In epidemiology, an outbreak is a sudden increase in occurrences of disease in excess of normal expectancy for the community, geographical area or season. This may affect a small and localized group of people or impact thousands across an entire continent. Outbreaks are maintained by infectious agents that spread directly from person to person, from animals or other environmental sources and by contaminated food. Human behavior nearly always contributes to the spread of disease outbreaks, whether they are controlled or uncontrolled.
Investigation of a suspected or confirmed outbreak requires enormous resources, skill and knowledge. However, the earliest detection or key clue can mean the difference between control or catastrophe. This article presents an approach that seeks to understand the dynamics of an outbreak through landscape-based epidemiological analysis, focusing on factors that limit or foster pathogen transmission.
In the United States, a “foodborne” outbreak is any cluster of illnesses in which two or more persons with initial dates of illness within 48 hours of each other experience onset of a similar acute, gastrointestinal illness following common foods or beverages consumed in close temporal proximity. All outbreaks are notifiable to the local health jurisdiction where cases occur; these jurisdictions must immediately notify DOH of any suspected or confirmed outbreak and provide case investigation completion or summary information within 7 days of identifying the suspect vehicle. Recent technological advances, such as whole genome sequencing (WGS) subtyping of clinical and environmental isolates from food and water products, are allowing public health and regulatory partners to identify the possible vehicle earlier in an investigation. This is known as sample-initiated retrospective outbreak investigations (SIROIs).