Dengue (fever)

Dengue is a viral disease caused by one of four very similar viruses (Den-1, Den-2, Den-3 and Den-4), and is transmitted to humans through the bites of mosquitoes that have previously bitten an infected person. There is no direct human-to-human transmission, but humans are the primary host of the virus. The virus circulates in the blood of an infected person for 2-7 days, during which time a mosquito could acquire it and infect others. In the western hemisphere, the primary vector is the Aedes aegypti mosquito, but cases of transmission by Aedes albopictus have also been reported. Dengue fever has been known for over two centuries and is particularly common during and after the rainy season in the tropical and subtropical regions of Africa, South-East Asia and China, India, the Middle East, Latin and Central America, Australia and several areas of the Pacific. In recent decades, the incidence of dengue has grown in many tropical regions. The increase in case numbers, driven by more frequent movement of goods and people, has serious implications from a global health perspective and poses a threat to countries of the northern hemisphere, especially in Europe, where dengue mostly occurs as an imported disease.