Four forestry plant in Mudanjiang with different geographic characteristics were investigated in 1989. 2178 people were inquired and examined. 74 cases including 54 of ECM, 12 of nervous system disorder and 8 of arthritis were confirmed as
Lyme disease. There were some patients at other places of forest areas of Mudanjiang. The prevalence rate of
Lyme disease ranged from 1% to 4.5% at four plants with higher rate in mountainous area than in hilly land. It is first report that one strain of
Lyme disease spirochetes was isolated from a patient with psychiatric derangement. It proved that Ixodes persulcatus play the leading role in transmission of
Lyme disease spirochetes, as the growth curve of Ixodes persul catus is coincident with that of the patient with ECM.