Table 5. Summary of positive samples in the four-year survey.
| 2008 | 2009 | 2010 | 2011 | |
| Mosquitoes | ||||
| Cx. pipiens pools | 387 | 1259 | 2367 | 1632 |
| WNV-positive (%) | 2 (0.5) | 27 (2.1) | 3 (0.1) | 0 |
| USUV-positive (%) | – | 54 (4.3) | 89 (3.8) | 74 (4.5) |
| Ae. albopictus pools | 86 | 108 | 131 | 192 |
| USUV positive (%) | – | 2 (1.9) | 2 (1.5) | 6 (3.1) |
| Birds | ||||
| Active surv. tested | 1378 | 1385 | 1068 | |
| WNV-positive (%) | 34 (2.5) | 2 (1) | 0 | |
| USUV-positive (%) | 7 (0.5) | 1 (0.1) | 14 (1.3) | |
| Passive surv. tested | 86 | 211 | 418 | |
| WNV-positive (%) | 6 (7) | 0 | 0 | |
| USUV-positive (%) | 4 (4.7) | 11 (5.2) | 11 (2.6) |