OPTIMISM AND INDIFFERENCE

As will be made clear throughout this report, the number and variety of microbial threats to human health are daunting. Just as clear, however, is the fact that tremendous strides have been and continue to be made in the battle against infectious diseases. In particular, advances in medical science and public health practices have vastly improved our understanding of and ability to control many of these illnesses.

Penicillin, discovered in 1929 and eventually produced in a usable form during World War II, was the first of a multitude of new antibiotics that have saved the lives of many who otherwise would have succumbed to bacterial infections. Similarly, the development and mass production of effective vaccines against such diseases as measles, pertussis, diphtheria, and polio have prevented large segments of the population from contracting these and other very serious diseases. More recently, advances in biotechnology, in particular, genetic engineering, have made it possible to produce drugs, vaccines, and other therapeutic agents with increased specificity.

Also important in the battle against infectious disease have been interventions against arthropod vectors of disease agents. Pesticides have played a critical role in suppressing arthropod-borne diseases in the United States and abroad. Unfortunately, excessive agricultural use of some pesticides has resulted in the destruction of nonpest insects and, in some cases, in food and water contamination. Public health use of these chemicals can also cause resistance in the very insects they are intended to kill. In the United States, these environmental and public health concerns led to a 1972 ban on the agricultural use of DDT, a broadly effective and inexpensive means of controlling many insect pests. Ten years later, U.S. production of the chemical ceased altogether, and there was a dramatic worldwide drop in its use. Increasingly, insect resistance and legal restrictions on pesticide use are hindering efforts to control disease-carrying vectors with the repertoire of potentially available chemicals.

One of the most effective ways of preventing epidemics of arthropodborne diseases has been to eliminate the sites in which the vectors breed and develop. This approach was attempted inadvertently as long ago as the sixth century B.C., when the Greeks and Romans undertook major engineering projects to drain marshy swamps in an effort to control outbreaks of fever, which it is now believed were due to malaria. General William C. Gorgas, a U.S. Army physician and engineer, effectively controlled malaria and yellow fever during construction of the Panama Canal (1904–1914) through a combination of drainage and larviciding (Gorgas and Hendrick, 1924). Another example is the eradication of Aedes aegypti from extensive areas of the Western Hemisphere by intensive control of the domestic water sources of this vector. Unfortunately, when such programs were ended,



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