Читать книгу Principles of Virology, Volume 2 - Jane Flint, S. Jane Flint - Страница 26

One powerful example of a deadly viral epidemic that influenced American history and changed how cities are managed is the yellow fever outbreak that occurred in Philadelphia, Pennsylvania. In 1793, when this epidemic occurred (and a full century before Walter Reed’s commission), nothing was known about yellow fever virus, the disease, or how it was spread. Worse, no one at the time knew that viruses existed, so the seemingly random way that individuals became sick com pounded the confusion and sense of helplessness. Further-more, this epidemic struck at a pivotal time for the fledgling Union. At that time, Philadelphia was the new nation’s temporary capital and a city of active commerce and trade. One can easily imagine the panic in Philadelphia when scores of individuals became ill and died of this mysterious disease within a very short time. In the 101 days between August 1 and November 9, some 5,000 people perished in a city of about 45,000, making this one of the most severe epidemics in the history of the United States (Fig. 1.4). There were few families that did not lose a relative to this disease, and many entire families were lost. Those who could flee the city did so, including the new president, George Washington, and his cabinet. Others stayed behind to aid the sick, including men of the Free African Society, who volunteered on the basis of the incorrect notion of Benjamin Rush, a prominent Philadelphia physician, that black people were immune to infection.

Figure 1.4 Deaths caused by the yellow fever epidemic in Philadelphia, 1793. This map records the locations of deaths due to yellow fever, with red and orange streets marking those with highest mortality. Yellow fever was most deadly near the northern wharves, where poorer people lived, and where Hell Town was located (just blocks away from Independence Hall and the current home of the Liberty Bell). These areas furnished breeding places for Aedes aegypti, the species of mosquito that transmits the disease. Adapted from Paul Sivitz and Billy G. Smith, with permission.

Because Philadelphia was a major port city, it is likely that the agent, which we now know was the yellow fever virus, was transported by infected individuals on cargo ships, and that standing water in the city provided a hospitable breeding ground for local mosquitos and rapid expansion of the disease along the wharves. Credit goes to Rush, who noticed identical symptoms in many victims and who recommended that individuals either leave the city or quarantine themselves, practices that helped to curtail the epidemic. Rush’s belief that the scourge arose from a pile of rotting coffee beans left on a dock, and his treatment regimen of purging and bloodletting, are less worthy of praise.

The city of Philadelphia was transformed after the epidemic. The outbreak, believed by many to be due to contaminated water (which was, in part, true), spurred the local government to establish a municipal water system, the first major city in the world to do so. Infirmaries to tend to the sick and isolate them from the healthy were developed. Finally, the epidemic promoted a city-supported effort to keep streets free of trash, leading to the development of a sanitation program that would be a model for similar programs elsewhere. Although an effective vaccine now exists, yellow fever still kills 30,000 people every year, about 90% of them in Africa.