Some Other Terms You Should Know
Now that you are becoming somewhat of a maven in the area of classical epidemiology, you should know the precise meaning of a few terms, so let’s start with epidemic itself. Traditionally, an epidemic refers to the outbreak of a disease in a localized group of people. It can be infectious and spread from one person to another by (1) carriers (i.e., people who are susceptible to the disease, although they may not be affected by it themselves, as with Mary for typhoid fever) or (2) vectors (intermediate organisms that carry the disease but do not have it, such as the anopheles mosquito for malaria or fleas for the plague). An epidemic can also be caused by the sudden introduction of some pathogen, as happened with Legionnares’ disease. Epidemics are usually limited in time, although the time can be long, as we are seeing in the case of AIDS.
In contrast, an endemic disease is said to be present if cases are continually occurring in some region, for example, the presence of river blindness or malaria in certain parts of Africa. When an epidemic escapes its local region and starts to affect people over a large portion of the country or even the world, it is said to be pandemic. In this regard, the bubonic plague of the fourteenth century would more properly be called a pandemic rather than an epidemic.
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| 5476. | Streiner DL, Norman GR. PDQ Epidemiology. 2nd ed. Hamilton, Ontario: BC Decker Inc.; 1996. |