Imagine if government officials decided that every man, woman and child in Ontario, Quebec or Manitoba should be forcibly vaccinated against the flu. In fact, cats, squirrels, raccoons and that annoying chihuahua down the street would get jabs, too. No exceptions. There are excellent reasons for doing this, the provinces would point out. Across Canada, close to 25,000 people get the flu each year and 2,000 people die from it. Even worse, people who have the flu can spread it to other people. Such a measure would save the health system a fortune.
Does this scenario sound ridiculous?
It should. And yet, this is what the people who want to spray pesticides to kill West Nile-bearing mosquitoes are advocating. Anyone can decide not to be vaccinated. People sometimes have good reasons for declining. Parents have gone to court to fight for their rights not to inject their children with proteins that convey immunity against measles, mumps and rubella. Some people just value their freedom to choose.
But when a tanker truck rolls through your neighbourhood sending plumes of synthetic poison into the air, your right to not be exposed is extinguished.
Spraying advocates argue pesticides are not very harmful to people, noting that, under safety standards set by the the U.S. Environmental Protection Agency, a child could stand in a shower of malathion -- the larvicide used to kill mosquitoes -- for 20 minutes without suffering any harm. Leaving aside the unscientific nature of this claim (Has it ever been tested? Whose child? Not mine, thanks.), it ignores the central premise in public health that nothing is completely safe. After countless studies, the evidence of harm from 2,4-D and DDT and many other pesticides is thin.
Does that mean they are safe? Not even close.
In public health, interventions are made only when the benefits are greater than the risks. The flu vaccine can have negative side effects. In rare cases, it causes death. But the lifesaving benefits of the vaccine for many people, especially the elderly, are a thousand-fold greater than its risks. Obversely, many communities across Canada have prohibited the use of pesticides for cosmetic purposes. This is because the risk of dandelions is a thousand times smaller than the small chance a child or creature could be harmed by these chemicals.
As a wise environmentalist once put it, "Why are we spraying these poisons in the suburbs, when the only crop we're trying to raise is children?"
Which brings matters to West Nile virus.
The number of deaths associated with the virus sounds alarming. Individually, each death is a tragedy. But West Nile is not the only pathogen that causes encephalitis, the fatal swelling of the brain. There are plenty, including La Crosse, Northway, Main Drain, and Lokern viruses, as well as Western equine encephalitis. Good old Missouri may not sound as exotic or frightening as the West Nile, but St. Louis encephalitis hits about 160 North Americans a year, killing about 20% of them. Last year, scientists at the Centers for Disease Control and Prevention reported on the first case of California encephalitis in 50 years in a 65-year-old man who had the bad luck to live near a brackish marsh in Marin County, near San Francisco Bay. West Nile has become a darling of the media, in large measure because it struck first in New York City. If its first victims had resided in, say, Yellowknife, it would not be the object of documentaries on CNN.
Public health officials must determine whether the benefits of spraying with malathion and other pesticides outweighs the risk of West Nile. In some places, it may. Mosquitoes die in northern climates in winter, reducing the risk for much of the year. But in Louisiana, Texas, Florida and tropical climates, they can infect people year-round, and the relative benefits of spraying may be greater there. For the same reason, it makes sense to spray DDT in parts of Africa and Asia where malaria is endemic. As many as 500 million cases occur each year, killing up to 3 million people, 90% of them children in poor countries.
But West Nile disease is a far cry from malaria.
Furthermore, nobody has proved spraying pesticides will stop West Nile in its tracks. It might. What if it doesn't? How can you judge the risks if the benefits are unclear?
What the public needs is a treatment. With the stunning pace of advancement in biotechnology, it should be easy to find a way to kill one uncomplicated virus. There is already a preventive vaccine for horses. But of course, before a West Nile vaccine could be injected into humans, scientists would have to prove any adverse side effects would be less dangerous than West Nile disease. Even if they could, governments could not force citizens to take mandatory jabs.
So why are so many people so willing to lie down and be sprayed?
Reprinted from the National Post 23 September 2002, with permission.