Last week the World Health Organization (WHO) reported that dengue is the world’s fastest-spreading tropical disease. As reported by Reuters, dengue is a threat that is present in more than 125 countries.
The WHO estimates that 50 and 100 million dengue infections occur worldwide every year, but acknowledges that this is likely a conservative figure. The CDC estimates that about 2.5 billion people, or 40% of the world’s population, live in areas where there is a risk of dengue transmission. The areas in which dengue is endemic include Asia, Africa and Latin America, but it is present on all continents.
Dengue fever is caused by any one of four dengue virus serotypes and is transmitted by the Aedes aegypti and Aedes albopictus mosquito species. Infection with one serotype does not provide immunity against other dengue serotypes, and multiple infections put people at risk for dengue hemorrhagic fever and dengue shock syndrome. Dengue symptoms typically begin four to seven days following the mosquito bite and last three to ten days. Dengue can present similarly to the flu and subside within a few days, or in its most severe forms, it may present with bleeding and fatal circulatory failure. The virus is transmitted person-to-person when mosquitoes drink infected blood and then feed on other humans. Dengue is endemic during seasons when Aedes mosquito populations are high, typically when increased rainfall allows for breeding. In late 2012, Europe experienced its first dengue outbreak since the 1920s as over 2000 people were infected on the Portuguese island of Madeira. From there, infected travelers spread the virus throughout Europe, to Russia, France, and Portugal, among other counties. Thankfully no further transmission has been documented, but travelers are routinely spreading dengue from other endemic areas to the United States and Europe.
New data sources are being applied to tracking dengue around the world. DengueMap, the result of a collaboration between HealthMap and the CDC, combines data from endemic areas recognized by CDC with real-time reports from a variety of different sources.
What can you do to prevent dengue? There are still no vaccines (though various trials are in process) that effectively prevent infection with dengue virus serotypes, but early recognition of infection and prompt treatment can significantly lower the risk of developing severe disease and complications. In the way of prevention, the WHO is trying to address dengue systematically by controlling the invasion of mosquito vectors at points of entry such as seaports, airports and land borders. The CDC recommends eliminating breeding sites for mosquitoes, such as emptying or covering outdoor containers containing standing water and using personal protective measures to prevent exposure to mosquitoes.