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.
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 %).
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 %).
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.
Below: HBV- status in HCWs in Tanzania. Prevalence of chronic HBV infection (HBsAg+, anti-HBc+, anti-HBs-), HBV immunity achieved by healed HBV infection (HBsAg-, anti-HBc+, anti-HBs+) or by vaccination (HBsAg-, anti-HBc-, anti-HBs+), indeterminate result (HBsAg-, anti-HBc+, anti-HBs-) and HBV susceptibility (HBsAg-, anti-HBc-, anti-HBs-) in Tanzanian HCWs in a tertiary hospital as determined by HBV serology. HBV: hepatitis B virus; HCWs: health care workers
1African Population and Health Research Center, Upper Hill, Nairobi Kenya
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