Clinical and molecular characteristics of hepatitis A virus infections during the years 1992–2003 in Ogaki, a centrally located city of Japan

BackgroundsThe emergence of imported hepatitis A virus (HAV) strains from other regions is a feature of acute hepatitis A in developed countries as well as the decrease in number of cases.ObjectivesBetween 1992 and 2003 we investigated the clinical and molecular characteristics of acute HAV infections experienced at a single institution located in a middle city of Japan.Study designA total of 172 patients were admitted to our institution between 1992 and 2003 with the diagnosis of acute hepatitis A. Clinical features of hepatitis and molecular epidemiology were analyzed.ResultsThe number of patients with acute hepatitis A markedly decreased during the study period. Phylogenetic analysis showed that all analyzed HAV strains belonged to HAV genotype IA. HAV strains clustered into four groups and strains of patients belonging to a cluster presented with HAV infection with an interval of more than 4 years.ConclusionsSeveral identical or closely related HAV strains with high homology continue to circulate in Ogaki, Japan, during a 12-year period, causing sporadic cases of acute hepatitis A infection with strains of genotype IA HAV.