Table 6.
Effect of the intermittent preventive treatment intervention on entomological inoculation rate in the entomology survey, stratified by time
| Number of female Anopheles spp collected | Number of nights of collection | Annual density of Anopheles spp per household | Number of mosquitoes positive for sporozoites | Sporozoite rate | aEIR* | Adjusted incidence rate ratio (95% CI)† | ||
|---|---|---|---|---|---|---|---|---|
| Full period of observation (July, 2014, to April, 2015) | ||||||||
| Control | 2000 | 959 | 762 | 40 | 2·00 | 15·2 | 1 | |
| Cluster median (IQR) | 54·5 (7·0–98·5) | 49·0 (45·0–50·0) | 398·0 (51·0–776·0) | 1 (0–2·5) | 1·2 (0–2·5) | 7·4 (0–19·6) | ·· | |
| Intervention | 1927 | 977 | 720 | 27 | 1·40 | 10·1 | 0·65 (0·25–1·65) | |
| Cluster median (IQR) | 24·0 (9·0–84·0) | 49·0 (48·5–50·0) | 172·0 (70·0–622·0) | 0 (0–2) | 0 (0–1·6) | 0 (0–14·5) | p=0·36 | |
| First 3 months of IPT (July to September, 2014) | ||||||||
| Control | 834 | 300 | 1015 | 18 | 2·16 | 21·9 | 1 | |
| Cluster median (IQR) | 11·0 (1·5–34·0) | 15·0 (15·0–15·0) | 268·0 (37·0–828·0) | 0 (0–1) | 0·46 (0–3·2) | 24·4 (0–24·4) | ·· | |
| Intervention | 667 | 301 | 809 | 14 | 2·10 | 17·0 | 0·75 (0·28–2·04) | |
| Cluster median (IQR) | 7·5 (3·5–27·0) | 15·0 (15·0–15·0) | 183·0 (88·0–657·0) | 0 (0–1) | 0 (0–3·1) | 0 (0–24·4) | p=0·58 | |
| Final 3 months of IPT (October to December, 2014) | ||||||||
| Control | 490 | 258 | 694 | 13 | 2·65 | 18·4 | 1 | |
| Cluster median (IQR) | 15·5 (1·0–30·0) | 14·0 (10·0–15·0) | 426·0 (37·0–790·0) | 0 (0–1) | 0 (0–3·4) | 0 (0–39·1) | ·· | |
| Intervention | 467 | 277 | 616 | 5 | 1·07 | 6·6 | 0·36 (0·10–1·33) | |
| Cluster median (IQR) | 8·0 (1·0–23·0) | 14·5 (14·0–15·0) | 195·0 (26·0–583·0) | 0 (0–0) | 0 (0–0) | 0 (0–0) | p=0·13 | |
| After IPT (January to April, 2015) | ||||||||
| Control | 676 | 401 | 616 | 9 | 1·33 | 8·2 | 1 | |
| Cluster median (IQR) | 21·0 (4·5–48·5) | 20·0 (20·0–20·0) | 384·0 (82·0–886·0) | 0 (0–1·0) | 0 (0–1·0) | 0 (0–18·3) | ·· | |
| Intervention | 793 | 399 | 726 | 8 | 1·01 | 7·3 | 0·85 (0·24–3·03) | |
| Cluster median (IQR) | 7·5 (3·5–46·5) | 20·0 (20·0–20·0) | 137·0 (65·0–849·0) | 0 (0–0) | 0 (0–0) | 0 (0–0) | p=0·80 | |
aEIR=annual entomological inoculation rate. IPT=intermittent preventive treatment.
*
Calculated from the household density of infective anophelines.
†
Adjusted for the main materials of the floor (cement or concrete, earth or sand, earth and dung, or other) and external walls (burnt bricks with plaster or other) and cluster.