Causes of Dengue
Dengue is caused by the dengue virus (DENV), an enveloped RNA flavivirus with four distinct serotypes (DENV-1 through DENV-4), transmitted primarily through the bite of infected Aedes mosquitoes, particularly Aedes aegypti and Aedes albopictus. 1, 2
Viral Etiology
- The dengue virus is a positive-stranded enveloped RNA virus belonging to the family Flaviviridae, consisting of three structural proteins and seven non-structural proteins 3
- Four antigenically distinct but closely related virus serotypes exist (DENV-1, DENV-2, DENV-3, and DENV-4), each with different genotypes 1, 3
- Infection with one serotype provides lifetime immunity to that specific virus but only short-term cross-immunity to the other serotypes, making secondary infections with different serotypes possible 1
Vector Transmission
- Day-biting mosquitoes of the genus Aedes, particularly Aedes aegypti, are the primary vectors of dengue fever 4
- Aedes albopictus also serves as a significant vector for dengue transmission 1, 2
- These mosquitoes are both diurnal (active during daytime) and container breeders, requiring specific prevention and control measures 5
- The virus is transmitted to humans through the bite of an infected mosquito during blood feeding 1, 2
Incubation Period
- The incubation period following mosquito bite ranges from 4-8 days before symptoms develop 4
Geographic Distribution and Risk Factors
- Dengue occurs primarily in tropical and subtropical regions, with widespread infections most commonly seen during the rainy season when Aedes mosquito breeding habitat is most favorable 1, 2
- The disease has been reported in more than 100 countries worldwide 3
Secondary Infection Risk
- Secondary infections with a different dengue serotype carry increased risk of severe disease manifestations (dengue hemorrhagic fever/dengue shock syndrome) through antibody-dependent enhancement (ADE) 1, 3
- The most commonly accepted theory for severe dengue infections is antibody-dependent enhancement, though other host and viral factors likely contribute 1
- In endemic areas, severe infections are most often seen in the latter half of the first year of life (when waning maternal antibodies may enhance infection severity) and in young school-age children experiencing secondary infections 1