Environmental health in emergencies

Environmental factors influencing the spread of communicable diseases

A number of environmental factors influence the spread of communicable diseases that are prone to cause epidemics. The most important of these are:

  • water supply
  • sanitation facilities
  • food
  • climate.

A lack of safe water, inadequate excreta disposal facilities, poor hygiene, poor living conditions and unsafe food can all cause diarrhoeal diseases. These diseases are a major cause of suffering and death in an emergency situation.

Climate can affect disease transmission in a variety of ways. The distribution and population size of disease vectors can be heavily affected by local climate. Flooding after heavy rains can result in sewage overflow and widespread water contamination. In addition, there is some evidence to suggest that pathogens can be spread from one region to another along air streams or by wind.

WHO’s response to communicable disease outbreaks is led by the Epidemic and Pandemic Alert and Response Department.

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