Background of disease 2. Description of the data 5. The geographic distribution of dengue, the frequency of epidemic cycles, and the number of cases of dengue have increased sharply during the last two decades. Dengue fever is a severe flu-like illness that affects infants, young children and adults, but rarely causes death.
Symptoms vary according to age.
Infection with dengue confers immunity to infection with the same dengue serotype, but aside from short-lived protection does not prevent infection with other serotypes. The condition of some patients progresses to shock. While the mechanisms that cause DHF are not completely understood, it is widely accepted that antibodies from previous dengue infections can predispose some individuals to develop DHF when infected by a second dengue serotype. Thus the co-circulation of several different dengue serotypes in a geographical area favours the occurrence of DHF in that area. Mosquitos acquire the virus while feeding on the blood of an infected person.