Overhead tank is the potential breeding habitat of Anopheles stephensi in an urban transmission setting of Chennai, India

Table 1 Immature density and relative breeding index (RBI) of Anopheles stephensi in overhead tanks (OHTs), wells and other breeding habitats

Month/year	OHT					Well					Other breeding habitats^b
Month/year	No. surveyed	% positivity	Immature density^a	Anopheles immature density	RBI	No. surveyed	% positivity	Immature density^a	Anopheles immature density	RBI	No. surveyed	% positivity	Immature density^a	Anopheles immature density	RBI
APR ‘13	95	55.8	9.3	9	1	99	35.4	17.8	2.7	0.5	9	33.3	6.1	1.9	1
MAY ‘13	77	54.6	8.6	8.2	1	76	59.2	15.6	2.5	0.8	5	60	10.3	8.4	0.8
JUN ‘13	80	53.8	5.8	5.3	0.9	76	69.7	13	2.4	0.8	16	75	14.6	5.5	0.9
JUL ‘13	78	56.4	8.5	8.3	0.9	74	56.8	19.8	2.8	0.7	22	36.4	28.1	1.8	0.7
AUG ‘13	81	66.7	10.6	10.5	1	81	59.3	11.6	1.4	0.8	29	17.2	148.9	9.9	1
SEP ‘13	66	59.1	11.7	10.9	0.9	67	34.3	8.4	1.1	0.5	27	7.4	8.4	0.3	0.1
OCT ‘13	80	67.5	9.7	9.5	1	80	28.8	6.2	0.4	0.4	18	11.1	0.1	0.1	0.5
NOV ‘13	74	56.8	5.4	5.4	0.9	79	32.9	2.8	0.4	0.6	18	22.2	34.1	5	0.8
DEC ‘13	75	48	4.4	4.4	0.8	80	28.8	3.2	0.5	0.6	13	15.4	30.8	4	0.4
JAN ‘14	101	50.5	6.4	6.3	0.9	99	31.3	3.8	0.6	0.5	2	0	0	0	0
FEB ‘14	76	55.3	2.9	2.9	1	81	30.9	6.8	1	0.8	6	16.7	6.9	0.5	1
MAR ‘14	77	52	3.8	3.6	1	82	23.2	9	0.5	0.8	3	33.3	38.5	3.6	1

RBI relative breeding index (number of habitats positive for An. stephensi divided by the total number of habitats positive for any mosquito)
^aIncludes the total density of Anopheles, Culex and Aedes species
^bOther breeding habitats include underground tanks or sumps, barrels or drums, plastic pots, plastic containers, cemented containers, curing pits in construction site

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