HIV Risk Factors and Injection Drug Use among Men who Have Sex with Men in Unguja Island, Zanzibar, Tanzania A. Holman1, M. Dahoma2, L. Johnston3, K. Sabin4, A. Othman2, R. Martin5, A. Kim4, M. Mussa2, C. Kendall6, T. Kibuka5, L. Nganga5 1Association 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 5HHS-Centers for Disease Control and Prevention, Global AIDS Program, Tanzania
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 Source: www.lib.utexas.edu/maps/tanzania.html
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
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.
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.
RDS Recruitment Seed
RDS Recruitment Wave 1
RDS Recruitment Wave 1 Wave 2
Wave 1 Wave 2 Wave 3
Wave 1 Wave 2 Wave 3 Wave 4
Wave 1 Wave 2 Wave 3 Wave 4 Wave 5…
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
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
Data Analysis • 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.
Proportion of MSM reporting injection drug use, Unguja, Zanzibar IDU MSM (N=66) • 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)
Reported previous month sex practices among IDU MSM (N=66) vs. non-IDU MSM (M=442) in Unguja, Zanzibar 95% CI
Reported sexual practices, risk perception and HIV testing among non-IDU MSM (N=442) and IDU MSM (N=66) in Unguja, Zanzibar
Prevalence of HIV and STIs among non-IDU MSM (N=442) and IDU MSM (N=66) in Unguja, Zanzibar
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.
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.
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
For more information Dr. Mohammed Dahoma Zanzibar AIDS Control Programme firstname.lastname@example.org Abigail Holman Centers for Disease Control and Prevention - Tanzania email@example.com