 - Infection by tick-borne encephalitis virus TBEV is a significant health concern for humans in Europe and Asia. A vaccine is available in these regions and in Canada, but not in the United States. Research studies in Europe have shown the vaccine to be effective in preventing infection among the general population, where disease is transmitted either by the bite of an infected tick most common or by ingestion of contaminated unpasteurized milk or milk products. Persons who work with the virus in a research setting, however, have the potential of being exposed in unnatural ways, and may come into contact with concentrations of virus higher than those found naturally in ticks. 