Mixed infections of hepatitis C virus as a factor in acute exacerbations of chronic type C hepatitis.

Twenty patients with chronic hepatitis C virus (HCV) infection and acute exacerbations (group A) were studied by polymerase chain reaction with genotype-specific primers to explore the role of mixed infections of HCV in acute exacerbations of chronic type C hepatitis. Another 26 patients who did not have acute exacerbation were matched controls (group B). Eleven (55%) of the group A patients had heterologous HCV, and their mean age was significantly younger than that of the 9 without heterologous infection (55 vs. 67 years, P < .05). In contrast, only 2 group B patients (7.7%) had heterologous HCV infection. In 10 of 13 patients with heterologous HCV infection, type III/2a virus emerged on type II/1b HCV, and viral interference was observed in half of them. The results support that mixed infections of HCV may be important in acute exacerbations of chronic type C hepatitis.