TBEV is the most important viral tick-borne zoonosis in Europe, and infection may lead to severeCNS disease, including encephalitis and myelitis. Climate changes have increased the tickdistribution in Sweden, increasing the risk areas of Tick-borne encephalitis (TBE) at severalregions including the Örebro county. The TBE virus (TBEV) is usually transmitted to humans viatick bites, however oral transmission through consumption of non-pasteurized dairy products havealso been described. Both TBEV and antibodies against the viral proteins have been detected inmilk of goats, sheep and cattle. Since the prevalence of TBEV in the tick population is low there is a need for new and robust surveillance techniques identifying novel risk areas of TBEV at earlystages.
In this study we have developed a strategy for identifying new TBEV foci. We have collected raw milk and colostrum samples from sheep and goats in the Örebro region. The milk samples were analyzed for the presence of TBEV antibodies by ELISA. In addition, the ELISA results were further verified by an in-house Western Blot assay where milk samples were used asprimary antibody to detect the Envelope-protein of TBEV. This method has so far revealed two novel TBEV foci within the Örebro county. Questing ticks and ticks feeding on sheep have been collected at areas of TBEV positive milk. The ticks are currently being analyzed for TBEV by PCR. The specific Örebro strains will be isolated from TBEV positive ticks and the viral genomeswill be further characterized using established next-generation sequencing technique.