A night-time city-wide pesticide aerial spraying campaign was launched over New York yesterday as health officials stepped up their fight against an outbreak of mosquito-borne encephalitis.
With nine confirmed cases, including three fatalities, city officials were examining another 60 people in hospital to see if they had been struck by the disease, named St Louis encephalitis after a 1975 outbreak in the Mississippi Valley. Symptoms appear some five to 10 days after a mosquito bite and include high fever, chills, convulsion, brain swelling and sometimes death.
Officials from the Atlanta-based Centers for Disease Control were in New York assisting in the campaign. Dr Roger Nasci, a CDC research entomologist, said the outbreak in a city the size of New York presented a challenge.
"Given that this is New York City, you have a very large population at risk," he said. "That's the reason for this very aggressive aerial spray approach to control the mosquitoes."
The insecticide, called Malathion, will be sprayed from three helicopters and one fixed-wing aircraft over the boroughs of Queens, where the outbreak began and which is home to much of the city's Irish population. In an effort to kill the mosquitoes when they are active, the spraying will be done from 5 p.m. to 10 p.m., then again from 4 a.m. to 8 a.m. Next, Brooklyn, the Bronx and Staten Island will be sprayed. Finally, Manhattan will be covered with spray from trucks, as officials said the density and presence of tall buildings there would make aerial spraying impractical.
The insecticide itself is not without environmental risk, but health officials were quick to point out that there is no evidence of long-term health risk from Malathion. Still, they cautioned people to stay indoors, keep windows shut and turn off air conditioning to prevent the spray from being blown inside. The spray can be an irritant to those with respiratory problems.
As police and fire department workers canvassed the streets of Brooklyn and Queens, distributing cans of insect repellent, Mayor Rudy Giuliani sought to allay residents' fears about both the disease and the treatment.
"There is no reason for unnecessary alarm or panic," the mayor said during a news conference. "There is no harm done in spraying even if we are overdoing it. The more dead mosquitoes, the better."
The first case of the disease appeared on August 10th, surprising doctors. Normally the disease is spread by insects that favour polluted rivers and storm drains. It has appeared mostly in the US midwest, Florida and Texas. Prof Edward Walker, a professor of entomology at Michigan State University, told the New York Times that its arrival in New York city is curious and could signal new behaviour by the mosquito. Officials said about 24 traps would be set around the city to monitor mosquito levels and track the effectiveness of the spraying.
The mayor's comments appeared to do little to convince residents that the city has acted quickly enough. Nor were many convinced they were being told the truth by officials.
"This is obviously a life or death situation that the city should have been worried about before," Ms Felicia Beltre, a hairdresser, told the New York Daily News. One of her customers, Ms Ivette Rios, said: "A lot more people could be sick right now and the city isn't telling us." Aerial spraying of Malathion is a familiar and controversial memory for California residents. In the 1980s the entire state was in the grips of an infestation by the Mediterranean fruit fly, which was threatening the lucrative agricultural industry. Environmentalists campaigned unsuccessfully for years against the spraying, and the matter became a hot political issue in several elections.