ACUTE hepatitis C is being diagnosed in a high-risk sexual health cohort in Madrid, with most cases occurring among men who have sex with men (MSM) and a substantial proportion reporting chemsex and slamsex. The findings also highlight a low spontaneous clearance rate and ongoing gaps in linkage to care.
Chemsex Patterns in Acute Hepatitis C Cases
The study identified 92 cases of acute or recent hepatitis C virus (HCV) infection between January 2023 and January 2025. Nearly all cases (98.9%) occurred in MSM, with most patients either living with HIV (76.1%) or using HIV pre-exposure prophylaxis (PrEP) (20.7%).
Chemsex was reported by 78.3% of patients. In this study, chemsex refers to the intentional use of psychoactive substances in sexual contexts. Within this subgroup, 52.8% also reported slamsex, defined as injecting of drugs during sexual activity.
Of the 54 with additional available data, 17 had concurrent sexually transmitted infections, indicating overlapping sexual health risks in this cohort.
Patient Profile and Viral Characteristics
The median age was 43 years, with 26.1% aged over 50 years. HCV genotype data from 84 patients showed genotype 1a in 59.8%, genotype 4 in 22.8%, and genotype 1b in 8.7%.
Viral burden was substantial, with HCV RNA exceeding 6 log in 44.6% of patients and 7 log in 19.6%, indicating high levels of viraemia in a significant subset of cases. Interpretation of these findings should take into account that more than three-quarters of patients were living with HIV, which may have influenced the clinical characteristics observed in this cohort.
Low Spontaneous Clearance and Treatment Pathways
Most patients (79.3%) were initially managed with watchful waiting and reassessed at 12 weeks to evaluate spontaneous clearance. However, clearance occurred in only 6.8% of those observed.
Following reassessment, 68 of 73 patients (93.2%) proceeded to direct-acting antiviral therapy, while a smaller number received immediate treatment at diagnosis. Among treated patients, sustained virological response was achieved, indicating effective viral eradication when therapy was completed.
Follow-Up Gaps and Service Implications
Loss to follow-up before treatment initiation occurred in 10.9% of cases, raising concerns about continuity of care within affected services. This is concerning given the elevated risk profile of this population. The combination of delayed treatment initiation and patient attrition highlights challenges in maintaining engagement across sexual health and HIV care pathways.
The pattern of high chemsex involvement, low spontaneous clearance, and treatment attrition supports calls for strengthened HCV testing, improved linkage to care, and integrated harm reduction and substance use support within HIV and PrEP services.
Reference
Asensi Díaz E et al. Acute hepatitis C related to chemsex: insights from a Spanish cohort. Sex Transm Infect. 2026;DOI:10.1136/sextrans-2025-056844.
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