Moreover, the DENV illness rates we documented in asymptomatic blood donors may underestimate infection rates in the larger human population because the donor human population might be at lower risk than those living in conditions most conducive to dengue transmission; consequently, our estimate of underreporting of medical dengue instances may be too traditional. Characterization of Dengue RNA-Positive Donations During the 2012 Rio Epidemic Of 23 412 donations collected by HemoRio during the study period, 16 241 donors (69%) consented to DENV RNA screening. These were tested by DENV TMA, and 87 (0.54%) were repeat reactive. All 87 TMA-reactive samples were confirmed as DENV RNA positive by polymerase chain reaction on an independent sample, and all were typed as DENV-4. Number ?Figure11 displays the pace of detection of viremic donations over time. Of the 87 viremic donations, 11 (12.6%) tested positive for DENV IgM. Viral lots were significantly higher in IgM-negative RS 8359 than in IgM-positive donations (median pre-IgM and post-IgM viral lots were 3.5 and 2.3 Log10 copies/mL, respectively; = .001). Open in a separate window Number 1. Proportions of dengue disease (DENV) transcription-mediated amplification (TMA) repeat-reactive donations during the study period ( .001). Larger changes were observed in neutralizing titer for subtype 4 than for the additional 3 subtypes (subtype 4 vs 1, RS 8359 .001; 4 vs 2, .001; 4 vs 3, = .03). Rates of Clinical Dengue Instances Relative to Seroincidence and NAT Yield Donations Number ?Number33 presents the weekly rate of reported dengue instances to the Rio general public health system relative to the pace of confirmed viremic donations by donors to HemoRio detected in the REDS-III study from February through June 2012. The number demonstrates that this donor NAT screening study was conducted during the 4 weeks that displayed the height of the epidemic and that the pace of viremic donations generally paralleled the increase, peak and decrease in medical case reports. During the study period, 113 500 medical instances of dengue were reported in Rio, representing 1.8% of 6.3 million inhabitants. When restricted to the 4.5 million Rio inhabitants in the age range eligible to donate blood (16C67 years old), there were 100 475 reported clinical cases of dengue, yielding a 2.3% estimated rate of clinical dengue instances. Juxtaposing the 2 2.3% rate of clinical case reports and the 6.2% seroincidence in asymptomatic donors, we inferred that approximately one-third of DENV-4 infections that occurred with this Rio epidemic resulted in reported disease (2.3% divided by 6.2%%) Open in a separate window Number 3. Upper panel, Assessment of rates of viremic donations recognized during the study period. Lower panel, Rates of reported instances of medical dengue for the Rio human population as a whole ( em solid collection /em ) and among those 16C67 years old ( em dashed collection /em ) who are eligible to donate blood. Abbreviation: TMA, transcription-mediated amplification. If DENV NAT screening had been performed on all 23 412 donations collected by HemoRio during the study period, we project that 125 DENV RNA-positive donations would have been recognized (87 recognized NAT RNA-positive donations, multiplied by 23 412 total donations, divided by 16 241 tested donations from consenting donors tested for DENV RNA). The percentage of the 100 475 medical instances reported in the donor-age Rio human population on the projected 125 RNA-positive donations recognized during the study period shows that there were approximately 800 instances of medical dengue disease per recognized NAT-positive donation. Conversation During the 4-month study period within the large epidemic in Rio in 2012, we estimate that approximately 6.2% of donors acquired DENV infections, approximately 0.54% of blood donations tested RNA positive, and approximately 1.8% of the general and 2.3% of the donor-age human population were reported as clinical case individuals. This is among the highest rates of DENV illness documented in blood RS 8359 donors based on NAT testing [12, 15C18]. To Rabbit Polyclonal to BAGE3 our knowledge, ours is the 1st study to conduct a serosurvey of blood donor samples to allow for the correlation of the incidence of illness with NAT detection rates in donors. We were also able to correlate these observations in blood donors, with rates of medical DENV instances reported in the related metropolitan area during a large DENV-4 epidemic inside RS 8359 a human population that RS 8359 is hyperendemic for DENV illness, as evidenced from the 88% rate of IgG antibodies in the Rio donor human population at the beginning of the study period. Based on the estimated 6.2% incidence derived from the incremental IgM seroconversion rate and the observed rate of DENV RNA-positive donations during.