Diagnostic accuracy of NS1 ELISA and lateral flow rapid tests for dengue sensitivity, specificity and relationship to viraemia and antibody responses.
BACKGROUND
Dengue is a public health problem in many countries. Rapid diagnosis of dengue can assist patient triage and management. Detection of the dengue viral protein, NS1, represents a new approach to dengue diagnosis.


RESULTS
The sensitivity and specificity of the Platelia NS1 ELISA assay and an NS1 lateral flow rapid test (LFRT) were compared against a gold standard reference diagnostic algorithm in 138 Vietnamese children and adults. Overall, the Platelia NS1 ELISA was modestly more sensitive (82%) than the NS1 LFRT (72%) in confirmed dengue cases. Both ELISA and LFRT assays were more sensitive for primary than secondary dengue, and for specimens collected within 3 days of illness onset relative to later time points. The presence of measurable DENV-reactive IgG and to a lesser extent IgM in the test sample was associated with a significantly lower rate of NS1 detection in both assays. NS1 positivity was associated with the underlying viraemia, as NS1-positive samples had a significantly higher viraemia than NS1-negative samples matched for duration of illness. The Platelia and NS1 LFRT were 100% specific, being negative in all febrile patients without evidence of recent dengue, as well as in patients with enteric fever, malaria, Japanese encephalitis and leptospirosis.


CONCLUSIONS
Collectively, these data suggest NS1 assays deserve inclusion in the diagnostic evaluation of dengue patients, but with due consideration for the limitations in patients who present late in their illness or have a concomitant humoral immune response.
Hang
Vu Ty
VT
Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Viet Nam.
Nguyet
Nguyen Minh
NM
Trung
Dinh The
DT
Tricou
Vianney
V
Yoksan
Sutee
S
Dung
Nguyen Minh
NM
Van Ngoc
Tran
T
Hien
Tran Tinh
TT
Farrar
Jeremy
J
Wills
Bridget
B
Simmons
Cameron P
CP
D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000276:immunology; D000917:Antibody Formation; D002648:Child; D002675:Child, Preschool; D003715:Dengue / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D003716:Dengue Virus / Q000276:immunology / Q000302:isolation & purification*; D042241:Early Diagnosis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014744:Vietnam; D019562:Viral Load; D017361:Viral Nonstructural Proteins / Q000097:blood*; D014766:Viremia / Q000097:blood / Q000175:diagnosis*
D000914:Antibodies, Viral; D011933:Reagent Kits, Diagnostic; D017361:Viral Nonstructural Proteins