Quebec clears way for use of aerial pesticides to combat West Nile virus
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* Barbara Sibbald

New Quebec legislation that allows aerial spraying of pesticides if the West Nile virus (WNV) becomes a public health hazard has angered environmentalists. They say the risks associated with the virus do not justify pesticide use.

Edith Smeesters, a biologist who heads the 1000-member Coalition for Alternatives to Pesticides ([www.cap-quebec.com](http://www.cap-quebec.com)), says the risk posed by the virus is minuscule. Smeesters says aerial spraying of malathion, the pesticide Quebec is planning to use, means that people will be unable to avoid it. She adds that the proposed spraying is posturing designed to demonstrate that the government is doing something to combat the virus, which killed 7 people in New York City in 1999 (see *CMAJ* 2000; 163[7]:878).

The virus itself usually circulates in a bird-mosquito-bird cycle that can spill over into humans. (Dead crows are one of the major signs that WNV has arrived.)

The Quebec government has taken a better-safe-than-sorry stance in preparing for its arrival. “We wondered how we would act if [the virus] actually arrived and we realized we didn't have the capacity to act quickly,” said Dr. Monique Douville-Fradet, the provincial epidemiologist. “If we aren't prepared we will be accused of doing nothing.” 

She says aerial pesticide spraying, designed to kill the mosquitoes that act as the vector, would be a last resort. “We don't want to do it,” she says. “We have to be convinced of a sustained transmission in time and location.”

The spraying is made possible by Bill 15, which was passed by the Quebec National Assembly in June. It overrides other legislation, including municipal pesticide bans (there are 10 in the Montreal area alone) and Ministry of Environment rules requiring special permits for aerial spraying.

Although the virus can prove fatal, mainly among elderly or immunosupressed people, it often causes little more than mild fever and headache. The virus has now been found in 12 US states; in Canada it is most likely to spread to Ontario and Quebec, and possibly Manitoba and the Atlantic provinces. Health Canada has issued surveillance information ([www.hc-sc.gc.ca/hpb/lcdc/bid/wnv/](http://www.hc-sc.gc.ca/hpb/lcdc/bid/wnv/)**)**.

Malathion is approved for use in both the US and Canada and is used routinely to control mosquitoes in Winnipeg. It is highly toxic to fish and aquatic invertebrates. Last summer it killed thousands of lobsters on the US eastern seaboard, spawning lawsuits from commercial fishermen.

Douville-Fradet is pushing for approval of resmethrin, a synthetic pyrethroid that is being used in New York City's program against WNV. Health Canada's Pest Management Regulatory Agency (PMRA) refused to give Quebec emergency approval for aerial use of resmethrin because another product — malathion — is already available.

Richard Aucoin, chief registrar at the PMRA, isn't surprised that Quebec is taking steps to deal with the virus. “It's probably safest to overreact than underreact,” he says. 

“When the first crow dies it will be quite interesting,” adds Douville-Fradet. “Once the virus is here, people's attitudes [about spraying pesticides] will change.”

![Figure1](http://www.cmaj.ca/https://www.cmaj.ca/content/cmaj/165/4/463.2/F1.medium.gif)

[Figure1](http://www.cmaj.ca/content/165/4/463.2/F1)

Figure. **Will West Nile virus threat change attitudes toward aerial spraying?** Photo by: Canapress