Dengue fever (ORPHA:99828)
Dengue fever (DF), caused by dengue virus, is an arboviral disease characterized by an initial non-specific febrile illness that can sometimes progress to more severe forms manifesting capillary leakage and hemorrhage (dengue hemorrhagic fever, or DHF) and shock (dengue shock syndrome, or DSS).
Epidemiology
DF is found in the tropics worldwide, especially in Southeast Asia, the Pacific region, and the Americas, with 40% of the global population at risk. An estimated 50 to 100 million cases of DF, 500,000 hospitalizations, and 20,000 deaths occur yearly worldwide.
Clinical description
The vast majority of dengue virus infections result in DF, which is characterized by sudden onset of fever, malaise, headache (classically retro-orbital), and myalgia/arthralgia, often followed soon after by a petechial rash, which may be pruritic. In most cases, symptoms will resolve within 7 days without further complications. However, in a small minority of patients, a brief period of deffervescence is followed by worsening abdominal symptoms (pain, nausea, vomiting, diarrhea), thrombocytopenia, hemorrhage (DHF: epistaxis, bleeding gums, gastrointestinal bleeding) and a capillary leak syndrome (DSS: hemoconcentration, hypoalbuminemia, pleural effusion, shock). DHF/DSS are seen most often in children under the age of 15 years. Risk is greater with secondary heterologous infection by one of the four dengue virus serotypes, but severe disease may be seen with first infections.
Etiology
Over 25 different viruses cause viral hemorrhagic fever. Dengue virus belongs to the Flaviviridae family, genus Flavivirus. Four distinct serotypes, with significant strain variation, are recognized. Dengue viruses are maintained in humans and transmitted between them by the bite of infected mosquitoes, most commonly Aedes aegypti but also Aedes albopictus). Person-to-person transmission has not been reported.
Diagnostic methods
Common diagnostic modalities include serologic testing by enzyme linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR). Virus isolation may also be performed in specialized laboratories. The viremic phase of DF/DHF is usually brief (first 3-5 days of illness), after which time detection of anti-dengue IgM antibodies, which appear as early as 2-4 days after disease onset, is the mainstay. Numerous commercial ELISA assays are available with varying degrees of sensitivity and specificity.
Differential diagnosis
DF is difficult to distinguish from a host of other febrile illnesses such as malaria and typhoid fever (see these terms), especially early in the course of disease before the rash appears. For DHF/DSS, other viral hemorrhagic fevers, leptospirosis, rickettsial infection (see these terms) and meningococcemia need to be excluded.
Management and treatment
As there is presently no antiviral drug available for DF/DHF, treatment is supportive, following the guidelines for treatment of severe septicemia. Insecticide-treated bed nets, room screens and elimination of larval development sites should be used in open-air settings to prevent further transmission.
Prognosis
Case-fatality rates for DF are less than 1% but may rise to as high as 40% in DHF/DSS, largely dependent upon whether access to advanced medical care exists. Children and persons with underlying chronic diseases such as diabetes, heart disease, and asthma are at increased risk. The most severe phase of disease usually lasts only a few days and survivors generally have no lasting sequelae.

                            Last update: 
                            December 2012


                            - Expert reviewer(s): 
                            Dr Daniel BAUSCH  -  Andrew BENNETT