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An epidemic (from Greek ἐπί epi "upon or above" and δῆμος demos "people") is the rapid spread of disease to a large number of hosts in a given population within a short period of time. For example, in meningococcal infections , an attack rate in excess of 15 cases per 100,000 people for two consecutive weeks is considered an epidemic.
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 ...
In the 1775–1782 North American smallpox epidemic data based on remnant settlements indicate at least 130,000 people died in the epidemic that started in 1775. [ 14 ] [ 15 ] During the Revolution General George Washington insisted his soldiers get inoculated else his forces might get decimated or the British try to use smallpox as a weapon.
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 ...
In epidemiology, a virgin soil epidemic is an epidemic in which populations that previously were in isolation from a pathogen are immunologically unprepared upon contact with the novel pathogen. [1] Virgin soil epidemics have occurred with European settlement , particularly when European explorers and colonists took diseases to lands they ...
A representation by Robert Seymour of the cholera epidemic depicts the spread of the disease in the form of poisonous air.. The miasma theory was the predominant theory of disease transmission before the germ theory took hold towards the end of the 19th century; it is no longer accepted as a correct explanation for disease by the scientific community.
Epidemic A new disease that is spreading or a previously endemic disease whose infection rate is increasing significantly. [8] [11] Seasonal flu frequently appears as an epidemic. [8] Pandemic An epidemic affecting a very large part of the world, generally multiple countries or multiple continents. [8] Seasonal flu is sometimes a global ...
Different bat species. While bats are essential members of many ecosystems, [24] they are also frequently implicated as frequent sources of emerging virus infections. [25] Their immune systems have evolved in such a way as to suppress any inflammatory response to viral infections, thereby allowing them to become tolerant hosts for evolving viruses, and consequently provide major reservoirs of ...