Dengue Fever Virus

Diagnosis

Indications for Testing

  • Flu-like illness with exanthem in endemic area
  • Patient with appropriate travel history

Criteria for Diagnosis

  • CDC case definition for dengue virus infections (2010)
    • Dengue fever
      • Clinical description

        Clinical Description of Dengue Fever

        • Acute febrile illness defined by the presence of fever and two or more of the following
          • Retro-orbital or ocular pain
          • Headache
          • Rash
          • Myalgia
          • Arthralgia, leukopenia, or hemorrhagic manifestations (eg, positive tourniquet test, petechiae; purpura/ecchymosis; epistaxis; gum bleeding; blood in vomitus, urine, or stool; or vaginal bleeding) but not meeting the case definition of dengue hemorrhagic fever
        • Anorexia, nausea, abdominal pain, and persistent vomiting may also occur but are not case-defining criteria for DF
        Laboratory criteria for diagnosis

        Laboratory Criteria for Diagnosis

        Confirmatory

        • Isolation of dengue virus from or demonstration of specific arboviral antigen or genomic sequences in tissue, blood, cerebrospinal fluid (CSF), or other body fluid by polymerase chain reaction (PCR) test, immunofluorescence, or immunohistochemistry, OR
        • Seroconversion from negative for dengue virus-specific serum immunoglobulin M (IgM) antibody in an acute phase (≤5 days after symptom onset) specimen to positive for dengue-specific serum IgM antibodies in a convalescent-phase specimen collected ≥5 days after symptom onset, OR
        • Demonstration of a ≥4-fold rise in reciprocal immunoglobulin G (IgG) antibody titer or hemagglutination inhibition titer to dengue virus antigens in paired acute and convalescent serum samples, OR
        • Demonstration of a ≥4-fold rise in PRNT (plaque reduction neutralization test) end point titer (as expressed by the reciprocal of the last serum dilution showing a 90% reduction in plaque counts compared to the virus infected control) between dengue viruses and other flaviviruses tested in a convalescent serum sample, OR
        • Virus-specific immunoglobulin M (IgM) antibodies demonstrated in CSF

        Presumptive/probable

        • Dengue-specific IgM antibodies present in serum with a P/N ratio ≥2

        Case Classification

        • Suspected – a clinically compatible case of DF, DHF or DSS that is epidemiologically linked to a confirmed case
        • Probable – a clinically compatible case of DF, DHF, or DSS with laboratory results indicative of presumptive infection
        • Confirmed – a clinically compatible case of DF, DHF, or DSS with confirmatory laboratory results
    • Dengue hemorrhagic fever (DHF)
      • Clinical description

        Clinical Description of Dengue Hemorrhagic Fever

        • Fever lasting from 2-7 days
        • Evidence of hemorrhagic manifestation or a positive tourniquet test
        • Thrombocytopenia (≤100,000 cells per mm3)
        • Evidence of plasma leakage shown by hemoconcentration (an increase in hematocrit ≥20% above average for age or a decrease in hematocrit ≥20% of baseline following fluid replacement therapy), OR pleural effusion, ascites, or hypoproteinemia
    • Dengue shock syndrome (DSS)
      • Clinical description

        Clinical Description of Dengue Shock Syndrome

        • All of criteria for DHF plus circulatory failure as evidenced by
          • Rapid and weak pulse and narrow pulse pressure (<20mm Hg), OR
          • Age-specific hypotension, cold, clammy skin, and restlessness

Laboratory Testing 

  • CDC clinical and laboratory guidance for Dengue fever

  • Nonspecific laboratory tests
    • CBC – frequently demonstrates leukopenia, thrombocytopenia, hemoconcentration
    • Serum transaminases – may be elevated
    • Serum electrolytes – hyponatremia not uncommon
  • Specific testing for laboratory diagnosis based on case-definition criteria
    • Dengue-specific antibodies – reciprocal IgG or IgM antibodies by ELISA in paired serum samples
      • IgM reaches peak at 6 days – not useful in critical stage of diagnosis
    • PCR – detect viral genomic sequences in autopsy tissue, serum, or CSF samples
    • Cell culture for DV requires specialized mosquito cell lines not routinely available in the clinical laboratory setting

Histology

  • Demonstration of DV antigen in autopsy tissue by immunohistochemistry, immunofluorescence, or in serum samples

Differential Diagnosis

Clinical Background

Dengue fever (DV) is the most prevalent mosquito-borne viral disease in humans.

Epidemiology

  • Incidence – 50-100 million cases worldwide annually
    • ~22,000 deaths (mostly among children) associated with the disease (WHO estimate)
    • Epidemics common in tropical and subtropical areas worldwide
  • Transmission
    • Transmitted by mosquito vectors
      • Aedes aegypti – subtropical and tropical locations worldwide
      • Aedes albopictus – Asia; also prevalent in southeastern U.S.
    •  Transplacental transmission possible

Organism

  • Caused by 1 of 4 DV serotypes (dengue 1-4)
    • Single-stranded RNA virus of the Flaviviridae family 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; yellow fever virus)
  • Infection with any strain results in lifelong homologous immunity
  • Reinfection with a heterologous serotype of DV enhances the infection – most severe clinical manifestations 
    • Dengue hemorrhagic fever (DHF) 
    • Dengue shock syndrome (DSS)

Clinical Presentation

  • Incubation – 4-7 days
  • Constitutional symptoms
    • Fever typically lasts 5-7 days
    • Headache and retro-orbital pain
    • Arthralgia, myalgia 
      • Severe myalgia ("breakbone fever")
    • Prostration – incubation period of 2-6 days
  • Rash
    • Typically involves flushing erythema of the face, neck, and chest during first 24-48 hours of symptoms
    • Petechial, diffuse erythematous or morbilliform – 50-80% of patients
      • Noted with “islands of sparing” – white skin in the middle of red skin
  • Hemorrhagic manifestations – epistaxis, petechiae, gum bleeding
  • Hematologic – leukopenia, thrombocytopenia
  • Lymphadenopathy
  • DHF/DSS
    • Majority of cases found in patients with recurrent dengue fever or who are reinfected with a different DV serotype
    • In infants, most often occurs from primary DV infection when the mother has previous immunity
      • Majority of cases in children <15 years
      • Death primarily in children between 5-15 years

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential
Initial nonspecific testing to assess presence of infectious process    
Aspartate Aminotransferase, Serum or Plasma 0020007
Method: Quantitative Enzymatic
Initial nonspecific testing for hepatic involvement    
Electrolyte Panel 0020410
Method: Quantitative Ion-Selective Electrode/Enzymatic
Initial nonspecific testing for metabolic abnormality    
Dengue Fever Virus Antibodies, IgG and IgM 0093096
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Identify dengue virus as infectious agent in hemorrhagic febrile illness

Usually requires paired convalescent samples For equivocal results, repeat testing in 10-14 days
Additional Tests Available
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Dengue Fever Virus Antibody, IgG 0093097
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Dengue Fever Virus Antibody, IgM 0093098
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay