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 fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS) (CDC, 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

•  Encephalitis/meningitis
  • Flavivirus
    • Yellow fever
    • Japanese encephalitis
    • Arbovirus – West Nile virus, eastern equine encephalitis, western equine encephalitis
• Other viruses
  • Epstein-Barr virus
  • Cytomegalovirus
  • Measles virus
  • Rubella virus
  • HIV (initial infection)
  • Lymphocytic choriomeningitis
• Bacteria
  • Salmonella typhi
  • Leptospira spp
  • Brucella spp
  • Neisseria meningitidis
  • Haemophilus influenzae
  • Rickettsia typhi
• Parasites
  • Plasmodium species
  • Babesia microti
  • Rickettsia rickettsii
• Sepsis
• Acute viral hepatitis
  • Hepatitis A, B, or C

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

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Test Name and Number	Comments
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