General Population Cohort (GPC)

i) Community mobilisation and mapping of households

The community mobilisation activity focuses on engaging with participants at both community and individual levels. The GPC setting covers 26 adjacent villages which are defined by Uganda’s subnational administrative boundaries, varying in size from 300 to 1500 residents. One pilot village enables pretesting of study tools and procedures. Local leaders (including members of the Local Government councils and Community Advisory Board) from these villages are sensitised on study plans and their permission and support is sought before holding community meetings. Each household which is mapped is assigned a unique identification number.

ii) Census

Every year, the Census assesses each household’s socioeconomic status, and the socio-demographic characteristics of the individuals within the household. Unique identification (ID) numbers were assigned to residents the first time they were surveyed and the same ID maintained over time in both the Census and Medical surveys. At every Census, newborns and new area residents are also assigned unique identification numbers. A census questionnaire is administered to a household head or an adult representative. Overall, over 96% of households approached for census consent and participate.

iii) Medical surveys

Based on the Census, eligible residents are invited to attend the Medical survey at a temporary village medical hub. The hubs are sequentially set up at a central location within each of the 26 villages. Eligible residents are defined by whether an individual spent or is planning to spend at least 3 months in a household within the study area. For each individual, data on health history, behaviour, and lifestyle are collected using a standard questionnaire while maintaining the same participant identification number used in the Census. Blood samples are also obtained and biophysical measurements taken in the same interview session. The questionnaire administered at each Medical survey round focuses on a particular scientific theme, and rounds are conducted every two years.

A robust infrastructure is in place for sample processing and storage, and data management. A clinic located at the field station provides general health care to all study participants who present with acute medical conditions (malaria and acute respiratory tract infections among others) and chronic diseases such as HIV, hepatitis B and C, hypertension, diabetes and dyslipidaemia identified during medical surveys.