Prevalence of occult hepatitis B infection in a highly endemic area for chronic hepatitis B: a study of a large blood donor population.
OBJECTIVE
The aim of the present study was to determine the population prevalence of occult hepatitis B (OHB) infection and its clinical profile in a highly endemic area of chronic hepatitis B virus disease.


METHODS
OHB was first identified by individual sample testing for hepatitis B surface antigen (HBsAg) followed by nucleic acid testing (NAT) and vice versa for 3044 (cohort 1, stored sera from donation within 1 year) and 9990 (cohort 2, prospective study) blood donors, respectively. OHB was confirmed meticulously by ≥2 out of 3 tests with detectable hepatitis B virus (HBV) DNA using a sensitive standardised assay. Detailed serology and viral load in the serum and liver were studied.


RESULTS
The prevalence of OHB was 0.13% (4/3044) and 0.11% (11/9967) for cohort 1 and 2, respectively. In cohort 2, 10 out of 11 OHB samples were positive for anti-HBc (hepatitis B core antigen) antibody (all were immunoglobulin G). Seven had detectable anti-HBs. The serum HBV DNA levels were extremely low (highest 14.1 IU/ml). Of the six donors who underwent liver biopsies, all had normal liver biochemistry, extremely low liver HBV DNA (highest 6.21 copies/cell) and nearly normal liver histology. For those with viral sequence generation, none had the common HBsAg mutant G145R.


CONCLUSIONS
The prevalence of OHB in a highly endemic area of chronic HBV was very low, thus implying a low impact on transfusion services. To implement universal screening, the high cost of NAT should be taken into account. OHB blood donors had very low HBV replication, and normal liver biochemistry and histology, conferring a favourable prognosis.
Yuen
Man-Fung
MF
Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Hong Kong.
Lee
Cheuk-Kwong
CK
Wong
Danny Ka-Ho
DK
Fung
James
J
Hung
Ivan
I
Hsu
Axel
A
But
David Yiu-Kuen
DY
Cheung
Ting-Kin
TK
Chan
Pierre
P
Yuen
John Chi-Hang
JC
Fung
Frederic Khe-Cheong
FK
Seto
Wai-Kay
WK
Lin
Che-Kit
CK
Lai
Ching-Lung
CL
D000293:Adolescent; D000328:Adult; D000368:Aged; D001782:Blood Donors / Q000706:statistics & numerical data*; D001803:Blood Transfusion; D002353:Carrier State / Q000453:epidemiology* / Q000473:pathology; D015331:Cohort Studies; D004279:DNA, Viral / Q000032:analysis; D019353:Endemic Diseases; D005260:Female; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000302:isolation & purification; D019694:Hepatitis B, Chronic / Q000453:epidemiology* / Q000473:pathology; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D055815:Young Adult
D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens