Injection drug use and sexually transmitted infections among men who have sex with men: A retrospective cohort study at an HIV/AIDS referral hospital in Tokyo, 2013-2022.

Men who have sex with men (MSM) who use injection drugs (MSM-IDU) are at high risk of sexually transmitted infections (STIs), but the long-term incidence is unclear. We conducted a single-centre retrospective cohort study using the clinical records of non-haemophilia men with human immunodeficiency virus (HIV) who visited the Institute of Medical Science, the University of Tokyo (IMSUT) Hospital, located in Tokyo, Japan, from 2013 to 2022. We analysed 575 patients including 62 heterosexual males and 513 MSM patients, of whom 6.8% (35/513) were injection drug use (IDU). Compared to non-IDU MSM, MSM-IDU had a higher incidence of hepatitis C virus (HCV) (44.8 vs 3.5 /1,000 person-years (PY); incidence rate ratio (IRR) [95% confidence interval (95% CI)], 12.8 [5.5-29.3], p < 0.001) and syphilis (113.8 vs 53.3 /1,000 PY; IRR, 2.1 [1.4-3.1], p < 0.001). The incidence of other symptomatic STIs (amoebiasis, chlamydia, and gonorrhoea infections) was <4/1,000 PY. In multivariable Poisson regression analysis, HCV incidence was associated with MSM (IRR, 1.8 × 106 [9.9 × 105-3.4 × 106], p < 0.001), IDU (IRR, 10.1 [4.0-25.6], p < 0.001), and syphilis infection during the study period (IRR, 25.0 [1.2-518.3]/time/year, p < 0.001). Among men with HIV, the prevalence of IDU in MSM and the long-term incidence of STIs in MSM-IDU were high. IDU and sexual contact are important modes of transmission of HCV among HIV-infected MSM in Tokyo.

The resurgence of syphilis in high-income countries in the 2000s: a focus on Europe.

Syphilis can cause severe complications and sequelae. Following a decrease in reported cases in European Union/European Economic Area (EU/EEA) and other high-income countries in the 1980s and 1990s as a result of the HIV epidemic and ensuing changes in sexual behaviour, trends started to increase in the 2000s in a number of EU/EEA Member States with higher rates among men and a large proportion of cases reported among men who have sex with men (MSM), particularly HIV-positive MSM. Trends in EU/EEA Member States vary however with some countries continuing to report decreases in the number of reported cases (mostly in the Eastern part of EU/EEA) whereas many Western European countries report increasing numbers of cases. Increasing rates among women, although still relatively low, have been observed in a number of countries leading to concerns around mother-to-child transmission of syphilis and congenital syphilis. Similar overall trends are observed in other high-income countries with the exception of Japan where rates among heterosexual men and women have been rising at alarming levels. Control of syphilis requires use of comprehensive, evidence-based strategies which take into account lessons learned from previous control efforts as well as consideration of biomedical interventions.