High Incidence of Potential HCV Re-infection in Australian Injection Drug Users

Because hepatitis C virus (HCV) is easily transmitted through sharing needles and other drug-injection equipment, injection drug users (IDUs) typically have a high rate of HCV infection. However, the incidence of re-infection has not been extensively studies.

As reported in the June 2007 Journal of Viral Hepatitis, researchers from Sydney, Australia, conducted a retrospective analysis of a cohort of IDUs to assess evidence of protective immunity to HCV through a comparison of incidence rates of initial HCV infection and re-infection.

Incidence of initial HCV infection was determined among HCV seronegative IDUs, and HCV re-infection was determined among IDUs with newly acquired HCV infection, HCV viremia, and subsequent HCV RNA clearance. Potential re-infection was defined as a positive HCV RNA test following at least 1 negative HCV viral load measurement.

Results

• The incidence of initial HCV infection was 17 per 100 person-years.

• The incidence of potential HCV re-infection was 42 per 100 person-years.

• After excluding cases without a change in HCV genotype and less than 3 consecutive HCV RNA negative measurements (which could indicate possible lab errors or re-activation of existing infection), the incidence of suspected re-infection was 31 per 100 person-years.

• After adjusting for HCV risk behavior variables, the incidence rate ratio of HCV re-infection to initial infection was 1.11 (P = 0.8).

Conclusion

Based on these findings, the researchers concluded that, "Several cases of HCV re-infection appear to have developed persistent infection."

07/03/07

Reference
JM Micallef, V Macdonald, M Jauncey, and others. High incidence of hepatitis C virus reinfection within a cohort of injecting drug users. Journal of Viral Hepatitis 14(6): 413-418. June 2007.