Epidemiology and long term prognosis of hepatitis C virus infection in Japan

Area of Science:

• Hepatology
• Virology
• Epidemiology

Background:

• Hepatitis C virus (HCV) infection is a significant public health concern, particularly in Japan.
• Prevalence of HCV antibodies in Japanese blood donors varies significantly by age group.
• Estimates suggest millions have contracted HCV infection through contaminated blood transfusions.

Purpose of the Study:

• To assess the prevalence of HCV antibodies in Japanese blood donors.
• To differentiate between active HCV infection and past exposure using serological markers and molecular assays.
• To understand the progression and long-term outcomes of chronic hepatitis C.

Main Methods:

• Analysis of HCV antibody positivity rates in different age demographics of blood donors.
• Confirmation of HCV carrier status using polymerase chain reaction (PCR) for HCV-RNA.
• Distinguishing between active infection and past infection based on antibody profiles (e.g., core antibody alone vs. multiple viral protein antibodies).

Main Results:

• HCV antibody positivity ranged from 0.2% in donors under 20 to 3.9% in those over 50.
• HCV carrier state was confirmed in 70% of antibody-positive individuals with multiple viral protein antibodies.
• Individuals positive for core antibody alone were HCV-RNA negative, indicating past infection (30% of cases).
• Acute hepatitis C progresses to chronic infection in approximately 90% of cases.
• Chronic hepatitis C has a higher propensity for cirrhosis and liver cancer compared to hepatitis B.
• Disease progression to cirrhosis and cancer averages 30 years, but is accelerated in elderly patients.

Conclusions:

• Age is a significant factor in HCV antibody prevalence among Japanese blood donors.
• Distinguishing active HCV infection from past exposure is crucial for patient management.
• Chronic hepatitis C poses a substantial long-term risk for developing cirrhosis and hepatocellular carcinoma, especially in older populations.