Dengue fever (DF) is an old disease; the fi rst record of a clinically compatible
disease being recorded in a Chinese medical encyclopaedia in 992. As the global ship-
ping industry expanded in the 18th and 19th centuries, port cities grew and became
more urbanized, creating ideal conditions for the principal mosquito vector, Aedes
aeg ypti. Both the mosquitoes and the viruses were thus spread to new geographic areas
causing major epidemics. Because dispersal was by sailing ship, however, there were
long intervals (10–40 years) between epidemics. In the aftermath of World War II,
rapid urbanization in Southeast Asia led to increased transmission and hyperendemicity.
The fi rst major epidemics of the severe and fatal form of disease, dengue haemorrhagic
fever (DHF), occurred in Southeast Asia as a direct result of this changing ecology. In
the last 25 years of the 20th century, a dramatic global geographic expansion of epidemic
DF/DHF occurred, facilitated by unplanned urbanization in tropical developing coun-
tries, modern transportation, lack of effective mosquito control and globalization. As
we go into the 21st century, epidemic DF/DHF is one of the most important infectious
diseases affecting tropical urban areas. Each year there are an estimated 50–100 million
dengue infections, 500 000 cases of DHF that must be hospitalized and 20 000–25 000
deaths, mainly in children. Epidemic DF/DHF has an economic impact on the com-
munity of the same order of magnitude as malaria and other important infectious dis-
eases. There are currently no vaccines nor antiviral drugs available for dengue viruses;
the only effective way to prevent epidemic DF/DHF is to control the mosquito vector,