Background
Methods
Study areas and context
Study interventions
LLINs (experimental control)
Larviciding with Bti
Community education and mobilization
Study design
Larval mosquito sampling
Adult mosquito sampling
Cross-sectional malaria surveys
Statistical analysis
Entomological analysis for vector characteristics and treatment effects
Plasmodium falciparum prevalence and treatment effects
Results
Entomological findings from adult and larval mosquito collection
Characteristics | Overall | Arm 1 | Arm 2 | Arm 3 | Arm 4 |
---|---|---|---|---|---|
Villages per site (houses per village) | 16 (10) | 4 (10) | 4 (10) | 4 (10) | 4 (10) |
Household membership: median number (range; N)a | |||||
Malindi | 8 (2–22; 1999) | 8 (2–18; 999) | 8 (3–19; 600) | 7 (3–18; 200) | 9 (2–22; 200) |
Nyabondo | 4 (1–9; 1546) | 5 (1–8; 365) | 4 (1–8; 388) | 4 (1–8; 374) | 4 (1–9; 419) |
Tolay | 5 (1–10; 3862) | 5 (1–10; 967) | 6 (3–10; 1109) | 5 (2–9; 958) | 4 (1–10; 828) |
Overall | 5 (1–22; 7407) | 5 (1–18; 2331) | 6 (1–19; 2097) | 5 (1–18; 1532) | 4 (1–22; 1447) |
Children characteristicsc | |||||
Median age, years (range; N) | |||||
Malindi | 7 (3–15; 1000) | 7 (5–13; 500) | 7 (6–13; 300) | 7 (3–10; 100) | 9 (3–15; 100) |
Nyabondo | 8 (4–13; 999) | 9 (6–13; 200) | 9 (4–13; 212) | 8 (5–13; 145) | 9 (5–13; 153) |
Tolay | 12 (4–19; 1600) | 12 (4–19; 400) | 11 (7–17; 400) | 12 (6–16; 400) | 12 (5–17; 400) |
Overall | 9 (3–19; 3599) | 9 (4–19; 1100) | 9 (4–17; 912) | 10 (3–16; 645) | 11 (3–17; 653) |
Baseline malaria infection prevalence %(95% CI) | |||||
Malindi | 5.4 (2.4–12.1) | 1.6 (0.6–4.0) | 12.0 (4.4–32.6) | 4.0 (1.5–10.4) | 6.0 (2.8–13.0) |
Nyabondo | 24.1 (17.0–34.1) | 24.5 (12.1–49.7) | 34.9 (25.9–47.0) | 17.9 (12.0–26.8) | 25.5 (19.6–33.2) |
Tolay | 1.4 (0.9–2.2) | 2.3 (1.5–3.4) | 1.3 (0.3–5.5) | 0.8 (0.4–1.4) | 1.3 (0.5–3.4) |
Overall | 8.8 (5.5–14.0) | 6.0 (2.7–13.3) | 12.6 (6.6–24.2) | 5.1 (2.3–11.4) | 7.7 (3.6–16.2) |
Entomological characteristicsd | |||||
Baseline mean number of vectors per house per night %(95% CI) | |||||
Anopheles spp.b | |||||
Malindi | 0.11 (0.07–17.9) | 0.18 (0.08–0.39) | 0.09 (0.03–0.26) | 0.04 (0.01–0.19) | 0.14 (0.06–0.32) |
Nyabondo | 0.02 (0.01–0.05) | 0 (0–0.14) | 0.04 (0.01–0.13) | 0.04 (0.01–0.13) | 0.02 (0–0.05) |
Tolay | 0.05 (0.02–0.09) | 0.05 (0.01–0.20) | 0.06 (0.01–0.21) | 0.06 (0.02–0.21) | 0.03 (0.01–0.18) |
