To examine recent trends of acute infection with hepatitis B virus (HBV) in Mito, located in a non-Metropolitan area of Japan, serum samples obtained from 17 patients with acute hepatitis B (AHB) and 243 patients with chronic HBV infection during 2001-2013 were subjected to HBV genotyping. HBV genotype A (GtA) was detected in 3 (1%), GtB in 64 (26%) and GtC in 174 (72%) of patients with chronic HBV infection, while GtA was most prevalent (47%) among the AHB patients. Of note, GtA was found significantly more frequently in AHB patients during 2008-2013 than in those during 2001-2007 (64%vs. 17%, p<0.0001). These increasing trends of GtA HBV infection via sexual transmission emphasize the necessity of preventive education and measures.
