From Africa to Asia to Latin America, around 2.5 billion people live in areas that are at risk of the disease, which has no vaccine or cure.
In Singapore, health workers are helping to combat the disease by aggressively controlling breeding sites, the report said. Government inspectors fine people for allowing water to build up in flower pots, which is a favourite breeding site.
Family doctors in Singapore look out for patients with suspicious symptoms. When cases are confirmed, researchers try to ascertain the subtype of mosquito and the location of the outbreak.
Singapore reported 14,000 dengue cases in 2005, but that fell to 3,597 cases in the first half of 2007, according to the WHO.