Dengue virus, a mosquito-transmitted flavivirus, is the most common arbovirus infection of humans. Any of four dengue virus serotypes (1, 2, 3, and 4) may cause illness. Infection confers long-lasting protection against reinfection with the same dengue virus serotype but not against other serotypes. Hence, repeated dengue virus infections are possible if an individual is exposed sequentially to several serotypes. Infection with dengue virus may result in dengue fever or the more severe forms of disease known as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS).

Classical dengue, or breakbone fever, is most commonly a self-limited, nonfatal acute viral illness in adults and children. An incubation period of 3 to 8 days precedes the sudden onset of fever to 39°C to 41°C (100.4°F to 102.2°F), frontal headache, muscle ache, and retroorbital pain. Prominent malaise and arthralgias may be accompanied by altered taste perception, nausea, and vomiting. Various rashes are often observed during illness, ranging from evanescent generalized maculopapular rashes to localized petechial rashes. Minor hemorrhagic manifestations such as epistaxis or gum bleeding may be present, but occasionally significant occult bleeding results from gastrointestinal ulcers. There is a characteristic transient depression of circulating neutrophil, lymphocyte, and platelet counts. Generally dengue fever resolves uneventfully, with defervescence in 7 days or less.