1. HIV Risk Factors and Injection Drug Use among Men who Have Sex with Men in Unguja Island, Zanzibar, Tanzania A. Holman 1, M. Dahoma 2, L. Johnston 3, K. Sabin 4, A. Othman 2, R. Martin 5, A. Kim 4, M. Mussa 2, C. Kendall 6, T. Kibuka 5, L. Nganga 5 1 Association of Schools of Public Health/Centers for Disease Control – Tanzania 2 Zanzibar AIDS Control Program, Ministry of Health and Social Welfare 3 Tulane University School of Public Health and Tropical Medicine 4 HHS-Centers for Disease Control and Prevention, Global AIDS Program, Atlanta, United States 5 HHS-Centers for Disease Control and Prevention, Global AIDS Program, Tanzania

2. Source: www.lib.utexas.edu/maps/tanzania.html www.lib.utexas.edu/maps/tanzania.html Zanzibar 2 islands forming semi-autonomous territory of the United Republic of Tanzania: Unguja and Pemba. Estimated population 1.1 million (2002 Census) Agriculture-based economy; Popular tourist destination 99% Muslim

3. Background Zanzibar has a concentrated HIV epidemic. –HIV prevalence is <1% in general population (Tanzania HIV/AIDS and Malaria Indicator Survey, 2007-08) Several ‘hidden’ populations with documented or presumed increased risk for HIV: –Injection-drug users: Illegal and increasingly common practice HIV prevalence 26% (2005) –Men who have sex with men (MSM) Illegal practice according to Zanzibar law No information on sex or drug-use practices Seroprevalence and behavioural survey conducted in 2007 among MSM in Unguja island provides opportunity to study prevalence of drug-use, sex practices, and HIV in this population

4. Objective To describe drug-use and sexual practices and prevalence of HIV and other selected infections among injection drug-using MSM in Unguja Island, Zanzibar.

5. Methods: Respondent-driven sampling (RDS) Chain-referral sampling method – adapted to attain probability-based sample of ‘hidden’ populations based on social network theory (Heckathorn 2007). Appropriate method for sampling highly socially networked populations, e.g. MSM in Zanzibar Recruitment –Initial recruits (seeds) identified through formative research and peer-educator contacts. –Successive waves of recruitment until sample size is reached.

6. RDS Recruitment Seed

7. RDS Recruitment Wave 1

8. RDS Recruitment Wave 1Wave 2

9. Wave 1Wave 2Wave 3

10. Wave 1Wave 2Wave 3Wave 4

11. Wave 1Wave 2Wave 3Wave 4Wave 5…

12. Study design (1) 10 seeds selected through formative research to initiate recruitment. April to June 2007, 509 MSM enrolled in survey. Eligibility: Men aged >15 years, living in Unguja and reporting engaging in anal sex with another man within 3 months before the survey. Dual incentives –~US$5 for participation in study –~US$1.75/peer successfully recruited into the study

13. Study design (2) Data collected Interview (119 items) Socio-demographic and network questions Sexual practices Injection and non-injection drug use practices HIV knowledge, risk perception, and previous HIV testing history Venipuncture blood sample HIV – rapid-test-based serial algorithm: SD Bioline HIV-1/2 3.0, Determine HIV ½ test, Unigold Hepatitis C – ACON virus test strip Hepatitis B – ACON virus test strip Syphilis – ACON Syphilis Ultra Rapid Test strip

14. Data Analysis 1.Adjusted proportion estimates (weighting based on participants’ probability of recruitment) and 95% confidence intervals calculated with RDS Analysis Tool 5.6 (RDSAT) 2. Unadjusted and adjusted odds ratios calculated in STATA 9.0 using weights generated in RDSAT.

15. Socio-demographic characteristics of study population (N=509) Adjusted proportion estimate (APE) Age (years) ≥ 3523.3% 25 - 3442.9% ≤ 2433.8% Marital Status Never married58.3% Married28.8% Separated/divorced/widowed12.8% Education >11 years20.2% 8-10 years44.3% 2-7 years35.5% Age at first sex >258.1% 16-2470.6% <1521.3% Gender of sex partners in the last year Males and female71.7% Exclusively males28.3%

16. Proportion of MSM reporting injection drug use, Unguja, Zanzibar Groups similar in marital status and education; IDU-MSM more likely to be 25 years or older (UOR 3.4, CI. 1.6 - 8.5). Non-IDU MSM (N=442) IDU MSM (N=66)

17. Injection drug use practices among MSM, Unguja, Zanzibar (N=66) Percent (APE) of MSM IDU (N) 95% CI Drug used last time injected Heroin66% (32)38.2-85.3 Cocaine34% (24)14.7-61.8 Needle sharing practices at last injection Used needle after someone else had used it51% (40)8.9-86.9 Passed a needle to someone after using it49% (26)13.1-91.1 Frequency of injecting drugs in past one month Daily or more often32% (16)12.1-72.1 Several times a week6% (11)0-17.5 Less than one time per week62% (35)26.5-79.4

18. Reported previous month sex practices among IDU MSM (N=66) vs. non-IDU MSM (M=442) in Unguja, Zanzibar 95% CI

19. Reported sexual practices, risk perception and HIV testing among non-IDU MSM (N=442) and IDU MSM (N=66) in Unguja, Zanzibar

20. Prevalence of HIV and STIs among non-IDU MSM (N=442) and IDU MSM (N=66) in Unguja, Zanzibar

21. Conclusions RDS a successful approach for recruitment of ‘hidden’ populations: potential for use to deliver prevention interventions and services. Injection drug use is associated with higher risk sexual practices, unsafe injection practices and HIV infection among MSM. High rates of unprotected sex with female and male partners: potential to serve as a bridge for HIV transmission between non-IDU MSM, heterosexual IDU, female partners and the general population. Poor access to HIV testing and related services.

22. Recommendations Need for targeted interventions for MSM IDU accounting for the overlap of high-risk sexual and drug using networks: STI testing and treatment, HIV counseling, testing, care and treatment, and linkages to IDU services. –Since dissemination meeting among stakeholders in November 2007, community-based peer educator initiatives for HIV prevention within the MSM community have been significantly scaled up. These initiatives should be provided ongoing support and links to existing services should be facilitated.

23. Acknowledgements Study participants and peer educators Zanzibar study staff Zanzibar AIDS Control Programme, Ministry of Health and Social Welfare Tulane University School of Public Health and Tropical Medicine Centers for Disease Control and Prevention – Tanzania & Atlanta

24. For more information Dr. Mohammed Dahoma Zanzibar AIDS Control Programme zacp@zanlink.com Abigail Holman Centers for Disease Control and Prevention - Tanzania holmana@tz.cdc.gov