A unique HAV strain circulated in patients with acute HAV infection with different risk exposures in Tuscany, Italy.

BACKGROUND: Acute Hepatitis A Virus (HAV) is reported to be an emergent problem in several developed countries. OBJECTIVES AND STUDY DESIGN: The aim of this study was to analyse the HAV strains circulating among individuals with acute HAV infection, apparently transmitted by different routes, in several districts of Tuscany in central Italy, during the year 2008. RESULTS: An outbreak of acute HAV infection occurred from May to August 2008 in Arezzo; 32 individuals were admitted to the hospital, in 25 of them at least a linkage with an infected food handler and/or household contacts was reported and in 3 homosexuality was a possible risk factor. In Florence, from January 2008 to August 2008, 41 individuals mainly homosexual men were admitted to two hospitals with the diagnosis of acute HAV. The phylogenetic analysis of VP1/2A region of HAV was used to characterize these HAV isolates. All viral sequences were assigned to genotype IA. All clustered in the same branch (bootstrap 82%) of phylogenetic tree, thus indicating the same circulating isolate. Apart of one isolate from France and one from Germany which were similar with the "Tuscany" strain reported here, high heterogeneity with the other European HAV strains reported in the GenBank in the last years, was observed. CONCLUSION: The detection of a unique HAV isolate circulating in different Tuscany districts, suggests sequential transmission of HAV infection in this geographical area through possible links among acute hepatitis cases. The application of safe food handling practices and vaccination of homosexual men may contribute to the prevention of HAV infection.