dengue
DENGUE

Dengue infection is caused by the dengue virus that belongs to the family Flaviviridae. It is generally self-limiting and rarely fatal.
There are 4 serotypes (DEN-1, DEN-2, DEN-3, DEN-4). Infection w/ dengue serotype confers lifetime protective immunity to that specific serotype; cross-protection for other serotypes is only short-term.
It is transmitted to humans through the bites of infected Aedes mosquitoes. It is primarily transmitted by female Aedes aegypti, a tropical and subtropical species.Humans & monkeys are the amplifying hosts after the mosquito bite.
After 4-10 days of incubation period, illness begins immediately.
The acute phase of illness lasts for 3-7 days, but the convalescent phase may be prolonged for a week and may be associated with weakness and depression especially in adults.

Prevention

  • Preventing or reducing the transmission of dengue virus is dependent on controlling mosquito vectors or disturbing human-vector contact
  • Vaccination against dengue viruses are currently being developed, with promising results

Methods of Vector Control

  • Methods to control transmission should target habitats of immature & adult stages of A aegypti, one of the most efficient vectors for arboviruses, in the household & places where human-vector contact occurs
    • These mosquitoes mostly stay within 100 meters from where they emerged, & feeds mainly during daylight hours

Environmental Management

  • Controlling mosquito vectors are achieved mainly by eradicating container habitats that are favorable oviposition sites & development of aquatic stages through prevention of access to containers or emptying & cleaning them regularly & by using insecticides or biological control agents to kill developing stages of adult vectors
  • Mosquito screens on windows or doors, mosquito nets, & clothing that covers the arms and legs may be used while sleeping during daytime to decrease human-vector contact

Chemical Control

  • Larvicides should be done as complementary to environmental management 
  • Adulticides are used to target adult vectors which is applied either as surface treatments or as space treatments
  • Individual & household protection are advised to minimize exposure of skin & be protected from bites of dengue vectors during their active hours
    • Repellents that contain DEET (N, N-diethyl-3-methylbenzamide), IR3535 (3-[N-acetyl-N-butyl]-aminopropionic acid ethyl ester), or Icaridin (1- piperidinecarboxylic acid-2-(2-hydroxyethyl)-1-methylpropylester) may be applied to skin or to clothes; Citronella-based repellents may also be considered
    • Mosquito nets that are insecticide-treated, insecticide aerosol products, or mosquito coils may also help

Vaccination

  • Due to the immunopathological component in dengue pathogenesis, development of a dengue vaccine focuses on the creation of a tetravalent vaccine that will provide long-term protection against all virus serotypes
  • The first dengue vaccine developed, CYD-TDV, is being reviewed by the World Health Organization (WHO) Strategic Advisory Group of Experts (SAGE) on Immunization
    • CYD-TDV is a live recombinant tetravalent dengue vaccine that will be used in individuals aged 9-45 years residing in endemic areas
    • Data from the 2 pivotal phase III clinical studies showed that CYD-TDV given on a 3-dose series on a 0/6/12 month schedule has a good safety profile with secondary analysis demonstrating efficacy against the four dengue serotypes & protection from severe disease & hospitalization
    • Recently, it was approved in few countries (eg Brazil, Mexico & Philippines) for prevention of dengue
  • Other vaccines under clinical trial evaluation include subunit, deoxyribonucleic acid (DNA) & purified inactivated as well as other live-attenuated vaccines
    • Additional vaccines under preclinical study evaluation are the virus-vectored & VLP-based vaccines
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