A disease outbreak is an abnormally large number of cases of a specific infection in a small area at a given time and place. A disease outbreak is a public health concern because it could lead to a higher risk of serious illness and death among a affected population and it might spread to other communities. A disease outbreak may also contribute to the emergence of new infectious agents.
Successful epidemiologic investigations of disease outbreaks often deliver valuable information about how infectious diseases are transmitted to people. Such information may include the identification of novel modes of transmission, for example, the E. coli O157:H7 outbreaks of 1993–2004 were associated with contaminated hamburger meat, unpasteurized apple drinks and swimming pools in addition to the previously known route of transmission through eating undercooked hamburger meat (Center for Disease Control and Prevention 2003).
Epidemics are often caused by factors like environmental degradation and changes to human behavior, which make people more susceptible to disease or increase their risk of becoming infected. These factors include the introduction of novel strains of infectious organisms, emergence of resistant pathogens and disruption to the natural habitats of infectious organisms.
The emergence of highly virulent infectious diseases such as Ebola, Dengue and Marburg virus highlights the need for stronger preparedness measures and enhanced global surveillance systems. At the same time, it is equally important that governments and individuals take preventive steps to protect themselves, e.g. by washing hands and covering sneezes and coughs.