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close this bookAn Overview of Disaster Management (Department of Humanitarian Affairs/United Nations Disaster Relief Office - United Nations Development Programme , 1992, 136 p.)
close this folderChapter 4. Natural hazards
close this folderCharacteristics of particular hazards and disasters 1
View the document(introduction...)
View the documentEarthquakes
View the documentTsunamis
View the documentVolcanoes
View the documentLandslides
View the documentTropical cyclones
View the documentFloods
View the documentDroughts
View the documentEnvironmental pollution
View the documentDeforestation
View the documentDesertification
View the documentPest infestations
View the documentEpidemics
View the documentChemical and industrial accidents


Definition: Exposure to a toxin resulting in pronounced rise in number of cases of parasitic or infectious origin.

Causal phenomena

Unsanitary conditions, crowding, poverty
Ecological changes that favor breeding of vector
Non-immune persons migrate to endemic disease area
Decline in nutritional status
Contamination of water or food supply

General characteristics

Risk of introduction or spread of the disease
Possible large number of cases
Severe disease leading to disability or death
Risk of social or economic disruption
Lack of adequate professional personnel, needed supplies
Danger of international transmission


Epidemics may increase due to rise in travel or migration and long-term dormant symptoms of sexually transmitted diseases. Reports of epidemics may increase due to better medical coverage. Prediction is assisted by epidemiological studies but may be constrained in newly formed settlements or emergency camps.

Factors contributing to vulnerability

Lack of immunity (or vaccination) to diseases
Poor nutrition, poor sanitation, poor water quality, crowding
Poorly organized health care delivery
Drug resistant diseases

Typical adverse effects

Illness and death
Social and political disruption, economic loss
Increased trauma in emergency settlements

Possible risk reduction measures

Structuring an emergency health service
Preparing a contingency plan with inventory of required resources
Establishing an early warning system through routine surveillance
Training of national staff in emergency operations

Specific preparedness measures

Intervention measures - Verify and confirm diagnosis; identify cases; find source of epidemic; treat cases and control spread; write report.
Community health education

Typical post-disaster needs

Emergency medical assistance; international aid, if outbreak uncontained

Impact assessment tools

Epidemiological surveys; evaluation of health care systems and emergency response