Update on prevalence of Babesia canis and Rickettsia spp. in adult and juvenile Dermacentor reticulatus ticks in the area of Poland (2016–2018)

Ornate dog tick, <i>Dermacentor reticulatus</i> is an important vector of <i>Babesia canis,</i> and <i>Rickettsia</i> spp. and other pathogens of veterinary and public health interest. The current study is the first to investigate the long-term changes in prevalence of these pathogens in expanding tick populations in Central Europe. Molecular techniques (PCR, sequencing) were applied for the detection of pathogen DNA in adult (n = 2497) and juvenile ticks (1096 larvae and 410 nymphs). DNA of <i>Rickettsia</i> spp. was identified in 35% of adults and 12.6% of juvenile ticks. DNA of <i>B. canis</i> was detected in 3% of adult ticks and only in ticks from the Eastern region (regional prevalence 6%). As previously, no <i>B. canis</i>-positive ticks were found in Western Poland, including ticks from Wrocław area (n = 298). DNA of <i>B. canis</i> was identified in 0.33% of juvenile ticks (in 3 pools of larvae and 2 nymphs) from the Eastern region. In the current study we confirmed high occurrence of <i>R. raoultii</i> in adults ticks from all four zones and relatively high prevalence of <i>B. canis</i> in the Eastern population of <i>D. reticulatus</i>, corresponding well with high incidence of canine babesiosis in this area of Poland. Finally, we confirmed <i>R. raoultii</i> and <i>B. canis</i> infection in all life stages of <i>D. reticulatus</i> ticks.