2. Material and methods
2.1. Study area
This study is carried out in Dhaka, the capital of Bangladesh. Our previous study showed that Dhaka is the highest risk area for dengue trans- mission in Bangladesh and the underlying cause of increased risk of dengue in this location remains unknown, which requires further investigation (Banu et al., 2012). Dhaka is located in central Bangladesh at 23°42′ north latitude and 90°22′ east longitude with an area of 1464 km2. Dhaka along with its metropolitan area had a population of 11.8 million (2011 census), making it the biggest city in Bangladesh. Dhaka has a hot, wet and humid tropical climate. The city is within the monsoon climate zone, with an annual average temperature of 25 °C and monthly means varying between 18 °C in January and 29 °C in August. Nearly 80% of the annual average rainfall of 1854 mm occurs between May and September.