Violence and mobility are increasingly being recognized as important risk factors contributing to the spread of HIV and sexually transmitted infection (STI) worldwide 1 2 3 4 5 6 7 8 9 10 11 . High rates of violence perpetrated against female sex workers (FSWs) have been consistently documented in developing countries 12 13 14 . In a study of mobile FSWs (those who travelled to two or more places for sex work over a two-year period) in India, approximately one-third reported experiencing violence 14 . Both in India and elsewhere, published literature indicates that FSWs exposed to violence were more likely to be infected with HIV and other STI than those who did not report such experiences 15 16 . Forced unprotected sexual encounters were described as the most likely cause for their heightened vulnerability to HIV 12 14 17 . Further, research indicates that forced sex was a barrier to condom negotiation 12 and increased the likelihood of condom failure 13 18 .

In addition to violence, recent research has identified employment-related mobility (intra-district, inter-district, or inter-state) as another major risk factor associated with HIV 4 8 9 10 19 20 21 22 23 . In India, as is the case globally, FSWs are highly mobile for sex work 5 due to police harassment 24 ; to escape stigma and discrimination 4 25 ; and to attract a different or wider client base 11 . Research suggests that FSWs who were mobile for sex work had higher rates of HIV as compared to non-mobile FSWs 5 10 , possible reasons being their experience of violence 11 14 17 , sexual risk behaviors such as unprotected sex 4 5 25 , lack of access to condoms 25 , inability to negotiate safe sexual practices 26 , and limited access to health care services 11 27 and HIV prevention programs 11 26 in new locations.

While studies have demonstrated the independent effect of mobility and experience of violence on FSWs’ sexual risk behaviors and STI, there is a paucity of literature on the combined relationship of mobility and violence on HIV risk behaviors, STI and HIV. This paper seeks to address this gap in the literature by examining: (a) the independent association between mobility for sex work and violence; and (b) the independent as well as the combined association of mobility for sex work and violence on risky sexual behaviors and STI, including HIV.

Our findings indicate that a large percentage of FSWs travelled outside their current place of residence and practiced sex work during these visits, and nearly one-fifth experienced violence in this high HIV prevalence state of southern India; these results are similar to prior findings in India 5 14 17 . Additionally, the present study documents that mobile FSWs who experienced violence were two times more likely to have been diagnosed with HIV compared to those who reported neither mobility nor violence. A possible reason for the observed high prevalence of HIV among this subgroup of FSWs could be their risky sexual behaviors, as evidenced in the current study.

Consistent with previous research, our study shows that mobile FSWs were more likely to be infected with HIV than those who were not mobile 5 10 30 . While mobility for sex work per se may not be directly associated with HIV, as seen in prior research, mobility may increase FSWs’ vulnerability to exploitation and abuse as a result of operating in new environments with unknown clients and the lack of community ties for social support 11 . Empirical research suggests that mobility for sex work among FSWs is common in India and around the world 4 5 10 11 23 31 , and our study further suggests that some sub-groups of FSWs were more likely to be mobile than others. For example, mobility was higher among FSWs who were currently or previously married or who had a regular non-paying partner than others; reasons for higher mobility among this sub-group could be to work in an environment of anonymity and to keep their sex worker identity separate from their private life 25 . Following their relocation to new areas, FSWs face several kinds of vulnerabilities including physical and sexual violence 11 14 , a finding also observed in our study, which indicates that a greater proportion of mobile FSWs were abused as compared to those who were not mobile.

The current research also indicates that one-fifth of FSWs had experienced violence in the past year, and the experience of violence was higher in selected groups; for example, those who were previously married. Further, a higher proportion of FSWs who had experienced violence were infected with HIV than their counterparts; a finding that is consistent with previous research 15 16 . As described earlier, the underlying reasons for these FSWs’ heightened vulnerability to HIV could be multiple, such as the experience of forced sex, which may pose barriers to adopting safe sex behaviours 32 . Indeed, consistent with findings from prior research 13 14 17 , we found that FSWs who experienced violence were less likely to report condom use with clients as compared to those who did not experience violence.

