From the Guidelines
Dengue is caused by the dengue virus, which is primarily transmitted through the bite of infected female Aedes mosquitoes, mainly Aedes aegypti and to a lesser extent Aedes albopictus. The virus belongs to the Flaviviridae family and has four distinct serotypes (DENV-1, DENV-2, DENV-3, and DENV-4) 1. When an infected mosquito bites a person, it injects the virus into the bloodstream, where it can replicate in various cells, particularly those of the immune system. The mosquitoes that spread dengue typically bite during the day, especially in the early morning and evening. These mosquitoes breed in standing water found in containers like flower pots, discarded tires, and water storage containers.
Key Factors in Dengue Transmission
- Climate change and climate variability have a direct influence on the epidemiology of vector-borne diseases, including dengue 1
- Climatic factors, such as temperature and rainfall, are intricately linked to the biology and transmission of vector-borne diseases
- Infection with one serotype provides lifelong immunity against that specific serotype but only temporary protection against the others
- Subsequent infections with different serotypes increase the risk of developing severe dengue, characterized by plasma leakage, fluid accumulation, respiratory distress, severe bleeding, or organ impairment
Prevention and Control
Prevention focuses on controlling mosquito populations and avoiding mosquito bites through:
- Insect repellent
- Protective clothing
- Eliminating breeding sites
- Controlling mosquito populations is crucial in preventing the spread of dengue. This can be achieved through a combination of methods, including the use of insecticides, elimination of breeding sites, and biological control methods 1.
In terms of diagnosis, serologic methods for detection of IgM- and/or IgG-class antibodies to the virus or detection of the DENV nonstructural protein 1 (NS1) antigen are commonly used 1. However, due to the similar antigenic profiles between members of the Flavivirus genus, false-positive results for antibodies to DENV may occur in patients with a prior flavivirus infection. Plaque reduction neutralization tests (PRNTs) are considered the reference standard for detection of antibodies to arthropod-borne viruses (arboviruses) and provide improved specificity over commercial serologic assays 1.
From the Research
Causes of Dengue
- Dengue fever is one of the most common mosquito-borne viral illnesses in the world, usually transmitted to humans through the bite of an infected Aedes aegypti or Aedes albopictus mosquito 2.
- Dengue infections are caused by four antigenically distinct but closely related viruses (DEN 1-4) 2, 3.
- Infection with any one of the viruses is thought to provide lifetime immunity to future infections from the same virus but only short-term cross-immunity to the other types, leading to the possibility of secondary infections 2.
- The most commonly accepted theory for the development of more severe dengue infections, such as dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), is that of antibody-dependent enhancement, although other factors likely play a role 2, 4, 3.
Transmission and Risk Factors
- Widespread infections are most commonly seen during the rainy season of endemic areas when the breeding habitat of the Aedes mosquito is most favorable 2.
- Infections complicated by DHF/DSS in areas where dengue is endemic are most often seen in the later half of the first year of life, when waning maternal antibodies may enhance the development of a more severe infection, and in young school-age children experiencing secondary infections 2.
- Different factors and mechanisms are thought to be involved in the presentation of DHF and DSS, including immune dysregulation, viral virulence, host genetic susceptibility, and preexisting dengue antibodies 4.