EN
The article presents the results of researche ( 1999-2000) on numbers and seasonal activity of Ixodes ricinus in selected lakesides and forests habitats of Szczecin and on occurence of the spirochetes Borrelia burgdorferi sensu lato in ticks. A total of 8065 ticks were collected from 6 localities: 647 larvae, 4549 nymphs, 1624 females and 1244 males. The spirochetes B. burgdorferi were found (using the PCR techniques) in 2271 specimens e.c. 28,1 % whole population. Numbers infected larvae were 216 (33,4 %), nymphs 1215 (26,7 %), females 490 (30,6 %), males 350 (28,1 %). This study shows that examinated habitats where I. ricinus is present are risk areas of human infection with Lyme disease spirochaetes.