Overall | 0.05 (0.04–0.07) | 0.06 (0.03–0.11) | 0.06 (0.03–0.11) | 0.04 (0.02–0.10) | 0.05 (0.02–0.09) |
Culex spp.b | |||||
Malindi | 0.77 (0.57–1.04) | 2.24 (1.16–4.30) | 0.29 (0.16–0.52) | 0.57 (0.37–0.88) | 0.20 (0.10–0.40) |
Nyabondo | 0.13 (0.10–0.18) | 0.12 (0.06–0.24) | 0.12 (0.06–0.23) | 0.04 (0.01–0.14) | 0.20 (0.13–0.33) |
Tolay | 0.06 (0.02–0.11) | 0.06 (0.02–0.22) | 0.04 (0.01–0.19) | 0.04 (0.01–0.19) | 0.08 (0.03–0.24) |
Overall | 0.26 (0.22–0.32) | 0.59 (0.38–0.90) | 0.14 (0.09–0.22) | 0.19 (0.13–0.28) | 0.32 (0.12–0.26) |
Baseline mean number of larvae per dipper % (95% CI) | |||||
Anopheles spp. | |||||
Malindi | 1.03 (0.43–2.42) | 0 | 1.60 (0.64–4.02) | 0.09 (0.01–1.30) | 0 |
Nyabondo | 0.11 (0.10–0.12) | 0.12 (0.10–0.14) | 0.08 (0.07–0.10) | 0.11 (0.09–0.12) | 0.13 (0.11–0.15) |
Tolay | 0.81 (0.67–0.97) | 0.58 (0.39–0.87) | 0.96 (0.72–1.28) | 0.81 (0.54–1.22) | 0.83 (0.57–1.20) |
Overall | 0.14 (0.13–0.14) | 0.14 (0.12–0.16) | 0.14 (0.12–0.15) | 0.12 (0.10–0.13) | 0.15 (0.13–0.17) |
Culex spp. | |||||
Malindi | 0.53 (0.27–1.05) | 0 | 0.71 (0.30–1.66) | 0.57 (0.16–1.99) | 0.16 (0.03–0.75) |
Nyabondo | 0.19 (0.18–0.20) | 0.20 (0.17–0.22) | 0.11 (0.10–0.13) | 0.23 (0.21–0.25) | 0.21 (0.19–0.24) |
Tolay | 1.16 (0.99–1.35) | 1.37 (1.01–1.87) | 0.99 (0.75–1.32) | 1.15 (0.72–1.84) | 1.14 (0.88–1.48) |
Overall | 0.22 (0.20–0.23) | 0.23 (0.20–0.27) | 0.15 (0.13–0.16) | 0.25 (0.23–0.27) | 0.25 (0.22–0.27) |
Interventions | Overall | Year 1: 2013 | Year 2: 2014 | Year 3: 2015 |
---|---|---|---|---|
DR, p-value | DR, p-value | DR, p-value | DR, p-value | |
Adult anopheline mosquito density | ||||
Overall | ||||
Arm 1 | Reference | |||
Arm 2 | 1.78 (1.25–2.55), p = 0.002 | 1.03 (0.39–2.70), p = 0.955 | 1.13 (0.66–1.96), p = 0.654 | 3.24 (1.79–5.85), p < 0.001 |
Arm 3 | 0.88 (0.58–1.34), p = 0.561 | 0.78 (0.27–2.24), p = 0.639 | 0.98 (0.56–1.72), p = 0.949 | 0.76 (0.35–1.66), p = 0.493 |
Arm 4 | 0.55 (0.34–0.88), p = 0.012 | 0.82 (0.31–2.13), p = 0.678 | 0.62 (0.33–1.19), p = 0.150 | 0.24 (0.07–0.77), p = 0.016 |
Malindi | ||||
Arm 1 | Reference | |||
Arm 2 | 2.36 (1.51–3.71), p < 0.001 | 0.51 (0.13–2.05), p = 0.346 | 1.19 (0.60–2.37), p = 0.611 | 6.17 (2.71–14.06), p < 0.001 |
Arm 3 | 0.86 (0.49–1.49), p = 0.582 | 0.24 (0.04–1.38), p = 0.109 | 0.77 (0.37–1.60), p = 0.479 | 2.00 (0.72–5.57), p = 0.182 |
