Dengue virus, a mosquito-borne flavivirus, is a leading cause of illness and death within the tropics and subtropics, with over a third of the world’s population at risk of infection. There are as many as 400 million cases worldwide per year with 500,000 resulting in hospitalization and 25,000 in death. Dengue is transmitted through the bites of the female Aedes aegypti and, to a lesser extent, Ae. albopictus mosquitoes. The mosquitos must be carrying one of the four dengue virus serotypes, DEN-1, DEN-2, DEN-3, or DEN-4. It is possible to be infected multiple times, but only once per serotype.
Symptoms typically develop 4 to 7 days after infection. These include a high fever, headache, retro-orbital pain, arthralgia, myalgia, nausea, vomiting, and a rash. An infected person may develop a minor facial rash before developing another more severe rash with flat or raised lesions on the skin. Those who have already had dengue experience a much more severe illness that may not be preventable by the DengvaxiaÒ CYD-TDV vaccine if they are infected again. Emergency cases include dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Young children or those experiencing a second case of dengue are more likely to experience DHF or DSS. DHF is characterized by increased vascular permeability, atypical blood clotting mechanisms, and hypovolemia, while patients with DSS experience abdominal pain, hemorrhage, and circulatory collapse. There is no cure for dengue and therefore only supportive care can be provided, such as rest, fluids, and pain relievers.
The most effective way to prevent dengue is to avoid mosquito bites by using insect repellant and wearing long sleeves and pants when traveling to endemic areas.
WHO has a specific global goal to decrease the mortality and morbidity from dengue by at least 50% and 25% in 2020 (based on 2010 numbers).
Thus far, the only licensed dengue vaccine is Dengvaxia® (CYD-TDV), though it has poor effectivity rates depending on the strain of dengue. Several other vaccine candidates are in development with the goal of being more effective, especially against patients that have already had dengue.