virus,? says Commissioner of Agriculture, Charles Bronson.

WNV is found in the wild bird population, and normal bird migration routes likely brought the disease to Florida from the New York area. It is closely related to both St. Louis encephalitis and dengue viruses, and was first seen in the United States in 1999. The outbreak of the West Nile virus in New York City and nearby counties and states in the summer and fall of 1999 was an unprecedented event.

The virus has now spread to other areas of the country. The disease spreads when mosquitoes feed on infected birds, which then transmit the virus to humans and animals. So far this year, there have been wild birds, all crows, reported as positive for West Nile virus in six states. New Jersey has reported the most positive crows, 33, but the most significant finding is the positive crow detected in Jefferson County in northern Florida.

That finding marks the farthest south that any West Nile virus activity has ever been confirmed in the Western Hemisphere. The Florida crow from which West Nile virus was isolated was collected in mid-June. Thirteen mosquito pools have been reported as West Nile virus positive in 2001. All the positive pools were in New Jersey.

In New Jersey, 20 residents have been approved for West Nile virus testing and samples from 19 people have been accepted. These individuals either had symptoms or signs that met the established West Nile virus testing criteria or exhibited most of the symptoms and are from counties where dead crows and/or mosquitoes with the virus have been discovered. Testing has shown that five individuals were not infected with West Nile virus, and results are pending for 14 others.

For the first time, West Nile virus has been confirmed in Massachusetts. The Massachusetts Department of Public Health (MDPH) announced July 20 that the disease has been confirmed by the State Laboratory Institute in an adult dead crow found in a wooded area near Willow Pond in Jamaica Plain, Massachusetts. State health authorities say the finding of West Nile virus in Massachusetts at this time is not surprising given that the virus has been found in an increasing number of birds and mosquitoes in the New York and Connecticut area.

The Connecticut State Mosquito Management Program says that for the first time this year the state has found West Nile virus in mosquitoes, The insects were collected on July 5 at Sleepy Hollow Park in the Springdale section of Stamford. All other mosquitoes tested in Connecticut to date are negative for the disease.

So far this year, New York state has reported seven dead birds, one live wild bird, and one infected mosquito pool, in Queens. In the year 2000, by the end of the mosquito season, all but one county in New York State had documented West Nile virus activity and the virus had been detected in 12 states and the District of Columbia.

Despite pesticide spraying for mosquito control last year in New York state, West Nile virus infection was confirmed in 1,263 dead birds, 400 mosquito pools, 10 live wild birds, eight sentinel chickens, two bats, 28 horses, one domestic rabbit, one squirrel, one chipmunk and 14 humans. Fourteen New York City residents - one of whom later died - and six others in New Jersey, were hospitalized due to West Nile virus infection in 2000.

Health officials are worried as far away as Texas. The Texas Department of Health is monitoring for West Nile virus. Paul Fournier, of the Texas health department's Bureau of Laboratories, Parasitology-Entomology Branch, says the primary way people can cut down on the multiplying families of mosquitoes is to eliminate breeding sites. People are encouraged to empty or get rid of cans, buckets, bottles, old tires, empty pots, plant saucers and other containers that hold water. You should also maintain your backyard pool or hot tub and be sure someone takes care of it if you are on vacation. To help keep mosquitoes out of the house, be sure door, porch and window screens are in good condition.

Mosquitoes are attacking horses as well. The first equine case of West Nile virus in the United States this year has been confirmed in a Florida horse by the National Veterinary Services Laboratories in Ames, Iowa. The positive horse was located in Jefferson County, Florida.

In addition, two other ill horses on two separate farms in the same county have been classified as probable cases of West Nile virus infection. This is the first report of West Nile virus infection of any animal species anywhere in the United States this year.

The Florida Department of Agriculture says this is the first ever case of West Nile virus infection in a U.S. horse residing south of Delaware. Previous earliest onset of clinical West Nile virus illness in a U.S. horse was August 17, 2000 in Staten Island, New York. This case comes at the beginning of Florida?s mosquito season. A vaccine for West Nile virus in horses is expected to be available in August for field trials in Florida.

