Despite an abundance of epidemiological evidence for horizontal transmission of hepatitis B virus (HBV), the transmission route remains to be fully elucidated. In a new approach, we evaluated quantitative HBV DNA content in serum, saliva and urine as a first step in exploring possible modes of horizontal transmission.
In an outpatient setting of an academic hospital, paired serum, saliva and urine samples were collected from 150 chronically infected HBV patients. A validated HBV DNA TaqMan assay was used to quantitatively measure HBV DNA.
Mean log HBV DNA in serum was 5.8 (range, undetectable to 10.0 log HBV DNA) copies/ml, 50% of the patients had an HBV DNA above 105 copies/ml in serum. Mean log HBV DNA level in saliva was 3.2 (range, undetectable to 7.5) copies/ml, 15% had an HBV DNA above 105 copies/ml in saliva. Mean log HBV DNA level in urine was 2.6 (range, undetectable to 5.4) copies/ml and 1% had an HBV DNA above 105 copies/ml in urine. A high, non-linear correlation was shown between HBV DNA in serum and saliva (Spearman's rho 0.82) and between serum and urine (Spearman's rho 0.74).
The significant amounts of HBV DNA found in saliva and urine in chronic HBV patients with high viraemia in serum may have implications for the understanding of hepatitis B epidemiology. The potential infectivity of these body fluids may provide an explanation for the 20% of cases of infection obtained through horizontal transmission for which the origin of infection is yet unknown.
Departments of aGastroenterology & Hepatology
cEpidemiology & Biostatistics, Erasmus MC, University Medical Centre Rotterdam
dMunicipal Health Service, Rotterdam, The Netherlands
Sponsorship: This study was funded by Erasmus University Trust fund.
Correspondence to Dr R.A. de Man, Department of Gastroenterology and Hepatology, Erasmus MC, University Medical Centre Rotterdam, Room Ca 326, Dr Molewaterplein 40, 3015 GD Rotterdam, The Netherlands
Tel: +31 10 463 3793; fax: +31 10 436 5916;
Received 4 May 2005 Accepted 11 July 2005