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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.

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 determine the prevalences of hepatitis B virus (HBV), hepatitis C virus (HCV), and human T lymphotropic virus type-1 (HTLV-1) infections in residents of the Solomon Islands, we surveyed 1,610 serum samples from 1,113 outpatients and 497 healthy volunteer blood donors at the Central Hospital in Honiara, the Solomon Islands. The prevalence of hepatitis B surface antigen (HBsAg) by radioimmunoassay (RIA) (n = 315, 19.6%) was significantly different from that of antibody to HCV (anti-HCV) by a second-generation enzyme immunoassay (EIA) (n = 4, 0.2%) and antibody to HTLV-1 (anti-HTLV-1) by an ELISA with Western blot analysis to verify the positivity (n = 49, 3.0%) (P < 0.0001, respectively). There were no significant differences in the prevalences of these markers between outpatients and blood donors. Hepatitis B e antigen (HBeAg) was detected by RIA in 130 (41.3%) of 315 HBsAg-positive samples. The distribution of HBsAg subtypes by EIA was 190 adr (60.3%), 111 ayw (35.2%), and 14 (0.4%) other subtypes. The HBeAg prevalence decreased with age in all groups for each subtype. There were no significant differences in the prevalence of HBeAg among HBsAg subtypes. We conclude that HBV infection is highly endemic in selected Solomon Islands populations, and that the high prevalence of HBeAg may be associated with the spread of HBV infection there.