epidemic (redirected from point epidemic)

epidemic, outbreak of disease that affects a much greater number of people than is usual for the locality or that spreads to regions where it is ordinarily not present. A disease that tends to be restricted to a particular region (endemic disease) can become epidemic if nonimmune persons are present in large numbers (as in time of war or during pilgrimages), if the infectious agent is more virulent than usual, or if distribution of the disease is more easily effected. Cholera and plague, endemic in parts of Asia, can become epidemic under the above conditions, as can dysentery and many other infections. Epidemics may also be caused by new disease agents in the human population, such as the Ebola virus. A worldwide epidemic is known as a pandemic, e.g., the influenza pandemic of 1918 or the AIDS pandemic beginning in the 1980s. A disease is said to be sporadic when only a few cases occur here and there in a given region. Epidemic disease is controlled by various measures, depending on whether transmission is through respiratory droplets, food and water contaminated with intestinal wastes, insect vectors, or other means. The Centers for Disease Control and Prevention tracks epidemics in the United States.

See also epdemiology.

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epidemic

1. (esp of a disease) attacking or affecting many persons simultaneously in a community or area

2. a widespread occurrence of a disease

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epidemic [¦ep·ə¦dem·ik]

(medicine)

A sudden increase in the incidence rate of a disease to a value above normal, affecting large numbers of people and spread over a wide area.

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Epidemic

The occurrence of cases of disease in excess of what is usually expected for a given period of time. Epidemics are commonly thought to involve outbreaks of acute infectious disease, such as measles, polio, or streptococcal sore throat. More recently, other types of health-related events such as homicide, drownings, and even hysteria have been considered to occur as “epidemics.”

Confusion sometimes arises because of overlap between the terms epidemic, outbreak, and cluster. Although they are closely related, epidemic may be used to suggest problems that are geographically widespread, while outbreak and cluster are reserved for problems that involve smaller numbers of people or are more sharply defined in terms of the area of occurrence. For example, an epidemic of influenza could involve an entire state or region, whereas an outbreak of gastroenteritis might be restricted to a nursing home, school, or day-care center. The term cluster may be used to refer to noncommunicable disease states.

In contrast to epidemics, endemic problems are distinguished by their consistently high levels over a long period of time. Lung cancer in males has been endemic in the United States, whereas the surge of lung cancer cases in women in the United States represents an epidemic problem that has resulted from increase in cigarette smoking among women in general. A pandemic is closely related to an epidemic, but it is a problem that has spread over a considerably larger geographic area; influenza pandemics are often global.

Disease and epidemics occur as a result of the interaction of three factors, agent, host, and environment. Agents cause the disease, hosts are susceptible to it, and environmental conditions permit host exposure to the agent. An understanding of the interaction between agent, host, and environment is crucial for the selection of the best approach to prevent or control the continuing spread of an epidemic.

For infectious diseases, epidemics can occur when large numbers of susceptible persons are exposed to infectious agents in settings or under circumstances that permit the spread of the agent. Spread of an infectious disease depends primarily on the chain of transmission of an agent: a source of the agent, a route of exit from the host, a suitable mode of transmission between the susceptible host and the source, and a route of entry into another susceptible host. Modes of spread may involve direct physical contact between the infected host and the new host, or airborne spread, such as coughing or sneezing. Indirect transmission takes place through vehicles such as contaminated water, food, or intravenous fluids; inanimate objects such as bedding, clothes, or surgical instruments; or a biological vector such as a mosquito or flea. See Epidemiology, Infectious disease