Clinical Description For Case Definitions

Dengue fever is most commonly an 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 (e.g., 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.

Dengue hemorrhagic fever is characterized by all of the following:

• 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, or ascites or hypoproteinemia.

Dengue shock syndrome has 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 and cold, clammy skin and restlessness.

Laboratory criteria for diagnosis for case definitions

1. Confirmatory
   1. Isolation of virus from or demonstration of specific arboviral antigen or genomic sequences in tissue, blood, cerebropspinal fluid (CSF), or other body fluid by polymerase chain reaction (PCR) test, immunofluorescence, or immunohistochemistry, or
   2. Seroconversion from negative for dengue-specific serum 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
   3. Demonstration of a ≥4-fold rise in reciprocal IgG antibody titer or hemagglutination inhibition titer to dengue antigens in paired acute and convalescent serum samples, or
   4. 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
   5. Virus-specific immunoglobulin M (IgM) antibodies demonstrated in CSF.
2. Presumptive/Probable
   1. Dengue-specific IgM antibodies present in serum with a P/N ratio ≥2.
3. Criteria for Epidemiologic Linkage
   1. Travel to an dengue endemic country or presence at location with ongoing outbreak within previous two weeks of dengue-like illness, OR
   2. Association in time and place with a confirmed or probable dengue case.

• Dengue case definition as defined by the U.S. Council for State and Territorial Epidemiologist PDF (115KB/15pages)
• CSTE Nationally Notifiable Condition List PDF(10.7KB/2pages)