Epidemic—The occurrence in a community or region of cases of an illness (or an outbreak) with a frequency clearly in excess of normal expectancy. The number of cases indicating presence of an epidemic will vary according to the infectious agent, size and type of population exposed, previous experience or lack of exposure to the disease, and time and place of occurrence; epidemicity is thus relative to usual frequency of the disease in the same area, among the specified population, at the same season of the year. A single case of a communicable disease long absent from a population or the first invasion by a disease not previously recognized in that area requires immediate reporting and epidemiologic investigation; two cases of such a disease associated in time and place are sufficient evidence of transmission to be considered an epidemic.
Definitions: UCLA School of Public Health. Epidemic. UCLA Fielding School of Public Health. 31 May, 2013. Web. http://www.ph.ucla.edu/epi/bioter/anthapha_def_a.html>
Each year in the United States, seasonal influenza kills more than 36,000 people and hospitalizes 200,000 more.
"The Associated Press, however, recently reported that the World Health Organization (WHO) revised its estimates of the number of dengue fever worldwide to be almost four times greater than previous estimate. The new estimates are that over 390 million people may have the disease, but many have only minor symptoms. The significance of this is that there is a much larger reservoir of the virus undetected in many populations that can be the source of infection among the general population."
Malaria is a mosquito-born, curable illness, but so far malaria has been inextricably linked with conditions of poverty, that make receiving care nearly impossible. In 2010, malaria caused an estimated 216 million clinical episodes, and 655,000 deaths. Nearly 86% of deaths were children.
"Cholera remains a global threat and is one of the key indicators of social development. While the disease no longer poses a threat to countries with minimum standards of hygiene, it remains a challenge to countries where access to safe drinking water and adequate sanitation cannot be guaranteed. Almost every developing country faces cholera outbreaks or the threat of a cholera epidemic."