Estimating the population size of female sex workers and transgender women  in Sri Lanka

Autoři: Ivana Bozicevic aff001;  Ariyaratne Manathunge aff002;  Zoran Dominkovic aff001;  Sriyakanthi Beneragama aff002;  Kelsi Kriitmaa aff003
Působiště autorů: World Health Organization Collaborating Centre for HIV Strategic Information, University of Zagreb School of Medicine, Zagreb, Croatia aff001;  National STD/AIDS Control Programme, Ministry of Health, Colombo, Sri Lanka aff002;  Philantrophy Advisory, Geneva, Switzerland aff003
Vyšlo v časopise: PLoS ONE 15(1)
Kategorie: Research Article
doi: 10.1371/journal.pone.0227689


We implemented population size estimation of female sex workers (FSW) and transgender women (TGW) in Sri Lanka in 2018 using several approaches (geographical mapping, service and unique object multiplier and a modified Delphi method during the stakeholder consensus meeting). Mapping was done in 49 randomly selected Divisional Secretariats, which provided a basis for extrapolation of size estimates to the national level. Two types of adjustments were applied on the mean (minimum-maximum) population estimate obtained during mapping: (1) an adjustment for mobility to reduce double counting of FSW and TGW frequenting multiple spots, obtained during mapping; (2) an adjustment for “a hidden population”, obtained from surveys among FSW and TGW. For the multiplier method, we used data from services of non-governmental organisations that FSW and TGW were in contact with, and surveys based on respondent-driven sampling. Surveys were carried out in the cities of Colombo (FSW, TGW), Kandy (FSW), Galle (FSW) and Jaffna (TGW). We estimated that there are 30,000 FSWs in Sri Lanka, with a plausible range of 20,000–35,000, which implies a prevalence of FSW of 0.56% (0.37–0.65%) among adult females. This study provided baseline estimates of 2,200 TGW in the country, with a plausible range of 2,000–3,500, which is 0.04% (0.04–0.07%) of adult male population. Our estimates of the proportional contribution of the FSW and TGW populations among the adult population in Sri Lanka are consistent with the The Joint United Nations Programme on HIV/AIDS (UNAIDS) recommended estimates for Asia and the Pacific. The results provide an important point for macro- and micro-level planning of HIV services, allocating programme resources and assessing programme coverage and quality.

Klíčová slova:

Asia – Census – Extrapolation – Female sex workers – HIV – HIV epidemiology – Sri Lanka – Surveys


1. Census of Population and Housing. Department of Census and Statistics, Sri Lanka. Available at Accessed July 16, 2019.

2. Country HIV Factsheets, UNAIDS. Available at Accessed on July 22, 2019.

3. Annual Report 2018. Colombo: National STD/AIDS Programme, Ministry of Health, Sri Lanka; 2018.

4. Abdul-Quader AS, Baughman AL, Hladik W. Estimating the size of key populations: current status and future possibilities. Curr Opin HIV AIDS. 2014; 9(2):107–14. doi: 10.1097/COH.0000000000000041 24393694

5. Quaye S, Fisher Raymond H, Atuahene K, Amenyah R, Aberle-Grasse J, McFarland W, et al. Critique and Lessons Learned from using Multiple Methods to Estimate Population Size of Men who have Sex with Men in Ghana. AIDS Behav. 2015; 19 Suppl 1:16–23.

6. UNAIDS/WHO Working Group on Global HIV/AIDS and STI Surveillance. Guidelines on Estimating the Size of Populations Most at Risk to HIV. Geneva: World Health Organization; 2010.

7. Wesson P, Reingold A, McFarland W. Theoretical and Empirical Comparisons of Methods to Estimate the Size of Hard-to-Reach Populations: A Systematic Review. AIDS Beh. 2017;21(7):2188–2206.

8. National Size Estimation of Most at Risk Populations (MARPs) for HIV in Sri Lanka. Colombo: National STD/AIDS Control Programme; 2013.

