Table 1.
Characteristics of blood donors and ZIKV seroprevalence for the two study periods, 2003–2004 and 2015
| 2003–2004 (n = 359) | 2015 (n = 687) | |||
|---|---|---|---|---|
| Gender ratio, male/female | 280/72 (3.9) | 425/256 (1.7) | ||
| Age (years), median | 20 | 28 | ||
| Interquartile range | 18–23 | 23–35 | ||
| Range | 16–63 | 17–79 | ||
| Laboratory assays | ||||
| Anti-Zika IgG ELISA result*, n (%) | Positive | Equivocal | Positive | Equivocal |
| 62/359 (17.3%) | 20/359 (5.6%) | 192/687 (27.9%) | 27/687 (3.9%) | |
| Zika VNT positive, n (%) | 13/62 (21.0%) | 3/20 (15.0%) | 62/192 (32.3%) | 6/27 (22.2%) |
| ZIKV seroprevalence | ||||
| Number of positive/total number | 16/359 | 68/687 | ||
| Percentage (95% CI) | 4.5% (2.6–7.1) | 9.9% (7.8–12.4) | ||
| ZIKV seroprevalence in females | ||||
| Number of positive/total number | 3/72 | 25/256 | ||
| Percentage (95% CI) | 4.2% (0.9–11.7) | 9.8% (6.4–14.1) | ||
| ZIKV seroprevalence in males | ||||
| Number of positive/total number | 11/280 | 43/425 | ||
| Percentage (95% CI) | 3.9% (2.0–6.9) | 10.1% (7.4–13.4) | ||
IQR = interquartile range; ZIKV = Zika virus; VNT = virus neutralization test. ZIKV seroprevalence = proportion of donors with positive ZIKV neutralization tests; CI = confidence interval.
* Result of anti-Zika IgG ELISA (Euroimmun) test following manufacturer’s instruction.