Detection of Babesia spp. in ticks and in blood of dogs and red deer in the Czech Republic.

Aim: To determine the occurrence of species of Babesia potentially pathogenic for humans in ticks and in the blood of dogs and deer in selected regions of the Czech Republic. To compare the prevalence of Babesia spp. in ticks with that of other tick-borne pathogens, such as Borrelia spp., Anaplasma spp., and Rickettsia spp.

Material and methods: Tick samples were individually homogenized. DNA was isolated from tick samples and animal blood. The detection of Babesia spp. was based on PCR of the 18S rRNA gene, and the identification to the species level was done by sequencing analysis of the PCR products.

Results: In 2014-2016, ticks and blood of dogs and deer collected in various areas of the Czech Republic were analyzed. In a set of 675 Ixodes ricinus ticks, the positivity rate for Babesia spp. varied from 0.0 to 3.3 %. The species Babesia venatorum, Babesia microti (both pathogenic for humans), and Babesia capreoli were identified in ticks by sequencing analysis. The prevalence of Babesia spp. in ticks compared to that of other pathogens such as Borrelia burgdorferi s. l. (29.3 %) or Anaplasma phagocytophilum (4.9 %) was lower and comparable to that of Rickettsia spp. (1.6 %). Co-infection with Borrelia burgdorferi s.l (B. venatorum - Borrelia garinii, Borrelia afzelii, and B. microti - B. afzelii) was found in a third of Babesia spp. positive ticks. Out of 109 dog blood samples, 3.7 % were positive for Babesia spp., specifically Babesia gibsoni and Babesia vulpes. Of 50 blood samples of wild deer from the natural ecosystem, the positivity rate reached 4.0 %. The species Babesia divergens, a major human pathogen, was identified. Out of 80 blood samples from farmed deer, 5.0 % were positive for the species Babesia odocoilei. Nucleotide sequences of the agents causing human babesiosis were deposited in the gene bank under accession numbers ON892053 (B. venatorum), ON892061 (B. microti), and ON892067 (B. divergens).

Conclusions: Using PCR of the 18S rRNA gene and amplicon sequencing, three species of Babesia causing human babesiosis were detected in the Czech Republic: B. divergens, B. venatorum, and B. microti. Babesia spp. pathogenic for humans pose a potential risk especially in asplenic and immunocompromised patients. The detected co-infections with Borrelia spp. can be the cause of a complicated course of the disease.