Column: West Nile: Where's the DDT?
 

Politically correct federal policy inhibits our ability to combat insect-borne diseases

West Nile virus has hit California particularly hard this year, causing at least 155 serious illnesses – more than twice as many as in any other state – and three deaths. During the nine-year outbreak, there have been more than 6,000 serious illnesses and over 300 deaths nationwide.

Many of these illnesses and deaths could have been prevented, but thanks to flawed, politically correct federal regulatory policy that inhibits society's ability to combat insect-borne diseases, the available tools are limited and largely ineffective.

West Nile virus is transmitted mainly between avian hosts and mosquitoes, and until the mid-1990s was associated with only mild infections of humans in Africa and the Middle East. After a single mutation in a viral gene, however, the virus became more virulent and caused severe outbreaks of encephalitis and other serious manifestations in Romania in 1996, and subsequently in Israel, Tunisia, Russia, and North America. Research on the virus provides evidence that the mutated virus enjoys an evolutionary advantage that enables it to adapt rapidly to changing environments, to spread, and to cause disease outbreaks.

The continuing challenges of new disease-causing organisms illustrate the need for resilience in public policy, but West Nile virus infection offers an object lesson in how to limit society's options, stifle resilience and let the pathogens get the upper hand.

The Web site of the Centers for Disease Control suggests several measures to avoid West Nile virus infection: wear clothes that expose little skin; use insect repellent; stay indoors during peak mosquito hours (dusk to dawn); and "get rid of mosquito breeding sites," by removing standing water and installing and maintaining screens.

Conspicuously absent from its list of suggestions is any mention of insecticides or widespread spraying, and there is scant information about them anywhere on the CDC's Web site.

I guess the Atlanta-based CDC officials don't get out much. You don't have to be a rocket entomologist to know that emptying birdbaths and the saucers under flower pots is not going to get rid of a zillion hungry mosquitoes in regions of the country that have woodlands or wetlands.

In the absence of a vaccine (the development of which has public policy problems of its own), elimination of the vehicle that spreads the disease – in this case, the mosquito – ought to be the key to preventing epidemics, but fundamental shortcomings in public policy limit the weapons that are available.

In 1972, on the basis of data on toxicity to fish and migrating birds (but not to humans), the Environmental Protection Agency banned virtually all uses of the pesticide DDT, an inexpensive and effective pesticide once widely deployed to kill disease-carrying insects. (How ironic that regulators banned DDT largely for its toxicity to birds: Now it's unavailable to combat a mosquito-borne viral disease that is killing birds by the hundreds of thousands.)

Not only did government regulators underplay scientific evidence of the effectiveness and relative safety of DDT, but they also neglected to make a distinction between its large-scale use in agriculture and more limited application for controlling carriers of human disease. Although DDT is a (modestly) toxic substance, there is a world of difference between applying large amounts of it in the environment – as American farmers did before it was banned – and using it carefully and sparingly to fight mosquitoes and other disease-carrying insects. A basic principle of toxicology is that the dose makes the poison.

The regulators who banned DDT also failed to take into consideration the inadequacy of alternatives. Because it persists after spraying, DDT works far better than many pesticides now in use, some of which are toxic to fish and other aquatic organisms. With DDT unavailable, many local jurisdictions are depleting their mosquito-control budgets by repeated spraying with short-acting, marginally effective insecticides. Moreover, even if mosquitoes becomes resistant to the killing effects of DDT, they are still repelled by it.

Not for the first time, the EPA's playing politics was inimical to the public interest.

The spraying of any pesticides – let alone DDT – has been greeted by near-hysterical resistance from environmental activists, who have attacked the killing of mosquitoes as "disrupting the food chain." And several years ago New York's Green Party literature declared, "These diseases only kill the old and people whose health is already poor."

Since the banning of DDT, insect-borne diseases such as malaria and dengue – and now West Nile virus – have been on the rise. The World Health Organization estimates that malaria kills about a million people annually, and that there are between 300 million and 500 million new cases each year.

This huge toll has caused some bureaucrats to rethink DDT's use. In 2005, the United States Agency for International Development endorsed DDT for malaria control, following the lead of the World Health Organization. But to control mosquitoes that carry West Nile virus, the pesticide would need to be used widely – albeit in small amounts – and it should be.

How can we drain the public policy swamp? First, the government should undertake a re-evaluation of the voluminous data on DDT that has been compiled since the 1970's, and U.S. regulators should make DDT available immediately for both indoor and outdoor mosquito control in the United States.

Second, the U.S. government should oppose international strictures on DDT.

Finally, federal officials should embark on a campaign to educate local authorities and citizens about the safety and potential importance of DDT. Right now, most of what people hear is the reflexively anti-pesticide drumbeat of the environmental movement. (This is the lamentable legacy of the benighted Rachel Carson and her acolytes.) In order to accomplish this, however, senior public health officials will need to come forth and champion the issue.

Because DDT has such a bad rap, it will be politically difficult to resurrect its use. But we should begin the process now. In the meantime, we'll just slather on the insect repellent, slap, scratch – and occasionally become infected with a life-threatening but preventable disease.