differences in borrelia infections in adult ixodes persulcatus and ixodes ricinus ticks (acari: ixodidae) in populations of north-western russia. | dark-field microscopy was used to determine the number of borrelia spirochetes in 630 standard preparations obtained from adult ixodid ticks (344 ixodes persulcatus and 286 i. ricinus) collected in 1989-92 in the leningrad region of russia. the average numbers of borrelia in i. persulcatus and i. ricinus preparations were 34.7 and 23.3 per 100 microscopic fields, respectively. the maximal individual values registered each year for ticks of both species were several hundred times greater than the ... | 1995 | 7621710 |