Skip to main content

Table 2 Spatial clusters (hotspots) of An. gambiae and human malaria infection prevalence in Dar es Salaam city: a flexible scan statistic was used to detect the clusters using FleXScan software Version 3.1.2 which is freely available on https://sites.google.com/site/flexscansoftware/download_e

From: Spatially aggregated clusters and scattered smaller loci of elevated malaria vector density and human infection prevalence in urban Dar es Salaam, Tanzania

  Phase 1: March–September 2010 Phase 2: October 2010–January 2013
Outcome variable Hotspot clusters Proportion of all mosquitoes or detected infections [%(n/N)] Proportion of all survey locations in clusters [%(n/N)] Proportion of survey locations under larviciding [%(n/N)] Expected mosquitoes or prevalent infections RR p Proportion of all mosquitoes or detected infections [%(n/N)] Proportion of all survey locations in clusters [%(n/N)] Proportion of survey locations under larviciding in [%(n/N)] Expected mosquitoes or prevalent infections RR p
Mean catches per trap night of female An. gambiae Primary cluster 13.6 (52/382) 3.7 (23/615) 34.8 (8/23) 12.89 4.58 <0.01 32.9 (23/70) 4.8 (67/1398) 67.2 (45/67) 6.10 5.22 <0.01
Secondary cluster 1 6 (23/382) 3.6 (22/615) 68.2 (15/22) 2.32 10.54 <0.01       
Secondary cluster 2 3.9 (15/382) 1.5 (9/615) 33.3 (3/9) 1.27 12.33 <0.01       
Secondary cluster 3 2.4 (9/382) 0.2 (1/615) 100 (1/1) 1.06 8.72 0.01       
Secondary cluster 4 2.1 (8/382) 0.2 (1/615) 100(1/1) 0.85 9.67 0.02       
Secondary cluster 5 1.6 (6/382) 0.2 (1/615) 0 0.56 10.82 0.05       
Total   29.6% (1 13/382) 9.3 (57/615) 49.1 (28/57)     32.9 (23/70) 4.8 (67/1398) 67.2 (45/67)    
Human malaria infection prevalence Primary cluster 39.4 (148/376) 29.8 (78/261) 46.2 (36/78) 124.31 1.82 <0.01 13.4 (114/852) 5.8 (5/86) 0.6 (3/5) 53.98 2.28 <0.01
Secondary cluster 1 15.7 (59/376) 10.0 (26/261) 50 (13/26) 18.73 2.40 <0.01 5.9 (50/852 3.5 (3/86) 100 (3/3) 21.15 2.45 <0.01
Secondary cluster 2        7.9 (67/852) 3.5 (3/86) 0 35.04 1.99 <0.01
Secondary cluster 3        7.3 (62/852) 4.7 (4/86) 0 33.33 1.93 <0.01
Secondary cluster 4        9.9 (84/852) 2.3 (2/86) 0 46.22 1.91 <0.01
Secondary cluster 5        3.2 (27/852) 1.2 (1/86) 0 10.57 2.60 <0.01
Total   55.1 (207/376) 39.8 (104/261 47.1 (49/104)     47.4  (404/852) 20.9 (18/86) 33.3 (6/18)    
  1. Hotspots of An. gambiae were identified using Poisson statistical model while those of infection prevalence were detected using binomial statistical model. The significance of the cluster (p value) was calculated based on MonteCarlo replications set at 9999. RR relative risk which refers to the standardized risk ratio of observed mean catches of mosquitoes or prevalent infections (indicated by ‘n’ in a thirdcolumn) over the expected mean of mosquito densities or prevalent infections