9. Yu D, Calleja JM, Zhao J, Reddy A, Seguy N. Estimating the size of key populations at higher risk of HIV infection: a summary of experiences and lessons presented during a technical meeting on size estimation among key populations in Asian countries. Western Pac Surveill Response J. 2014;5(3):43–9. doi: 10.5365/WPSAR.2014.5.2.008 25320676

10. Thein ST, Aung T, McFarland W. Estimation of the number of female sex workers in Yangon and Mandalay, Myanmar. AIDS Behav. 2015; 19(10):1941–7. doi: 10.1007/s10461-015-1169-9 26267254

11. Johnston LG, Prybylski D, Raymond HF, Mirzazadeh A, Manopaiboon C, McFarland W. Incorporating the service multiplier method into respondent-driven sampling surveys to estimate the size of hidden and hard-to-reach populations. Case studies from around the world. Sex Transm Dis 2013; 40: 304–301. doi: 10.1097/OLQ.0b013e31827fd650 23486495

12. Emmanuel F, Isac S, Blanchard JF. Using geographical mapping of key vulnerable populations to control the spread of HIV epidemics. Expert Rev Anti Infect Ther. 2013;11(5):451–3. doi: 10.1586/eri.13.33 23627850

13. Thilakavathi T, Chakrapani V, Selvaraj V, Noronha E, Narang A, Mehendale S. Mapping and Size Estimation of Hijras and Other Trans-Women in 17 States of India: First Level Findings. Int J Health Sci Res. 2015; 5(10): 1–10.

14. Baral SD, Poteat T, Strömdahl S, Wirtz AL, Guadamuz TE, Beyrer C. Worldwide burden of HIV in transgender women: a systematic review and meta-analysis. Lancet Infect Dis. 2013;13(3):214–22. doi: 10.1016/S1473-3099(12)70315-8 23260128

15. Chakrapani V, Willie TC, Shunmugam M, Kershaw TS. Syndemic Classes, Stigma, and Sexual Risk Among Transgender Women in India. AIDS Behav. 2019;23(6):1518–1529. doi: 10.1007/s10461-018-2373-1 30565093

16. Report on the National Size Estimation of the Most at Risk Populations for HIV in Sri Lanka. Colombo: National STD/AIDS Control Programme; 2018.

17. Random Integer Set Generator. Available at Accessed on 26 July 2019.

18. Integrated Biological and Behavioural Surveillance Survey among Key Populations at Higher Risk of HIV in Sri Lanka 2017/2018. Colombo: National STD/AIDS Control Programme and Management Frontiers, Ltd.; 2018.

19. Heckathorn DD. Respondent-driven sampling: A new approach to the study of hidden populations. Social Problems. 1997; 44(2): 174–199.

20. Handcock MS, Fellows IE, Gile KJ, 2014. RDS Analyst: Software for the Analysis of Respondent-Driven Sampling Data. Version 0.51.

21. Gile KJ. Improved Inference for Respondent-Driven Sampling Data with Application to HIV Prevalence Estimation. J Am Stat Assoc. 2011; 106: 135–146.

22. Khalid FJ, Hamad FM, Othman AA, Khatib AM, Mohamed S, Akh A, et al. Estimating the number of people who inject drugs, female sex workers, and men who have sex with men, Unguja Island, Zanzibar: results and synthesis of multiple methods. AIDS Behav. 2014;18(Suppl 1):S25–31.

23. Dalkey NC. The Delphi method: an experimental study of group opinion, RM-5888-PR. Santa Monica, CA: The RAND Corporation; 1969.

24. Quick Start Guide for Spectrum. Geneva: UNAIDS, 2018.

25. 2015 Size Estimation of Key Affected Populations in the Philippines. Manila: Epidemiology Bureau, Department of Health, Philippines, 2016.

26. Poudel T, Gupta S, Bhattarai Rajan, Rawal BB. Mapping and Size Estimation of Key Populations in Nepal. Journal of Gandaki Medical College-Nepal. 2019; 1 (12): 39–42.

27. Poteat T, Scheim A, Xavier J, Reisner S, Baral S. Global Epidemiology of HIV Infection and Related Syndemics Affecting Transgender People. J Acquir Immune Defic Syndr. 2016.15;72 Suppl 3:S210–9.

28. Size estimation of transgender population in Cambodia. Phnom Penh: Family Health International 360 Cambodia; 2013.

29. Quaye S, Fisher Raymond H, Atuahene K, Amenyah R, Aberle-Grasse J, McFarland W, et al. Critique and lessons learned from using multiple methods to estimate population size of men who have sex with men in Ghana. AIDS Behav. 2015;19 (Suppl 1):16–23.

Článek vyšel v časopise


2020 Číslo 1