Arm 4 | 0.69 (0.38–1.25), p = 0.224 | 0.79 (0.23–2.68), p = 0.704 | 0.69 (0.32–1.48), p = 0.342 | 0.42 (0.08–2.33), p = 0.320 |
Nyabondo | ||||
Arm 1 | Reference | |||
Arm 2 | 1.93 (0.72–5.13), p = 0.189 | 10.58 (0.25–450.16), p = 0.218 | 5.04 (0.92–27.64), p = 0.063 | 0.13 (0.01–2.01), p = 0.146 |
Arm 3 | 2.10 (0.79–5.54), p = 0.135 | 8.98 (0.20–409.40), p = 0.260 | 5.98 (1.11–32.11), p = 0.037 | 0.13 (0.01–2.01), p = 0.146 |
Arm 4 | 0.80 (0.25–2.54), p = 0.705 | 4.62 (0.10–211.94), p = 0.433 | 1.69 (0.24–12.08), p = 0.602 | 0.16 (0.01–1.97), p = 0.151 |
Tolay | ||||
Arm 1 | Reference | |||
Arm 2 | 0.44 (0.15–1.30), p = 0.136 | 1.10 (0.15–7.84), p = 0.924 | 0.25 (0.04–1.61), p = 0.143 | 0.38 (0.05–3.04), p = 0.361 |
Arm 3 | 0.51 (0.18–1.43), p = 0.201 | 1.15 (0.16–8.04), p = 0.888 | 0.40 (0.08–1.94), p = 0.256 | 0.32 (0.04–2.92), p = 0.313 |
Arm 4 | 0.29 (0.08–1.05), p = 0.059 | 0.60 (0.06–6.02), p = 0.664 | 0.16 (0.01–1.71), p = 0.129 | 0.32 (0.04–2.92), p = 0.313 |
Adult culicine mosquito density | ||||
Overall | ||||
Arm 1 | Reference | |||
Arm 2 | 0.69 (0.53–0.89), p = 0.004 | 0.24 (0.14–0.40), p < 0.001 | 1.35 (0.85–2.15), p = 0.199 | 1.03 (0.67–1.60), p = 0.879 |
Arm 3 | 0.49 (0.37–0.65), p < 0.001 | 0.32 (0.20–0.52), p < 0.001 | 0.52 (0.29–0.92), p = 0.026 | 0.80 (0.50–1.29), p = 0.366 |
Arm 4 | 0.38 (0.28–0.51), p < 0.001 | 0.30 (0.19–0.47), p < 0.001 | 0.40 (0.21–0.77), p = 0.006 | 0.37 (0.21–0.68), p = 0.001 |
Malindi | ||||
Arm 1 | Reference | |||
Arm 2 | 0.71 (0.51–0.98), p = 0.037 | 0.13 (0.06–0.28), p < 0.001 | 1.60 (0.94–2.71), p = 0.081 | 1.14 (0.64–2.04), p = 0.652 |
Arm 3 | 0.51 (0.36–0.73), p < 0.001 | 0.26 (0.13–0.49), p < 0.001 | 0.48 (0.24–0.94), p = 0.032 | 1.29 (0.67–2.49), p = 0.440 |
Arm 4 | 0.22 (0.14–0.35), P < 0.001 | 0.09 (0.04–0.21), p < 0.001 | 0.25 (0.11–0.59), p = 0.001 | 0.65 (0.29–1.45), p = 0.288 |
Nyabondo | ||||
Arm 1 | Reference | |||
Arm 2 | 0.85 (0.38–1.89), p = 0.684 | 0.98 (0.37–2.62), p = 0.973 | 10.31 (0.02–6705.85), p = 0.480 | 0.36 (0.06–2.30), p = 0.282 |
Arm 3 | 0.55 (0.22–1.37), p = 0.199 | 0.36 (0.09–1.46), p = 0.153 | 3.75 (0–3846.25), p = 0.709 | 0.96 (0.24–3.80), p = 0.949 |
Arm 4 | 2.06 (1.06–3.99), p = 0.033 | 1.73 (0.76–3.95), p = 0.191 | 37.00 (0.07–19,853.62), p = 0.260 | 0.64 (0.14–2.96), p = 0.566 |
Tolay | ||||
