Volume 13, Number 2—February 2007
Research
Reduced Efficacy of Insecticide-treated Nets and Indoor Residual Spraying for Malaria Control in Pyrethroid Resistance Area, Benin
Raphael N’Guessan*, Vincent Corbel†, Martin Akogbéto‡§, and Mark Rowland
Table 2
Experimental hut results of lambdacyhalothrin (insecticide)-treated nets (ITNs) and indoor residual spraying (IRS) against Anopheles gambiae, Ladji (pyrethroid resistance) and Malanville (pyrethroid susceptibility) field stations*
| Ladji (pyrethroid resistance) | Malanville (pyrethroid susceptibility) | ||||
|---|---|---|---|---|---|
| ITN | Untreated net | Lambdacyhalothrin 18 mg/m2 | Untreated net | Lambdacyhalothrin 18 mg/m2 | |
| Total collected | 689a | 386b | 363a | 267b | |
| Deterred, % | _ | 44.0 | ._ | 26.4 | |
| Exiting, % (CI) | 25.0† (21.7–28.2) | 29.0† (24.5–33.5) | 36.1 (31.1–41.0) | 46.8‡ (40.8–52.8) | |
| Blood-fed, % (CI) | 82.0† (79.1–84.9) | 82.1† (78.3–85.9) | 77.7† (73.4–81.9) | 3.0‡ (0.9–5.0) | |
| Blood-feeding inhibition, % | _ | 0 | _ | 96.1 | |
| Personal protection, % (no. bloodfed) | – (572) | 44.6 (317) | – (282) | 97.2 (8) | |
| % Dead (CI) | 13.6† (11.1–16.2) | 29.8‡ 25.2–34.4) | 3.6† (1.7–5.5) | 98.5‡ (97.0–99.9) | |
| Insecticidal effect, % (no. dead) | – (94) | 3.0 (115) | – (13) | 68.9 (263) | |
| IRS | Unsprayed hut | Lambdacyhalothrin 30 mg/m2 | Unsprayed hut | Lambdacyhalothrin 30 mg/m2 | |
| Total collected | 203† | 117‡ | 498† | 395‡ | |
| Deterred, % | _ | 42.4 | _ | 20.7 | |
| Exiting, % (CI) | 45.8† (38.9–52.7) | 58.1† (49.2–67.1) | 54.4† (50.0–58.8) | 63.3† (58.5–68.0) | |
| Blood-fed, % (CI) | 87.7† (83.2–92.2) | 73.5‡ (65.5–81.5) | 93.8† (91.6–95.9) | 69.6‡ (65.1–74.2) | |
| Blood-feeding inhibition, % | _ | 16.2 | _ | 25.8 | |
| Personal protection, % (no. bloodfed) | – (178) | 51.7 (86) | – (467) | 41.1 (275) | |
| Dead, % (CI) | 12.3† (7.8–16.8) | 30.8† (22.4–39.1) | 1.4† (0.4–2.4) | 72.1‡ (67.7–76.6) | |
| Insecticidal effect, % (no. dead) | – (25) | 5.4 (36) | – (7) | 55.8 (285) | |
*For each untreated–treated pair, values not sharing the same superscript are significantly different at the 5% level.. CI, 95% confidence interval.
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