Laboratory diagnosis of primary and secondary dengue infection.
BACKGROUND
Dengue fever is routinely detected in many laboratories using commercial tests for the specific detection of dengue IgM antibodies.


OBJECTIVE
We have studied the sensitivity of IgM antibody detection in paired serum samples of 43 patients with either with primary dengue (PD) or secondary dengue (SD).


METHODS
Two consecutive samples were drawn from 23 Vietnamese and 20 German patients. All patients were selected for a positive PCR and for the fact that consecutive serum samples were available. The diagnosis of PD was based on seroconversion to dengue antigen and in SD on the detection of virus RNA in the presence of anti-dengue IgG antibodies.


RESULTS
In samples of patients with PD fever taken during days 1-3 of the disease no IgM antibody could be detected. During days 4-7 and after day 7, IgM antibody was detected in 55% and 94%, respectively. In patients with SD fever, even less positive IgM samples were found in samples taken during days 4-7 (47%) and after day 7 (78%). IgG titers were significantly higher in SD compared to PD patients, although high (>1280) titers were also found in some PD patients.


CONCLUSIONS
In numerous acute dengue fever patients an early diagnosis will be obtained only by combining IgM antibody detection with detection of virus or virus RNA using RT-PCR.
Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Bernhard Nocht Strasse 74, 20359 Hamburg, Germany.
Stefan
S
Schilling
Diana
D
Ludolfs
Le
L
Van An
Herbert
H
Schmitz
D000914:Antibodies, Viral / Q000097:blood; D019411:Clinical Laboratory Techniques; D003715:Dengue / Q000175:diagnosis* / Q000821:virology; D003716:Dengue Virus / Q000276:immunology* / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood*; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000097:blood; D012680:Sensitivity and Specificity; D013997:Time Factors
D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012367:RNA, Viral