Battling Resistance to Antibiotics and Pesticides: An Economic Approach. Ramanan Laxminarayan, ed. Resources for the Future, Washington, DC, 2003. 400 pp., illus. $65.00 (ISBN 1891853511 cloth).
I should state at the outset that, although the book in review is about the economics of battling evolved resistance to pesticides and antibiotics, I am a microbiologist and much more familiar with antibiotics than with pesticides. Furthermore, living in a country whose economy is handled by politicians with scant respect for rational analysis, I had not even realized that the economic approaches described here were possible.
Ramanan Laxminarayan, the editor of Battling Resistance to Antibiotics and Pesticides, is a fellow at the Washington, DC, think tank Resources for the Future and an expert on the intersection of economics and public health, especially resistance and the management of malaria. More than half of the book is devoted to pesticides. Most chapters deal with specific mathematical models borrowed from economic theory and applied, sometimes with modification, to resistance. Although I lack the mathematical background to evaluate the math critically, the book includes, intercalated among the mathematical chapters, critical discussions by biologists knowledgeable about the modeling. These discussions offer clear explanations of the issues and allow the reader to compare models that approach similar problems in different ways. In sum, the reader gets a pretty good idea of the goals and the reach of each model, and the big picture is very interesting.
The models grapple with a very complex phenomenon. Dealing with multiple types of resistance, coselection, and non-Darwinian evolution, while also reckoning with the social forces that must be considered in combating antibiotic resistance, is an immense task. One revealing example contrasts two models, one of which seeks to incorporate the biological cost of resistance traits in the absence of selective pressure from antibiotics. Biological questions about this cost are far from resolved, and there is not yet enough evidence to establish its magnitude. But results from the models, when compared with the behavior of pathogens in the real world, can help researchers decide which model more closely resembles nature. Another model that shows itself to be particularly useful in understanding the treatment of infectious diseases comes, surprisingly enough, from highway traffic management. Mathematical modeling aside, the book is packed with data on the economic impact of resistance, data that are useful to keep in mind when discussing the real-world relevance of research on antibiotic resistance.
The part of the book that deals with pesticides centers on the strategies deployed to slow the pace at which bugs become resistant to Bacillus thuringiensis (Bt) toxin, which has been genetically engineered into many crops. The principal strategy—namely, scattering wild-type crops among crops containing the toxin—is discussed by authors advocating a variety of approaches. Using a comparable strategy for antibiotics would clearly be impractical and unethical: We could hardly deny access to antibiotics to some fraction of the population so that they could serve as reservoirs of susceptible bacteria. Nonetheless, it is widely believed that restrictions on the use of quinolone antibiotics in children have kept resistance to these drugs from spreading more rapidly than it has; in a sense, then, children may be serving as reservoirs of susceptibility to pathogens, much as wild-type crops are reservoirs of susceptibility to Bt toxin.
Resistance to antibiotics, and most likely to pesticides as well, is mainly a consequence of the abuse of these powerful weapons. Some antibiotics are prescribed for nonexistent illnesses, for example, or for conditions unlikely to be affected by them. Advocates of the rational use of antibiotics are increasingly trying to persuade physicians to refrain from prescribing antibiotics in such instances. But these advocates usually operate in an academic mode, delivering colorless talks and papers. They are competing against costly and aggressive promotional campaigns designed by pharmaceutical companies to persuade physicians to prescribe as many antibiotics as possible in the short term. This policy runs counter to the best interests of society in a number of ways, yet companies pursue that policy because it seems to be profitable to do so. Although educational efforts are making some progress, pharmaceutical companies will continue to promote abuse unless biomedical scientists provide compelling evidence to corporations that it is better to keep antibiotics useful for a long time than to “burn” them fast in search of quick revenues. I do not believe that researchers can yet produce such compelling evidence, but after reading Laxminarayan's book, I know there are ways in which it might be attempted.
