Hepatitis C Virus (HCV) infection is one of the major public health issues of the 21st Century. In the UK, it is estimated that 200,000 to 450,000 individuals, mostly persons who have injected drugs, are infected with HCV 12. Many studies of the prevalence and determinants of HCV among injecting drug users (IDUs) have been undertaken 3 but few have focussed on women who work as street prostitutes to finance their drug habit 4; previous studies among female sex workers have generally involved a low proportion (≤ 5%) of IDUs 56. The investigators report the survey findings of such a population in Glasgow, a city with one of the highest prevalences of injecting drug use in Europe (2.7% of 20–29 year olds in 1990) 7.

The sample was not necessarily representative of Glasgow's street sex workers due to potential participation bias as a consequence of refusal to be studied, and selection bias due to the approach of convenience sampling in a health and social care setting for this population. Nevertheless, the finding that nearly three-quarters of respondents had attended the DIC within one year of beginning street sex work is consistent with a very high proportion of Glasgow's city centre street-workers accessing this service; further, the average number of women attending the DIC during the 1990s was 500–1,000, a figure similar to the estimated number of women working as street sex workers in Glasgow at any one time 11.

Adjusting for the 85% sensitivity of the saliva test, the HCV antibody prevalence among IDU sex workers was 81%, a rate which is considerably higher than those (60–70%) recorded, contemporaneously, for Glasgow IDUs generally 112. Indeed, this prevalence is considerably higher than any recorded among IDU populations throughout the UK between 1991 and 2005 13.

The HCV antibody prevalence of 50% among sex workers who began to inject in the previous two years – between 1997 and 1999 – indicates that harm reduction interventions, such as needle/syringe exchange and methadone maintenance treatment – introduced in the late 1980s and early 1990s – had not controlled the spread of HCV in this population. This rate was significantly (χ²(1) = 10.3, p = 0.001) higher than that found in a community-wide sample of IDUs, recruited in Glasgow during 1999, who had injected for under two years (20% in saliva, 27/136; unpublished data, Health Protection Scotland). Despite the provision of a wide range of services at the DIC, including guidance about safe injecting, counselling and needle and syringe provision, and that the DIC was attended by a large proportion of participants within 12 months of their injecting and sex working debuts, the incidence of HCV infection among this group remains high. Research has shown that while harm reduction programmes (e.g. methadone maintenance treatment and needle exchange programmes) have been effective in reducing the incidence of HIV 1415, they have been less successful in reducing the incidence of HCV 16171819. Some authors have suggested this may be the result of the harm reduction effort focusing on needle and syringe sharing 20 when the sharing of injecting paraphernalia other than needles and syringes (e.g. spoons and filters) has been demonstrated to increase HCV transmission 212223. However, data on paraphernalia was not collected in the current study.

The two principal determinants of HCV antibody positivity – ever sharing needles/syringes and frequency of imprisonment – have been widely recognised among IDUs 192425, though, hitherto, not specifically in this sub-group.

The high rate of HCV antibody positivity (48%) among the IDUs who declared never sharing needles and syringes is not an uncommon finding. Poor recall, mendacity and the acquisition of HCV through, for example, the sharing of other injecting equipment such as spoons and filters 26 are possible reasons for this observation.

Since the women reported that they almost always used condoms when engaging in sexual intercourse with their clients and since the efficacy of HCV transmission through such unprotected behaviour is known to be low, appreciable sexual transmission of infection between such sex workers and their clients is unlikely to occur. HCV prevalence surveys of non-IDU sex workers, the numbers of whom were considerably greater than that recruited in this investigation, indicate rates of less than 1% 4272829.

This study examines the prevalence and determinants of hepatitis C virus infection among female drug injecting sex workers, an understudied and difficult to reach population. Women who engage in street sex work to finance their drug use are a particularly desperate, chaotic and vulnerable population. The HCV antibody prevalence among IDU sex workers sampled was 81%. Therefore, this study demonstrates that their HCV infection risk may be greater than that for other IDUs. Furthermore, the majority of those interviewed reported using condoms with clients highlighting the effectiveness of the DIC in addressing sexual risk taking behaviour among sex workers. Therefore, it is unlikely that the increased prevalence is a result of sexual transmission, rather the results demonstrate that ever sharing needles and syringes and the frequency of incarceration were associated with HCV antibody positivity. Thus, those responsible for designing interventions to prevent HCV infection among IDUs should consider the special needs of this group. Since 1999, a methadone clinic has been operational at the DIC and a needle exchange service established in hostels for homeless persons – many of whom are IDU sex workers. It remains to be seen how effective these additional initiatives have been in stemming the spread of HCV among this population.

The authors declare that they have no competing interests.

Avril Taylor conceived of the study, participated in its design, project managed the study and drafted and critically revised the manuscript. Sharon Hutchinson performed the statistical analysis, and drafted and critically revised the manuscript. Gail Gilchrist participated in the study design, collected data and samples, and drafted early manuscript. Sheila Cameron conducted analysis of saliva samples. Susan Carr conceived of the study, and participated in its design. David Goldberg conceived of the study, participated in its design and critically revised the manuscript. All authors read and approved the final manuscript.