Sero-prevalence of antibodies to hepatitis A virus among Australian blood donors.

Abstract

Aim: Australia has a low incidence of hepatitis A virus (HAV), with the majority of cases in travellers. Nonetheless, the sero-prevalence of antibodies against HAV among Victorians has increased over the last two decades, likely to be a result of vaccination and increased travel/immigration. This study measured the prevelance of HAV antibodies in blood donors from around Australia to determine if a similar rate exists in other states.

Methods: Samples were collected from donors between January and July 2011 from Australian capital cities. All samples (n = 2109) were tested with a commercially available enzyme immunoassay for total anti-HAV antibody (levels >=20 IU/mL were considered sero-positive).

Results: Anti-HAV antibody was detected in 51.4% (95% CI 49.27-53.53%) of donors. Some variability was observed between cities; the highest rates were seen in Sydney donors (57.33%; 95% CI 51.74-62.93%), while the lowest in donors from Brisbane (43.67%; 95% CI 38.05-49.28%). Not surprisingly, sero-prevelance increased with increasing donor age.

Conclusions: This study demonstrated that over half of donors tested had anti-HAV antibodies, with relatively high rates in all capital cities. Given increased HAV vaccination rates, measuring naturally-acquired HAV infection in blood donors has become increasingly difficult and a serological test discriminating naturally-occurring from vaccine-induced immunity may be of interest.