People may be displaced from where they live by natural or man-made disasters, force or the threat of force, or other pressures. The term “refugee” refers to displaced persons who cross an international border. The country to which they flee is referred to as the “host country”. In contrast, “internally displaced persons” do not cross an international border and remain within their country of origin.

Displaced persons may move as a large group over a short period or move in small groups over months or years. Large concentrations of displaced persons may be found in poor, peripheral, and under-served sections of large cities. The sudden arrival of large numbers (sometimes hundreds of thousands) can create a health emergency. This protocol addresses rapid health assessment in all emergencies owing to sudden displacement of both refugees and internally displaced persons.

The rapid health assessment has to include the host population because of the additional stress that may be placed on local organizations.