A Note on Distribution of Breeding Sources of Aedes aegypti (Linnaeus) in the City of Kolkata, India, Following an Outbreak of Dengue during 2012

Abstract

An Aedes aegypti (larval) survey was conducted by the vector control department of Kolkata Municipal Corporation (KMC), following an outbreak of dengue in Kolkata City in July 2012. Results obtained are startling. Small discarded items were the major breeding sources of Ae. aegypti (prime vector of dengue). Outdoor containers such as battery shells at market places, old tyres at garages and tyre-retreading centres and wells at construction sites represented the first, second and third categories of preferred breeding sites of this vector mosquito. In the past, Ae. aegypti in Kolkata City was quite photophobic with regard to its breeding habit; it used to breed more indoors—mostly in small uncovered masonry tanks used for water storage indoors. But the very mosquito now breeds more outdoors; it has become photophilic. Ecological compulsion created by the people of Kolkata through periodic emptying and cleaning of their masonry tanks and other indoor water storage containers following the KMC’s intensive mass awareness campaigns over the past several years, seemed to have compelled Ae. aegypti to shift its breeding sites from indoors to outdoors for its better survival in the city’s environment. The need for active involvement of some other departments of KMC—besides the health department—such as the departments of solid waste management, building, water supply and drainage, too, was clearly pointed out by the study. Accordingly, multipronged strategies—including prompt destruction of the breeding sources of Ae. aegypti right from the month of January by involving all the concerned departments—were planned and religiously implemented by KMC during 2013. The concerted efforts yielded commendable results: the number of dengue cases downslided from a staggering 1852 (with 2 deaths) in 2012 to a comfortable 238 (with no death) in 2013.