A Seroepidemiological Study of Hepatitis C Virus (HCV) in an Area with a High Prevalence of Chronic Liver Disease in the Kyushu District of Japan

Abstract

The incidence of hepatitis vims type C (HCV) in an area, Futase, of Iizuka city in Chikuho province in the northeastern part of Fukuoka prefecture in Kyushu, Japan, was estimated by screening sera for anti-HCV antibodies. Titers of anti human T-lymphotropic virus type I (HTLV-I) antibodies and hepatitis virus type B surface antigens (HBs) were also determined. The area of the present study is known to have a particularly high prevalence of chronic liver diseases, because coal mining was the key industry until a few decades ago. Also, in the old days it was rather isolated from the neighboring vicinities by surrounding mountains. The subjects of the present survey were 310 patients (117 males and 193 females) with various chronic diseases who visited Futase Social Insurance Hospital during a two year period from 1991 to 1992. Anti-HCV antibodies were detected in the sera of 55 patients, which is an overall positive rate of 18% (26% in male and 14% in female patients). This is extremely high compared to an estimated nationwide average positive rate of 1.6%. Even in 270 patients with normal liver function, the incidence was as high as 10%. The incidences were particularly high in groups of patients aged 40 through 49, 50 through 59 and 60 through 69, ranging from 20 to 23%, while they were as low as 13 and 17% in those aged 70 through 79 and 80 through 89 years, respectively. A high incidence, 57%, was estimated for the patients with impaired liver function due to chronic liver diseases, especially in those concomitantly having diabetes meUitus (DM), 91%. The incidence of anti-HCV antibodies was the highest, 100%, in patients having both liver cirrhosis (LC) and DM. This was followed by those having chronic hepatitis (CH) and DM concomitantly and by those with LC alone, 86% each, and by those with CH alone 44%. Furthermore, the genotypes of the HCV in the sera of ∗ nine randomly selected carrier patients who had anti-HCV antibodies, even though they had diseases other than hepatic diseases and their liver functions were normal, were examined by the polymerase chain reaction method employing type-specific primers for DNA amplification. As a result, all the HCV strains were type II. On the other hand, there were no apparent differences in the incidences of HTLV-I in the area of the present study and in neighboring provinces of the same prefecture, Fukuoka. From the facts described above, it can be suggested that HCV and HTLV-I were transmitted by routes other than blood transfusion. The high incidence of HCV among the Futase residents in Chikuho is probably related to the high prevalence of chronic liver diseases. The endemic situation of HCV in this area is very similar to that found in eastern Saga, a neighboring prefecture. © 1994, Kurume University School of Medicine. All rights reserved.