Table 2. Multivariate Poisson regression analysis of seasonal and climatic factors associated with Anopheles stephensi mosquito abundance with and without lag effect after rainfall periods, US military base, Djibouti, September 2019–August 2020*.
| Variable | No lag effect |
1-mo lag effect |
|||
|---|---|---|---|---|---|
| IRR (95% CI) | p value | IRR (95% CI) | p value | ||
| Seasons | |||||
| Winter | 4.2 (2.7–6.3) | <0.0001 | 4.12 (2.7–6.2) | <0.0001 | |
| Spring | 2.8 (1.9–4.2) | <0.0001 | 2.86 (1.9–4.2) | <0.0001 | |
| Fall | 1.3 (0.8–1.9) | 0.3 | 1.19 (0.8–1.8) | 0.42 | |
| Summer |
Referent |
|
|
Referent |
|
| Temperature, °C | |||||
| <30 | 2.4 (1.9–3.1) | <0.0001 | 2.2 (1.7–2.9) | <0.0001 | |
| >30 |
Referent |
|
|
Referent |
NA |
| Rain amounts, mm/wk | |||||
| 40–155 | 0.33 (0.2–0.7) | 0.004 | 1.2 (0.8–1.8) | 0.4 | |
| 21.1–39.9 | 1.1 (0.8–1.5) | 0.6 | 1.5 (1.2–2.1) | 0.0024 | |
| 5–21 | 0.9 (0.6–1.3) | 0.53 | 0.9 (0.6–1.5) | 0.7 | |
| 0.2–4.9 | 0.7 (0.6–0.9) | 0.005 | 1.4 (1.2–1.7) | 0.0002 | |
| 0 |
Referent |
|
|
Referent |
|
| *NA, not applicable; IRR, incidence rate ratio. | |||||