There is no specific treatment for dengue fever. However, careful clinical management by experienced physicians and nurses frequently saves the lives of Dengue haemorrhagic fever patients. With appropriate intensive supportivetherapy, mortality may be reduced to less than 1%. Maintenance of the circulating fluid volume is the central feature of DHF case management.
Vaccine development for dengue and Dengue haemorrhagic fever is difficult because any of four different viruses may causedisease, and because protection against only one or two dengue viruses could actually increase the riskof more serious disease. Nonetheless, progress is being made in the development of vaccines that mayprotect against all four dengue viruses. Such products may become available for public health usewithin several years.
Prevention and control
At present, the only method of controlling or preventing dengue and DHF is to combat the vectormosquitoes.
In Asia and the Americas, Aedes aegypti breeds primarily in man-made containers like earthenwarejars, metal drums and concrete cisterns used for domestic water storage, as well as discarded plasticfood containers, used automobile tyres and other items that collect rainwater. In Africa it also breedsextensively in natural habitats such as tree holes and leaf axils.
In recent years, Aedes albopictus, a secondary dengue vector in Asia, has become established in: the United States, several Latin American and Caribbean countries, in parts of Europe and in one Africancountry. The rapid geographic spread of this species has been largely attributed to the internationaltrade in used tyres.
Vector control is implemented using environmental management and chemical methods. Proper solidwaste disposal and improved water storage practices, including covering containers to prevent access byegg laying female mosquitoes are among methods that are encouraged through community-basedprogrammes.
The application of appropriate insecticides to larval habitats, particularly those which are considereduseful by the householders, e.g. water storage vessels, prevent mosquito breeding for several weeks butmust be re-applied periodically. Small, mosquito-eating fish and copepods (tiny crustaceans) have alsobeen used with some success. During outbreaks, emergency control measures may also include theapplication of insecticides as space sprays to kill adult mosquitoes using portable or truck-mountedmachines or even aircraft. However, the killing effect is only transient, variable in its effectivenessbecause the aerosol droplets may not penetrate indoors to microhabitats where adult mosquitoes aresequestered, and the procedure is costly and operationally very demanding. Regular monitoring of thevectors' susceptibility to the most widely used insecticides is necessary to ensure the appropriate choiceof chemicals. Active monitoring and surveillance of the natural mosquito population should accompanycontrol efforts in order to determine the impact of the programme.