Implications of high prevalence of recreational drug use among cases of infectious syphilis: insights from state-wide surveillance data, South Australia, July 2022 - September 2023.

BACKGROUND

Both injecting drug use (IDU) and drug use by non-injecting routes only (non-IDU) are recognised internationally as behavioural risk factors for syphilis. In Australia, this association has predominantly been assessed in sexual health services. To generate evidence supporting regular screening and timely symptomatic testing of all at-risk populations, South Australia in 2022 commenced routine collection of drug use information for statutory syphilis surveillance.

METHODS

We analysed reported IDU and non-IDU for all cases of infectious syphilis notified during the period 1 July 2022 - 30 September 2023 by demographic, clinical, and diagnosing provider characteristics. We used descriptive analyses and univariable logistic regression to compare IDU cases and non-IDU cases separately to cases reporting no drug use.

RESULTS

There were 450 notifications during the 15-month period. Among the 92% of notifications with available information, IDU was reported for 10% of cases and non-IDU for 17%. Drug use of any kind was more common among females, cases diagnosed outside specialist services, and heterosexual and bisexual cases. Differences by city versus regional or remote location and symptom status were less notable. Only the increased odds of IDU among females (odds ratio (OR): 2.8; 95% confidence interval (95% CI): 1.2-6.3) and the increased odds of either type of drug use among cases reporting sexual partners of a different sex (IDU: OR: 2.5; 95% CI: 1.2-5.3; non-IDU: OR: 3.0; 95% CI: 1.7-5.4) and of partners of both sexes for non-IDU (OR: 3.0; 95% CI: 1.4-6.6) reached statistical significance.

CONCLUSION

These data demonstrate a high prevalence of IDU and non-IDU amongst syphilis cases diagnosed outside sexual health services. Females and heterosexuals report drug use more frequently than men who have sex with men (MSM). In response, the correctional and drug and alcohol sectors have been engaged to increase routine screening and primary care providers alerted to recreational drug use as a risk factor for syphilis.