Okal, J., Geibel, S., Muraguri, N., et al. Sexually Transmitted Infections (June 2013), E-publication ahead of print.
To estimate the size of three key populations - men who have sex with men (MSM), female sex workers (FSWs) and people who inject drugs (PWID) in Nairobi, Kenya, the authors triangulated data using three size estimation methods for each population as part of a larger behavioral surveillance study that recruited participants from 2010 to 2011. Estimates of 29,494 FSWs (range: 10,000-54,467); 11,042 MSM (range: 10,000-22,222); and 6,216 (5,031-10,937) PWID in Nairobi were determined, which underscores that these high-risk key populations do in fact exist in Nairobi. Also, because MSM subgroups may be hidden, the upper plausible estimate for this population could be two times greater. The authors used the service multiplier method, the "Wisdom of the Crowds" method, and literature and demographic data. Based on this analysis, the authors then presented the population estimates to community representatives and stakeholders, such as the Kenyan government and HIV program representatives, who helped synthesize, verify, and build consensus on the population estimates. These key population estimates may serve as a foundation for planning HIV prevention, care, and treatment activities by the Kenyan government and donor groups. The authors concluded that future HIV surveillance activities should include population size estimates, and apply additional methods to improve these estimates.