The four-year-old U.S. outbreak of West Nile virus is a significant threat to public health. Midway through the West Nile season, the mosquito-borne virus has been found in animal hosts (primarily birds and horses) in 44 states, and in humans has caused more than 4,000 serious illnesses and almost 100 deaths in 37 states.
In 2001, there were more than 4,000 cases and almost 300 deaths. Although we may be on the verge of a major epidemic, there is no treatment and a vaccine is at least a decade away.
Federal public-health officials have recognized the seriousness of the problem, but their response has been tepid and politically correct. The website of the Centers for Disease Control suggests “avoiding mosquito bites” by wearing clothes that expose little skin, using insect repellent, staying indoors during peak mosquito hours (dusk to dawn); “mosquito-proofing your home” by removing standing water and installing and maintaining screens; and “helping your community” by reporting dead birds and checking to see whether there are local mosquito-control programs.
Conspicuously absent from its list of suggestions — and also from CDC director Julie Gerberding’s remarks at her frequent public appearances — is any mention of insecticides or widespread spraying. Anyone curious about the role of pesticides in battling mosquitoes and West Nile is directed to a maze of other websites.
Perhaps the Atlanta-based CDC officials don’t get out much. Residents of areas such as coastal Maine, Texas, Florida, and the Carolinas; the cotton-growing regions of the Deep South; the lake country of the northern Midwest; and the marshlands of the Delaware Valley and Chesapeake Bay could tell the bureaucrats that they’re on the wrong track: Emptying birdbaths and the saucers under flower pots is not going to get rid of a zillion hungry mosquitoes.
WAR AGAINST DDT
In the absence of a vaccine (the development of which, as discussed below, 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. Allowing green politics to preempt science, regulators also cited the possibility that DDT posed a cancer risk for humans, an assertion based on studies that showed an increased incidence of the illness in mice that were fed extremely high doses of the pesticide. (The validity of extrapolating these high-dose animal studies to minuscule exposures in humans was and remains in doubt.)
Not only did government regulators discount the overwhelming scientific evidence of the effectiveness and relative safety of DDT, but they also failed to appreciate the distinction between its large-scale use in agriculture and its more limited application for controlling insect carriers of human disease. Although DDT is a (modestly) toxic substance, there is a big difference between applying large amounts of it in the environment — as American farmers did before it was banned — and applying it carefully and sparingly to fight mosquitoes and other disease-carrying insects. The use of DDT use for insect control would require relatively small amounts of the chemical. This is an important distinction: 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. Also, the need to spray other insecticides repeatedly — especially in marshlands and forests, where mosquito-breeding areas are large — drives up costs and depletes public coffers. Last summer, budgetary limitations compelled Maryland to turn down requests for spraying from communities that were badly infested with mosquitoes. And Caddo Parish, Louisiana, which currently spends more than $360,000 a year on mosquito control (yet has the most human cases of West Nile-virus infections in the state), uses much of its mosquito-control budget for spraying with pyrethroid pesticides, but these products can’t keep up; they are inactivated within an hour or two.
MOSQUITO-PRIORITY RATING
Even without DDT, currently approved pesticides controlled mosquitoes moderately well last year in much of the eastern and southern United States, in spite of the near-hysterical resistance to spraying by environmental activists, who have attacked the killing of mosquitoes as “disrupting the food chain.” And New York’s Green-party literature declared, “These diseases only kill the old and people whose health is already poor.” These activists seem to regard epidemics of infectious diseases as a valid method of human population control. (Interestingly, Illinois led the nation in both West Nile infections and deaths in 2002 because government officials, bullied by radical environmentalists, rejected the widespread spraying of insecticides.)
Since the banning of DDT, insect-borne diseases such as malaria and dengue — and now West Nile virus — have been on the rise. (Had they been declining, activists would probably have demanded that we protect the infectious agents as endangered species.) 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.
A few recent success stories can be found, however; countries that have continued to use DDT have lower death rates and smaller economic losses than those that have instituted bans. For example, India reduced the number of cases of malaria from approximately 75 million in 1951 to around 50,000 in 1961; the incidence remains low today because India continues to use DDT. And during the six years following Ecuador’s 1993 decision to increase DDT use, there was a 60 percent decrease in malaria cases. By contrast, the number of new cases rose 90 percent during the same period in Bolivia, Paraguay, and Peru, all of which stopped spraying DDT altogether in 1993.
