Community-based control of Aedes aegypti by adoption of eco-health methods in Chennai City, India

Figures & data

Figure 1. Map of India with study site indicated.

Figure 2. Wooden cover to prevent Aedes breeding in cement tanks.

Table 1. Knowledge about dengue and dengue prevention in the study population before and after the intervention, Chennai

Per cent of cluster dwellers who:	Baseline (n = 2000 households)	Intervention areas (n = 1000 households)	Control areas (n = 1000 households)	Intervention versus control (P value)
had heard about dengue	94·0	98·2	90·1	t = 3·950 (P<0·05*)
considered dengue serious	63·0	90·6	46·1	t = 9·908 (P<0·05*)
knew that mosquitoes transmit dengue	55·0	90·7	57·4	t = 9·198 (P<0·05*)
knew that dengue is preventable	55·0	87·4	43·7	t = 6·650 (P<0·05*)
knew about mosquito life cycle	29·5	89	29·2	t = 17·314 (P<0·05*)
knew about vector breeding in clean water	26·1	87·5	28·4	t = 15·282 (P<0·05*)

Note: *Significant.

Table 2. Major container types and numbers with pupae found during the wet season base line survey (November–December 2009) in Chennai

			Intervention						Control
Type of container	Total number of container	Proportion to total containers	Container positive	Proportion to container+ve to total	No. of pupae in positive container	% of all pupae	Total number of containers	Proportion to total containers	Container positive	Proportion of container+ve to total	No. of pupae in positive container	% of all pupae
Cement tank*	73	0·021	19	0·062	366	7·34	58	0·019	22	0·099	431	13·14
Coconut shells	14	0·004	5	0·016	89	1·79	6	0·002	5	0·023	52	1·58
Disused container	156	0·045	87	0·282	1342	26·92	58	0·020	41	0·185	691	21·06
Flower vases	25	0·007	16	0·052	329	6·59	16	0·005	7	0·031	130	3·96
Grinding stone	55	0·016	31	0·101	514	10·31	41	0·014	32	0·144	692	21·09
Plastic/metal drum	260	0·076	63	0·205	1222	24·51	193	0·066	36	0·162	558	17·00
Plastic pot	1434	0·417	17	0·055	205	4·11	1168	0·397	13	0·595	53	1·62
Tyres	24	0·007	21	0·068	279	5·60	14	0·005	13	0·595	166	5·06
Miscellaneous†	1396	0·406	49	0·159	639	12·82	1387	0·472	53	0·239	508	15·48
Total (including all containers	3437		308		4985		2941		222		3281

Notes: *Cement tanks, which were the predominant producers of Aedes pupae, had lost their relative importance after the Corporation (public sector) had treated them with temephos, just before our survey in the wet season.

†Miscellaneous containers recorded were ceramic jar, bowl, bucket, metal containers, mud pot, refrigerator trays, and tree holes.

Figure 3. Pupae per person index (95% confidence interval) in intervention and check clusters (August 2009 to November 2010) Chennai, India.

Table 3. Summary of entomological indices in the wet season

Indicators	Intervention (1000 houses)		Control (1000 houses)		Difference between arms (intervention and control) wet season	Difference in reduction, baseline to post-intervention, between two arms (P value)
	Baseline (November–December 2009)	Evaluation (October–November 2010)	Baseline (November–December 2009)	Evaluation (October–November 2010)
House index (%)	19·6	4·2	17·2	16·5	−14·7	P = 0·012*
Change from baseline		15·4		0·7
% reduction from baseline		78·6%		4·1%
Container index (%)	8·91	1·05	7·51	5·72	−6·06	P = 0·0057*
Change from baseline		7·86		1·79
% reduction from baseline		88·2%		23·8%
Breteau index	30·8	4·3	22·2	21·4	−25·7	P = 0·0011*
Change from baseline		26·5		0·8
% reduction from baseline		86·0%		3·6
Pupae per person index	1·075	0·004	0·729	0·355	−0·35	P = 0·0200*
Change from baseline		1·071		0·374
% reduction from baseline	99·6	99·6		51·3

Note: *Significant.