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Epidemiology of hepatitis C virus in japan
1Department of Hygiene, Hiroshima University School of Medicine, Hiroshima, Japan.
Insights
Hepatitis C virus (HCV) prevalence is higher in older populations in Japan, likely due to post-WWII infections. The number of HCV carriers is expected to halve in the next decade as older generations decline.
Area of Science:
- Hepatology
- Epidemiology
- Public Health
Background:
- Hepatitis C virus (HCV) infection demonstrates an age-dependent prevalence in Japan.
- Blood screening data from Japanese Red Cross centers and sentinel studies confirm higher HCV rates in older individuals.
- This age-related pattern suggests historical transmission events, potentially linked to illicit intravenous amphetamine use post-World War II.
Purpose of the Study:
- To analyze the age-specific prevalence of Hepatitis C virus (HCV) infection in Japan.
- To investigate the historical factors contributing to the observed age-dependent prevalence.
- To project future trends in HCV carrier numbers based on current infection rates and generational shifts.
Main Methods:
- Analysis of blood screening data from Japanese Red Cross blood centers.
- Corroboration using data from a sentinel study in an HCV-endemic area.
- Estimation of current HCV carrier numbers and projection of future prevalence based on generational turnover.
Main Results:
- A clear positive correlation between age and HCV prevalence was observed in the Japanese population.
- The prevalence of HCV infection is significantly higher among the elderly.
- The estimated number of HCV carriers (age 20-64) is 691,852, with a projected decrease to approximately 50% within the next decade due to low new infection rates.
Conclusions:
- The high prevalence of HCV in Japan's elderly population is attributed to past transmission events.
- Current low rates of new HCV infections will lead to a natural decline in the overall carrier population.
- Hepatitis C virus (HCV) infection prevalence is decreasing spontaneously in Japan through generational replacement.
Abstract:
Blood screening for hepatitis C virus (HCV) antibodies at Japanese Red Cross blood centers has indicated an age-dependent prevalence of HCV infection in the general population of Japan: the older the age, the higher the prevalence. The same pattern was corroborated by the sentinel study conducted in an HCV-endemic area. The high prevalence of HCV in the elderly is most likely due to a spread of HCV infection during the turmoil period just after World War II: in particular by illicit intravenous amphetamine abuse. Fortunately, however, since the rate of newly acquired infection is currently too low to influence HCV prevalence in each age group, the total number of HCV carriers (estimated to be 691,852 for the age group 20-64 years) would decrease spontaneously with generation takeover to approximately 50% of the current number during the decade to come.