Background Mobile unit (MU) HIV testing is an alternative method of providing healthcare access. We compared demographic and behavioural characteristics, HIV testing history, and HIV prevalence between people seeking testing at a MU vs. fixed community clinic (FC) in Lima, Peru.

Methods Our analysis included men and transwomen (TW) in Lima ≥ 18 years old seeking HIV testing at their first visit to a community-based clinic’s MU or FC from Oct. 2007-Nov. 2009. Behavioral characteristics, including HIV testing history, and HIV serostatus of the following populations were compared in MU vs. FC attendees: TW, men who have sex with men (MSM), and heterosexually self-identified men who have sex with men and women (MSMW).

Results A greater percentage of MU attendees self-identified as transgender (8% vs. 3% FC, p < 0.05) or heterosexual (52% vs. 15% FC, p < 0.05). MU and FC sites attracted similar proportions of MSMW (52% MU vs. 57% FC). MU attendees were more likely to engage in compensated sex (10% MU vs. 4% FC, p < 0.05), not use condoms during their last sexual encounter (64% MU vs. 45% FC, p < 0.05), and be a first-time HIV tester (50% MU vs. 41% FC, p < 0.05; see Table 1).

MU HIV prevalence was 5% (vs. 17% FC, p < 0.05). Among first-time testers, HIV prevalence in both MSM and TW was not significantly different between MU and FC attendees (MSM: 13% MU vs. 19% FC p = 0.14; TW: 41% MU vs. 50% FC p = 0.71).

Conclusion MU testing reached large numbers of high-risk (TW/MSM) and potentially bridging (MSMW) populations engaged in unsafe sexual behaviours. MU HIV prevalence for MSM/TW first-time testers was similar to that of the FC, making MU outreach a worthy complement to FC testing. Further investigation into whether MU attendees would not otherwise access HIV testing is warranted to determine the impact of MU testing.