Dengue is an infectious tropical disease spread by mosquitoes carrying the dengue virus. Sometimes dengue develops into a possibly lethal form called dengue haemorrhagic fever (DHF). The disease has spread dramatically over the last few decades. Approximately two fifths of the world population is currently at risk. Areas in Asia and the Western Pacific have been particularly affected by dengue. There is presently no vaccine for the virus. The only prevention method for the virus is the elimination of the mosquitoes that carry it.

The UNHCO estimates that there are approximately 50 million dengue infections globally each year. In 2007, there were over 890,000 cases of dengue reported in the Americas. Of those cases, 26,000 were DHF. It is endemic in over 100 African countries. Prior to 1970, only nine countries were known to have had DHF epidemics- that number had increased four-fold by 1995.

Dengue is spread by several different mosquito species, particularly the A. aegypti mosquito. There are four types of dengue. Infection by one type provides lifelong immunity for that type but conveys only short term immunity to the others. Risks of severe complications increase if there is a subsequent infection by another type.

Since there is currently no dengue virus, prevention depends upon the control of the mosquitoes that transmit it. The UNHCO is promoting an Integrated Vector Control program that consists of five elements:

(1) Legislation and social mobilization to strengthen public health institutions and communities,

(2) cooperation between public and private health care organizations,

(3) a holistic approach to disease prevention with maximum usage of resources,

(4) appropriate targeting of interventions using evidence-based decision making,

(5) building capacity to ensure local responses are adequate.