Acute hepatitis C related to chemsex: insights from a Spanish cohort

Background Despite the transformative impact of direct-acting antivirals (DAAs) on hepatitis C control, acute/recent hepatitis C virus (HCV) infections continue to be diagnosed in contemporary clinical practice. We describe acute/recent HCV cases diagnosed at a tertiary hospital in Madrid among men who have sex with men (MSM), including people living with HIV (PLHIV) and pre-exposure prophylaxis (PrEP) users. Methods We conducted a retrospective, single-centre descriptive study including acute/recent HCV cases reported between January 2023 and January 2025. Cases were defined by detectable HCV RNA following a previously negative HCV serology or after a cured HCV infection (reinfection). Chemsex was defined as intentional use of psychoactive substances in sexual contexts; slamsex as injecting drugs in sexual contexts. Patients initially managed with watchful waiting were reassessed at 12 weeks to assess spontaneous clearance. Results Ninety-two cases were included; median age was 43 years (IQR 36–52) and 24 (26.1%) were >50 years. In total, 91 out of 92 (98.9%) were MSM; 70 (76.1%) were PLHIV and 19 (20.7%) were PrEP users. Among 84 patients with genotype data, 55 (59.8%) had genotype 1a, 8 (8.7%) 1b, and 21 (22.8%) genotype 4. HCV RNA was >6 log in 41 (44.6%) and >7 log in 18 (19.6%). Chemsex was reported by 72 (78.3%); among them, 38 (52.8%) reported slamsex. Among those with available data, 17 out of 54 (31.5%) had another sexually transmitted infection. Watchful waiting was initially adopted in 73 (79.3%); 5 out of 73 (6.8%) achieved spontaneous clearance at 12 weeks. Of those observed, 68 (93.2%) initiated DAAs; 9 (9.8%) were treated at diagnosis. Ten (10.9%) were lost to follow-up before treatment initiation; sustained virological response was achieved in treated patients. Conclusions Acute/recent HCV diagnoses occurred predominantly among MSM, including PLHIV and PrEP users, with frequent reporting of chemsex/slamsex. Low spontaneous clearance and losses before treatment initiation highlight the need for targeted HCV testing and linkage to care in HIV/PrEP and sexual health services, alongside harm reduction and substance use support.