Mirpur has been selected for this study. Mirpur is a part of the Dhaka metropolitan area with an estimated population of over 2.5 million people. Different socio-economic groups of communities live in the area. The icddr,b hospitals treat more patients from Mirpur than from any other part of Dhaka. We have selected 9 wards in Mirpur (7-13, 15 and 41) for the study out of 16 wards. The selection has been based on the high number of cholera patients from these wards visiting the icddr,b hospitals over the last few years. Before starting the study we will commission a census of these high cholera incidence wards in Mirpur. The census team will create geographic information system (GIS) database by digitizing buildings and other structures in the target wards using satellite derived images. The digitized buildings and structures will be verified for ground verification. The census team will visit each building and ascertain whether or not people are living in the building. Based on this survey, the team will assess whether the people living in each building/structure are a high risk group or not. The census team then will collect verbal consent from the respondent and other information about the household . We will conduct a de jure census and will enumerate 324,178 high risk residents from the target wards.