Dengue fever

Dengue fever is a viral disease caused by the dengue virus. It is spread through the bite of mosquitos and attacks the body's white blood cells. In 80% of people exposed to it, it resolves itself after causing only a slight fever. In 15% of patients, it also causes a rash accompanied by aches and pains of the muscles and joints. It's endemic and epidemic in much of the tropics, but the virus exists in the wild in many other tropical areas.
In the remaining 5% of patients, the disease is serious and life threatening. It causes a very high fever, a widespread rash, bleeding of the mucous membranes, leading to edema which reduces the volume of blood, causing organ damage, shock and widespread hemorrhage. About 26% of patients who reach this stage will die of the disease, although the mortality rate drops sharply with treatment.
Unlike many diseases, it is more likely to be severe in younger people, and particularly healthy and well fed younger people. It also tends to be more severe when the patient has another underlying condition such as asthma or diabetes.
There is no vaccine against dengue, so prevention is directed at keeping mosquito populations low. Even in very sick patients, treatment is supportive as the disease will run its course in about seven days. Most patients only need to drink fluids, but sicker patients may need intravenous fluids or transfusions. Invasive procedures must be avoided due to the risk of bleeding. Acetaminophen is used to treat the pain and aspirin and ibuprofen have to be avoided as they will often make the symptoms worse. Fluid levels must be checked as during the recovery phase, patients may retain fluids as they flow back into the bloodstream.
Dengue fever at Wikipedia
Dengue fever at Mayo Clinic
Dengue fever