Molecular identification of Babesia parasites isolated from Ixodes ricinus ticks collected in northwestern Poland

In the present study, PCR has been applied to detect and analyze DNA of Babesia spp. extracted from Ixodes ricinus ticks. Collection of I. ricinus was made in 6 forested areas of Zachodniopomorskie Voivodship, Poland, during 2 seasonal peaks of tick activity, i.e., spring and autumn, 2001. In total, 1,328 I. ricinus were collected and processed for PCR with F34 and R323 primers. Babesia spp. was detected in 28 (2% of 1,328 tested) ticks; 26 were identified as B. divergens. The other 2 were identified as B. microti. PCR was conducted with 18S rRNA specific primers and sequencing was processed to precisely identify and compare these isolates with B. microti and B. divergens sequences from Europe, North America, and Asia obtained from the GenBank. Analysis revealed that sequences of B. microti from northwestern Poland are almost identical (99.94%) with those referred to as "Munich strain"; both form a clade different from other European strains, as well as those from Asia and North America (called B. microti, sensu stricto). An investigation performed with B. divergens sequences showed that the sequence from northwestern Poland is 99.94% homologous to an isolate from Ireland ("Purnel"), and differs in just a few nucleotides from other European sequences. Phylogenetic analysis revealed that the sequence of B divergens isolated from Polish ticks form a group that comprise 4 European sequences from Great Britain and Ireland and is, therefore, closely related to other European and North American B. divergnens sequences.