top-shadow

Dengue Fever

Dengue Fever

The worldwide failure of controlling the mosquito Aedes aegypti, the major global insect vector of dengue virus, has made this disease a major global health problem. Infection with one or more dengue viruses imperils an estimated 2·5 billion people living in tropical and subtropical countries, mostly in large and small cities. About 50–100 million individuals are infected every year! As many as 500,000 cases of severe hospitalizations with dengue infection occur annually due to dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS). In many countries, dengue is one of the leading causes of pediatric hospitalization, and is thus regarded as one of the major tropical diseases.

Control strategies, such as broad spectrum pesticides, currently have very limited effect, and are often impossible to implement. This is because the A. aegypti mosquitoes prefer to lay their eggs in closed fresh water vessels, used for drinking water. The problem of developing an effective vaccine that will be useful for general use like yellow fever virus immunization, is still far from realization. Indeed, optimistic scenarios quote 2020 as the earliest time-point for such a vaccine. Moreover, the inherent difficulty in the interaction between the various viral strains, which often exasperates symptoms, means that demonstrating safety and efficacy of such a vaccine may mean marketing authorization for such a vaccine will be even further down the road.
Control of DENV (Dengue virus) spread relies primarily on reduction of vector populations by elimination of domestic water sources and insecticide applications. This strategy succeeded in most tropical locations during the 1950s–1970s campaigns to eliminate yellow fever, but was not sustained. A. aegypti has recently re-infested most tropical and subtropical locations, and DENV has returned with a vengeance. Increases in air travel have resulted in the movement of virus strains among transmission areas, providing opportunities for sequential infection of populations by 2 or more serotypes, resulting in an increased incidence of DHF and DSS in many areas. Although the virus circulates in endemic cycles, it periodically causes acute, widespread epidemics, such as in 1987 when 175,000 cases with more than 1000 deaths were reported from Thailand, or in 1996 when Brazil reported 180,000 cases, or again in 1998 when 1.3 million cases of dengue fever and DHF and over 3,500 deaths were reported from Latin America, the South-East Asia Region and the Western Pacific Region. More recently (2004), an outbreak was reported from Indonesia with more than 650 deaths.

Back to Top