here was 100% positive agreement [49] between the DENV RT-PCR assay and NS1 antigen detection, and the DENV RT-PCR method revealed viral RNA in two additional samples in which no NS1 antigen could be detected (Fig. 4). Furthermore, the DENV RT-PCR assay detected viral RNA in all samples up to 5 days after disease onset (Fig. 4A), and a detection rate of at least 70% has previously been reported for RT-PCR in this time interval [12], [28], [50]. It is generally accepted that when DENV IgM levels become detectable, the viral load will have declined below measureable levels [6]. Nevertheless, in our study, 82% and 57% of the samples collected 6 and 9 days, respectively, after disease onset tested positive for viral RNA by the DENV RT-PCR assay, even though all patients had seroconverted (IgM and/or IgG) at the indicated time points (Fig. 4A). Similar to the results presented in 2008 by Dumoulin et al. [51], we were unable to detect DENV in samples obtained 10 days after appearance of symptoms.