Dengue 3 Virus
Family: Flaviviridae Genus: Flavivirus
Major epidemics of dengue have occurred in the Caribbean, South America, the Pacific, Asia, and Africa. Dengue is a powerful health concern in many countries, especially in areas with urban slums and breeding places for mosquitos. The power of the virus is increased by that fact that at the present time, prospects for control are poor.
Dengue is caused by one of four closely related, but antigenically distinct, virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4). Infection with one of these serotypes does not provide cross-protective immunity, so people living in a dengue-endemic area can have four dengue infections during their lifetimes. Dengue is transmitted through the Aedes aegyptia, a domestic day biting mosquito common in the tropics. The incubation period is about two to seven days. Infection with dengue viruses produces a spectrum of clinical illness ranging from a nonspecific viral syndrome to severe and fatal hemorrhagic disease. The three clinical profiles include dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. Dengue fever is a painful but non lethal syndrome characterized by rash, sudden onset of fever, severe headache, and other flu-like symptoms. Dengue hemorrhagic fever results in fluid loss through leaky blood vessels, leading to dyhydration, hypotension, severe jaundice, gastrointestinal hemorrhages and kidney failure. This can sometimes worsen to dengue shock syndrome which is the most severe form of the disease in which a child can die of shock in hours. Important risk factors include the strain and serotype of the infecting virus, as well as the age, immune status, and genetic predisposition of the patient.
As shown by the doctrine of original antigenic sin, the body has the same immune response as its first infection, even if this is not the appropriate response. This is the problem with dengue infections. Dengue only causes serious problems such as hemorrhagic fever and shock syndrome during the second infection of a different strain of the dengue virus. Antibody dependent enhancement increases the ability for uptake of the dengue virus via Fc receptors, enhances virion replication, and therefore makes the second infection of a different strain of the dengue virus much more serous then the first strain.
? Because of the lack of cross protection between the dengue viruses, it is necessary to develop a vaccine protecting against all four dengue serotypes. There is no licensed vaccine for dengue because none of them guard against all for strains of the virus. The most common method for control is mosquito control, however it is hard to spray using insecticides because the Aedes aegypti live in places hard to reach with pesticides. Other problems with this methods is the appearance of pesticide resistant mosquitos. Control of mosquito breeding is possible by draining stagnant water supplies.
Game action: Ooops! You forgot your insect repellent…
Medical Virology by White and Fenner p 434-443