Background
Methods
Study site
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In Djougou district:Zountori: a urban area of Djougou (09°42′10.1″ N latitude and 01°40′55.4″ E longitude);Barienou: a rural village of Djougou (09°42′58.4″ N latitude and 01°46′06.5″ E longitude) (Fig. 1).
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In Copargo district:Parakounan: a urban area of Copargo (09°50′19.3″ N latitude and 01°32′39.5″ E longitude);Kataban: a rural village of Copargo (09°54′34.3″ N latitude and 01°31′26.9″ E longitude);
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In Kandi district:Kossarou: a urban area of Kandi (11°07′29.32″ N latitude and 2°56′9.57″ E longitude);Sonsoro: a rural village of Kandi (11°4′58.91″ North latitude and 2°13′37.60″ East longitude);
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In Gogounou district:Bantansoue: a urban area of Gogounou (10°50′30.6″ N latitude and 2°50′20.3″ E longitude);Gounarou: a rural village of Gogounou (10°52′20.8″ N latitude and 2°50′51.2″ E longitude) (Fig. 1).
Ethical considerations
Anopheles adult collection
Mosquito processing
Estimation of entomological parameters
Data analysis
Results
Vector species composition
Regions | Districts | Anopheles gambiae s.l. |
Anopheles funestus
|
Anopheles pharoensis
|
Anopheles ziemanni
|
Anopheles coustani
|
Anopheles paludis
|
---|---|---|---|---|---|---|---|
Donga | Djougou | 1086 | 60 | 0 | 0 | 1 | 0 |
Copargo | 1188 | 8 | 2 | 1 | 8 | 1 | |
Sub-total | 2274 | 68 | 2 | 1 | 9 | 1 | |
Alibori | Kandi | 869 | 4 | 0 | 1 | 0 | 0 |
Gogounou | 645 | 1 | 1 | 0 | 0 | 0 | |
Sub-total | 1514 | 5 | 1 | 1 | 0 | 0 | |
Total | 3788 | 73 | 3 | 2 | 9 | 1 |
Variability of human biting rates
Variables | Modalities | May | June | July | August | October | January | February | HBR/night | CI-95% | RR and CI-95% | p (Wald) |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Donga | Djougou | 2 | 2.88 | 9.13 | 13.06 | 9.06 | 2.38 | 5.13 | 6.55a | [6.07–7.06] | 1 | – |
Copargo | 0.75 | 7.06 | 10.56 | 16.63 | 10.5 | 1.5 | 2.25 | 7.51b | [7.00–8.06] | 1.15 [1.03–1.27] | 0.0089 | |
Alibori | Kandi | 0.13 | 4.19 | 6.75 | 8.75 | 10.81 | 0.25 | 0.31 | 4.78c | [4.37–5.22] | 0.73 [0.65–0.82] | < 0.001 |
Gogounou | 0.38 | 1.31 | 4.56 | 9 | 10.63 | 2 | 0.94 | 4.4c | [4–4.83] | 0.67 [0.59–0.76] | < 0.001 | |
