Mosaic pattern of Borrelia infection in a continuous population of the tick Ixodes ricinus (Acari : Ixodidae)

An array of 12 20 x 20 m quadrats in a mixed forest near Poteply, Central B ohemia, Czech Republic, was investigated for the abundance and spatial dist ribution of host-questing Ixodes ricinus nymphs and their infection with bo rreliae. Tick densities were estimated by flagging and their borrelia infec tion status was determined by direct immunofluorescence. While the tick pop ulation appeared to be continuous and homogeneous based on quadrat counts, their infection with borreliae evinced a mosaic pattern. The nymphal infect ion rates ranged between 1.6 and 10.5% (mean = 6.0%) with significant diffe rences between adjacent quadrats. Home ranging of small rodents (Apodemus f lavicollis and Clethrionomys glareolus) inhabiting the forest seems to be r esponsible for the spatial pattern of borrelial infection.