Arm 1 | Reference | |||
Arm 2 | 0.95 (0.40–2.26), p = 0.912 | 0.68 (0.09–5.01), p = 0.705 | 0.79 (0.13–4.65), p = 0.795 | 1.11 (0.35–3.56), p = 0.856 |
Arm 3 | 0.79 (0.32–1.95), p = 0.605 | 0.64 (0.08–4.88), p = 0.667 | 1.24 (0.25–6.09), p = 0.793 | 0.62 (0.16–2.36), p = 0.484 |
Arm 4 | 0.67 (0.26–1.76), p = 0.420 | 1.24 (0.22–6.94), p = 0.807 | 0.90 (0.15–5.33), p = 0.911 | 0.32 (0.06–1.66), p = 0.174 |
Interventions | Overall | Year 1: 2013 | Year 2: 2014 | Year 3: 2015 |
---|---|---|---|---|
DR, p-value | DR, p-value | DR, p-value | DR, p-value | |
Anopheline larval mosquito density | ||||
Overall | ||||
Arm 1 | Reference | |||
Arm 2 | 0.65 (0.57–0.74), p < 0.001 | 0.90 (0.73–1.11), p = 0.330 | 0.85 (0.70–1.04), p = 0.124 | 0.21 (0.16–0.28), p < 0.001 |
Arm 3 | 0.93 (0.83–1.05), p = 0.234 | 0.85 (0.69–1.06), p = 0.143 | 0.92 (0.76–1.13), p = 0.447 | 0.88 (0.72–1.08), p = 0.225 |
Arm 4 | 0.96 (0.85–1.07), p = 0.441 | 1.11 (0.90–1.36), p = 0.340 | 0.83 (0.68–1.02), p = 0.072 | 0.85 (0.69–1.05), p = 0.125 |
Malindi | ||||
Arm 1 | Reference | |||
Arm 2 | 0.15 (0.10–0.21), p < 0.001 | 39.74 (0.01–311,676.8), p = 0.421 | 0.13 (0.08–0.21), p < 0.001 | 0.03 (0.01–0.08), p < 0.001 |
Arm 3 | 0.24 (0.16–0.36), p < 0.001 | 2.72 (0–40,914.24), p = 0.839 | 0.11 (0.05–0.24), p < 0.001 | 0.37 (0.22–0.62), p < 0.001 |
Arm 4 | 0.07 (0.05–0.10), p < 0.001 | 0 | 0.09 (0.05–0.15), p < 0.001 | 0.03 (0.01–0.06), p < 0.001 |
Nyabondo | ||||
Arm 1 | Reference | |||
Arm 2 | 0.80 (0.67–0.94), p = 0.008 | 0.68 (0.54–0.87), p = 0.002 | 1.44 (1.06–1.94), p = 0.018 | 0.26 (0.16–0.41), p < 0.001 |
Arm 3 | 1.54 (1.32–1.79), p < 0.001 | 0.87 (0.69–1.09), p = 0.215 | 2.17 (1.63–2.88), p < 0.001 | 1.99 (1.47–2.69), p < 0.001 |
Arm 4 | 1.51 (1.29–1.76), p < 0.001 | 1.05 (0.84–1.32), p = 0.675 | 1.35 (0.99–1.84), p = 0.058 | 2.33 (1.72–3.15), p < 0.001 |
Tolay | ||||
Arm 1 | Reference | |||
Arm 2 | 0.79 (0.55–1.11), p = 0.175 | 1.65 (0.86–3.16), p = 0.134 | 0.62 (0.35–1.10), p = 0.101 | 0.63 (0.32–1.24), p = 0.182 |
Arm 3 | 1.03 (0.69–1.52), p = 0.892 | 1.39 (0.67–2.89), p = 0.370 | 1.07 (0.57–2.02), p = 0.840 | 0.76 (0.36–1.60), p = 0.468 |
Arm 4 | 0.74 (0.53–1.03), p = 0.077 | 1.42 (0.75–2.67), p = 0.277 | 0.59 (0.34–1.02), p = 0.059 | 0.58 (0.31–1.08), p = 0.086 |
Culicine larval mosquito density | ||||
Overall | ||||
Arm 1 | Reference | |||
