Infections and Sexual Behavior Among Injecting Drug Users in Melbourne (2012–2022)
Overview
This decade-long study of 1229 people who inject drugs (PWID) attending a Melbourne sexual health clinic revealed a significant increase in syphilis positivity from 0.6% to 10.0% between 2012 and 2021. Gay and bisexual men who have sex with men (gbMSM) exhibited higher rates of infections compared to men who have sex with women only (MSWO) and women. Hepatitis C virus (HCV) testing rates were low, highlighting a critical gap in prevention efforts.
Background
Injection drug use is relatively uncommon in Australia but is associated with increased vulnerability to blood-borne viruses (BBVs) such as HIV, hepatitis B (HBV), hepatitis C (HCV), and other sexually transmitted infections (STIs). Despite extensive needle and syringe programs reducing BBV transmission, PWID continue to experience poorer health outcomes and engage in risky sexual behaviors. Overlapping risk factors exist between PWID and LGBTQ populations, particularly gbMSM, who have higher rates of illicit drug use and sexual risk behaviors. Updated data on STI and BBV prevalence among PWID are essential to inform targeted harm reduction strategies.
Data Highlights
Infection
2-year Positivity (%)
Cases/Total Tested
95% CI
HIV (new)
2.6
22/861
1.6–3.8
Infectious Syphilis
6.8
59/866
5.2–8.7
Gonorrhea
8.6
77/892
6.8–10.7
Chlamydia
8.7
95/1093
7.0–10.5
HBV
0.6
3/545
0.1–1.6
HCV Antibody
10.0
45/448
7.4–13.2
Key Findings
Syphilis positivity increased significantly from 0.6% in 2012/2013 to 10.0% in 2020/2021 (Ptrend = .0033).
gbMSM had the highest overall infection positivity (29.1%) compared to MSWO (19.8%) and women (17.0%) (P < .001).
HIV new positivity was 2.6%, infectious syphilis 6.8%, gonorrhea 8.6%, chlamydia 8.7%, HBV 0.6%, and HCV antibody 10.0% among tested PWID.
Only 37.6% of PWID were tested for HCV, indicating suboptimal screening coverage.
Unsafe injecting and sexual practices remain common among PWID, contributing to ongoing transmission risks.
Clinical Implications
Clinicians should prioritize comprehensive STI and BBV screening, especially for syphilis and HCV, in PWID populations, with particular attention to gbMSM who are at higher risk. Increasing HCV testing rates and integrating sexual risk reduction counseling into harm reduction programs are critical to reducing infection burden. Tailored prevention strategies addressing both injecting and sexual behaviors are needed to curb rising syphilis rates and other infections.
Conclusion
PWID attending sexual health services in Melbourne exhibit high and increasing rates of syphilis and other STIs, with gbMSM disproportionately affected. Enhanced testing and targeted prevention efforts are essential to mitigate the burden of infections in this vulnerable population.
References
Authors/Source/2024 -- Infections and Sexual Behavior Among Injecting Drug Users Attending a Sexual Health Clinic in Melbourne, Australia: A Decade of Data from 2012 to 2022
