Because there was no difference in NS1

antigen positive rates in primary and secondary DENV infections, the data were combined and analyzed. NS1 antigen positive rates were 88%–96% on days 1–5, 75%–100% on days 6–10, and 36%–60% on ≥day 11 (Figure 1). RT-PCR positive rates were over 70% on days 1–5 (Figure 1); however, positive rates were low or there were no positive samples on days 6–10 and ≥11 days. IgM positive rate was 60% on days 1–5, but were nearly 100% on days 6–10 and ≥11 days. The rate of detection of each assay alone was 88% for NS1 assay, 73% for IgM ELISA, and 51% for RT-PCR. NS1 Ag ELISA in combination of RT-PCR yielded a detection rate of 89% (chi-squared test, p = 0.80 in comparison to NS1 ELISA alone, Tables 1 and 2). Although the rate of detection using the NS1 ELISA in combination with RT-PCR

was 93% from days 1–5 and days 6–10 after onset SB203580 clinical trial of disease, the rate of detection was 50% from ≥11 days after onset of disease. The detection rates of NS1 in combination with IgM ELISA (detection rate = 93%, chi-squared, p = 0.02 in comparison to NS1 ELISA) was, however, consistently above 90% at days 1–5, days 6–10, and ≥11 days after onset of disease. Thus, the results suggest that a combination of NS1 ELISA and IgM ELISA was sufficient this website to yield a 93% detection rate of dengue cases from days 1–5, days 6–10, to ≥11 days in our study (Table 2). NS1 antigen positive rates were compared among four DENV serotypes. Positive rates were from 68% to 89% (DENV-1 = 89%; DENV-2 = 82%; DENV-3 = 81%; DENV-4 = 68%) using Biorad NS1 antigen ELISA (Table 3). The detection rate of the NS1 Biorad assay from days 1–10 after onset of disease for DENV-1 was 92/95 (97%), DENV-2 = 53/62 (85%), DENV-3 = 61/71 (86%), and DENV-4 = 26/31 (84%). On day 11 and after, rate of detection of the NS1 for DENV-1 was 31% (4/13), DENV-2 = 40% (2/5), DENV-3 = 16% (1/6), and DENV-4 = 0% (0/7). As the number of serum samples examined in days ≥11 after onset of disease was small,

detection rates between serotypes were compared with those on days 1–10 after onset of disease. The detection rate of NS1 was highest using samples from DENV-1 patients (97%) as compared to detection rates of Phospholipase D1 pooled serotypes (85%, Fisher’s exact test, p < 0.01, days 1–10). The differences between detection rates of DENV-2, DENV-3, and DENV-4 for days 1–10 were not statistically significant (Fisher's exact test, p > 0.05). DENV antigen NS1 positive rates by ELISA were compared in primary and secondary DENV infections from days 1–5, days 6–10, and ≥11 days. Positive rates were at similar levels in primary and secondary DENV infections (Table 4). At days 1–5 after onset of disease, the mean IgG index for secondary infection was 2.1 (positive >1.1) and primary infection serum samples were negative for IgG (mean IgG index for primary infection = 0.7).