Dengue fever laboratory tests: Difference between revisions

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Revision as of 19:01, 11 June 2014

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

The earliest abnormality in the complete blood count is decreased white cell count, which usually occurs during the febrile phase. Leukopenia should alert the physician to a high probability of dengue. The platelet count usually begins to drop when the temperature is returning to normal and is followed by findings indicative of plasma leakage such as elevated hematocrit levels and hypoproteinemia. However, hemoconcentration may be abated by excessive fluid administration and white cell count may increase as a result of stress response. Serology and virology tests are used to confirm the diagnosis of dengue virus infection.

Laboratory Findings

Electrolyte and Biomarker Studies

Serology and PCR (polymerase chain reaction) studies are available to confirm the diagnosis of dengue if clinically indicated.

Platelet Count

The platelet count will drop until the patient's temperature is normal.

Hematocrit

In the presence of GI bleeding, the hematocrit can drop.
In the presence of severe dehydration, the hematocrit may rise (hemoconcentration).

Laboratory Diagnostics

Laboratory Method, Interpretation, and Sample Characteristics for Confirmed and Probable Dengue

A diagnosis of dengue virus infection is confirmed by the detection of the virus, the viral genome or NS1 antigen, or seroconversion of IgM or IgG (from negative to positive IgM/IgG or fourfold increase in the specific antibody titer) in paired sera.^[1]

Definition	Method	Interpretation	Sample Characteristics
Confirmed Dengue Infection	Viral isolation	Virus isolated	Serum (collected at 1–5 days of fever) or necropsy tissues
	Genome detection	Positive RT-PCR or positive real-time RT-PCR
	Antigen detection	Positive NS1 Ag
	Antigen detection	Positive immunohistochemical	Necropsy tissues
	IgM seroconversion	From negative IgM to positive IgM in paired sera	Acute serum (days 1–5) and convalescent serum (15–21 days after first serum)
	IgG seroconversion	From negative IgG to positive IgG in paired sera or 4-fold increase IgG levels among paired sera
Probable Dengue Infection	Positive IgM	Positive IgM	Single serum collected after day 5
Probable Dengue Infection	High IgG levels	High IgG levels by ELISA or hemagglutination inhibition assay (≥1280)	Single serum collected after day 5

Referemces

↑ "Handbook for Clinical Management of dengue" (PDF).

[WHO2012-1] "Handbook for Clinical Management of dengue" (PDF).

[1]

@@ Line 5: / Line 5: @@
 ==Overview==
+The earliest abnormality in the [[complete blood count]] is decreased [[white cell]] count, which usually occurs during the febrile phase. [[Leukopenia]] should alert the physician to a high probability of dengue. The [[platelet]] count usually begins to drop when the temperature is returning to normal and is followed by findings indicative of plasma leakage such as elevated [[hematocrit]] levels and [[hypoproteinemia]]. However, [[hemoconcentration]] may be abated by excessive fluid administration and [[white cell]] count may increase as a result of [[stress response]]. [[Serology]] and [[virology]] tests are used to confirm the diagnosis of dengue virus infection.
 ==Laboratory Findings==
@@ Line 23: / Line 26: @@
 ==Laboratory Diagnostics==
+=====Laboratory Method, Interpretation, and Sample Characteristics for Confirmed and Probable Dengue=====
+A diagnosis of dengue virus infection is confirmed by the detection of the virus, the viral genome or NS1 antigen, or seroconversion of IgM or IgG (from negative to positive IgM/IgG or fourfold increase in the specific antibody titer) in paired sera.<ref name=WHO2012>{{cite web | title = Handbook for Clinical Management of dengue | url = http://apps.who.int/iris/bitstream/10665/76887/1/9789241504713_eng.pdf?ua=1 }}</ref>
+{| style="border: 0px; font-size: 85%; margin: 3px;" align=center
+! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Definition}}
+! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Method}}
+! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Interpretation}}
+! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Sample Characteristics}}
+|-
+! style="padding: 5px 5px; background: #DCDCDC;" rowspan=6 | Confirmed Dengue Infection
+! style="padding: 5px 5px; background: #DCDCDC;" | Viral isolation
+| style="padding: 5px 5px; background: #DCDCDC;" | Virus isolated
+| style="padding: 5px 5px; background: #DCDCDC;" rowspan=3 | Serum (collected at 1–5 days of fever) or necropsy tissues
+|-
+! style="padding: 5px 5px; background: #DCDCDC;" | Genome detection
+| style="padding: 5px 5px; background: #DCDCDC;" | Positive RT-PCR or positive real-time RT-PCR
+|-
+! style="padding: 5px 5px; background: #DCDCDC;" rowspan=2 | Antigen detection
+| style="padding: 5px 5px; background: #DCDCDC;" | Positive NS1 Ag
+|-
+| style="padding: 5px 5px; background: #DCDCDC;" | Positive immunohistochemical
+| style="padding: 5px 5px; background: #DCDCDC;" | Necropsy tissues
+|-
+! style="padding: 5px 5px; background: #DCDCDC;" | IgM seroconversion
+| style="padding: 5px 5px; background: #DCDCDC;" | From negative IgM to positive IgM in paired sera
+| style="padding: 5px 5px; background: #DCDCDC;" rowspan=2 | Acute serum (days 1–5) and convalescent serum (15–21 days after first serum)
+|-
+! style="padding: 5px 5px; background: #DCDCDC;" | IgG seroconversion
+| style="padding: 5px 5px; background: #DCDCDC;" | From negative IgG to positive IgG in paired sera or 4-fold increase IgG levels among paired sera
+|-
+! style="padding: 5px 5px; background: #F5F5F5;" rowspan=2 | Probable Dengue Infection
+! style="padding: 5px 5px; background: #F5F5F5;" | Positive IgM
+| style="padding: 5px 5px; background: #F5F5F5;" | Positive IgM
+| style="padding: 5px 5px; background: #F5F5F5;" rowspan=2 | Single serum collected after day 5
+|-
+! style="padding: 5px 5px; background: #F5F5F5;" | High IgG levels
+| style="padding: 5px 5px; background: #F5F5F5;" | High IgG levels by ELISA or hemagglutination inhibition assay (≥1280)
+|}
 ==Referemces==