Abstract
Occult hepatitis B infection (OBI) is defined as the presence of hepatitis B virus (HBV) DNA in the liver or serum in the absence of detectable HBV surface antigen (HBsAg). OBI poses a risk for the development of cirrhosis and hepatocellular carcinoma. The prevalence of OBI in Kenya is unknown, thus a study was undertaken to determine the prevalence and molecular characterization of OBI in Kenyan populations at high risk of HBV infection. Sera from two Nairobi cohorts, 99 male sex workers, primarily having sex with men (MSM-SW), and 13 non-MSM men having HIV-positive partners, as well as 65 HBsAg-negative patients presenting with jaundice at Kenyan medical facilities, were tested for HBV serological markers, including HBV DNA by real-time PCR. Positive DNA samples were sequenced and MSM-SW patients were further tested for hepatitis C virus (HCV) infection. Of the 166 HBsAg-negative samples tested, 31 (18.7%; 95% confidence interval [CI] 13.5-25.3) were HBV DNA positive (i.e., occult), the majority (20/31; 64.5%) of which were HBV core protein antibody positive. HCV infection was not observed in the MSM-SW participants, although the prevalence of HBsAg positivity was 10.1% (10/99; 95% CI 5.6-17.6). HBV genotype A was predominant among study cases, including both HBsAg-positive and OBI participants, although the data suggests a non-African network transmission source among MSM-SW. The high prevalence of HBV infection among MSM-SW in Kenya suggests that screening programmes be instituted among high-risk cohorts to facilitate preventative measures, such as vaccination, and establish entry to treatment and linkage to care.
Highlights
Infection with hepatitis B virus (HBV) in which viral surface antigen (HBsAg) is undetectable yet HBV DNA is detectable in the liver, and possibly in the serum, defines occult hepatitis B infection (OBI) [1]
Sixty-four MSM-SW and 7 non-MSM anti-HBc negative samples were tested for HBV DNA and HBV surface antigen (HBsAg); 4 of 64 anti-HBc negative specimens tested from MSM-SW were HBsAg positive, 3 of which were HBV DNA positive (S1A Fig, Table 2), establishing a prevalence of HBsAg positive chronic infection among MSM-SW of 10.1% (10/99; 95% CI 5.6–17.6)
OBI was observed in 1 non-MSM and 10 MSM-SW HBsAg negative men for an OBI prevalence of 8.3% (1/12; 95% CI 0.4–35.4) and 11.2% (10/89; 95% CI 6.2–19.5), respectively (Table 2)
Summary
As the prevalence of OBI in Kenya is not known, the aim of this study was to investigate and characterize OBI in several Kenyan populations at high risk of infection; jaundiced patients seeking medical care, men having HIV-positive partners and male sex workers
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