Settings | Urban area | 0.13 | 0.63 | 2.78 | 5.09 | 4.28 | 0.72 | 0.78 | 2.18a | [1.99–2.39] | 1 | – |
Rural area | 1.50 | 7.09 | 12.72 | 18.63 | 16.22 | 2.34 | 3.53 | 9.42b | [9.01–9.85] | 4.27 [3.85–4.75] | < 0.0001 | |
Location | Indoor | 1.06 | 3.53 | 8.50 | 12.13 | 11.97 | 1.97 | 2.81 | 6.37a | [6.03–6.72] | 1 | – |
Outdoor | 0.56 | 4.19 | 7.00 | 11.59 | 8.53 | 1.09 | 1.50 | 5.25b | [4.95–5.58] | 0.83 [0.76–0.89] | < 0.001 | |
Seasonality | Dry season | 0.81 | – | – | – | – | 1.53 | 2.16 | 2.27a | [2.07–2.47] | 1 | – |
Rainy season | – | 3.86 | 7.75 | 11.86 | 10.25 | – | – | 9.95b | [9.51–10.40] | 4.38 [3.97–4.83] | < 0.0001 |
Sporozoite index of Anopheles gambiae
Districts | Sites | May | June | July | August | October | January | February | Mean | Mean | Mean (7 months) | CI 95% | p-value |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
(DS) | (RS) | (RS) | (RS) | (RS) | (DS) | (DS) | (DS) | (RS) | |||||
Kandi | Sonsoro* | ||||||||||||
Thorax | 38 | 119 | 175 | 166 | 244 | 10 | 29 | 77 | 704 | 781 | 0.212 | ||
Thorax+ | 6 | 6 | 9 | 4 | 30 | 0 | 0 | 6 | 49 | 55 | |||
SI | 15.79 | 5.04 | 5.14 | 2.41 | 12.30 | 0 | 0 | 7.79a | 6. 96a | 7.042 | [5.34–9.06] | ||
Kossarou | |||||||||||||
Thorax | 7 | 4 | 6 | 16 | 49 | 2 | 4 | 13 | 75 | 88 | |||
Thorax+ | 1 | 0 | 0 | 0 | 8 | 1 | 0 | 2 | 8 | 10 | |||
SI | 14.29 | 0 | 0 | 0 | 16.33 | 50 | 0 | 15.38a | 10.67a | 11.36 | [5.58–19.90] | ||
Total | |||||||||||||
Thorax | 45 | 123 | 181 | 182 | 293 | 12 | 33 | 90 | 779 | 869 | |||
Thorax+ | 7 | 6 | 9 | 4 | 38 | 1 | 0 | 8 | 57 | 65 | |||
SI | 15.56 | 4.88 | 4.97 | 2.20 | 12.97 | 8.33 | 0 | 8.89a | 7.32a | 7.47 | [5.81–9.43] | ||
Gogounou | Gounarou* | ||||||||||||
Thorax | 7 | 8 | 33 | 93 | 167 | 22 | 22 | 51 | 301 | 352 | 0.0016 | ||
Thorax+ | 0 | 1 | 2 | 10 | 27 | 0 | 1 | 1 | 40 | 41 | |||
SI | 0 | 12.50 | 6.06 | 10.75 | 16.17 | 0 | 4.55 | 1.96a | 13.29b | 11.65 | [8.48–15.46] | ||
Bantansoue | |||||||||||||
Thorax | 0 | 23 | 64 | 72 | 71 | 33 | 30 | 63 | 230 | 293 | |||
Thorax+ | 0 | 1 | 1 | 2 | 5 | 3 | 1 | 4 | 9 | 13 | |||
SI | – | 4.35 | 1.56 | 2.78 | 7.04 | 9.09 | 3.33 | 6.35a | 3.91a | 4.44 | [2.38–7.46] | ||
Total | |||||||||||||
Thorax | 7 | 31 | 97 | 165 | 238 | 55 | 52 | 114 | 531 | 645 | |||
Thorax+ | 0 | 2 | 3 | 12 | 32 | 3 | 2 | 5 | 49 | 54 | |||
SI | 0 | 6.45 | 3.09 | 7.27 | 13.45 | 5.45 | 3.85 | 4.39a | 9.23a | 8.37 | [6.35–10.78] | ||
