Tick-borne encephalitis transmitted by unpasteurised cow milk in western Hungary, September to October 2011

In October 2011, a cluster of four tick-borne encephalitis (TBE) cases was identified in Hungary. Initial investigations revealed a possible link with consumption of unpasteurised cow milk sold by a farmer without authorisation. We performed a cohort study including all regular customers of the farmer. Overall, eleven cases (seven confirmed and four suspected) were identified. Customers who had consumed the farmer’s unpasteurised cow milk had more than a two-fold increased risk for being a TBE case, although not at statistically significant level.