Hepatitis C virus transmission during colonoscopy evidenced by phylogenetic analysis.

Background: Nosocomial transmission events still play an important role in hepatitis C virus (HCV) spreading. Among most reported medical procedures involved in nosocomial transmission, endoscopy procedures remain controversial and might be underestimated.

Objective: The aim of the study was to investigate a case of nosocomial person-to-person transmission of HCV in an endoscopy unit.

Study Design: An acute HCV infection was detected in a person that had undergone a colonoscopy after an HCV-infected patient. Serum samples from both persons were subjected to a molecular epidemiology study. The HCV NS5B genetic region was amplified and directly sequenced and the E1-E2 region was amplified, cloned and sequenced (20 clones per specimen). All sequences were subjected to phylogenetic analyses. A conventional epidemiological investigation was performed to determine the most likely cause of HCV transmission.

Results: NS5B sequence analysis revealed that both persons were infected with closely related HCV-1b strains. Furthermore, phylogenetic analysis of E1-E2 sequences evidenced a direct transmission between patients. The epidemiological investigation pointed out to anesthetic procedures as the most likely source of HCV transmission. The index case, not having spontaneously cleared the infection 10 months after infection, required antiviral treatment, which resulted in a sustained virological response.

Conclusions: The molecular epidemiology study performed provided evidence of a person-to-person transmission of HCV during a colonoscopy procedure, and the anesthetic procedure was the most likely source of HCV transmission. This study highlights the importance of strictly following standard precautions by healthcare workers in order to prevent nosocomial HCV transmission.