Total (Alibori region) | Thorax | 52 | 154 | 278 | 347 | 531 | 67 | 85 | 204 | 1310 | 1514 | ||
Thorax+ | 7 | 8 | 12 | 16 | 70 | 4 | 2 | 13 | 106 | 119 | |||
SI | 13.46 | 5.19 | 4.32 | 4.61 | 13.18 | 5.97 | 2.35 | 6.37a | 8.09a | 7.86 | [6.55–9.33] | ||
Djougou | Barienou* | ||||||||||||
Thorax | 56 | 57 | 251 | 198 | 145 | 51 | 171 | 278 | 651 | 929 | 0.223 | ||
Thorax+ | 15 | 4 | 6 | 25 | 16 | 3 | 15 | 33 | 51 | 84 | |||
SI | 26.79 | 7.02 | 2.39 | 12.63 | 11.03 | 5.88 | 8.77 | 11.87a | 7.83a | 9.04 | [7.27–11.07] | ||
Zountori | |||||||||||||
Thorax | 0 | 0 | 33 | 59 | 41 | 18 | 6 | 24 | 133 | 157 | |||
Thorax+ | 0 | 0 | 1 | 5 | 2 | 1 | 0 | 1 | 8 | 9 | |||
SI | – | – | 3.03 | 8.47 | 4.88 | 5.56 | 0 | 4.17a | 6.02a | 5.73 | [2.65–10.60] | ||
Total | |||||||||||||
Thorax | 56 | 57 | 284 | 257 | 186 | 69 | 177 | 302 | 784 | 1086 | |||
Thorax+ | 15 | 4 | 7 | 30 | 18 | 4 | 15 | 34 | 59 | 93 | |||
SI | 26.79 | 7.02 | 2.46 | 11.67 | 9.68 | 5.80 | 8.47 | 11.26a | 7.53a | 8.56 | [6.96–10.38] | ||
Copargo | Kataban* | ||||||||||||
Thorax | 13 | 189 | 274 | 284 | 198 | 35 | 56 | 104 | 945 | 1049 | 1 | ||
Thorax+ | 0 | 8 | 16 | 34 | 21 | 3 | 0 | 3 | 79 | 82 | |||
SI | 0 | 4.23 | 5.84 | 11.97 | 10.61 | 8.57 | 0 | 2.88a | 8.36a | 7.81 | [6.26–9.61] | ||
Kparakouna | |||||||||||||
Thorax | 1 | 11 | 27 | 61 | 21 | 4 | 14 | 19 | 120 | 139 | |||
Thorax+ | 0 | 0 | 0 | 6 | 5 | 0 | 0 | 0 | 11 | 11 | |||
SI | 0 | 0 | 0 | 9.84 | 23.81 | 0 | 0 | 0a | 9.16a | 7.91 | [4.01–13.71] | ||
Total | |||||||||||||
Thorax | 14 | 200 | 301 | 345 | 219 | 39 | 70 | 123 | 1065 | 1188 | |||
Thorax+ | 0 | 8 | 16 | 40 | 26 | 3 | 0 | 3 | 90 | 93 | |||
SI | 0 | 4 | 5.32 | 11.59 | 11.87 | 7.69 | 0 | 2.44a | 8.45b | 7.83 | [6.36–9.50] | ||
Total (Donga region) | Thorax | 70 | 257 | 585 | 602 | 405 | 108 | 247 | 425 | 1849 | 2274 | ||
Thorax+ | 15 | 12 | 23 | 70 | 44 | 7 | 15 | 37 | 149 | 186 | |||
SI | 21.43 | 4.67 | 3.93 | 11.63 | 10.86 | 6.48 | 6.07 | 8.71a | 8.06a | 8.18 | [7.08–9.38] | ||
Total (rural areas) | Thorax | 114 | 373 | 733 | 741 | 754 | 118 | 278 | 510 | 2601 | 3111 | 0.086 | |
Thorax+ | 21 | 19 | 33 | 73 | 94 | 6 | 16 | 43 | 219 | 262 | |||
SI | 18.42 | 5.09 | 4.50 | 9.85 | 12.47 | 5.08 | 5.76 | 8.43a | 8.42a | 8.42 | [7.46–9.45] | ||
Total (urban areas) | Thorax | 8 | 38 | 130 | 208 | 182 | 57 | 54 | 119 | 558 | 677 | ||
