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The Plague of Athens (c. 1652 –1654) by Michiel Sweerts, illustrating the devastating epidemic that struck Athens in 430 BC, as described by the historian Thucydides. The United States Centers for Disease Control and Prevention defines epidemic broadly: "Epidemic refers to an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in ...
The number of cases varies according to the disease-causing agent, and the size and type of previous and existing exposure to the agent. Outbreaks include many epidemics, which term is normally only for infectious diseases, as well as diseases with an environmental origin, such as a water or foodborne disease. They may affect a region in a ...
An epidemic is the rapid spread of disease to a large number of people in a given population within a short period of time; in meningococcal infections, an attack rate in excess of 15 cases per 100,000 people for two consecutive weeks is considered an epidemic. [1]
A medical dictionary definition of pandemic is "an epidemic occurring on a scale that crosses international boundaries, usually affecting people on a worldwide scale". [15] A disease or condition is not a pandemic merely because it is widespread or kills many people; it must also be infectious.
Researchers also may assess whether a disease outbreak is sporadic, or just an occasional occurrence; endemic, with a steady level of regular cases occurring in a region; epidemic, with a fast arising, and unusually high number of cases in a region; or pandemic, which is a global epidemic. If the cause of the infectious disease is unknown ...
Dengue fever is on the rise in Puerto Rico, and island officials have declared it an epidemic. At least 549 cases have been reported so far and more than 340 people have been hospitalized ...
The concept of waves in epidemics has implications especially for communicable diseases. A working definition for the term "epidemic wave" is based on two key features: 1) it comprises periods of upward or downward trends, and 2) these increases or decreases must be substantial and sustained over a period of time, in order to distinguish them ...
An endemic disease always has a steady, predictable number of people getting sick, but that number can be high (hyperendemic) or low (hypoendemic), and the disease can be severe or mild. [3] [4] Also, a disease that is usually endemic can become epidemic. [3] For example, chickenpox is endemic in the United Kingdom, but malaria is not.