Volume 18, Number 4—April 2012
Dispatch
Neuroinvasive Disease and West Nile Virus Infection, North Dakota, USA, 1999–2008
Table
Correlation of WNV IgG seroprevalence among blood donors with WNND, by sex and age group, North Dakota, USA, 2002–2008*
Sex and age group, y | No. donors | Seroprevalence, % (95% CI) | Seropositivity, RR (95% CI) | Total population† | WNV-infected population‡ | No. WNND cases§ | Ratio of WNND cases to WNV infections (95% CI) | WNND, RR (95% CI) | Inverse of ratio¶ |
---|---|---|---|---|---|---|---|---|---|
Male | 2,349 | 9.2 (6.1–8.3) | 279,252 | 26,122 | 119 | 0.0045 (0.0038–0.0054) | 220 | ||
16–24 | 321 | 12.8 (9.1–16.4) | Referent | 56,156 | 7,188 | 10 | 0.0014 (0.0008–0.0026) | Referent | 719 |
25–44 | 562 | 8.7 (6.4–11.1) | 0.7 (0.5–1.0) | 89,968 | 7,827 | 22 | 0.0028 (0.0018–0.0042) | 2.0 (1.0–4.2) | 356 |
45–64 | 1,132 | 9.3 (7.6–11.0) | 0.7 (0.5–1.0) | 90,701 | 8,435 | 34 | 0.0040 (0.0029–0.0056) | 2.9 (1.4–5.9) | 248 |
≥65 | 334 | 6.3 (3.7–8.9) | 0.5 (0.3–0.8) | 42.427 | 2,672 | 53 | 0.0198 (0.0152–0.0258) | 14.3 (7.3–28.0) | 50 |
Female | 2,165 | 7.2 (6.2–8.3) | 271,968 | 18,353 | 63 | 0.0034 (0.0027–0.0044) | 291 | ||
16–24 | 316 | 9.8 (6.5–13.1) | Referent | 50,274 | 4,926 | 4 | 0.0008 (0.0003–0.09) | Referent | 1,231 |
25–44 | 600 | 6.7 (4.7–8.7) | 0.7 (0.4–1.1) | 78,869 | 5,284 | 16 | 0.0030 (0.0018–0.0049) | 3.7 (1.2–11.1) | 330 |
45–64 | 1,010 | 7.5 (5.9–9.2) | 0.8 (0.5–1.1) | 87,775 | 6,583 | 17 | 0.0026 (0.0016–0.0042) | 3.2 (1.1–9.4) | 387 |
≥65 | 239 | 2.9 (0.8–5.1) | 0.3 (0.1–0.7) | 55,050 | 1,596 | 26 | 0.0163 (0.0111–0.0241) | 20.1 (7.0–57.4) | 61 |
Total | 4,514 | 8.2 (7.4–9.0) | 551,220 | 44,511 | 182 | 0.0041 (0.0035–0.0047) | 244 |
*WNV, West Nile virus; WNND, WNV neuroinvasive disease; RR, relative risk.
†Source: US Census Bureau, 2010.
‡Seroprevalence × population.
§Data from Centers for Disease Control and Prevention; ArboNET.
¶No. WNV infections/no. WNND cases.