either for economic reasons or because limitations had been put on the use of pesticides, vector populations grew to pre-eradication levels (Soper et al., 1943).
Historically, advances in U.S. public health have come as a result of one or more major health crises—usually in the form of an epidemic or the fear of one. In the nineteenth century, for example, state and local authorities were willing to spend relatively large sums on sanitary and quarantine measures during epidemics, but once the danger was past, funds were eliminated and the health regulations fell into neglect. Fortunately, that pattern has changed somewhat; in its place, we have established and now maintain a system of health regulations and sanitary measures that generally protect the health of the U.S. population. Over time, however, systems deteriorate, and enforcement of regulations may become more lax. It is essential, therefore, that we continue vigorous efforts to prevent the introduction of infectious agents.
The practices of public sanitation and personal hygiene have dramatically reduced the incidence of certain infectious diseases. In the United States, the mistaken notion that exposed refuse was somehow responsible for outbreaks of yellow fever led to early efforts at sanitary control. In 1796, for example, the New York Medical Society declared that local conditions, especially the "intolerable stench" around the city's docks and the filth around slaughterhouses, were primarily responsible for outbreaks of epidemic fever, including yellow fever (Duffy, 1990). Laws were passed to establish a permanent health office to enforce quarantine regulations and to authorize the cleanup of city streets.
Clean water supplies and their protection from human and other wastes are now fundamental public health principles. Where good sanitary practices are followed, many diseases that once were epidemic, including cholera, are successfully controlled. The same may be said for personal hygiene. Hand washing is an effective method of preventing the spread of many infectious agents, including cold and enteric viruses. Similarly, safe food-handling practices, including proper storage, cleaning, and preparation, have resulted in fewer cases of bacterial food poisonings, among other benefits. The pasteurization of milk, which was instituted to prevent the transmission of bovine tuberculosis to humans, has been equally effective against other diseases such as brucellosis and salmonellosis.
The use of quarantine, another approach to controlling infectious diseases, dates back at least to the Middle Ages. The name itself derives from