Where is the risk of dengue fever most acute and what should be done?
The viruses that cause dengue fever and dengue haemorrhagic fever are transmitted by the mosquito Aedes aegypti, and in Asia to a lesser extent by Ae. albopictus. Aedes aegypti breeds mainly in water collections in artificial containers in the environment of human settlements, but not in groundwater pools and puddles, nor in swamps or other large natural bodies of water. Effective prevention and control of epidemic dengue requires control of vectors. No vaccine exists for dengue..
Prevention of mosquito-breeding in drinking-water containers, by covering them to exclude mosquitoes, frequently emptying them (at least once per week), or treating them with insecticide, e.g., temephos 1% sand granules, will contribute to the prevention of dengue outbreaks. However, this may not be sufficient in settlement areas where there are small, freshwater collections in other artificial containers and miscellaneous debris. Depending on feasibility, chemical larvicides may also be applied under these conditions. Portable equipment for space spraying will be needed in areas with difficult road access. To the extent possible, affected populations may be provided with mosquito repellents.
Source reduction is the mainstay of dengue prevention. This should be backed up by chemical control whenever mosquito populations expand rapidly.