A disease outbreak occurs when more cases of a certain infectious disease occur in a specific time and place than expected. An outbreak is usually associated with a specific exposure (risk factor) and can be caused by transmission from person to person through direct contact, or from an exposed person to others via food or water that was contaminated, fomites (inanimate objects like tables or doorknobs), or airborne transmission. An epidemiological investigation requires the use of methods of descriptive and, where appropriate, analytical epidemiology.

Although many improvements in outbreak preparedness and response have been made, diagnostic delays remain a persistent challenge in global health. Historical misdiagnoses can provide lessons for transforming outbreak responses from reactive to anticipatory, potentially averting future epidemics by improving early recognition of emerging pathogens within their complex ecological and social contexts. This can be achieved through systematic consideration of multiple working hypotheses, development of sustainable local diagnostic capacity, enhancement of clinician-to-public-health communication networks, implementation of cognitive debiasing strategies, and strengthening of One Health surveillance platforms.

Everyone can help protect themselves from the risk of disease outbreaks by practicing basic public health measures. These include washing your hands often with soap and running water for at least 20 seconds, not touching your eyes, nose or mouth, covering your cough or sneeze, and cleaning or disinfecting high-touch objects and surfaces. Vaccination, travel advising and careful food and water selection can also reduce your risk of infection if you are traveling to areas with moderate-to-high disease risk.