STI self-report was higher among the KP groups compared to the general population (MSM: 11.9%, FSW: 33.5%, PWID: 22.0% vs Men: 5.0% and Women: 7.0%). The high-burden of STIs among KPs are consistent with other studies and underscores the importance of integrating STI prevention efforts in KP prevention and treatment services (19, 20). This is especially important among FSW where a third of the FSW participants self-reported STI infection, thus highlighting the generalized risk of STI infection among this entire population group.
The results from MSM show that STI self- report was associated with receptive (vs insertive) sex, which is consistent with findings from other studies in the region (21). Other risk factors consistent with the literature included circumcision, which may be a result of decreased perception of risk. Physical and sexual violence were also major risk factors for STI infection among FSW and the socio-cultural dynamics contributing to this vulnerability, such as gender power inequalities, economic disparities, and criminalization of sex work, have been explored previously (19, 22, 23).
The results suggest that having other work aside from sex work is associated with more risk, however this requires further investigation given that it is contrary to findings among FSW in Uganda where having employment outside of sex work was considered a protective factor (19).
While HIV infection was only significantly associated with STI self-report among MSM (11, 12), the similar modes of sexual transmission necessitate a need for concentrated efforts to encourage safer sexual behaviours, such as condom use. This is especially important when considering the greater odds of STI-self report among FSW reporting non-condom use with their last client and MSM reporting non-condom use with their last male partner. Given the dynamics of bridging populations - a subgroup of people who have sexual contact with both key populations and the general population such as MSM married to women, clients of FSW and non-client sexual partners of FSW - non-condom use represents a potential public health risk to the wider population (2). Access to HIV prevention services was associated with STI-self report among FSW and PWID, although this may be a result of having symptoms which put one in contact with health services.
Our findings draw attention to the intersectionality of key population groups and their risk behaviours. For example, sex work was associated with STI self-report for PWID, while illicit drug use was a risk factor among both FSW and MSM (22); these overlapping risk profiles were also found in other studies (20). Our results emphasize that treatment and prevention efforts are limited when only considering the primary risk behaviour of a population while isolating others. Any efforts targeted to key populations must adopt a people-centred approach to address overlapping risk behaviours.
Although the sample size of female PWID in our study was too small to perform meaningful analysis (n = 25), other studies have pointed to the unique vulnerabilities of female PWID (25). Qualitative studies among female PWID in Mozambique would provide more information about the gendered nature of risk factors in this group.
Finally, there were greater odds of self-report among FSW residing in Beira and PWID residing in Nampula. Limited resources require the geographic prioritization of efforts based on evidence and require the standardized implementation of quality treatment and prevention services.
Since the implementation of these BBS surveys, the National HIV Program has scaled up prevention, care and treatment efforts for KPs in Mozambique. In 2016, National Guidelines were published that aimed to integrate HIV prevention and treatment services for KPs into the health sector (26). These included the creation of standardized package of services for KPs with structural, biomedical and behavioural interventions, including STI screening, diagnosis and treatment. The guidelines commit to offering evidence-based quality services with a people-centred approach free from stigma and discrimination. The guidelines also aimed to strengthen the linkage between community and clinical services to ensure HIV testing among these hard to reach populations. The importance of STI prevention and control among Key Populations was further outlined in the 2018–2021 National Strategic Plan for the Prevention and Control of STIs (6). Future BBS surveys will be able to assess the extent KPs engagement with the health system, experiences of stigma and STI self-report.
Although this is the first analysis of risk factors associated with STIs among MSM, FSW and PWID in Mozambique, there are several limitations to consider. First, the reliance of self-reported STI symptoms, rather than laboratory testing of common and treatable STIs such as syphilis, chlamydia, and gonorrhoea, could have potentially underestimated STI prevalence by excluding asymptomatic cases. In addition, symptoms such as, discharge, may not necessarily have been the result of an STI. Second, not all survey measures were included in the three surveys (e.g. stigma/discrimination), thus it is not possible to compare risk factors across the different population groups. Additionally, the survey is also subject to the limitations to the survey design such as social desirability, interviewer and recruitment bias. It is also not possible to assess temporality, which, for example, can influence the interpretation of the association of STIs with access to HIV prevention services among FSW and PWID where it is not possible to determine if access to services brought people in contact with diagnosis or if perhaps having an STI symptom may have caused one to seek out services. Finally, the analysis pooled results from across the survey cities thus severing social networks and chains. As a result, these findings need to be interpreted with caution and cannot be generalized to the full MSM, FSW and PWID in the survey cities nor to key populations in Mozambique. Despite the limitations, however, the results of the analysis point to the high burden of STIs among key population groups in Mozambique and provide the evidence needed to advocate for comprehensive and integrated policies and health systems approaches to improve STI screening and case management among high-risk groups in Mozambique.