Genetic analysis of hepatitis A virus strains recovered from the environment and from patients with acute hepatitis.

The molecular epidemiology of hepatitis A virus (HAV) was studied by analysing HAV strains recovered from environmental water samples over a 7 year period and strains recovered from patients with acute hepatitis over a 5 year period. A total of 54 samples of raw domestic sewage and 66 samples of river water were collected. HAV particles were concentrated and detected by nested RT-PCR. HAV infection in patients with acute hepatitis was serologically diagnosed in 26 of 74 serum samples, which were also analysed by nested RT-PCR. HAV RNA was detected in 57.4% of sewage samples, 39.2% of Llobregat river water samples, 20% of Ter river water samples and 61.6% of serum samples. The HAV genomes detected were characterized further by directly sequencing a region of the 5' non-translated region, the VP1/2A junction region and, in some samples, the 2B region. Results showed a 95% prevalence of genotype I, with nearly 50% being either subgenotype IA or subgenotype IB. Various strains were found simultaneously in both environmental and clinical samples. These strains were closely related to those described in distant geographical areas. Genotype IIIA was also found in 5% of sewage samples and in 12.5% of serum samples. Strains belonging to a common endemic genotype were not identified. The abundance of HAV in the environment produces a situation of sanitary risk, especially considering the low prevalence of antibodies in the young population.