Dengue fever is an illness transmitted by mosquitoes in tropical and subtropical areas of the world. Symptoms of dengue fever include a high fever, headaches, joint pain, and a rash. The rash may not be visible on darker skin tones.

Many people recover from dengue fever within a week and some people never experience signs of infection at all. However, symptoms can also progress into a life-threatening condition known as severe dengue or dengue hemorrhagic fever. Severe dengue is a medical emergency that can cause organ damage, internal bleeding, a drop in blood pressure (shock), and death.