An emergency changes the conditions for medical care. Demand rises suddenly, while roads, communications, supplies and health facilities may be damaged. The first task is to identify urgent needs, provide initial care and organize the response so that it can continue once the acute phase is over.
The same principles apply after a natural disaster, during an outbreak of infectious disease or when violence forces people from their homes — but each situation needs its own assessment. The health problems particular to each setting are covered in disaster medicine and conflict and humanitarian health.