Arm 2 | 0.88 (0.79–0.98), p = 0.016 | 0.59 (0.50–0.71), p < 0.001 | 2.46 (2.01–3.02), p < 0.001 | 0.39 (0.32–0.48), p < 0.001 |
Arm 3 | 1.23 (1.11–1.37), p < 0.001 | 1.06 (0.90–1.25), p = 0.489 | 1.84 (1.48–2.28), p < 0.001 | 0.86 (0.72–1.04), p = 0.114 |
Arm 4 | 1.37 (1.24–1.52), p < 0.001 | 1.05 (0.89–1.25), p = 0.535 | 2.27 (1.85–2.79), p < 0.001 | 1.11 (0.93–1.32), p = 0.244 |
Malindi | ||||
Arm 1 | Reference | |||
Arm 2 | 3.33 (1.93–5.76), p < 0.001 | 13.41 (0–41,102.22), p = 0.526 | 12.44 (2.55–60.58), p = 0.002 | 2.81 (1.49–5.27), p = 0.001 |
Arm 3 | 1.82 (0.96–3.45), p = 0.064 | 20.09 (0.01–68,418.63), p = 0.470 | 2.79 (0.45–17.39), p = 0.272 | 1.53 (0.75–3.13), p = 0.246 |
Arm 4 | 1.04 (0.59–1.84), p = 0.880 | 0 | 6.37 (1.31–31.12), p = 0.022 | 0.41 (0.20–0.83), p = 0.014 |
Nyabondo | ||||
Arm 1 | Reference | |||
Arm 2 | 0.65 (0.57–0.75), p < 0.001 | 0.57 (0.47–0.70), p < 0.001 | 2.88 (2.13–3.89), p < 0.001 | 0.10 (0.07–0.15), p < 0.001 |
Arm 3 | 1.51 (1.34–1.70), p < 0.001 | 1.19 (1.00–1.42), p = 0.052 | 3.49 (2.60–4.70), p < 0.001 | 0.97 (0.79–1.19), p = 0.759 |
Arm 4 | 1.41 (1.25–1.59), p < 0.001 | 1.10 (0.92–1.32), p = 0.310 | 2.09 (1.53–2.87), p < 0.001 | 1.32 (1.08–1.61), p = 0.006 |
Tolay | ||||
Arm 1 | Reference | |||
Arm 2 | 0.69 (0.51–0.93), p = 0.014 | 0.72 (0.41–1.28), p = 0.269 | 0.76 (0.49–1.16), p = 0.203 | 0.56 (0.30–1.07), p = 0.078 |
Arm 3 | 0.64 (0.45–0.91), p = 0.014 | 0.84 (0.45–1.56), p = 0.576 | 0.64 (0.38–1.10), p = 0.106 | 0.45 (0.21–0.94), p = 0.035 |
Arm 4 | 0.78 (0.59–1.03), p = 0.082 | 0.83 (0.49–1.42), p = 0.500 | 0.88 (0.58–1.33), p = 0.537 | 0.57 (0.32–1.03), p = 0.064 |
Epidemiological findings from the school-level surveys
Schools (children) | Year 1: 2013 | Year 2: 2014 | Year 3: 2015 | Overall | ||
---|---|---|---|---|---|---|
PfPR % [95% CI]b | PfPR % [95% CI]b | PfPR % [95% CI]b | PfPR % [95% CI]b | Multivariablea aOR [95% CI], p-value | ||
Overall | 38 (11,846) | 5.4 (2.4–12.1) | 6.9 (4.4–10.7) | 23.9 (16.2–35.1) | 13.3 (8.8–20.0) | |
Malindi | 10 (3000) | 5.4 (2.4–12.1) | 7.9 (4.4–14.2) | 3.7 (1.9–7.2) | 5.7 (3.1–10.4) | Reference |
Nyabondo | 12 (4046) | – | 15.7 (10.9–22.6) | 49.5 (41.5–58.9) | 32.4 (26.1–40.1) | 9.1 (7.6–10.9), p < 0.001 |
Tolay | 16 (4800) | – | 1.0 (0.7–1.4) | 3.2 (2.5–4.1) | 1.7 (1.4–2.1) | 0.3 (0.2–0.4), p < 0.001 |
