When a person is exposed to dengue for the first time, the disease usually is not severe. When the same person is later infected by a different dengue serotype, the body produces antibodies against the previous dengue serotype. The new dengue virus uses these antibodies to infect more cells, thus leading to severe dengue disease. Such a secondary infection may lead to dengue hemorrhagic fever or dengue shock syndrome with high fatality rates. The ADE phenomenon has made development of vaccines and antibody therapeutics against Dengue a tremendous challenge. A vaccine works by creating antibodies against the included serotypes.

Currently there are no approved vaccines for the prevention of dengue, nor drugs for treatment of dengue virus infection. The worldwide market size for an effective anti-dengue treatment may be as large as that for Hepatitis C virus treatment, reaching billions of dollars, based on current population exposure data. Dengue, dengue hemorrhagic fever and dengue shock syndrome are emerging as serious global health problems. Dengue is endemic throughout much of the world and now threatens over 3 billion people world-wide or 40% of the world's population. Because of its world-wide distribution, dengue is considered an emerging threat in the United States. Dengue is officially considered a "neglected tropical disease" by the World Health Organization. About 50-100 million people are infected by dengue virus every year. Recently, the government of Cali, Columbia declared a dengue emergency because of the number of dengue infections and deaths. Globalization and climate change along with changes in the ecology of the virus-carrying mosquito are accelerating the spread of the virus. Without proper treatment, DHF fatality rates can exceed 20%. (Source: WHO Dengue and dengue hemorrhagic fever Fact Sheet No. 117, March 2009; who.int/mediacentre/factsheets/fs117/en/).

SOURCE NanoViricides, Inc.