A disease outbreak is the occurrence of cases of a particular disease in excess of what would normally be expected within a community, geographical area or season. It is usually caused by a pathogen that spreads directly from person to person or through human behaviours, but can also be maintained by environmental factors such as poor regional design and hygiene, dirty drinking water, overcrowding, rapid climate change, overcrowded travel or migration patterns and uncontrolled livestock movement.
Recent large outbreaks of highly pathogenic and virulent infectious diseases have highlighted the need for robust health care systems, preparedness plans and enhanced global surveillance. These include a number of zoonotic diseases such as plague, diphtheria, Ebola, monkeypox and Zika and non-zoonotic cholera, measles, polio and seasonal influenza. These events underscore the need for global cooperation, increased capacity for early detection and response, and enhanced surveillance.
Disease outbreak investigation is one of the most important activities in a disease control effort, and it plays a crucial role in determining the centre, source and cause of the infection, thus enabling appropriate control measures to be instituted. This involves the use of descriptive epidemiology, which describes the disease and its spread. Analytical epidemiology, a more sophisticated form of descriptive epidemiology, aims to formulate and test hypotheses and draw conclusions independently from laboratory methods.
The core set of activities that must be performed in any outbreak is shown in the diagram below. These activities shift through the different phases of the outbreak, with analytical epidemiology being more relevant in the earliest phase and control actions assuming greater importance in later stages.
About the Author
