High HIV and hepatitis C prevalence amongst injecting drug users in Mauritius: findings from a population size estimation and respondent driven sampling survey.

BACKGROUND: Mauritius, an Indian Ocean Island nation of approximately 1,000,000 people, has a large number of injecting drug users (IDUs), many of whom are infected with HIV and HCV. Mauritius has been expanding harm reduction and HIV services based in the belief that HIV prevalence amongst IDUs is somewhere between 30 and 60% and the IDU population size is around 20,000. In 2009, the government of Mauritius conducted a survey to estimate the infection prevalence and risk factors and to estimate the population size of IDUs in order to more effectively expand programmes.
METHODS: Men and women aged >15 years living in Mauritius and injecting illicit drugs in the past three months were recruited using respondent driven sampling (RDS). Consenting participants were interviewed about HIV-risk behaviours and tested for HIV, syphilis, HCV and HBV. Six multipliers were collected from service data and by the 'unique identifier' method in conjunction with the RDS survey. Proportions were calculated using the RDS analysis tool.
RESULTS: 511 IDUs enrolled in the survey; 61.2% reported injecting 2-3 times/day and 29.3% reported past month injection with a previously used needle. Amongst the 60% of IDUs who reported having sexual intercourse in the past three months, 39.5% did so with ≥2 partners. Almost all IDUs (98.1%) reported inconsistent condom use in the past 12 months. HIV prevalence was 47.4%, HCV 97.3%, HBV 9.0%, and syphilis 2.7%; 99.7% of those infected with HIV were also infected with HCV. Our population size estimates put the number of IDUs in Mauritius at around 9500, lower than previous estimates.
CONCLUSIONS: We observed high rates of HCV and HIV infection amongst IDUs in Mauritius. The scale-up of targeted HCV and HIV prevention, care and treatment services for IDUs should be a high priority.