This study provides new insights into the transmission of the hepatitis C virus (HCV), which predominantly affects the liver and is often contracted through the injection of drugs. However, this research explicitly addresses the transmission among men who have sex with men (MSM). Researchers undertook a prospective cohort study in New York City involving MSM with HIV who had previously cleared an initial HCV infection. The purpose was to explore the incidence and risk factors for HCV reinfection over nearly two decades. The study revisited two risk behaviours identified in earlier research: the receipt of semen in the rectum and sexualised methamphetamine use, including instances where methamphetamine was injected. The analysis used a multivariable approach with a Cox proportional hazards model.
The results revealed that the rate of HCV reinfection was ten times higher than the rate of primary infection in New York City, highlighting that sexual transmission of the virus is neither inefficient nor unusual. Moreover, the introduction of highly effective, direct-acting antiviral treatments did not reduce the reinfection rate, indicating that these treatments do not mitigate the spread of HCV among MSM in the city. Notably, the sole risk factor linked to reinfection was the receipt of semen into the rectum, whereas sexualised methamphetamine use did not pose a significant risk.
This finding underscores a broader implication: only a limited number of sexual networks exhibit a high prevalence of HCV, and sexualised methamphetamine use is more of an indicator of membership in these high-prevalence networks than a direct mediator of transmission. This distinction challenges the traditional understanding of HCV transmission dynamics within this community.
The significance of this research stems from the historical perspective that HCV was predominantly transmitted parenterally, not sexually, and that MSM was not considered at high risk for HCV infection. Initial reports of HCV outbreaks among MSM around twenty years ago showed low infection rates, reinforcing the belief that HCV transmission among this group was rare and atypical. The methods of transmission have been a point of contention, with most evidence pointing to sexual transmission. Yet, many experts continued to attribute these cases to conventional risk factors such as drug use and blood exposure. This study, however, affirms that sexual transmission through semen is a viable and standard route among MSM, independent of drug use.
Dr. Fierer commented on the research, noting, “This study enhances our previous work on HCV among MSM in New York City, offering the most definitive evidence to date that the primary mode of HCV transmission among MSM in the city is sexual, which is distinct from the traditional transmission route via blood contact during drug injection. Given that neither condoms nor current treatments have proven effective at preventing HCV, there is a pressing need for innovative prevention strategies. We are immensely grateful to the hundreds of men who initially came to us as patients and subsequently engaged as study participants, helping us to investigate this newly recognised transmission route. We are committed to continuing our collaborative efforts to develop effective interventions to curb this ongoing epidemic.” This statement highlights the ongoing challenges and the critical need for new approaches to address the spread of HCV within these communities.
More information: Daniel S Fierer et al, Hepatitis C Virus Reinfection Among Men Who Have Sex With Men With HIV in New York City, Clinical Infectious Diseases. DOI: 10.1093/cid/ciae297
Journal information: Clinical Infectious Diseases Provided by The Mount Sinai Hospital / Mount Sinai School of Medicine
