Construction sites as an important driver of dengue transmission: implications for disease control

BMC Infectious Diseases

Table 1 Case details of major (≥10 cases) and minor (< 10 cases) clusters: Overall and construction site-associated clusters

	2013				2014				2015				2016
Total no. of clusters	1705				1823				1319				1721
No. of clusters based on size^a	≥10		< 10		≥10		< 10		≥10		< 10		≥10		< 10
No. of clusters based on size^a	199 (11.7%)		1506 (88.3%)		133 (7.3%)		1690 (92.7%)		108 (8.2%)		1211 (91.8%)		102 (5.9%)		1619 (94.1%)
Average cases per cluster	30.7		3.3		39.7		2.9		31.3		2.9		26.4		3.0
Construction site-associated clusters	Yes		No		Yes		No		Yes		No		Yes		No
Construction site-associated clusters	50 (2.9%)		1655 (97.1%)		88 (4.8%)		1735 (95.2%)		41 (3.1%)		1278 (96.9%)		50 (2.9%)		1671 (97.1%)
Cluster size^a	≥10	< 10	≥10	< 10	≥10	< 10	≥10	< 10	≥10	< 10	≥10	< 10	≥10	< 10	≥10	< 10
No. of clusters	33	17	166	1489	32	56	101	1634	9	32	99	1179	10	40	92	1579
No. of cases	1336	62	4777	4893	2473	216	2805	4707	537	102	2845	3391	360	135	2331	4661
Average cases per cluster	40.5	3.6	28.7	3.3	77.1	3.9	27.8	2.9	59.7	3.2	28.7	2.9	36	3.4	25.3	3.0
Odds ratio^b (95% CI)	17.4 (9.49–31.9)				9.24 (5.73–14.9)				3.35 (1.55–7.21)				4.29 (2.07–8.85)

^a≥10 = major clusters; < 10 = minor clusters
^bOdds ratio of construction site-associated clusters expanding into major clusters. CI confidence interval

ISSN: 1471-2334