Background: Tick-borne encephalitis is caused by a virus that is transmitted to man by tick-bite. The virus is found in central and eastern parts of Europe and also in Sweden.
Material and methods: We report the first two cases of tick-borne encephalitis resulting from transmission of virus in Norway.
Results: Both patients had been to the island of Tromøy on the south coast of Norway. The course of the disease was very different in the two patients. One patient had significant neurological dysfunction. The other patient had intense headache, but no motor dysfunction. Both patients had reduced general health and fever, and leukocytosis and increased protein was found in the spinal fluid. The incubation period is most often 1 to 2 weeks. The disease may have a bi-phasic course with initial fever, headache and muscle pain. One week later symptoms of encephalitis follow. Subclinical infection is common, especially in children. One third of patients get permanent sequelae after encephalitis. Diagnosis is made by demonstration of antibodies in serum. Treatment is symptomatic.
Interpretation: These two patients indicate that there may be a reservoir of TBE virus in Norway.