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Dengue Etiology
Both dengue fever and dengue hemorrhagic fever are caused by dengue virus , an RNA virus belonging to the small group of arbovirus -be named for viruses transmitted by arthropods - which described four types today, each properties antigenically different. Any of the four types of the virus is capable of producing classic dengue. It is proposed that an initial infection creates the conditions for immune subsequent infection produces a dengue hemorrhagic fever, but others argue that a first dengue infection is capable of producing at once a dengue hemorrhagic fever.
Serotypes 1 and 2 were isolated in 1945 , and 1956 types 3 and 4, where the virus type 2 the most immunogenic of the four.
Dengue virus, like other flaviviruses contains an RNA genome surrounded by a nucleocapsid symmetry icosahedral , 30 nm in diameter , which consists of C-protein of 11 kd and a wrap- lipid of 10 nm thickness associated with a protein membrane (M) and one envelope (E), leading to projections that protrude from the surface of virions
What is Dengue Virus?
The Dengue virus is a member of the virus family Flaviviridae and is transmitted to people through the bite of the mosquitos Aedes aegypti and Aedes albopictus. Dengue virus is now believed to be the most common arthropod-borne disease in the world. Dengue is mainly found in the tropics because the mosquitoes require a warm climate. A major fear of epidemiologists is that the mosquitoes will develop resistance to cooler climates and then be able to infect people in the United States and other temperate climates. The virus is transmitted when a mosquito of the Aedes genus bites an individual infected with dengue virus. The virus in the blood of the infected individual then infects the mosquito and travels from the mosquito's stomach to its salivary glands were the virus multiplies. The virus is then injected into another person when the mosquito injects anticoagulants that prevent blood clotting when the mosquito is feeding. The mosquito remains able to transmit dengue for its entire life.
Each year, 100 million people become infected with dengue virus. People first reported the existence of dengue-like disease in 1779 but it was most likely present long before in first appeared in literature. However, the majority of deaths that result from dengue infection result from Dengue Hemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS). People who develop DHF have a 5% chance of death but if they go on to develop DSS then the mortality rate can rise as high as 40%.
