HEPATITIS-C VIRUS SUBTYPE 3B INFECTION IN A HOSPITAL IN JAPAN - EPIDEMIOLOGIC-STUDY

To elucidate the epidemiology of infection with hepatitis C virus (HCV ) subtype 3b (a rare subtype thought to have originated in Southeast A sia) in Japan, we examined the genotypic subtype in 1397 patients with HCV-related chronic liver diseases. Of 1330 patients with identified HCV RNA genotypes, 960 had subtype 1b, 243 had subtype 2a, 97 had subt ype 2b, 14 (1.1%) had subtype 3b, and 16 had other types of HCV or mix ed subtypes. The age, gender, and severity of liver disease in patient s with HCV subtype 3b did not differ from these features in patients w ith other subtypes. Eleven of the 14 patients with the 3b subtype had once worked at Company A in Tokyo, Japan. Multivariate logistic analys is showed that working history at that company was independently assoc iated with the incidence of the subtype; the risk ratio was 207.2 (P < 0.0001). All 11 patients from Company A had received medical services , between 1953 and 1981, at Clinic C, which undertook medical care of the company staff. All 11 patients had received repeated intramuscular or intravenous injections for treatment of various diseases or for pr eventive vaccination for contagious diseases. The rare HCV subtype 3b, appeared to have been transmitted among the employees of a company th rough the performance of certain medical practices.