Hepatitis E epidemic in Sapporo area by single source strain of HEV genotype 4

We encountered a series of sporadic cases of hepatitis E (n=8) from late September to middle of October 2009 in Sapporo and its suburbs. Surprisingly, HEV sequences from these patients segregated to a very compact cluster, suggesting a single-source epidemic. Moreover, they are closely related to the "Sapporo strain" or the "Kitami/Abashiri strain" which is known to have caused severe hepatitis in Kitami and Abashiri area, far from Sapporo, several years before. Advanced livestock marketing and food-distribution system might have caused the spread of this HEV strain.