Outbreaks and Investigations

Virginia Dato

Center for Public Health Practice, University of Pittsburgh, Graduate School of Public Health, Pittsburgh, Pennsylvania

Richard Shephard

Australian Biosecurity Cooperative Research Centre for Emerging Infectious Disease, Brisbane, Australia

Michael M.Wagner

RODS Laboratory, Center for Biomedical Informatics, University of Pittsburgh, Pittsburgh, Pennsylvania

1. INTRODUCTION_

In Ernest Hemingway's novel The Sun Also Rises, when Mike Campbell, a Scottish expatriate and World War I veteran, is asked how he went bankrupt, he replies, "gradually, then suddenly.'' Often, this is how outbreaks of disease appear. Outbreaks can wreak much havoc before they are noticed, and they can grow at an exponential rate before they are brought under control. Some outbreaks spread so far we call them epidemics, or pandemics if they encompass the entire planet. Some outbreaks have never been brought under control. The only certainty is that an outbreak becomes more difficult to stop through human intervention the longer it goes unnoticed.

Chapter 2 presents many examples of outbreaks that differ in their origins and in how they were detected, characterized, contained, or continued to develop. Some of these outbreaks have impacted not only health but history itself.These examples illustrate the basic goals, tasks, and activities of biosurveillance and provide a sense of how the methods of biosurveillance have evolved over time.

2. HISTORICAL OUTBREAKS_

The lives of humans, animals, and microbial organisms have been irrevocably intertwined throughout evolution. Humans rely on these organisms to perform some of the basic functions of life; for instance, the organisms that reside in the gastrointestinal tract of humans participate in the digestion of food. Mitochondria, which provide the energy that fuels our cell processes (Penniston, 1997), evolved from bacteria that were incorporated into primitive cells during the early stages of evolution. Of course, not all interactions between microbial organisms and humans are favorable. Human (and animal and plant) populations have been battling these unseen living organisms throughout the course of history and, in many instances, losing. William H. McNeill (1989), in his book Plagues and Peoples, summarizes the scientific evidence of disease outbreaks that predate recorded history.

Hippocrates (460-377 bc) wrote some of the oldest surviving descriptions of disease outbreaks. He described an outbreak of mumps on the island of Thasos, now present-day Greece. Hippocrates also described what appear to be outbreaks of malaria, diphtheria, tuberculosis, and influenza (McNeill, 1989). Thucydides, a contemporary of Hippocrates, described an outbreak that decimated the Athenian army and many civilians in 430 to 429 bc (McNeill, 1989). When the outbreak ended, it left a weakened Athenian empire that soon fell to Sparta.

The Black Plague killed 25% to 50% of Europe's population between 1348 and 1351 (EyeWitness to History.com, 2001). Smallpox wiped out a large portion of the native population of Hispaniola (now Haiti and the Dominican Republic) and spread from there to Mesoamerica (present-day Mexico), contributing to the demise of the Aztecs (McNeill, 1989).

Until the 20th century, the world's urban population was so routinely devastated by infectious diseases that only constant in-migration from the countryside could maintain the population of growing cities (McNeill, 1989).

The 20th century brought technological and medical advancements—improved sanitation, vaccines, and antibiotics— that quickly reduced mortality due to infectious disease. Figure 2.1 demonstrates the steady decline in the death rate in the United States as infectious diseases were gradually controlled with these tools. The death rate reaches its lowest point in 1980, just after natural smallpox was eradicated and just before the appearance of AIDS.

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