Epidemic and pandemic
Epidemic, from the Greek meaning "prevalent among the people," is mostcommonly used to describes an outbreak of an illness or disease in which thenumber of individual cases significantly exceeds the usual or "expected" number of cases in any given population. In the United States, the Centers for Disease Control (CDC) takes the average cases of, let's say, influenza,in 122 cities nationwide over the preceding five years. If influenza cases in any area significantly exceed that percentage baseline, it is said to be ofepidemic proportions. The term is also used to describe almost any occurrence which increases drastically or becomes rampant--for example, auto thefts from parking lots or a significant increase in gang-related violence. Pandemic, which means "all the people," describes and epidemic which occurs inmore than one country or population simultaneously. An excellent example of adisease which has reached pandemic proportions is the AIDS/HIV virus.Human obesity, certainly less fatal than AIDS but which causes numerous health problems, has risen so drastically worldwide that it is now being considered a pandemic.
Diseases which reach epidemic proportions thrive in dense populations. Person-to-person contact is often necessary to spread the bacteria or virus, and groups of people, such as school children and service men and women, are particularly vulnerable. One of the most notorious viruses world-wide is the influenza virus, serious strains of which have killed tens of millions of people over the course of human history. Greek physician, Hippocrates, producedthe first known record of a flu epidemic in 412 b.c. Just before the end of World War I, a pandemic of "Spanish Flu" killed more than 20 million people world-wide--more than the number of people killed by the war--and a half-million people in the United States alone. In 1968, the "Hong KongFlu" pandemic infected more than 50 million people in the United States alone, causing an estimated 20,000 deaths.
In Europe during the 14th century, a pandemic of the bubonic plague, or BlackDeath, killed approximately 40 million people. Outbreaks in the 1990s in India, Zaire, Madagascar, Brazil, Peru, and China have raised concern among someepidemiologists of new pandemics. Frank Fenner, at Canberra's John Curtain School of Medical Research in Australia, believes the ease of modern transportation world-wide, a rising number of refugees from Third World countries, andchanging sexual habits in First World countries, create fertile ground for the spread of this and other killer diseases today.
In the study of epidemiology, medical scientists attempt to determine the circumstances in which infectious diseases thrive, then track and attempt to regulate their occurrence and distribution. In 1942, the United Nations formed an agency called the World Health Organization (WHO) in an effort to help control epidemics and pandemics of diseases like tuberculosis, venereal disease, and malaria, as well as establish purified water and sanitationsystems, public health education, health planning, and the training of health workers. Today, WHO's responsibilities include "1) the development of national and international infrastructure and resources to recognize, monitor, prevent, and control communicable diseases and emerging health problems,including antibiotic resistance, and 2) research and training on the diagnosis, epidemiology, prevention, and control of communicable diseases and emerging health problems." Nationally, the Public Health Service plays a major rolein research and prevention of epidemics and pandemics.