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Table 2 Association of malaria infection status with age, sex, LLINs, IRS, number of tests conducted per participant, geographical location, season and IRS insecticide used

From: Incremental impact upon malaria transmission of supplementing pyrethroid-impregnated long-lasting insecticidal nets with indoor residual spraying using pyrethroids or the organophosphate, pirimiphos methyl

Category DP % N/N (I) OR [95 % CI] P
Overall 21.7 31,974/147,257 (25,354) 0.13 [0.08, 0.21] <0.001
Age
 <1 14.2 501/3535 (1735) 1.26 [1.09, 1.45] 0.001
 1–4 24.0 6127/25,505 (5677) 2.75 [2.54, 2.98] <0.001
 5–10 27.4 10,066/36,779 (7608) 3.62 [3.35, 3.91] <0.001
 11–14 26.0 4892/18,840 (4746) 3.36 [3.09, 3.65] <0.001
 15–24 20.3 4491/22,077 (5685) 2.04 [1.88, 2.22] <0.001
 25–44 14.9 4028/27,044 (5807) 1.24 [1.14, 1.34] <0.001
 ≥45 13.8 1796/13,027 (2903) 1 [NA] NA
Sex
 Male 23.3 16,068/79,208 (12,008) 1 [NA] NA
 Female 20.3 15,750/67,567 (13,228) 0.86 [0.83, 0.90] <0.001
Interventions
 LLINs 20.0 20,613/103,149 (20,706) 0.89 [0.85, 0.93] <0.001
 IRS 17.4 7568/43,560 (9926) 0.87 [0.82, 0.93] <0.001
 Number of tests conducted per participant 21.7 31,974/147,257(25,354) 0.97 [0.97, 0.98] <0.001
Type of visit
 Passive 43.4 6416/14,785 (8922) 1 [NA] NA
 Active 19.2 25,281/131,359 (22055) 0.29 [0.28, 0.31] <0.001
 Clusters
Luangwa district
Sinyawagora RHC 19.7 1314/6655 (1959) 2.86 [1.65, 4.97] <0.001
Kasinsa RHC 16.7 2232/13,402 (3429) 4.67 [2.78, 7.84] <0.001
Chitope RHC 19.6 3419/17,463 (1215) 2.92 [2.04, 4.17] <0.001
Luangwa High School RHC 16.5 2854/17,320 (1158) 7.37 [4.31, 12.61] <0.001
Mphuka RHC 24.9 2981/11,957 (2147) 7.37 [4.31, 12.61] <0.001
Mandombe RHC 10.3 1386/13,508 (1805) 1.54 [0.89, 2.66] 0.119
Luangwa Boma RHC 6.4 839/13,161 (2033) 1 [NA] NA
Nyimba district
Kacholola RHC 26.7 3108/11,654 (1166) 7.50 [4.75, 11.84] <0.001
Hofmeyer RHC 41.9 2601/6214 (2120) 15.81 [10.20, 24.52] <0.001
Mtilizi RHC 37.6 2238/5949 (2024) 12.35 [7.72, 19.76] <0.001
Mtilizi RHP 25.3 2478/9788 (3379) 13.49 [8.45, 21.56] <0.001
Chinambi RHC 31.9 1740/5463 (1741) 9.16 [5.79, 14.48] <0.001
Mkopeka RHC 32.8 2761/8413 (1311) 14.22 [8.55, 23.63] <0.001
Chipembe RHC 32.1 2023/6310 (1916) 13.54 [8.03, 22.84] <0.001
Season
 Hot & wet (Dec–April) 25.3 18,283/72,217 (20,243) 4.20 [3.67, 4.81] <0.001
 Cool & dry (May–Aug) 23.9 11,216/46,860 (16,513) 3.25 [2.80, 3.76] <0.001
 Hot & dry (Sept–Nov) 8.7 2444/27,983 (12,590) 1 [NA] NA
Insecticide applied for IRS
Deltamethrine
1–3 months since last spray 13.3 322/2419 (2166) 0.81 [0.65, 1.01] 0.064
4–6 months since last spray 23.8 2411/10,150 (4231) 1.07 [0.94, 1.23] 0.295
7–12 months since last spray 13.6 2128/15,640 (4434) 1.16 [1.03, 1.30] 0.013
Never sprayed and >13 months since last spray 22.8 27,083/118,899 (23,233) 1 [NA] NA
Lambdacyhalothrin
1–3 months since last spray 4.7 145/3102 (1526) 0.69 [0.53, 0.90] 0.006
4–6 months since last spray 9.4 207/2199 (1264) 1.26 [1.01, 1.57] 0.042
7–12 months since last spray 4.5 157/3508 (1469) 0.94 [0.74, 1.21] 0.653
Never sprayed and >13 months since last spray 22.7 31,435/138,299 (24,931) 1 [NA] NA
Primiphosmethyl EC
1–3 months since last spray 18.9 1922/10,194 (5527) 0.77 [0.69, 0.85] <0.001
4–6 months since last spray 28.8 2666/9259 (5926) 0.64 [0.58, 0.71] <0.001
7–12 months since last spray 16.0 1793/11,184 (5760) 0.63 [0.56, 0.71] <0.001
Never sprayed and >13 months since last spray 21.9 25,563/11,6471 (22,311) 1 [NA] NA
Primiphosmethyl CS
1–3 months since last spray 13.0 468/3590 (2675) 0.37 [0.31, 0.43] <0.001
4–6 months since last spray 30.6 1386/4536 (3349) 0.24 [0.21, 0.27] <0.001
7–12 months since last spray 49.5 95/192 (191) 1.35 [0.85, 2.15] 0.204
Never sprayed and >13 months since last spray 21.6 29,995/138,790 (24,588) 1 [NA] NA
  1. The association of malaria infection with age, sex, use of LLINs, use of IRS, geographical location (cluster), number of tests conducted per participant, season and insecticide used in IRS was determined using GLMM; with observed malaria RDT determined status as a binary dependent outcome with the independent categories of age, sex, access and use of LLINs or IRS, insecticide used in IRS, number of tested conducted per participant and seasons. The models included date and participant nested within CHW catchment nested within geographical location (cluster) as random effects except for one in which cluster was treated as a categorical variable to determine the effects of each cluster. The final model consisted of age, sex, access and use of LLINs or IRS, insecticide used in IRS, season, number of tests conducted per participant and geographical location as the determinants of malaria infection
  2. DP RDT-determined diagnostic positivity, n Number RDT positive, N Total number tested by RDT, I Number of individuals that participated in RDT testing, OR Odds ratio, CI Confidence intervals, P Probability of the null hypothesis, NA Not applicable because reference group