Use of Dengue Nonstructural Protein 1 Antigen for the Early Diagnosis of Dengue Infection

Abstract

To the Editors: Chuansumrit et al1 reported on the use of dengue nonstructural protein 1 antigen testing for the earlier diagnosis of dengue virus (DENV) infection after the onset of fever. The additional IgM antibody quantification upsurge in sensitivity was remarkable.1 The combined assay would improve case management during the initial phase of illness when, accompanied by viremia, clinical presentations could be ambiguous. Moreover, the positive detection rate of dengue NS1 antigen-capture enzyme-linked immunosorbent assay (ELISA) was higher even than established diagnostic test methods of virus isolation and molecular detection of dengue RNA by reverse transcriptase-polymerase chain reaction (RT-PCR), for diagnosis of acute infection.2 A rapid point-of-care diagnostic for Japanese encephalitis (JEV), DENV, chikungunya (CHIKV), and West Nile virus (WNV) would be indispensable in routine laboratories lacking facilities available in academic or research hospitals. During the late incubation period or early febrile phase, cases are highly infectious with their blood teeming with viral RNA. If the offender mosquitoes bite a person during that phase of illness, there would be viral multiplication in the mosquito, along with viral amplification and dissemination in the community. For example, any infection by JEV, DENV, CHIKV, or WNV would be highly viremic. There would be no indication for antibiotics and no specific chemotherapy would be feasible for JEV, DENV, CHIKV, or WNV, but patients would require appropriate clinical management along with a public health response. Such viral infection would occur either alone or along with others. Concurrent infection was detected during a follow-up study of a dengue outbreak in India during the 1990s. Of 30 serum samples collected, 8 cases were positive for dengue IgM antibodies, 2 were positive for all the 3 infections, namely DENV, JEV and WNV, whereas 1 sample was positive for 2 infections, namely, JEV and WNV.3 Point-of-care assay like the rapid, immunochromatographic kits for CHIKV,4 would be essential. The multifaceted rapid assays to diagnose mosquito-borne viruses in the field would deserve fiscal support. Fiscal input would be cost-effective towards the decisive aim of effective public health and clinical response against JEV, DENV, WNV, and CHIKV. Subhash C. Arya, PhD, MBBS Nirmala Agarwal, FRCOG Department of Microbiology and Infection Control Sant Parmanand Hospital Delhi, India