Dengue (lab compub)

• Dengue fever


  Mosquito-transmitted virus and the leading cause of arthropod-borne viral disease in the world
• Also known as

  Breakbone fever
• Vector


  • Aedes aegypti/albopictus & Stegomyia mosquito
• Causative agent


  DENV (dengue virus) single-stranded RNA viruses of the genus Flavivirus
• Dengue virus serotypes


  • DEN-1
  • DEN-2
  • DEN-3
  • DEN-4
• Clinical presentation


  • Muscle spasms (myalgias)
  • Joint pain (arthralgias)
  • Dandy fever, or seven-day fever/ high fever (40°C/104°F)
  • Severe headache (Frontal headache)
  • Pain behind the eyes (retro-orbital pain)
  • Nausea
  • Vomiting
  • Swollen glands
  • Rash (hemorrhagic manifestation)
• Virion composition


  • 3 structural proteins (core, membrane and envelope) and 7 non-structural (NS1, NS2a, NS2b, NS3, NS4, NS4b, and NS5) proteins
• Infection with one dengue virus provides life-long immunity, but there is no cross protective immunity to the other dengue viruses
• Most primary infections are usually asymptomatic or manifest as a mild febrile illness, although they can also cause hemorrhagic fever in some patients, especially in infants born to DENV-immune mothers
• Subsequent infection with a different serotype is known as secondary dengue infection and may lead to severe clinical manifestations such as dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS)
• Transmission through the mosquito bite

  Virus is transmitted to humans through the bites of infected female mosquitoes, primarily the Aedes aegypti mosquito
• Human-to-mosquito transmission


  1. Mosquitoes can become infected by people who are viremic with DENV (symptomatic, pre-symptomatic, or asymptomatic)

  2. Can occur up to 2 days before someone shows symptoms and up to 2 days after the fever has resolved
• Maternal transmission


  Possibility of transmission from a pregnant mother to her baby, with risk linked to timing of dengue infection during pregnancy. Can result in pre-term birth, low birthweight, and fetal distress
• Other transmission modes


  • Rare cases via blood products, organ donation and transfusions
  • Transovarial transmission within mosquitoes
  • Infected female mosquitoes transmitting to offspring
• Epidemiology


  • Dengue is found in tropical and sub-tropical climates, mostly in urban and semi-urban areas
  • Primary vectors are female Aedes aegypti and Aedes albopictus mosquitoes, with A. albopictus' range expanding and associated with increasing numbers
• Dengue hemorrhagic fever


  Severe and sometimes fatal form of dengue disease, characterized by high fever, hemorrhagic phenomena, and early signs of shock
• WHO criteria for DHF

  • Fever or recent history of fever lasting 2–7 days
  • Any hemorrhagic manifestation
  • Thrombocytopenia (platelet count of <100,000/mm^3)
  • Evidence of increased intravascular permeability
• Risk factors for dengue

  • Population density
  • Access to reliable water source
  • Knowledge, attitude, and practice
  • Climate & environment
• Prevention and control measures


  • Wear clothes that cover as much of your body as possible
  • Use mosquito nets, ideally sprayed with insect repellent
  • Use window screens
  • Use mosquito repellents containing DEET, Picaridin or IR3535
  • Stop mosquitoes from laying eggs in or near water
• June was declared Dengue Awareness Month (Proclamation No. 1204) since 1998 to highlight how prevention and control of dengue would require collaborative efforts among national and local government agencies as well as private NGOs
• Safety first, science always!