Table 1.
West Nile virus neuroinvasive disease cases, incidence rates/100,000 persons, and incidence rate ratios before and after aerial spraying in treated and untreated areas—Collin, Dallas, Denton, and Tarrant Counties, Texas, 2012
| Area | Before aerial spraying | After aerial spraying | IRR* | (95% CI) | Ratio of IRRs† | (95% CI) | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Cases | Population | IR | Cases | Population | IR | |||||
| Treated | 185 | 2,530,019 | 7.31 | 7 | 2,529,557 | 0.28 | 26.42 | (12.42−56.20) | 2.50 | (0.98−6.35) |
| Untreated | 148 | 3,085,121 | 4.80 | 14 | 3,084,755 | 0.45 | 10.57 | (6.11−18.28) | ||
*
IR before cut-off date/IR after cut-off date.
†
IRR in treated areas/IRR in untreated areas.
IR = Incidence rate; IRR = incidence rate ratio; CI = confidence interval.