The Return of Infectious Disease

Laurie Garrett

From Foreign Affairs, January/February 1996

Article preview: first 500 of 4,601 words total.

Summary:  After wiping out smallpox and winning other battles against the microbes, modern medicine ran into the aids virus. With urbanization and jet travel bringing people together in greater concentrations and more rapidly, infectious diseases are enjoying new opportunities to spread--and to evolve drug-resistant and more lethal strains. Advances in genetics make the threat of biological warfare even more threatening. It is time to write a better prescription for public health.

Laurie Garrett is the author of The Coming Plague: Newly Emerging Diseases in a World Out of Balance. She is a medical and science reporter for Newsday.

THE POST-ANTIBIOTIC ERA

Since World War II, public health strategy has focused on the eradication of microbes. Using powerful medical weaponry developed during the postwar period--antibiotics, antimalarials, and vaccines--political and scientific leaders in the United States and around the world pursued a military-style campaign to obliterate viral, bacterial, and parasitic enemies. The goal was nothing less than pushing humanity through what was termed the "health transition," leaving the age of infectious disease permanently behind. By the turn of the century, it was thought, most of the world's population would live long lives ended only by the "chronics"--cancer, heart disease, and Alzheimer's.

The optimism culminated in 1978 when the member states of the United Nations signed the "Health for All, 2000" accord. The agreement set ambitious goals for the eradication of disease, predicting that even the poorest nations would undergo a health transition before the millennium, with life expectancies rising markedly. It was certainly reasonable in 1978 to take a rosy view of Homo sapiens' ancient struggle with the microbes; antibiotics, pesticides, chloroquine and other powerful antimicrobials, vaccines, and striking improvements in water treatment and food preparation technologies had provided what seemed an imposing armamentarium. The year before, the World Health Organization (WHO) had announced that the last known case of smallpox had been tracked down in Ethiopia and cured.

The grandiose optimism rested on two false assumptions: that microbes were biologically stationary targets and that diseases could be geographically sequestered. Each contributed to the smug sense of immunity from infectious diseases that characterized health professionals in North America and Europe.

Anything but stationary, microbes and the insects, rodents, and other animals that transmit them are in a constant state of biological flux and evolution. Darwin noted that certain genetic mutations allow plants and animals to better adapt to environmental conditions and so produce more offspring; this process of natural selection, he argued, was the mechanism of evolution. Less than a decade after the U.S. military first supplied penicillin to its field physicians in the Pacific theater, geneticist Joshua Lederberg demonstrated that natural selection was operating in the bacterial world. Strains of staphylococcus and streptococcus that happened to carry genes for resistance to the drugs arose and flourished where drug-susceptible strains had been driven out. Use of antibiotics was selecting for ever-more-resistant bugs.

More recently scientists have witnessed an alarming mechanism of microbial adaptation and change--one less dependent on random inherited genetic advantage. The genetic blueprints of some microbes contain DNA and RNA codes that command mutation under stress, offer escapes from antibiotics and other drugs, marshal collective behaviors conducive to group survival, and allow the microbes and their progeny to scour their environments for potentially useful genetic material. Such material is present in stable rings or pieces of DNA and RNA, known as plasmids and transposons, that move freely among microorganisms, even jumping between species of bacteria, fungi, and parasites. Some plasmids carry the genes for resistance to five or more different families of antibiotics, or dozens of individual ...

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