Table 2. Incidence rate ratios of West Nile neuroinvasive disease (WNND) in 2002–2005 and 2006 in Louisiana parishes and Mississippi counties*.
| State, area | West Nile neuroinvasive disease incidence rate† |
Incidence rate ratio (95% CI) | |||||
|---|---|---|---|---|---|---|---|
| 2002‡ | 2003‡ | 2004‡ | 2005‡ | 2002–2005§ | 2006¶ | ||
| Louisiana | |||||||
| Affected | 5.6 | 1.3 | 0.2 | 1.4 | 2.1 | 4.4 | 2.09 (1.48–2.94) |
| Unaffected |
4.1 |
2.7 |
2.7 |
3.2 |
3.2 |
1.5 |
0.47 (0.35–0.64) |
| Mississippi | |||||||
| Affected | 6.1 | 2.1 | 0.8 | 1.5 | 2.6 | 6.5 | 2.45 (1.77–3.47) |
| Unaffected | 5.5 | 1.7 | 1.2 | 1.3 | 2.4 | 1.7 | 0.71 (0.55–1.03) |
*WNND incidence rates increased 2-fold in the hurricane-affected regions of both states. The unaffected regions showed a decrease in WNND incidence rates (Louisiana) and no change in incidence (Mississippi). CI, confidence interval. †No. cases/100,000. ‡Population estimate based on 2000 US Census (8). §Cumulative WNND incidence = (no. WNND cases 2002 + 2003 + 2004 + 2005) / cumulative population (Census 2000 [8] × 100,000). ¶Population estimate based on 2006 US Census estimate (7).