The HIV/AIDS Surveillance Project mapping approach: an innovative approach for mapping and size estimation for groups at a higher risk of HIV in Pakistan

We developed a mapping approach to gather data on distribution, number of settings, operational typologies and estimated size of female sex workers (FSWs), male sex workers, hijra sex workers and injection drug users in Pakistan. Data were collected across 12 major cities in Pakistan. Broader methodological steps involved dividing each target city into smaller geographical units and collecting data within each zone from secondary and tertiary key informants, also known as level 1. Level 2 ensured involvement of the communities themselves in validating these estimates, followed by triangulation of the finalized results. Rates for each subgroup per 1000 adult men or women were computed and rolled up into provincial estimates to be summed up into national estimates. FSWs formed the largest group reported, with estimates of 79 127 and five different subtypologies. Injection drug users were the second largest group, followed by male sex workers and hijra sex workers with estimates of 31 555, 19 320 and 14 702, respectively. We estimated approximately 167 501 FSWs in Pakistan, with an overall national rate of 4. 4 FSWs per 1000 adult women. A total of 71 911 male sex workers in addition to 39 262 hijra sex workers were calculated with rates of 1.7 and 0.9 per 1000 men, whereas injection drug users had an overall estimate of 102 042. This relatively simple methodology provides a scientific and systematic approach, which can be used in the region to estimate population sizes, understand geographical distribution of these groups and recognize the various operational typologies and dynamics of these populations for developing effective prevention strategies.