Markedly high seroprevalence of hepatitis B virus infection in comparison to hepatitis C virus and human T lymphotropic virus type-1 infections in selected Solomon Islands populations.

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 5 315, 19.6%) was significantly different from that of antibody to HCV (anti-HCV) by a second-generation enzyme immunoassay (EIA) (n 5 4, 0.2%) and antibody to HTLV-1 (anti-HTLV-1) by an ELISA with Western blot analysis to verify the positivity (n 5 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. Hepatitis B virus (HBV), hepatitis C virus (HCV), and human T lymphotropic virus type-1 (HTLV-1) are spread by infected blood, sexual intercourse, and transmission from mother to child. 1-7 These viruses can either be latent or be- come persistent infections, and are the most significant vi- ruses causing malignant diseases, including hepatocellular carcinoma caused by HBV and HCV 8 and adult T cell leu- kemia/lymphoma associated with HTLV-1. 9 The Solomon Is- lands are located in the southwestern Pacific Ocean (5-128S, 156-1708E) in the tropical zone. There have been no recent investigations of the these three viral infections among res- idents of the Solomon Islands. We conducted a large-scale serologic study of outpatients and blood donors at the Cen- tral Hospital in Honiara to determine the seroprevalences of HBV, HCV, and HTLV-1 in the Solomon Islands. Infection with HBV is an especially serious problem in many countries, and it has been conservatively estimated that there are 350 million chronic HBV carriers throughout the world. The southwestern Pacific area, including the Sol- omon Islands, is reported to be hyperendemic for HBV in- fection. 10 Hepatitis B e antigen (HBeAg) positivity correlates with ongoing viral synthesis and accounts for the high in- fectivity of HBV. 6 Our laboratory previously reported that HBeAg prevalence in HBsAg-positive subjects differed de- pending on hepatitis B surface antigen (HBsAg) sub- types. 11,12 There are no reports of the differences in preva- lences of HBeAg among HBsAg-positive subjects of the Solomon Islands based on HBsAg subtypes. Thus, the pos- sible relationship between HBeAg prevalence and HBsAg subtypes was examined.