In epidemiology, an outbreak occurs when there is a higher number of cases of a disease in a particular place and time than usual. This increase may stay in a small area or spread over a wide area. Depending on the type of disease, an outbreak can last days or years.
An important aspect of outbreak investigations is identifying the source and mode of transmission. The investigation of outbreaks combines analytical and statistical techniques with microbiological, toxicological, and clinical methods. The purpose of an outbreak is to determine the cause of an infection in order to prevent it from occurring again.
Using an outbreak approach to public health provides an opportunity for the community to participate in prevention measures. This includes educating the public on hand washing, covering sneezes and coughs and isolating ill family members. Community engagement is also an integral part of the response to an epidemic eliciting positive behaviour change such as changing traditional burial practices and avoiding mosquito breeding sites. Anthropologists and communication experts are routinely included in outbreak response teams.
An outbreak is a group of epidemiologically linked cases that appear to be greater than expected for a specific place and time period, based on information from local health department surveillance records and other sources such as registries. The term is often used interchangeably with the word cluster, but there are some important differences. Specifically, the term cluster typically refers to an investigation where two or more cases are shown by an epidemiological study to have had a common exposure (e.g., ingestion of a common food), while an outbreak has a wider scope and may include cases without a known exposure.