Eckert, Eric, The World and I
Although industrialized nations have seen great advances in controlling infectious diseases in the twentieth century, these historic great killers of humanity remain entrenched in the developing world and are resurging in the developed world.
"Flu epidemic threatens thousands in southern China." "Killer virus spread by rats." Although these headlines may seem historic, they are current. Today, at the end of the twentieth century, infectious diseases still wreak havoc in some parts of the world. They herald a failure to realize the infectious disease-free society once promised by modern science.
Despite socioeconomic developments and great advances in medical science in the last hundred years, infectious disease is still the leading cause of death worldwide, causing about one-third of all deaths in 1997. In the developing world, the role of diseases has changed discouragingly little over the centuries. Millions of children still die from diarrheal diseases and respiratory infections each year. In industrialized nations, the last century has seen a dramatic decline in deaths due to infectious pathogens, but these killers remain a threat. In the United States, for example, pneumonia--a lung disease caused by a variety of bacteria and viruses--is by itself responsible for more than 25,000 deaths each year.
The stow of infectious disease in society is one of great successes and dismal failures: the triumph of smallpox eradication in the mid-twentieth century and the defeat of patients contracting fatal infectious diseases inside the sterile environment of a modern hospital. Finally, it is an unfinished stow still unfolding as the medical community faces the challenge of emerging new pathogens and reemerging familiar ones.
The epidemiologic transition
Infectious diseases have always posed serious threats to human health. Ever since man began to live in communities, the close human contact has provided fertile conditions in which infectious agents have spread relatively unchecked. Toward the end of the nineteenth century, however, this situation began to change in the more industrialized countries.
Infectious diseases were rapidly curtailed through improvements in both living conditions and medical technology. With fewer people dying of infectious diseases, chronic illnesses such as diabetes and heart disease became more prevalent. This society-wide shift from infectious diseases to chronic illnesses as the primary cause of death is called the "epidemiologic transition." Coupled with shifts toward an industrialized society with improvements in living standard and education, the epidemiologic transition promotes radical changes in the social structure of a people.
Before the transition, parents tried to ensure the family's prosperity by having large numbers of children. After the transition, the improved health and social conditions reduce the need for large families. During the transition, however, death rates decline decades before birth rates, and population grows explosively. Our century began with a human population totaling less than 2 billion and ends with our numbers nearing 6 billion and still growing explosively.
At the beginning of the epidemiologic transition, modernized sanitation and better hygiene protected communities from contact with disease hosts such as rats and insects. Later, the discovery, development, and widespread use of antibiotics and insecticides gave doctors potent drugs for treating infected persons and weapons for preventing the transmission of diseases from person to person. Deaths from infectious diseases in industrialized societies began to drop at an astonishing rate.
The top killers in the United States in 1900 were first the respiratory diseases, pneumonia and tuberculosis, and second, diarrheal diseases; together they accounted for almost one-third of all deaths. By 1990, only pneumonia remained on the list of major causes of death, but it had dropped to sixth place. …