[Hepatitis C: epidemiology and therapy--with special reference to long-term prognosis after IFN therapy].

Blood transfusion or blood products are a important route for transmission of hepatitis C virus(HCV) infection. Routes of infection other than blood transfusion are medical treatments including hemodialysis, exposure of hospital employees to needles contaminated with blood, drug abusers, acupuncture, tattooing, certain types of sexual behavior and mother-to-infant infection. The prevalence of anti-HCV antibodies in blood donors in Kumamoto Prefecture was 1.30%(1,704 of 131,376) between February and October 1992 and 0.46%(622 of 132,847) between April 1998 and May 1999, respectively. Also, the prevalence of anti-HCV was 22.9%(126 of 550) in the highly endemic area. The prevalence of HCV infection was evaluated in 548 patients undergoing hemodialysis, and 216 members of the hospital dialysis staff. Of 548 hemodialysis patients, 166(30.3%) were positive and significantly higher than those for either hospital staff members(2.3%; p < 0.01) or healthy blood donors(1.3%; p < 0.01). Patients with a history of blood transfusion tended to have a higher positivity rate for anti-HCV than did the non-transfused group. Positivity for anti-HCV was related to the duration fo hemodialysis. Although hemodialysis patients remain a high-risk group for HCV infection, the prevalence of anti-HCV antibodies has decreased recently thanks to the use of erythropoietin for renal anemia, the universal screening of blood donors for anti-HCV antibodies, and improvements in infection control measures for this virus. To evaluate the effect of interferon(IFN) therapy on the incidence of hepatocellular carcinoma(HCC) or decompensated liver cirrhosis, 490 patients with chronic hepatitis or liver cirrhosis type C who had undergone liver biopsy since 1987, were followed periodically. Of these patients, 411 received IFN and 79 were untreated. The degree of liver fibrosis was assessed from stage F0(no fibrosis) to stage F4(cirrhosis). Response to IFN was determined virologically and biochemically. HCC developed in IFN-treated patients and in 17 untreated patients with stage F3 or F4 fibrosis. In multivariate analysis, IFN therapy was associated with a reduced risk of HCC, especially among patients with sustained virological response(CR), among those with persistently normal serum ALT levels, and among those with ALT levels less than two times the upper limit of normal(PR). Also, the cumulative incidence of decompensated liver cirrhosis and cumulative survival in treated and untreated patients differed significantly. None of the patients with CR or PR progressed to the decompensated state and all patients with CR or PR have survived to date. In conclusion, IFN therapy significantly reduces the risk for HCC or decompensated cirrhotic stage, especially among virological or biochemical responders.