title: High prevalence of occult hepatitis B virus infection in Taiwanese intravenous drug users.
abstract: The epidemiology and impact of occult HBV infection in intravenous drug users remain largely unknown. The aim of the study was to investigate the prevalence of occult HBV infection among intravenous drug users in Taiwan. Molecular assays were used to determine the level of serum HBV DNA and the genotype in 304 intravenous drug users negative for both HBsAg and anti-HCV. Of 304 intravenous drug users, 125 (41.1%) were positive for serum HBV DNA. The genotype distribution of HBV was as follows: B, 55 (44%); C, 29 (23%); and mixed B and C infections, 41 (33%). The mean and median serum HBV DNA levels in 125 intravenous drug users with occult HBV infection were 4.0 +/- 0.6 and 4.0 log(10) copies/ml, respectively. The mean serum HBV DNA level in carriers with mixed genotype B and C infections was significantly higher than those infected with HBV genotype B or genotype C alone (mean, 4.2 +/- 0.6 log(10) vs. 3.9 +/- 0.5 log(10), and 3.9 +/- 0.7 log(10) copies/ml, P = 0.01 and 0.05, respectively). The amino acid sequence determination of HBV surface gene in 20 intravenous drug users with occult HBV infection selected at random showed no mutation of amino acid at codon 145. In conclusion, the prevalence of occult HBV infection and mixed HBV genotype infections are not uncommon in intravenous drug users residing in an HBV endemic areas. In addition, intravenous drug users with occult mixed genotype B and C infections have significantly higher viral loads than those with occult infection of single HBV genotype.
authors.affiliation: Department of Gastroenterology, Ren-Ai Branch, Taipei City Hospital, Taipei, Taiwan.
authors.forename: Chih-Lin
authors.initials: CL
authors.lastname: Lin
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Liu
authors.forename: Pei-Jer
authors.initials: PJ
authors.lastname: Chen
authors.forename: Ming-Yang
authors.initials: MY
authors.lastname: Lai
authors.forename: Ding-Shinn
authors.initials: DS
authors.lastname: Chen
authors.forename: Jia-Horng
authors.initials: JH
authors.lastname: Kao
mesh_terms: D000328:Adult; D000368:Aged; D004279:DNA, Viral / Q000097:blood*; D005838:Genotype; D006509:Hepatitis B / Q000453:epidemiology* / Q000821:virology; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011329:Prisoners; D011330:Prisons; D015819:Substance Abuse, Intravenous / Q000150:complications*; D013624:Taiwan / Q000453:epidemiology
chemical_list: D004279:DNA, Viral