Dengue fever is caused by any of four related dengue virus serotypes transmitted by Aedes mosquitoes. It manifests as a sudden onset of fever, headache, muscle and joint pains. In some cases it can progress to severe dengue hemorrhagic fever or dengue shock syndrome, characterized by bleeding, low blood pressure and organ failure. There is no vaccine or specific antiviral treatment, so management focuses on relief of symptoms and careful fluid replacement to prevent shock. Prevention relies on controlling mosquito populations and avoiding mosquito bites.