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Human T-lymphotropic virus type 1 (HTLV-1) infection is known to affect hepatitis C virus (HCV) clearance and to accelerate the development of hepatocellular carcinoma in HCV-infected patients. In this study, we found the prevalence and titer of an antibody recognizing the central region of the HTLV-1 Gp46 protein to be associated with the severity of chronic liver disease. The antibody prevalence was significantly correlated with the stage of chronic liver disease (P < 0.0001): 3 (14.3%) of 21 patients with minimal-mild chronic hepatitis, 12 (24%) of 50 with moderate-severe chronic hepatitis, 7 (87.5%) of 8 with liver cirrhosis, and 13 (100%) of 13 with hepatocellular carcinoma. These results indicate that the antibody may be a useful marker of the deterioration of liver disease in patients co-infected with HCV and HTLV-1. This antibody may be useful for the diagnosis of liver diseases and the development of more effective treatments.

The aim of this study was to determine the predominant hepatitis B virus (HBV) genotype in the Solomon Islands and determine if there is any racial correlation between genotype and hepatitis B e antigen (HBeAg) production in Japanese and Melanesian individuals. A total of 403 serum samples from 206 Melanesian HBV carriers in the Solomon Islands and 197 Japanese carriers from Fukuoka (n = 106) and Okinawa (n = 91) living in Japan in 2001 were tested. The HBV genotypes of 206 Melanesian subjects were 114 with genotype C (55.3%) and 92 with genotype D (44.7%). The HBV genotypes of 197 Japanese subjects were 74 with genotype B (37.6%) and 123 with genotype C (62.4%). The total HBeAg prevalence of subjects in Fukuoka (36.8%) was significantly higher than that of subjects in Okinawa (14.3%) (P < 0.0001) and subjects in the Solomon Islands (35.0%; P = 0.0014, by the Mantel-Haenszel test). The genotype C prevalences were significantly different, ranging from 24.2% in Okinawa, to 54.4% in the Solomon Islands, to 95.3% in Fukuoka (all P < 0.0001, by chi-square test). The prevalence of HBeAg positivity was significantly higher in Melanesian genotype C subjects (42.0%) than Melanesian genotype D subjects (26.6%) (P = 0.0310). Similarly, the prevalence of HBeAg positivity was significantly higher in Japanese genotype C subjects (36.6%) than Japanese genotype B subjects (9.5%) (P < 0.0001). These findings indicate that that HBV was of genotypes C and D in the Solomon Islands, and that the pathogenesis of HBV-infected patients is related to HBV genotype rather than race.

To investigate the chronologic change of mother-to-child transmission of human T lymphotropic virus type I (HTLV-I) in Okinawa, Japan, the presence of antibody to HTLV-I was tested in 4,187 healthy residents between, 4,528 nursery school children, and 3,837 pregnant women between 1968 and 2000. The chronologic change of the feeding method and the length of the breast-feeding period among 1,117 healthy mothers from 1937 to 1995 were also obtained by interview. Age-adjusted prevalence of HTLV-I among healthy residents decreased from 9.1% in 1968-1970 to 7.8% in 1981-1984 and to 6.3% in 1996-1998. The crude prevalence of antibody to HTLV-I among healthy residents less than 20 years old decreased significantly from 4.6% in 1968-1970 to 0.1% in 1996-1998 (P < 0.0001). The prevalence of antibody to HTLV-I among nursery school children decreased significantly over the study period, from a high of 1.8% in 1984 to a low of 0.2% in 1998 (P = 0.03). The prevalence among pregnant women decreased significantly from 5.6% in 1989-1992 to 3.7% in 1997-2000 (P = 0.0275). Prior to 1967, all healthy mothers breast-fed their children. After 1968, the use of bottled and mixed milk (breast milk and bottled milk) increased, with bottled milk becoming predominant after 1990 (89%). The percentage of healthy mothers breast-feeding for more than one year significantly decreased from 68.3% in 1937-1947 to 0.4% in 1990-1995 (P < 0.0001). Infection with HTLV-I in Okinawa has decreased mainly due to a reduction in the number of mothers breast-feeding and a shortening of the breast-feeding period. However, because the mother-to-child transmission rate among non-breast-feeders decreased from 12.8% in 1986-1991 to 3.2% in 1995-1999, there may be other factors involved in the decrease in mother-to-child transmission.

