Extract of CDC and WHO website

Dengue is found in tropical and sub-tropical regions around the world, predominantly in urban and semi-urban areas.

The global prevalence of dengue has grown dramatically in recent decades. The disease is now endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, South-east Asia and the Western Pacific. South-east Asia and the Western Pacific are most seriously affected.

Dengue haemorrhagic fever (DHF), a potentially lethal complication, was first recognized in the 1950s during the dengue epidemics in the Philippines and Thailand, but today DHF affects most Asian countries

Dengue, a rapidly expanding disease in most tropical and subtropical areas of the world, has become the most important arboviral disease of humans. More than 2.5 billion persons now live in areas at risk of infection, and attack rates for reported disease in epidemics are in the range of 1 per thousand to 1 per hundred of the population. Infection rates (that is, proportion of the population that is infected, including persons who do not get severe symptoms or are not reported) can be five- to ten-fold greater. The case-fatality ratio for DHF averages about 5% worldwide, but can be kept below 1% with proper clinical management.

Epidemics caused by all four virus serotypes have become progressively more frequent and larger in the past 25 years. As of 2004, dengue fever is endemic in most tropical countries of the South Pacific, Asia, the Caribbean, the Americas, and Africa.

Additionally, most tropical urban centers in these regions have multiple dengue virus serotypes co-circulating (hyperendemicity), which increases dengue transmission and the risk of DHF. Future dengue incidence in specific locales cannot be predicted accurately, but a high level of dengue transmission is anticipated in all tropical areas of the world for the indefinite future. The incidence of the severe disease, DHF, has increased dramatically in Southeast Asia, the South Pacific, and the American tropics in the past 25 years, with major epidemics occurring in many countries every 3-5 years.

The first major epidemic in the Americas occurred in Cuba in 1981, and a second major epidemic of DHF occurred in Venezuela in 1989-1990. Since then, outbreaks, sporadic cases, or both, of confirmed DHF have occurred in most tropical American countries. After an absence of 35 years, several autochthonous cases of dengue fever occurred in southern Texas in 1980, 1986, 1995, 1997, 1998 and 1999, associated with imported cases and epidemic dengue in adjacent states in Mexico. After an absence of 56 years, a limited outbreak of dengue fever occurred in Hawaii in 2001, associated with imported cases and epidemic dengue in the South Pacific.