New York renews war on mosquitoes after return of deadly West Nile virus

New York City is once again poised to declare war on summer mosquitoes. The blitz follows the revelation by health officials this week that the deadly West Nile virus has been found in two dead crows on Staten Island, inside the metropolitan area, and in mosquitoes collected in two counties abutting the city.

New York City is once again poised to declare war on summer mosquitoes. The blitz follows the revelation by health officials this week that the deadly West Nile virus has been found in two dead crows on Staten Island, inside the metropolitan area, and in mosquitoes collected in two counties abutting the city.

Spray trucks will blanket large areas of Staten Island, one of New York City's five boroughs, with insecticide this evening. Residents will be ordered to stay indoors with their pets, to close windows and to turn off air conditioners while the operation is completed, even though temperatures are expected to be high.

The city has been on mosquito alert all summer after last year's outbreak of the West Nile virus. It was the first time that West Nile had surfaced in the Western hemisphere, prompting suspicions of a bio-terror attack, which were never substantiated. The outbreak left seven people dead, infected 62 others and triggered a huge ground and aerial insecticide-spraying campaign.

It had been hoped that the virus might have perished during the winter months. All such optimism has now been dashed and this week's spraying promises to be only the start of a long war of attrition.

Carried by mosquitoes, the virus is typically passed to crows before it begins to infect humans. Rudolph Giuliani, the city Mayor, stressed that no cases of human infection have so far been detected this year. Speaking at a press conference, he urged residents not to panic. Referring to the plans to spray, however, the Mayor added: "It is absolutely necessary that we do this."

Officials at the Center for Disease Control in Atlanta conceded that it is probably only a matter of time before human infections begin in the New York area. West Nile virus can cause fatal swelling of the brain and attack the central nervous system. Most at risk are the elderly, the very young and anyone with a diminished immune system.

Spraying in the two counties just beyond the city, Westchester and Suffolk, was scheduled to begin last night, weather permitting.

Officials were also concerned that the type of mosquito found to be carrying the virus in Westchester feeds during the hours of both day and night. Last year, only night-feeding mosquitoes were found to be infected.

In response to controversy about possible risks to human health from the insecticide used last summer, the city is this time using a new insecticide known as Anvil.

Officials warn, however, that this can still irritate the skin and cause breathing difficulties in some people.

Residents across the city and neighbouring counties are being urged to eliminate all standing water in their homes - for instance, in blocked gutters and discarded tyres - in an effort to reduce mosquito habitats. They are also being asked to wear insect repellent and to stay indoors as much as possible after dusk or to cover up with clothing. Repellent will be distributed free in some neighbourhoods this week.

Mr Giuliani said that helicopter spraying would begin only if further evidence were to be found of the virus spreading and threatening the human population.