The aims of this retrospective survey were to determine the epidemiologic distribution of hepatitis B virus (HBV) genotypes and analyze the genotype-related clinical differences among Japanese patients with chronic HBV infection. The 158 surveyed patients with chronic HBV infection lived in Fukuoka and Okinawa were serially tested for serum alanine aminotransferase (ALT) and hepatitis B e antigen (HBeAg). Follow-up was for a period of 10.8 +/- 6.4 years (mean +/- SD). The HBV genotypes were determined in sera by an enzyme-linked immunosorbent assay and detection of HBV DNA in serum was done by the transcription-mediated amplification-hybridization protection assay. Genotypes B and C were found in 58 (36.7%) and 100 (63.3%) of the patients, respectively. Genotype B was predominant in Okinawa (B = 86.9%, C = 13.1%), whereas genotype C was predominant in Fukuoka (B = 5.2%, C = 94.8%). The HBeAg positivity and ALT abnormality rates at the start of the observation period were significantly higher in patients with genotype C (66.0% and 84.0%) than in patients with genotype B (34.5% and 22.4%) (P < 0.05, respectively). The annual rate of spontaneous HBeAg disappearance in patients with genotype B was much higher than in patients with genotype C (8.38% versus 2.34%, respectively). Patients with genotype C who were continuously HBeAg negative from entry had a significantly higher ALT abnormality (58.8%) than those with genotype B (19.2%) (P < 0.05). Interestingly, patients with genotype C who became HBeAg negative after treatment with interferon had a high ALT abnormality (58.8%). All patients with an ALT abnormality were positive for HBV DNA in their serum. These findings indicate that patients with HBV genotype C have more severe liver deterioration because of the delay of HBeAg disappearance and continued HBV replication after HBeAg disappearance.

Sera of 4,050 residents from Japan, 276 from the Solomon Islands, and 602 from Nepal were tested by an enzyme-linked immunosorbent assay to determine the prevalence of antibody to Chlamydia pneumoniae. The prevalence of IgG and IgA antibodies was significantly higher in the Solomon Islands (64.9% and 82.2%) and Nepal (73.1%, and 69.8%) than in Japan (53.6% and 41.1%). These prevalence rates increased throughout the teenage years in the Solomon Islands and Japan and leveled off with age, whereas in Nepal the prevalence rates gradually increased with age. The prevalence of a high (> 3.0) IgA antibody index, which is suggestive of acute infection, was significantly higher in the Solomon Islands (34.8%) than in Japan (3.2%) and Nepal (10.5%). The prevalence of IgG antibody ranged from 46.4% to 67.7%, and the prevalence of IgA antibody ranged from 33.7% to 61.8% in the four difference areas of Japan. These findings indicate considerable differences in the prevalence of antibodies to C. pneumoniae by age in these nations and between the regions of Japan tested.

To clarify the relationship between Strongyloides stercoralis, infection with human T cell lymphotropic virus type-1 (HTLV-1), and serum immunoglobulin E (IgE) levels, epidemiologic investigations of these two infections were conducted in inhabitants of Okinawa, a subtropical zone in Japan. Blood and feces samples were taken from 1,347 healthy inhabitants (554 males and 793 females). Antibody to HTLV-1 was measured by particle agglutination, enzyme-linked immunosorbent assay, and Western blotting. The presence of Strongyloides was determined by direct detection of rhabditiform larvae in fresh stool on agar-plate cultures. Serum IgE levels in 127 inhabitants were measured by a fluoroenzyme immunoassay. Antibody to HTLV-1 was detected in 23.0% of the blood samples and was more frequent in females (25.1%) than in males (20.0%) (P < 0.05). Strongyloides were detected in 21.9% of the feces samples and were more frequent in males (31.9%) than in females (14.9%) (P < 0.001). The prevalence of both infections increased with age, especially in persons 50 years of age and older: The prevalence of Strongyloides infection was significantly higher in HTLV-1 carriers (31.6%) than in those without HTLV-1 infection (P < 0.001). The level of IgE was low in HTLV-1 carriers, and significantly lower in HTLV-1 carriers than in noncarriers among inhabitants with Strongyloides infection. Both HTLV-1 and Strongyloides infections are endemic in the area studied.