The Global Threat

To the Editors:

Richard Horton is certainly correct in pointing to the prospect of new diseases, or of partially immune to antibiotics strains of diseases, and urging that we prepare for it [“Infection: The Global Threat,” NYR, April 6]. The problem is more difficult than he implies because of the need to balance environmental considerations against potential defenses.

At one point he criticizes WHO for announcing that a time would soon be approaching when malaria would be “no longer of major importance.” WHO made this statement back in the days when malaria had almost been wiped out by the widespread use of DDT to kill the transmitting mosquitoes. Then came Silent Spring, with its violent attack on DDT. The environmental effects of DDT were greatly emphasized, and its prevention of malaria was never once mentioned in that book. The United States, a country where malaria was not very important, banned DDT and missionary activity throughout the rest of the world got it dropped elsewhere. The result was the revival of malaria.

I am not arguing that the banning of DDT was undesirable. There were environmental effects, and the weighing of those environmental effects against the death of something like a million per year from malaria is not an easy problem.

The second area where weighting is needed is the development of new drugs. The new chemical entity may cure the disease, but it may have secondary effects which are worse than the disease. The FDA has the power to prevent the issuance of new drugs (and medical devices) until their safety and effectiveness has been proved. Their procedures lead to very significant delays in the introduction of the new drugs. Some people are saved because of the prevention of the use of drugs that turn out to be dangerous. Others die because drugs that could save them are held back. The FDA procedures also make the invention of a new drug much less profitable and hence lead to a reduction in the amount of research for new cures.

The reduction in the rate at which new cures are made available should be balanced against the likely dangers of new drugs. Most people who have looked at the problem think the FDA is too conservative, but the proper balance is clearly a difficult problem.

Having raised these problems, I regret to say that I have no remedy. We must give careful consideration to these problems, and a one-sided approach is not very helpful. I have no solution to the problem raised by DDT and malaria long ago, but I do think that both sides should be presented.

Gordon Tullock
Karl Eller Professor of Economics and Political Science
University of Arizona
Tucson, Arizona

Richard Horton replies:

I share Gordon Tullock’s skepticism about the ease with which simplistic notions of environmental holism can be translated into practical strategies to prevent the spread of emerging infectious diseases. His points, however, miss their mark.
First, Tullock suggests there has been a deep conflict between the environmental effects of DDT and the uncontained endemic threat of malaria; but this was not an unavoidable conflict. The fallacy of the DDT eradication campaign, as Laurie Garrett points out, was the uncritical belief that DDT would be the final word in insectborne disease. For malaria, such artificial pressure on genetic selection simply encouraged the emergence of DDT-resistant strains of the Anopheles mosquito. When this evolutionary consequence was combined with the termination of funding for the DDT program in 1963, a dramatic return of malaria was assured.

That there has been an acceleration of natural selection through our crude efforts to control infection—and a need for new drugs to combat resistant variants of old diseases—leads to Tullock’s second claim: that overly conservative drug regulatory policies have delayed treatment. Christopher H. Foreman provides an especially lucid account of these issues in his Plagues, Products, and Politics (The Brookings Institution, 1994). Chloride-deficient infant-feeding formulas, the Dalkon shield, perilous L-tryptophan and vitamin E supplements, and the damaging swine-flu vaccine program—all are instances that support the case for stringent regulations. To relax the criteria for regulatory approval, to skip elements of the approval process, or to base evaluations on flexible (and inevitably adhoc) calculations of risks and benefits is to court disaster. Some would argue that speeded-up procedures that were used to approve some largely ineffective anti-HIV drugs were, in the long run, examples of such an ill-thought-out strategy.

Are remedies as elusive as Professor Tullock suggests? Perhaps. But the powerful political and commercial influences that inhibit the process by which solutions could be found are easier to identify. We would surely agree that the short-term fears and calculations which now dominate the unpredictable forces of the marketplace militate against the careful and reflective evaluation that he calls for. One suspects that only a natural disaster of the dimensions of the HIV pandemic—affecting a relatively large proportion of citizens, from all the different communities in an industrialized nation—will provide the necessary motivation to reconsider current procedures and take a longer-term view.

A further important obstacle is the lack of interdisciplinary research into both the ecology of diseases and into human behavior. These fields are seen by many as inexact, and therefore inferior relations, when compared, for example, to the “big science” of human genome research. Yet the construction of a new investigative model seems to me to offer one tangible remedy of sorts. By bringing economic, geographic, and social perspectives to bear on basic science, we might come close to achieving the more reasoned approach that Tullock asks for. Only as they confront clear and confirmed evidence of future threats will scientists and politicians be drawn to reflect more critically on the risks of global infection.