Management of Dengue Fever Dr David Tran 16/09/09
Classic clinical dengue fever • Incubation period 3 to 14 days (usually 4 to 7 days) • Sudden onset of fever with severe headache • Retro-orbital pain, fatigue • Often associated with myalgia and arthralgia • Duration of fever usually 5 to 7 days • Sometime maculopapular rash(50% to 66% of cases) • Other non specific signs as inflamed pharynx, gastro-intestinal symptoms
Hemorrhagic manifestations / biologic abnormalities • Petechiae, purpura • Gum bleeding, epistaxis, menorrhagia, gastro-intestinal bleedings (rare) • Thrombocytopenia, leukopenia with lymphopenia • Mild elevation of hepatic transaminases & LDH
Dengue hemorrhagic fever & Dengue shock syndrome • Physiopathology: capillary leakage & hemorrhagic manifestations. • 4 to 7 days after the onset (at approximately the date of defervescence) • Abdominal pain, vomiting, consciousness troubles, hypothermia • Marked decrease in platelet count. • Mortality: up to 10 or 20%
Diagnosis of dengue hemorrhagic fever (triad of symptoms) • Hemorrhagic manifestations • Platelet count < 100.000 (often >3rd day of illness) • Evidence of plasma leakage (Hematocrite pleural effusion, ascites, hypoproteinemia)
Lowest platelet count by day of illness in adult dengue hemorrhagic patients
Dengue shock syndrome • Rapid weak pulse & low blood pressure (BP < 90mmHg) • The duration of this shock is short after appropriate volume replacement therapy (Colloid or Cristalloid infusions) • Mortality rate is up to 40%
Serodiagnosis of dengue fever • Serology (IgM capture ELISA) • Problem: negativity of the test early in the course of the disease > should be performed only 4 to 5 days after the onset of fever. • IgM: remain positive for 3 to 6 month • IgG: remain positive for life
Dengue NS1 antigen testing • Early detection of Ag NS1 in blood sample of infected patients > confirm early acute infection • Detection of all 4 types of dengue serotypes • Result available in 15 min. (BioRad® chromatographic strip test) • High specificity (100%) and positive predictive value
Although in some reports, the same efficiency of detection for virus of the 4 serotypes has been described for the Dengue Early ELISA and Strip tests (Dussart et al., 2008), A recent analysis of the performance of these tests in Vietnam suggests a lower sensitivity for DENV-2 compared with DENV-1 and DENV-3.
Problem of sensibility of NS1 detection tests(Ramirez, diagnostic microbiology & infectious disease, Sept 2009) These tests in Vietnam suggests a lower sensitivity for DENV-2 compared with DENV-1 and DENV-3. Also, a decreased sensitivity for DENV-4 with the Dengue Early ELISA has been reported in studies from South America (Bessoff et al., 2008; Dussart et al., 2008). A lower sensitivity for DENV-2 has been described in samples from Vietnam (Hang et al., 2009) tested by the PLATELIA™systems (ELISA and Strip) and belonging to the Asian genotype 1 (according to the classification of Twiddy et al., 2002).
Sensitivity of NS1 Ag detection tests according to the day of illness(Mc Bride, Diagnostic Microbiology & Infectious Diseases, 64 – 2009 – 31,36)
Management of dengue virus infected patient • Most of cases can be managed on an outpatient basis (antipyretic like paracetamol, bed rest, oral hydratation) • Platelet counts and hematocrite determination should be repeated at least every 24 hours • Patient with platelet count < 100.000 should be hospitalized (high risk for dengue hemorrhagic & dengue shock syndrome)