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International HCV transmission in European MSM requires DAA scale-up

In Switzerland, men who have sex with men from other countries likely account for about one-quarter acute hepatitis C infections, according to a study presented at the Conference on Retroviruses and Opportunistic Infections, also known as CROI. The researchers recommend joint European scale-up schemes for DAA therapy.

“Scale-up of direct-acting antivirals, or DAA therapy, is happening all over Europe and independently in several countries, but Europe is highly interconnected and hepatitis C transmission knows no borders,” Luisa Salazar-Vizcaya, PhD, from the University Hospital of Bern, Switzerland, said in her presentation. “Mathematical models suggest that scale-up of DAAs has the potential to curve the epidemic of hepatitis C among HIV-positive MSM.”

After establishing the likely geographic origin of infection, Salazar-Vizcaya and colleagues sequenced the HCV genotype 1a infections of 66 HIV-positive MSM patients to estimate the Swiss epidemic of HCV acquired by contact with MSM from abroad. Sampling dates ranged from June 2002 to May 2016.

Based on reconstructed phylogenies, the researchers found that 97% of the study sequences were located in MSM clusters, 96% of which were found among five transmission clusters within Europe, and 90% of the sequences from acute infections in Swiss MSM were within transmission clusters.

The estimated range of transmission between Swiss patients was from 38% to 76%; between German and Swiss patients ranged from 7% to 41%; and between other European regions and Swiss patients ranged from 0% to 28%.

“We estimate that as much as 44% of our sequences were likely acquired by men not living in Switzerland,” Salazar-Vizcaya concluded. “This would suggest that international transmission networks may need to be taken into account, not only in planning but also in the assessment of the impact of DAA scale-up programs.” – by Talitha Bennett

Reference: Salazar-Vizcaya L, et al. Abstract 130. Presented at: Conference on Retroviruses and Opportunistic Infections; March 4-7, 2018; Boston.

Disclosure: Salazar-Vizcaya reports no relevant financial disclosures.