Thorax+ | 1 | 1 | 2 | 13 | 20 | 5 | 1 | 7 | 36 | 43 | |||
SI | 12.50 | 2.63 | 1.54 | 6.25 | 10.99 | 8.77 | 1.85 | 5.88a | 6.45a | 6.35 | [4.63–8.46] | ||
Grand total | Thorax | 122 | 411 | 863 | 949 | 936 | 175 | 332 | 629 | 3159 | 3788 | ||
Thorax+ | 22 | 20 | 35 | 86 | 114 | 11 | 17 | 50 | 255 | 305 | |||
SI | 18.03 | 4.87 | 4.06 | 9.06 | 12.18 | 6.29 | 5.12 | 7.95a | 8.07a | 8.05 | [7.20–8.96] |
Entomological inoculation rate of Anopheles gambiae
Districts | Parameters | Dry season | Rainy season | Total | RR (95% CI) | p (Wald) |
---|---|---|---|---|---|---|
(May–January–February) | (June–October) | |||||
Kandi | HBR/night | 0.25 | 7.625 | 4.78 | ||
SI | 8.89 | 7.32 | 7.48 | |||
EIR/night | 0.022 | 0.558 | 0.358 | |||
EIR/month | 0.66a | 16.74b | 10.75 | 1 | – | |
Gogounou | HBR/night | 1.25 | 6.375 | 4.4 | ||
SI | 4.4 | 9.2 | 8.37 | |||
EIR/night | 0.055 | 0.588 | 0.368 | |||
EIR/month | 1.645a | 17.648b | 11.06 | 1.03 [1.012–1.046] | 0.0006 | |
Djougou | HBR/night | 3.4 | 8.53125 | 6.55 | ||
SI | 11.3 | 7.5 | 8.56 | |||
EIR/night | 0.38 | 0.64 | 0.561 | |||
EIR/month | 11.48a | 19.26b | 16.85 | 1.56 [1.54–1.58] | < 0.001 | |
Copargo | HBR/night | 1.65 | 11.1875 | 7.5 | ||
SI | 2.44 | 8.45 | 7.82 | |||
EIR/night | 0.04 | 0.945 | 0.588 | |||
EIR/month | 1.21a | 28.36b | 17.66 | 1.64 [1.62–1.66] | < 0.001 |
Districts | Sites | May | June | July | August | October | January | February | EIR/night | EIR/month | EIR/year | RR (95% IC) | P (Wald) |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Kandi | Sonsoroa | ||||||||||||
HBR/night | 0 | 8.25 | 13.25 | 15.75 | 17.63 | 0.38 | 0.38 | < 0.0001 | |||||
EIR/night | 0 | 0.42 | 0.68 | 0.38 | 2.17 | 0 | 0 | 0.6 | 18.08 | 216.96 | 1 | ||
Kossarou | |||||||||||||
HBR/night | 0.25 | 0.13 | 0.25 | 1.75 | 4 | 0.13 | 0.25 | ||||||
EIR/night | 0.04 | 0 | 0 | 0 | 0.65 | 0.06 | 0 | 0.12 | 3.47 | 41.7 | 0.19 [0.17–0.21] | ||
Total | |||||||||||||
HBR/night | 0.13 | 4.19 | 6.75 | 8.75 | 10.81 | 0.25 | 0.31 | ||||||
EIR/night | 0.019 | 0.204 | 0.336 | 0.192 | 1.402 | 0.021 | 0 | 0.358 | 10.75 | 128.94 | |||
Gogounou | Gounaroua | ||||||||||||
HBR/night | 0.75 | 0.63 | 3 | 10.88 | 14.38 | 1.75 | 1 | < 0.0001 | |||||
EIR/night | 0 | 0.08 | 0.18 | 1.17 | 2.32 | 0 | 0.05 | 0.57 | 17.2 | 206.43 | 1 | ||
Bantansoue | |||||||||||||
HBR/night | 0 | 2 | 6.13 | 7.13 | 6.88 | 2.25 | 0.88 | ||||||
