title: Prevalence of hepatitis B virus infection among health care workers in a tertiary hospital in Tanzania.
abstract: BACKGROUND
  Sub-Saharan Africa has a high prevalence of hepatitis B virus (HBV) infections. Health care workers (HCWs) are at high risk of contracting HBV infection through their occupation. Vaccination of HCWs against HBV is standard practice in many countries, but is often not implemented in resource-poor settings. We aimed with this cross-sectional study to determine HBV prevalence, HCW vaccination status, and the risk factors for HCWs contracting HBV infection in Tanzania.
  
  
  METHODS
  We enrolled 600 HCWs from a tertiary Tanzanian hospital. Their demographics, medical histories, HBV vaccination details and risk factors for contracting blood-borne infections were collected using a standardized questionnaire. Serum samples were tested for HBV and hepatitis C virus (HCV) markers by ELISA techniques, PCR and an anti-HBs rapid test. HCWs were divided in two subgroups: those at risk of contracting HBV (rHCW 79.2%) via exposure to potentially infectious materials, and those considered not at risk of contracting HBV (nrHCW, 20.8%).
  
  
  RESULTS
  The overall prevalence of chronic HBV infection (HBsAg+, anti-HBc+, anti-HBs-) was 7.0% (42/598). Chronic HBV infection was found in 7.4% of rHCW versus 5.6% of nrHCW (p-value = 0.484). HCWs susceptible to HBV (HBsAg-, anti-HBc-, anti-HBs-) comprised 31.3%. HBV immunity achieved either by healed HBV infection (HBsAg-, anti-HBc+, anti-HBs+) or by vaccination (HBsAg-, anti-HBc-, anti-HBs+) comprised 36.5% and 20.2%, respectively. 4.8% of participants had indeterminate results (HBsAg-, anti-HBc+, anti-HBc-IgM-, anti-HBs-). Only 77.1% of HCWs who received a full vaccination course had an anti-HBs titer >10 ml/U. An anti-HBs point-of-care test was 80.7% sensitive and 96.9% specific. There was a significantly higher risk for contracting HBV (anti-HBc+) among those HCW at occupational risk (rHCW) of older age (odds ratios (OR) in rHCW 3.297, p < 0.0001 vs. nrHCW 1.385, p = 0.606) and among those HCW being employed more than 11 years (OR 2.51, p < 0.0001***). HCV prevalence was low (HCV antibodies 1.2% and HCV-RNA 0.3%).
  
  
  CONCLUSIONS
  Chronic HBV infection is common among Tanzanian HCWs. One third of HCWs were susceptible to HBV infection, highlighting the need for vaccination. Due to high prevalence of naturally acquired immunity against HBV pre-testing might be a useful tool to identify susceptible individuals.
authors.affiliation: Department of Tropical Medicine, Medical Mission Hospital, Salvatorstrasse 7, 97074, Wuerzburg, Germany. andreas.mueller@missioklinik.de.
authors.forename: A
authors.initials: A
authors.lastname: Mueller
authors.affiliation: Department of Tropical Medicine, Medical Mission Hospital, Salvatorstrasse 7, 97074, Wuerzburg, Germany. lorainestoetter@gmail.com.
authors.forename: L
authors.initials: L
authors.lastname: Stoetter
authors.affiliation: Bugando Medical Centre, P.O. Box 1370, Mwanza, United Republic of Tanzania. samuelkalluvya@yahoo.com.|CUHAS, P.O. Box 1370, Mwanza, United Republic of Tanzania. samuelkalluvya@yahoo.com.
authors.forename: S
authors.initials: S
authors.lastname: Kalluvya
authors.affiliation: Department of Tropical Medicine, Medical Mission Hospital, Salvatorstrasse 7, 97074, Wuerzburg, Germany. stich@missioklinik.de.
authors.forename: A
authors.initials: A
authors.lastname: Stich
authors.affiliation: Bugando Medical Centre, P.O. Box 1370, Mwanza, United Republic of Tanzania. cmajinge@hotmail.com.
authors.forename: C
authors.initials: C
authors.lastname: Majinge
authors.affiliation: Institute of Virology and Immunobiology, University of Wuerzburg, Versbacher Strasse 7, 97078, Wuerzburg, Germany. weissbrich@vim.uni-wuerzburg.de.
authors.forename: B
authors.initials: B
authors.lastname: Weissbrich
authors.affiliation: Medical Mission Institute, Salvatorstrasse 7, 97067, Wuerzburg, Germany. christa.kasang@medmissio.de.
authors.forename: C
authors.initials: C
authors.lastname: Kasang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data*; D016174:Hepacivirus / Q000276:immunology / Q000302:isolation & purification; D006509:Hepatitis B / Q000453:epidemiology*; D006510:Hepatitis B Antibodies / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000097:blood; D017325:Hepatitis B Vaccines / Q000627:therapeutic use; D006515:Hepatitis B virus / Q000276:immunology / Q000302:isolation & purification; D006526:Hepatitis C / Q000453:epidemiology; D018937:Hepatitis C Antibodies / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D013636:Tanzania / Q000453:epidemiology; D062606:Tertiary Care Centers / Q000706:statistics & numerical data*; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D018937:Hepatitis C Antibodies