Introduction

An epidemic of infectious disease is a dreaded event that evokes fears of danger, mortality, and the unknown. This is true even today, when we have known for more than a century that microbes rather than evil spirits, rotting food, or bad air cause disease. Unlike most natural disasters, whose terrors are confined to a particular time and place, an epidemic proceeds slowly and invisibly, in a silent, unpredictable, and inexorable way, lasting for weeks or months or even longer. The unsettling idea of an active, hidden, and malevolent force is reflected in the word we use to describe a newly emerged epidemic—an outbreak—which suggests that something dangerous and sinister has broken out of its restraints, like a monster escaped from a dungeon or a madman from a prison for the criminally insane.

No wonder that an outbreak can make us feel unprotected and helpless, especially when the basic facts—where the outbreak started, what microbe caused it, and how it is spread—are unknown. You cannot easily run away from an invisible enemy, or barricade your family and friends in an attic or basement until the epidemic is over. And if the cause of the epidemic is a new or drug-resistant microbe, even the experts may be unable to tell us (at least at first) how to protect ourselves and our loved ones.

Thus, microbes remain a disturbing prospect to most people and a formidable adversary to scientists and doctors. Despite healthcare advances such as vaccines and antibiotics, modern medicine has not been able to “conquer” infectious microbes, because of their amazing ability to change, adapt, evolve, and spread to new places. As the Nobel Prize winning microbiologist Joshua Lederberg liked to say. “Pitted against microbial genes, we have mainly our wits.”1 Our microbial adversaries not only overcome the obstacles we put in their way (e.g., by developing drug resistance) but also take advantage of modern technologies that allow them to spread in new ways and flourish in new niches. Microbes can live in modern ventilation systems, travel to new continents by airplane, and contaminate centrally-processed food products shipped to stores and restaurants in different locations. Microbes also benefit from increasing urbanization, mis-use of antibiotics, and increased opportunities to “jump” from animals to humans as more people use rain forests and other wilderness areas for settlement, agriculture, recreation, or tourism. Finally, as we learned during the anthrax incidents in 2001, human beings can deliberately spread pathogenic microbes as a weapon of warfare or terror.

Terrorism aside, some of the greatest dangers from infectious disease we face today are from microbes that develop drug resistance—like tuberculosis or staph or strep bacteria—and from new microbes that emerge unexpectedly from animal reservoirs, like the viruses that cause AIDS, SARS, and pandemic influenza. Because these diseases are new, we do not always have tools to treat them or prevent their spread. I remember the shock and disbelief I felt in 1983 when a young man I knew, a lively, charming graduate student in his late twenties, died within a few weeks of falling ill with a rare fungal pneumonia, now known to be an opportunistic infection of AIDS. His doctors’ helplessness recalled the days before antibiotics and vaccination, when deaths from infectious disease were common. I imagined what it must have been like in 1923, when my own grandfather, a doctor in New York City, died of bacterial meningitis contracted from a patient. There was no vaccine and no treatment. This is what we potentially face—even today, in the twenty-first century—with each outbreak of a new or newly drug-resistant disease.

What type of person is ready and able to pit his or her wits against the endless inventiveness of infectious microbes? The goal of this book is to answer this question by describing the scientific adventures of a special group of people—known formally as field epidemiologists and informally as medical detectives—who investigate outbreaks and figure out how to stop them, working in close partnership with public health laboratory scientists. These curious, determined, and intrepid individuals tend to be an unusual hybrid of “people-person” and scientific nerd. Like homicide detectives, they witness human suffering and elicit information from people in acute distress as part of their basic duties. Like physicians and nurses, they put themselves at risk while helping patients who may carry contagious diseases. Unlike a policemen or healthcare provider, however, they typically investigate many cases at once as part of a single mission, trying to figure out what all the cases have in common. In each case, their methodology involves the collection of medical and public health data that is carefully recorded, stripped of its human sorrows, and analyzed in the most wonkish of ways, using graphs, tables, and (above all) statistics. Public health statistics—“people with the tears wiped away”2—are the stock-in-trade of medical detectives, who have unshakable faith in their power to uncover the disease patterns behind the grief, loss, and pain caused by an epidemic. In many cases, medical detectives use their statistical findings not only to control disease but also to find ways to prevent future outbreaks once the immediate emergency is over.

The successes of these brave individuals often go unremarked and unsung. Most are employed by state and local health departments, and their work typically occurs behind the scenes, unknown to the general public. Most of the time, when they prevent disease spread, illness or death, no one is aware of it. As a result, the importance of what they do may be overlooked, and their jobs may be endangered by budget cuts, especially at times of recession and belt-tightening. I hope that Deadly Outbreaks helps to attract the next generation of epidemiologists by highlighting the indispensable role of medical detectives in maintaining the public health system that protects the nation’s health.