Clinically, dengue fever has been recognized for more than 200 years, and a disease similar to dengue haemorrhagic fever (DHF) was first described in northern Australia at the end of the past century (1). Although several dengue epidemics or pandemics have been described in previous centuries and in the first half of this century, a remarkable increase of the incidence of the two diseases has been noted since the 1950s. A main concern was the appearance of an epidemic of DHF in the Philippines in 1954, which rapidly spread to Thailand, Viet Nam, Indonesia and to other Asian and Pacific countries, becoming endemic and epidemic in several of them (1). The first DHF epidemic in the Americas occurred in Cuba in 1981 (2); subsequently 24 other countries in the Region have reported DHF. Also of great concern has been the occurrence of several pandemics and countless epidemics of dengue fever over the past 40 years, with considerable health, social and economic consequences.