European Subtype Tick-borne Encephalitis Virus inIxodes persulcatusTicks

diagnosed cases ranged from July 20 to October 4, 2009.Cases peaked in early September and subsided in early October.The median age of patients with confi rmed or probable disease was 47.3 years (range 3-96 years).Infections occurred in all age groups, but most infections occurred among persons 41 to 65 years of age; 118 (60.2%) were women, and 172 were farm workers.Confi rmed and clinically diagnosed cases occurred in 18 villages, which were part of 7 towns.Most cases (182) were reported in Yiting, where the fi rst case was confi rmed, and in particular, were in persons who lived in the villages of Qingsu, 100 cases; Fantianzhu, 49 cases; Xitian, 19 cases; Shangzhai, 4 cases; and Xiateng, 4 cases.The outbreak shows that DENV-3 subtype III is easily transmitted among humans and mosquitoes and can adapt effi ciently to a new area.Other countries where the climate is similar to that of Zhejiang Province (subtropical monsoon) should be aware of the risk for expansion of DENV-3 subtype III transmission.Clinical vigilance and strong epidemiologic and laboratory surveillance are essential.