How can we drain the public-policy swamp? First, the U.S. government should undertake a reevaluation of the voluminous data on DDT that have been compiled since the 1970s. It should also make DDT available for mosquito control in the United States.
Second, the United States should oppose international strictures on DDT. This includes retracting American support for the United Nations Persistent Organic Pollutants Convention, which severely stigmatizes DDT and makes it exceedingly difficult for developing countries — many of which are plagued by malaria — to use the chemical.
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. To accomplish this, however, a senior public health official will need to come forth and champion the issue. CDC director Gerberding’s unwillingness even to mention the P-word — pesticide — makes her a non-starter. The U.S. Surgeon General, Richard Carmona, seems a likely candidate — or at least he would be if he weren’t completely invisible. (One wonders whether he has settled permanently into the “undisclosed location” inhabited by Vice-President Dick Cheney during crises.)
Avoiding mosquito bites isn’t the only approach to the prevention of West Nile-virus infection. Vaccines are another answer, and several years of progressively increasing numbers of infections should have afforded ample time to begin work on one. But because it has become so hard to make money at vaccine development, that is wishful thinking.
Producers are abandoning the field in droves. From 1967 to 1984, the number of U.S. vaccine manufacturers fell from 37 to 15, while the number of FDA-approved vaccines declined from 380 to 88. There are now only five major producers and a few dozen products. As a result, the country has recently experienced dangerous shortages of several essential vaccines, and many school systems have been forced to waive immunization requirements because there aren’t enough vaccines available.
Again, the problem is flawed public policy.
For example, the U.S. Centers for Disease Control and Prevention — the largest domestic purchaser of vaccines — uses its buying clout to compel deep discounts for purchases. Recently, the CDC rejected Wyeth Lederle Vaccines’ proposed price of $58 per dose for its pneumococcus vaccine, demanding (and getting) a discount of $10 per dose. Don’t expect Wyeth Lederle to invest much in vaccine R&D anytime soon.
Arbitrary and excessive regulation also blocks progress. Consider, for example, the FDA’s position on a vaccine to prevent meningitis C, a bacterial illness that infects thousands of Americans and kills hundreds each year. No state-of-the-art vaccine against this infectious disease is approved for use in the United States, although three excellent products are available in Canada and Europe. The safety and efficacy of these vaccines have been amply demonstrated, with more than 20 million doses administered. Yet the FDA refuses to recognize the foreign approvals, although reaching agreement on such “reciprocity” of approvals is supposed to be a high priority for regulators.
Finally, the potent trial-lawyer lobby opposes changes in vaccine liability that would reduce the frequency of huge, unwarranted judgments.
What can we do to make vaccine development more attractive, so that future outbreaks of West Nile and other infectious diseases can be prevented?
First, accept reciprocity of vaccine regulatory approvals between the United States and the European Union. This would cut development costs significantly.
Second, stop public agencies from demanding extortionate prices for vaccines.
Third, give companies tax credits to defray research and development costs, more favorable patent terms, and similar measures to increase the payoff for developing vaccines.
Fourth, exempt vaccination from plans in which the insured must pay “first dollar” health-care costs — an arrangement that discourages consumers from opting for discretionary, preventive medical interventions.
Finally, indemnify companies against damages caused by side effects from FDA-approved vaccines.
These reforms won’t come easy. Eco-babble, green hysteria, and intransigence at the EPA will probably preclude a return to the use of DDT in this country, as will its inclusion on the list of chemicals to be banned in the U.N.’s Persistent Organic Pollutants Convention. As to new incentives for vaccine production, getting the government to adopt them will be about as easy as dragging a child to the doctor for a painful shot. Therefore, in the meantime, we’ll have no choice but to slather on the insect repellent, slap, scratch — and occasionally become infected with a life-threatening but preventable disease.
— Henry I. Miller, a physician, is a fellow at the Hoover Institution.