EIR/night | 0 | 0.09 | 0.1 | 0.2 | 0.48 | 0.2 | 0.03 | 0.17 | 5.17 | 62.05 | 0.30 [0.28–031] | ||
Total | |||||||||||||
HBR/night | 0.38 | 1.31 | 4.56 | 9 | 10.63 | 2 | 0.94 | ||||||
EIR/night | 0 | 0.08 | 0.14 | 0.65 | .43 | 0.11 | 0.04 | 0.369 | 11.06 | 132.73 | |||
Djougou | Barienoua | ||||||||||||
HBR/night | 4 | 5.75 | 15.88 | 20 | 14.38 | 4.38 | 9.75 | < 0.0001 | |||||
EIR/night | 1.07 | 0.4 | 0.38 | 2.53 | 1.59 | 0.26 | 0.86 | 1.003 | 30.1 | 361.19 | 1 | ||
Zountori | |||||||||||||
HBR/night | 0 | 0 | 2.38 | 6.13 | 3.75 | 0.38 | 0.5 | ||||||
EIR/night | 0 | 0 | 0.03 | 0.085 | 0.049 | 0.056 | 0 | 0.057 | 1.72 | 20.64 | 0.11 [0.10–0.12] | ||
Total | |||||||||||||
HBR/night | 2 | 2.88 | 9.13 | 13.06 | 9.06 | 2.38 | 5.13 | ||||||
EIR/night | 0.54 | 0.20 | 0.22 | 1.52 | 0.88 | 0.14 | 0.43 | 0.562 | 16.85 | 202.17 | |||
Copargo | Katabana | ||||||||||||
HBR/night | 1.25 | 13.75 | 18.75 | 27.88 | 18.5 | 2.88 | 3 | < 0.0001 | |||||
EIR/night | 0 | 0.582 | 1.095 | 3.337 | 1.962 | 0.246 | 0 | 1.027 | 30.81 | 369.72 | 1 | ||
Kparakouna | |||||||||||||
HBR/night | 0.25 | 0.38 | 2.38 | 5.38 | 2.5 | 0.13 | 1.5 | ||||||
EIR/night | 0 | 0 | 0 | 0.529 | 0.595 | 0 | 0 | 0.151 | 4.52 | 54.24 | 0.14 [0.13–0.15] | ||
Total | |||||||||||||
HBR/night | 0.75 | 7.06 | 10.56 | 16.63 | 10.50 | 1.50 | 2.25 | ||||||
EIR/night | 0 | 0.28 | 0.56 | 1.92 | 1.24 | 0.11 | 0 | 0.589 | 17.66 | 211.91 | |||
Urbanization | Rural areasa | ||||||||||||
HBR/night | 1.5 | 7.09 | 12.72 | 18.63 | 16.2 | 2.34 | 3.53 | < 0.0001 | |||||
EIR/night | 0.27 | 0.36 | 0.57 | 1.83 | 2.023 | 0.119 | 0.203 | 0.793 | 23.79 | 285.54 | 1 | ||
Urban area | |||||||||||||
HBR/night | 0.13 | 0.63 | 2.78 | 5.09 | 4.28 | 0.72 | 0.78 | ||||||
EIR/night | 0.016 | 0.017 | 0.043 | 0.318 | 0.470 | 0.063 | 0.014 | 0.138 | 4.15 | 49.83 | 0.176 [0.174–0.179] |
Seasonal variation of the parity of Anopheles gambiae
Districts | Dry season (May–January–February) | Rainy season (June–October) | p-value | ||||
---|---|---|---|---|---|---|---|
Number dissected | Parous | Parous rate (%) | Number dissected | Parous | Parous rate (%) | ||
Djougou | 105 | 86 | 81.90 | 395 | 281 | 71.14 | 0.0361 |
Copargo | 58 | 53 | 91.38 | 408 | 288 | 70.59 | 0.0014 |
Kandi | 9 | 9 | 100 | 358 | 248 | 69.27 | 0.1055 |
Gogounou | 46 | 41 | 89.13 | 261 | 179 | 68.58 | 0.0074 |
Total | 218 | 189 | 86.70 | 1422 | 996 | 70.04 | 0.00042 |