While there is growing recognition of the effect of mobility and violence individually on the health of FSWs, including their vulnerability to HIV 1 2 3 4 7 33 34 , this study, to our knowledge, is amongst the first to assess the combined effect of mobility and violence on sexual risk behaviors and STI, including HIV, among FSWs. The prevalence of HIV increased twofold among respondents who reported both mobility for sex work and violence, compared to those who reported neither. Although not statistically significant, a higher proportion of mobile FSWs who experienced violence were infected with STI as compared to those who were neither mobile nor reported violence. This lack of significant association could be because of the low prevalence of STI diagnosed among this group of FSWs. Additionally, infections that occurred as a result of violence may have been treated as there is indiscriminate use of antimicrobials in India due to the easy availability of drugs over-the-counter without a medical prescription 35 .

While this study underlines the strong association between violence, mobility and the prevalence of HIV among FSWs, the results should be interpreted with caution in light of certain limitations. First, the key independent variables considered in this study were based on self-reported responses, and the limitations of self-reported data are widely recognized 36 . Moreover, violence may have been underreported perhaps due to the stigma attached with reporting of violence or the sex workers’ perception of reporting based on only severity of violence 36 . However, the use of trained and experienced research staff while conducting the IBBA may have increased respondents’ comfort level at the time of interview and reduced underreporting. Second, in the multivariate analyses we have only accounted for factors that were measured in the survey; therefore, the associations of key independent and dependent measures could have been affected by omission variable bias. Third, while our study analyzes recent mobility status and experience of violence, the HIV seropositivity data reflect only prevalence. Therefore we cannot determine whether there is any temporal relationship between violence, mobility and HIV infection. However, this study is based on the assumption that FSWs who reported experience of violence and mobility in the recent past may have also experienced similar vulnerabilities since their entry into the sex work. Finally, the findings of this study cannot be generalized to all FSWs across India as sex work in India is complex in nature and characterized by inter- and intra-regional differences. For example, in the north Indian states, the sex work industry is relatively visible, and is largely brothel-based, whereas in the southern states a significant proportion of sex work is home-based or street-based 37 38 39 . However, the study results can be generalized to other geographical areas with similar sex work settings, volume of mobility and HIV prevalence. Nonetheless, these limitations do not compromise the internal validity of the data: our findings are consistent with the results of previous studies that have assessed the association between violence, mobility and sexual risk behaviors/HIV and advance the knowledge on the inter-linkages between these risk factors and sexual risk behaviors/HIV. However, future research could provide critical information on several key issues that would have implications for HIV programming. For example, studies that include temporal data could provide insights on the causal relation between mobility and violence; that is, whether mobility among FSWs leads to the experience of violence or vice versa, so that programmatically FSWs most vulnerable could be addressed through appropriate structural interventions. Additionally, studies could explore the extent to which FSWs’ degree of mobility (less mobile versus more mobile) and exposure to violence are associated with sexual risk taking behaviour and HIV.

Our finding that mobile FSWs who have experienced violence are particularly vulnerable to HIV has significant implications for the design of HIV prevention programs. To reach FSWs with different vulnerabilities, interventions would need to implement strategies that recognize and address both issues of violence and mobility among FSWs. Moreover, intervention programs need to recognize that as mobile FSWs have recently moved to new places for sex work, they may be poorly informed about HIV prevention support and service programs in the new area, and additional efforts would be required to connect them to suitable local services, such as the availability of crisis response systems that provide appropriate information and timely services to address violence.

In the context of the study finding that mobile FSWs who also experience violence are at greater risk of acquiring HIV than others, special efforts are needed to address the vulnerabilities of this subgroup of sex workers. Ongoing and future programs need to explore the ways in which they can improve accessibility to support structures and services for sex workers on the move. Additionally, the ongoing efforts of community mobilization 40 41 need to be expanded to create an enabling environment and safe spaces for FSWs from perpetrators of violence. Further, it would be important to identify all FSWs who move to different places for sex work and orient them to prevention and crisis response services in the new location, which would help augment existing efforts to reduce the spread of HIV in India and elsewhere.

The author(s) declare that they have no competing interests.

SR led conceptualization, conducted all analyses, and wrote the manuscript. DG assisted with writing and editing of the paper. BM and RMM assisted with the analyses. NS assisted with conceptualization of analytic approach and interpretation of study findings. All authors have read and approved this final submitted manuscript.