For the last few years, New York has attacked its West Nile carrying mosquitoes by spraying malathion throughout the city. Now evidence has turned up that the spray may have been more deadly than the insects.

For months, the malathion sat in deep south warehouses and outdoor storage tanks, baking in the summer sun. Destined for mosquito-control programs, the insecticide was supposed to be stored at temperatures no higher than 77 degrees F to avoid conversion to a more deadly poison. But it sat unrefrigerated in parts of the country where the mercury can climb toward 100 day after day.

Documents from the manufacturer, Cheminova, indicate the company was aware that its products were stored improperly by users as early as 1996, and such practices apparently continue. No one knows exactly how toxic the chemical has become at any given site, or how much of that malathion has been shipped north for use in New York?s attack on the West Nile virus.

In 1984, two children in Mississippi were killed after being exposed to Cheminova?s methyl parathion. Six years later, the death of a California farm worker who?d ingested parathion led to federal rules aimed at cutting use of the pesticide in half. In 1996, two more Mississippi children were made severely ill by the pesticide. Five workers were killed and another 2800 were sickened in Pakistan during a 1976 malaria-eradication program. The cause was isomalathion, created when the spray was improperly stored. The Cheminova company has been a favorite target of groups like Greenpeace.

Now a lawsuit by Long Island Sound lobstermen alleges some of the chemical was sprayed there, beginning in 1999. They say it killed off crustaceans in the tristate area and perhaps harmed humans as well. Early evidence from the Environmental Protection Agency indicates the lobstermen may be right. While downplaying the potential damage, the EPA recently reported that tests of malathion in New York-area holding tanks found traces of a poisonous neurotoxin called isomalathion?a byproduct created when malathion (also known as Fyfanon) is exposed to high temperatures.

Yet from the beginning of his all-out aerial assault, Mayor Rudy Giuliani assured the public that proper precautions had been taken and the spraying posed little risk. Stay inside, he advised, and close your windows. Giuliani couldn?t warn New Yorkers of the possible extra hazard due to overheating, because he didn?t know about it.

Politicians in other areas have been more curious. Documents released in a lawsuit show that in 1996, a Louisiana official asked Cheminova whether storage at high temperatures made its product more dangerous. In an internal memo marked ?URGENT URGENT URGENT URGENT URGENT,? an executive with the Danish company cautioned against giving a straight answer. ?If you want to give answers in black and whit [sic],? he wrote, ?the correct answer . . . is ?YES.??

The letter was obtained by the legal firm Smith, Jones & Fawer as part of its action on behalf of Floridians who say they were victims in a war against medflies. The firm is also pushing for a class-action suit on behalf of the local lobstermen. And there?s talk of filing a suit on behalf of people in New York who think they?ve been harmed by the spraying. Cheminova has consistently defended its product in the press, saying it is safe and has been tested for isomalathion before being sent to customers.

For now, New York City has decided against another round of malathion, although it reserves the right to use the chemical. Spraying began in other parts of the state last month. Three dozen people sought treatment at a hospital after they were swamped by a malathion cloud at a softball game for teenage girls in Glens Falls.

?The problem is people think if something is legally approved and sold, then it must be safe,? Canadian doctor and pesticide specialist Libuse Gilka says. ?They don?t realize that those approving these things are only slowly learning about the side effects.?

Activists and investigators on behalf of the Florida lawsuit claim that when the chemical arrives from Denmark it?s warehoused in Georgia and southern Texas in sweltering conditions. From those depots, it?s distributed to places such as New York and Florida. Also, New York violated instructions that the EPA required Cheminova to provide. Users are not supposed to spray Fyfanon over bodies of water, near foods, directly on people, or in places where people will return within 12 hours. Those demands are incompatible with the spraying of a city packed with more than 8 million people and dotted with outdoor caf

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