High prevalence of hepatitis C virus infection in Airin district, Osaka, Japan: A hospital-based study of 1162 patients

Aim: The Airin district, located in Nishinari-ku, Osaka, is known as Japan's largest slum area, and has the largest concentration of day laborers in the country. We conducted a large hospital-based study to determine the prevalence of hepatitis C virus (HCV) infection in the district. Methods: The subjects were 1162 men (mean age, 57 +/- 9 years) admitted to the Osaka Socio-Medical Center Hospital between April 2005 and March 2008. Their case records were retrospectively reviewed. Results: Anti-HCV antibodies were found in 218 (18.8%) patients; in contrast, only 24 (2.1%) patients had hepatitis B surface antigen. The prevalence of anti-HCV antibodies was 59% among the 122 patients admitted for liver diseases and 14% among the 1040 patients with other diseases. Among 927 patients with normal alanine aminotransferase levels (<= 40 IU/L), 128 (13.8%) had anti-HCV antibodies. The prevalence of anti-HCV antibodies increased with age significantly (P < 0.001). At least 33 of the 218 (15%) patients with anti-HCV antibodies admitted to having a history of injection drug use. Interferon therapy was initiated in 26 patients (11 with genotype 1, 14 with genotype 2 and one unclassifiable), but only six completed their scheduled regimens. Hepatocellular carcinoma was diagnosed in 20 patients, but only seven had early-stage disease in which curative treatment, such as surgical hepatectomy or percutaneous ablation, was indicated. Conclusion: The prevalence of HCV infection in the Airin district is extremely higher than that in the Japanese general population. Patient education and strict action against illegal drug use are indispensable to prevent the spread of HCV infection from the district.