Approach to non-invasive sampling in dengue diagnostics: Exploring virus and NS1 antigen detection in saliva and urine of travelers with dengue

Abstract

BackgroundDengue diagnostics currently relies on serum and plasma tests. Although the proof of concept for detecting dengue virus (DENV) RNA and nonstructural protein 1 (NS1) antigen from urine and saliva has been demonstrated, few studies have explored their use in diagnostics. ObjectivesTo investigate the occurrence, excretion kinetics, and diagnostic potential of DENV-RNA and NS1 antigen in the urine and saliva of dengue patients. Study designWe examined serial serum, urine (n=50) and saliva (n=48) samples of 14 Finnish travelers with dengue. All samples were analyzed by NS1 ELISA and DENV RT-PCR, and the first and last serum specimens were tested for DENV IgG and IgM. In addition, biochemical parameters were studied from the urine and clinical and laboratory data of the patients were collected. ResultsDENV-NS1 protein and RNA proved detectable from saliva and urine using tests developed for serum samples. RNA/NS1 detection showed a diagnostic sensitivity of 64%/54% and 60%/56% for urine and saliva, respectively. RNA analyses performed on days 7–13 after onset of symptoms revealed the sensitivity for urine (72%) to be greater than for serum (31%) or saliva (50%). The concentration of urine samples had no impact on RNA detection. ConclusionsNoninvasive sampling enables an alternative approach to dengue diagnostics. The performance of the NS1 antigen assay may be improved by optimizing it for urine and saliva samples. The prolonged excretion of DENV-RNA in urine extends the sampling time window for molecular diagnostics and surveillance.