Table 2.
Odds of above average West Nile virus (WNV) incidence in a county for each standard deviation increase in seasonal* temperature or precipitation† by region, United States, 2004–2012‡
| Area | Seasonal temperature z-score | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fall | Winter | Spring | Summer | |||||||||
| Odds ratio | 95% CI | P value | Odds ratio | 95% CI | P value | Odds ratio | 95% CI | P value | Odds ratio | 95% CI | P value | |
| National | 1.1 | (1.1, 1.2) | < 0.01 | 1.6 | (1.5, 1.7) | < 0.01 | 1.2 | (1.1, 1.2) | < 0.01 | − | − | − |
| East/West | ||||||||||||
| East | − | − | − | 1.8 | (1.7, 2.0) | < 0.01 | 1.1 | (1.0, 1.2) | 0.01 | − | − | − |
| West | 1.2 | (1.1, 1.3) | < 0.01 | 1.3 | (1.2, 1.4) | < 0.01 | 1.2 | (1.1, 1.3) | < 0.01 | − | − | − |
| NOAA Region | ||||||||||||
| Northeast | − | − | − | 1.7 | (1.4, 2.0) | < 0.01 | − | − | − | 1.7 | (1.3, 2.2) | < 0.01 |
| Southeast | − | − | − | 2.1 | (1.7, 2.6) | < 0.01 | 1.5 | (1.1, 1.9) | < 0.01 | − | − | − |
| Ohio Valley | − | − | − | 1.8 | (1.6, 2.0) | < 0.01 | − | − | − | − | − | − |
| Upper Midwest | 1.8 | (1.4, 2.3) | < 0.01 | − | − | − | − | − | − | − | − | − |
| East South Central | 0.8 | (0.7, 0.9) | < 0.01 | 2.9 | (2.2, 3.7) | < 0.01 | − | − | − | 0.8 | (0.6, 0.8) | < 0.01 |
| West South Central | 0.8 | (0.7, 0.9) | < 0.01 | 2.3 | (1.9, 2.9) | < 0.01 | − | − | − | 0.8 | (0.7, 0.9) | < 0.01 |
| Northern Rockies / Plains | 2.0 | (1.7, 2.4) | < 0.01 | − | − | − | 1.7 | (1.4, 2.1) | < 0.01 | − | − | − |
| Southwest | − | − | − | − | − | − | 1.3 | (1.0, 1.6) | 0.02 | − | − | − |
| West | − | − | − | 1.3 | (1.0, 1.7) | 0.04 | − | − | − | − | − | − |
| Northwest | − | − | − | 0.2 | (0.1, 0.3) | < 0.01 | 8.2 | (3.0, 22.7) | < 0.01 | − | − | − |
| Seasonal precipitation z-score | ||||||||||||
| Fall | Winter | Spring | Summer | |||||||||
| Area | Odds ratio | 95% CI | P value | Odds ratio | 95% CI | P value | Odds ratio | 95% CI | P value | Odds ratio | 95% CI | P value |
| National | 0.9 | (0.9, 1.0) | 0.01 | 1.2 | (1.1, 1.2) | < 0.01 | 0.8 | (0.8, 0.9) | < 0.01 | − | − | − |
| East/West | ||||||||||||
| East | 0.9 | (0.7, 0.8) | < 0.01 | − | − | − | 0.7 | (0.7, 0.8) | < 0.01 | − | − | − |
| West | − | − | − | 1.4 | (1.3, 1.5) | < 0.01 | 0.9 | (0.9, 1.0) | 0.02 | − | − | − |
| NOAA region | ||||||||||||
| Northeast | − | − | − | 0.7 | (0.6, 0.9) | < 0.01 | 0.5 | (0.4, 0.6) | < 0.01 | − | − | − |
| Southeast | 0.7 | (0.5, 0.8) | < 0.01 | 0.8 | (0.7, 0.9) | < 0.01 | − | − | − | − | − | − |
| Ohio Valley | − | − | − | − | − | − | 0.6 | (0.5, 0.7) | < 0.01 | − | − | − |
| Upper Midwest | 0.8 | (0.7, 0.9) | < 0.01 | 1.2 | (1.0, 1.3) | 0.01 | 0.9 | (0.7, 1.0) | 0.04 | − | − | − |
| East South Central | − | − | − | 1.3 | (1.2, 1.5) | < 0.01 | 0.8 | (0.7, 0.9) | < 0.01 | − | − | − |
| West South Central | − | − | − | 1.7 | (1.5, 2.0) | < 0.01 | 0.8 | (0.7, 0.9) | < 0.01 | − | − | − |
| Northern Rockies/Plains | 0.7 | (0.6, 0.8) | < 0.01 | − | − | − | 0.9 | (0.8, 1.0) | 0.02 | 0.7 | (0.6, 0.8) | < 0.01 |
| Southwest | 1.4 | (1.1, 1.7) | < 0.01 | 1.2 | (1.0, 1.5) | 0.02 | − | − | − | 1.2 | (1.1, 1.5) | 0.01 |
| West | − | − | − | − | − | − | 1.5 | (1.2, 1.8) | < 0.01 | − | − | − |
| Northwest | 1.9 | (1.4, 2.6) | < 0.01 | 2.3 | (1.5, 3.3) | < 0.01 | − | − | − | 1.5 | (1.1, 2.0) | 0.01 |
*
Fall (Oct–Dec), Winter (Jan–Mar), Spring (Apr–May), Summer (July–Sept).
†
Climate z-scores are relative to the temperature/precipitation in a season from the 2004–2012 baseline period.
‡
Values selected for each model were based on a backward stepwise procedure with a stay criteria of P < 0.05. Variables that were not significant, and therefore dropped from the model, are shown as –.