Table 1. Serological results for Zika, dengue and chikungunya in Bolivian blood donors.
| IgG ELISA | Total No. |
Positive No. (% [95% CI]) |
Equivocal No. (%) |
Negative No. (%) |
VNTa | No. | Positive No. (% [95% CI]) |
VNT/ELISA (%) |
|---|---|---|---|---|---|---|---|---|
| Zika | Zika | |||||||
| Beni | 105 | 65 (61.9) | 5 (4.8) | 35 (33.3) | 70 | 41 (39.0 [30–48]) | 63.1 | |
| Santa Cruz | 200 | 122 (61.0) | 12 (6.0) | 66 (33.0) | 134 | 43 (21.5 [16–27]) | 35.2 | |
| Tarija | 196 | 19 (9.7) | 3 (1.5) | 174 (88.8) | 22 | 1 (0.5 0–1.5]) | 5.3 | |
| La Paz | 162 | 3 (1.9) | 1 (0.6) | 157 (96.9) | 4 | 0 (0.0) | 0.0 | |
| Cochabamba | 152 | 4 (2.6) | 3 (2.0) | 145 (95.4) | 7 | 0 (0.0) | 0.0 | |
| Chikungunya | ||||||||
| Beni | 60 | 28 (46.7 [34–59]) | 0 (0.0) | 32 (53.3) | ||||
| Santa Cruz | 108 | 59 (54.6 [45–64]) | 1 (0.9) | 48 (44.4) | ||||
| Tarija | 111 | 6 (5.4 1–10]) | 0 (0.0) | 105 (94.6) | ||||
| La Paz | 93 | 3 (3.2 0–7]) | 0 (0.0) | 90 (96.8) | ||||
| Cochabamba | 77 | 6 (7.8 2–14]) | 0 (0.0) | 71 (92.2) | ||||
| Dengue | ||||||||
| Beni | 60 | 54 (90.0 [82–98]) | 0 (0.0) | 6 (10.0) | ||||
| Santa Cruz | 108 | 101 (93.5 [89–98]) | 1 (0.9) | 6 (5.6) | ||||
| Tarija | 111 | 49 (44.1 [35–53]) | 3 (2.7) | 59 (53.2) | ||||
| La Paz | 93 | 11 (11.8 5–18]) | 0 (0.0) | 82 (88.2) | ||||
| Cochabamba | 77 | 8 (10.4 4–17]) | 0 (0.0) | 69 (89.6) |
Serology for Zika virus was performed for the complete population of the study using a commercial NS1-based IgG ELISA screening assay followed by a Virus Neutralisation Test (VNT) for samples with ELISA positive or equivocal results. Serology for dengue and chikungunya viruses was performed for a randomly selected sample corresponding to ca. fifty per cent of the complete population studied. Testing was performed with commercial assays using purified virus particles (dengue) and recombinant proteins (chikungunya) as viral antigens. Percentages are expressed as the proportion of positives in the total population tested in ELISA.
aVirus Neutralisation test