Early diagnosis of dengue in travelers: comparison of a novel real-time RT-PCR, NS1 antigen detection and serology.
BACKGROUND
The increased traveling to dengue endemic regions and the numerous epidemics have led to a rise in imported dengue. The laboratory diagnosis of acute dengue requires several types of tests and often paired samples are needed for obtaining reliable results. Although several diagnostic methods are available, proper comparative data on their performance are lacking.


OBJECTIVE
To compare the performance of novel methods including a novel pan-DENV real-time RT-PCR and a commercially available NS1 capture-EIA in regard to IgM detection for optimizing the early diagnosis of DENV in travelers.


METHODS
A panel of 99 selected early phase serum samples of dengue patients was studied by real-time RT-PCR, NS1 antigen ELISA, IgM-EIA, IgG-IFA and cell culture virus isolation.


RESULTS
The novel real-time RT-PCR was shown specific and sensitive for detection of DENV-1-4 RNA and suitable for diagnostic use. The diagnostic rate using combination of RNA and IgM detection was 99% and using NS1 and IgM detection 95.9%. The results of RNA and NS1 antigen detection disagreed in 15.5% of samples that had only RNA or NS1 antigen detected.


CONCLUSIONS
The diagnostic rates of early samples are higher when either RNA or NS1 antigen detection is combined with IgM detection. Besides the differences in the RNA and NS1 detection assays, the observed discrepancy of results could suggest individual variation or differences in timing of these markers in patient serum.
Huhtamo
Eili
E
Department of Virology, Haartman Institute, Faculty of Medicine, University of Helsinki, PO Box 21, Haartmaninkatu 3, FI-00014 University of Helsinki, Finland. eili.huhtamo@helsinki.fi
Hasu
Essi
E
Uzcátegui
Nathalie Y
NY
Erra
Elina
E
Nikkari
Simo
S
Kantele
Anu
A
Vapalahti
Olli
O
Piiparinen
Heli
H
D000914:Antibodies, Viral / Q000097:blood*; D000956:Antigens, Viral / Q000097:blood; D001483:Base Sequence; D003715:Dengue / Q000175:diagnosis* / Q000276:immunology / Q000821:virology; D003716:Dengue Virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D016415:Sequence Alignment; D012698:Serologic Tests / Q000379:methods; D014195:Travel; D017361:Viral Nonstructural Proteins / Q000097:blood*
D000914:Antibodies, Viral; D000956:Antigens, Viral; C082515:NS1 protein, dengue-1 virus; D017361:Viral Nonstructural Proteins