This field manual is intended to help health professionals and public health coordinators working in emergency situations prevent, detect and control the major communicable diseases encountered by affected populations. The manual deals with the fundamental principles of communicable disease control in emergencies, which are: rapid assessment - to identify the communicable disease threats faced by the emergency-affected population, including those with epidemic potential, and define the health status of the population, by conducting a rapid assessment; prevention - to prevent communicable disease by maintaining a healthy physical environment and good general living conditions; and surveillance - to set up or strengthen disease surveillance system with an early warning mechanism to ensure the early reporting of cases, to monitor disease trends, and to facilitate prompt detection and response to outbreaks. It also deals with outbreak control - to ensure outbreaks are rapidly detected and controlled through adequate preparedness (i.e. stockpiles, standard treatment protocols and staff training) and rapid response (i.e. confirmation, investigation and implementation of control measures); and disease management - to diagnose and treat cases promptly with trained staff using effective treatment and standard protocols at all health facilities.