Dengue Fever Virus

Dengue Fever Virus

 

Dengue is the most prevalent mosquito-borne viral disease in humans.

Epidemiology

  • Incidence – 50-100 million cases worldwide each year
  • Transmission
    • Dengue fever virus is transmitted by mosquito vectors
      • Aedes aegypti in the sub-tropical and tropical Americas
      • Aedes albopictus in Asia
    • Infection with any strain results in lifelong homologous immunity
    • Reinfection with a heterologous serotype of dengue virus enhances the infection, resulting in the most severe clinical manifestations of dengue fever, dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS)
    • Epidemics of dengue fever are common throughout the world

Organism

  • Dengue fever is caused by 1 of 4 dengue virus serotypes (dengue 1-4)
    • Dengue virus belongs to the family Flaviviridae
    • The virus consists of a single strand of RNA surrounded by an icosahedral nucleocapsid
  • Cross reactions between members of Flaviviridae are common (eg, Banzi virus; Japanese, St. Louis, and Murray Valley encephalitis viruses; Rocio virus; West Nile virus and yellow fever virus)

Clinical Presentation

  • Incubation is 4-7 days
  • Constitutional
    • Fever typically lasts 5-7 days
    • Headache and retroorbital pain
    • Myalgia and arthralgia
    • Prostration (incubation period of 2-6 days)
    • Severe myalgias (Breakbone fever)
  • Rash – petechial, diffuse erythematous or morbilliform  
  • Hemorrhagic manifestations – epistaxis, petechiae, gum bleeding
  • Hematologic – leukopenia, thrombocytopenia
  • Lymphadenopathy
  • Infection can lead to DHF, resulting in renal failure and DSS
    • Majority of cases occur in children <15 years
    • Death occurs primarily in children between the ages of 5 and 15 years

Diagnosis

  • Laboratory testing
    • Laboratory diagnosis of dengue fever depends on 1 or more of the following 4 criteria
      • Isolation of the virus from clinical specimens using cultured mosquito cells
      • Detection of a fourfold or greater change in reciprocal IgG or IgM antibodies by ELISA in paired serum samples
      • Demonstration of dengue virus antigen in autopsy tissue by immunohistochemistry or immunofluorescence or in serum samples by EIA
      • Detection of viral genomic sequences in autopsy tissue, serum, or CSF samples using PCR

Differential Diagnosis

  • Malaria
  • Typhoid fever
  • Leptospirosis
  • Other viral hemorrhagic fevers
  • Epstein-Barr viral infection
  • Cytomegaloviral infection
  • HIV – initial infection
  • Measles
  • Rubella
  • Meningococcal disease
  • Sepsis
  • Brucellosis

Treatment

  • No vaccine available, treatment is supportive

See Also