tick-borne encephalitis

any of several types of epidemic encephalitis spread by the bites of ticks (usually species of Ixodes) that are infected with flaviviruses. They are most common during the spring and summer months, range from mild to fatal, and may affect organs outside the nervous system. Occasionally they may be spread via raw milk from goats, sheep, or cows infected with the virus. The most common and severe type is Russian spring-summer encephalitis; a rare, also serious type is Powassan encephalitis; a milder type is called Central European encephalitis. Called also forest-spring or vernal e.