The area is representative of many rural and riverine deltas in Bangladesh, and is one of the richest and longest-running longitudinal data sources within the developing world.

[3] In 1960, a group of American and Bangladeshi scientists journeyed across a cholera-prone sub-district of Bangladesh on a barge-turned-floating cholera hospital.

In 1966, a Health and Demographic Surveillance System (HDSS) was established in Matlab to record data regarding birth, death and migration.

Initially the main purpose was to conduct cholera vaccine trials and to track the trends of public health problems of rural Bangladesh.

One of the most important roles Matlab played in the field of public health was through the development of an oral rehydration solution (ORS).

It is now considered one of the most important medical advances of the 20th century and estimated to have saved around 50 million lives globally.

Traditional Birth Attendants (dais, elderly illiterate women mostly) used to work to detect and record data of the vital events through weekly household visit.

[6] A typical village in Bangladesh consists of several baris – groups of houses centered around courtyards – which function as economic and social units.

a) Initial census and regular update rounds - CHWs collect data through monthly household visits.