- Dengue haemorrhagic fever (DHF), a potentially lethal complication, was first recognized in the 1950s.. - 2.5 billion people – two fifths of the world's population – are now at risk - In 2007 alone, there were more than 890 000 reported cases of dengue in the Americas. - The disease is now endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, South-east Asia and the Western Pacific - An estimated 500 000 people with DHF require hospitalization each year... - About 2.5% of those affected die,a very large proportion being children. - Without proper treatment, DHF fatality rates can exceed 20%..