Dengue fever/dengue hemorrhagic fever(DF/DHF) is found in tropical and sub-tropical
regions around the world, predominantly in urban and semi-urban areas. The viruses which
cause DF and DHF belong to the family Flaviviridae, genus Flavivirus. There are four serotypes of dengue viruses, designated DEN-1,-2,-3 and -4; the major vector is Aedes aegypti (WHO, 1993, 1999a,b). In 1954, the first outbreak of DF occurred in Southeast Asia, the first place it occurred in was the Philippines in 1956; the second outbreak also occurred in the Philippines (WHO, 1993).