Study arm | ||||||
Overall | ||||||
Arm 1 | 19 (3240) | 1.6 (0.6–4.0) | 6.1 (3.0–12.3) | 13.0 (5.6–30.3) | 7.7 (3.8–15.5) | Reference |
Arm 2 | 18 (2942) | 12.0 (4.4–32.6) | 9.3 (4.6–18.6) | 28.1 (15.6–50.5) | 17.1 (9.5–30.7) | 2.1 (1.7–2.5), p < 0.001 |
Arm 3 | 15 (2193) | 4.0 (3.8–4.2) | 4.1 (1.8–9.1) | 19.6 (8.8–44.0) | 10.4 (4.3–24.9) | 0.9 (0.7–1.1), p = 0.356 |
Arm 4 | 16 (2643) | 6.0 (5.6–6.3) | 5.8 (2.8–11.8) | 35.2 (21.1–58.7) | 19.3 (10.3–36.1) | 1.7 (1.4–2.0), p < 0.001 |
Malindi | ||||||
Arm 1 | 5 (1500) | 1.6 (0.6–4.0) | 5.8 (1.7–20.2) | 2.0 (1.0–4.0) | 3.1 (1.1–8.9) | Reference |
Arm 2 | 3 (900) | 12.0 (4.4–32.6) | 13.3 (7.7–23.0) | 7.7 (3.3–17.7) | 11.0 (5.4–22.5) | 3.8 (2.7–5.5), p < 0.001 |
Arm 3 | 1 (300) | 4.0 (3.8–4.2) | 2.0 (1.8–2.2) | 1.0 (0.8–1.2) | 2.3 (2.0–2.6) | 0.7 (0.3–1.7), p = 0.460 |
Arm 4 | 1 (300) | 6.0 (5.6–6.3) | 8.0 (7.6–8.2) | 3.0 (2.4–3.4) | 5.7 (5.2–6.0) | 1.9 (1.1–3.3), p = 0.033 |
Nyabondo | ||||||
Arm 1 | 2 (400) | – | 18.5 (9.7–35.0) | 47.3 (35.8–62.3) | 31.1 (21.2–45.6) | Reference |
Arm 2 | 4 (1380) | – | 24.5 (18.2–33.0) | 61.6 (46.0–82.4) | 45.6 (37.0–56.2) | 1.9 (1.5–2.3), p < 0.001 |
Arm 3 | 2 (816) | – | 14.0 (10.3–18.9) | 40.8 (28.1–59.3) | 29.1 (20.3–41.8) | 0.9 (0.7–1.2), p = 0.456 |
Arm 4 | 4 (1450) | – | 14.6 (9.9–21.5) | 58.4 (46.9–72.7) | 41.8 (35.6–49.1) | 1.6 (1.3–2.0), p < 0.001 |
Tolay | ||||||
Arm 1 | 4 (1200) | – | 1.6 (1.2–2.2) | 4.3 (3.7–5.0) | 2.4 (1.9–2.9) | Reference |
Arm 2 | 4 (1200) | – | 0.9 (0.4–2.0) | 3.3 (1.5–6.9) | 1.7 (1.0–2.9) | 0.7 (0.4–1.3), p = 0.235 |
Arm 3 | 4 (1200) | – | 0.6 (0.2–1.7) | 3.5 (3.0–4.1) | 1.6 (1.2–2.2) | 0.6 (0.4–1.2), p = 0.180 |
Arm 4 | 4 (1200) | – | 0.8 (0.3–1.7) | 2.0 (1.0–4.0) | 1.2 (1.0–1.4) | 0.5 (0.3–0.9), p = 0.032 |
Age (years) | ||||||
≤ 5 | 739 (6.3%) | 2.6 (0.2–30.6) | 7.1 (3.9–13.0) | 52.3 (39.2–69.8) | 36.0 (26.1–49.7) | 2.3 (1.8–2.8), p < 0.001 |
6–10 | 6787 (57.8%) | 5.5 (2.4–12.6) | 9.4 (6.4–14.0) | 26.0 (17.5–38.6) | 15.5 (10.5–22.8) | 1.6 (1.3–1.9), p < 0.001 |
> 10 | 4216 (35.9%) | 6.7 (1.3–33.9) | 4.1 (2.3–7.2) | 9.4 (5.4–16.3) | 5.8 (3.4–9.9) | Reference |
Gender | ||||||
Male | 6021 (51.4%) | 6.1 (2.6–14.1) | 7.5 (4.7–12.0) | 23.1 (15.7–34.0) | 13.5 (9.0–20.4) | 1.1 (0.9–1.2), p = 0.635 |
Female | 5704 (48.7%) | 4.7 (1.9–11.5) | 6.3 (4.2–9.7) | 24.7 (16.7–36.5) | 13.0 (8.6–19.8) | Reference |