Dengue fever is a viral disease transmitted by mosquitoes and is endemic in tropical and subtropical regions. Because of the severe myalgias and arthralgias, it has been called "breakbone fever". Dengue fever is most prevalent in southeast Asia, but also occurs in Africa, Europe, South America, and southern regions of North America (South Texas). It may also occur in non-endemic regions in travelers from endemic regions.
Primary versus secondary versus tertiary infection
There are four serotypes of dengue. An initial infection is primary Dengue, a subsequent infection with a second serotype is secondary Dengue, and so on. In primary infection, IgM antibodies rise after 5–6 days and may last 2-3 months; IgG antibodies rise after 7–10 days. During a secondary infection very high levels of IgG may occur during the acute phase whereas IgM are lower and sometimes absent.
The World Health Organization has classified Dengue fever as:
- Undifferentiated fever (viral syndrome). Patients may have fever, severe headache, retro-orbital pain, fatigue, rash, and severe myalgia and arthralgia ("breakbone fever"). Patients may also have lymphadenopathy, injected conjunctivae, and mild respiratory and gastrointestinal symptoms.
- Dengue fever syndrome has at least two of: 1) headache; 2)retro-orbital pain; 3) myalgia, 4) arthralgia; 4) rash; 5) hemorrhagic manifestations; 6) leucopenia. There must be other confirmed cases of dengue fever in the geographic area.
- Dengue hemorrhagic fever (plasma leakage) must meet four of the following criteria: 1) fever or history of fever lasting 2–7 days; 2) positive tourniquet test or spontaneous bleeding; 3) platelet count 100x109/L or less; 4) plasma leakage shown either by hemoconcentration with changes in packed-cell volume, or by the development of pleural effusions or ascites.
- Dengue shock syndrome is Dengue hemorrhagic fever with shock. Grade III is narrowing of the pulse pressure or hypotension for age; Grade IV is no detectable pulse or blood pressure.
- Intravenous fluids. Crystalloid solutions such as Ringer's lactate may be better than colloid solutions.
Dengue fever is caused by infection of one of the four Dengue fever viral serotypes (DEN-1, DEN-2, DEN-3, and DEN-4). The Dengue fever viruses are classified as flaviviruses (family Flaviviridae, genus Dengue).
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