Epidemic

Types of Epidemics

Epidemics are classified based on origin and pattern of transmission of disease. Epidemics can involve a single exposure to a disease or pathogen, multiple, or continuous exposures to disease causing agents. The disease involved in an epidemic can be transmitted by a vector (disease carrying agent) like a rat that carries bubonic plague, from person to person transmission (lack of hand washing or cramped living conditions), or from a common source such as contaminated water or food source.

For example, a common water supply with cholera caused an epidemic in London in the middle of the 19th century. Many London citizens had uncontrollable diarrhea and other symptoms that used this water source. However, concluding the water source as the main point of transmission of disease was not so easy. To combat this epidemic, a large-scale epidemiological study was performed by a medical pioneer in this field, Dr. John Snow. His systematic methods used to study outbreaks and epidemics are the basis for epidemiological study used today.

Epidemics such as influenza, cholera (mentioned above), malaria, tuberculosis and most recently avian influenza virus, or bird flu, have inflicted millions across the globe. These diseases are preventable and their infection rate increases in the developing world with too few treatment measures. It is important to realize that not just the region or area that has the epidemic is affected—the whole world population feels ripple effects of these epidemics in a myriad of ways. These recent epidemics are able to move quickly transmitting from person to person in smaller communities and then moving across the globe passing socioeconomic barriers and inadequate treatment measures. For example, the affects of HIV/AIDS has graduated from epidemic to pandemic as new cases are growing and no population or community are immune. Indeed, everyone is negatively affected across the globe with this pandemic—medically, socially, economically, living standards, and in many other unforeseeable ways—HIV/AIDS affects everyone. However, the regions hardest hit with HIV/AIDS are sub-Saharan Africa, central Asia, and Latin America.

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