Abundance of Ixodes ricinus Ticks (Acari: Ixodidae) and the Diversity of Borrelia Species in Northeastern Poland

Abstract

Monitoring the abundance of ticks and the prevalence of pathogens in ticks is an important activity in assessing the risk of tick-borne diseases and helps to develop preventive measures. This study aimed to estimate the density of <i>Ixodes ricinus</i>, the prevalence of <i>Borrelia</i> species, and their diversity in northeastern Poland. The overall mean <i>I. ricinus</i> density was 9.7 ticks/100 m². There were no differences between years, subregions, or habitats of study. The <i>Borrelia</i> infection rate was higher in females (22.6%) and males (14.3%) than in nymphs 5.5% (MIR). The most infected ticks came from the eastern subregion (10.1%) where the incidence of borreliosis among the inhabitants was over 20% higher than in the other subregions. In the infected ticks, <i>B. afzelii</i> (38.3%) and <i>B. garinii</i> (34.5%) were predominant. <i>B. bavariensis</i> was confirmed in <i>I. ricinus</i> in Poland for the first time. The most polymorphic was <i>B. garinii</i>. <i>B. miyamotoi</i> (belonged to the European type) was identified as a mono-infection in 0.9% of ticks and in 1.5% as a co-infection with <i>B. afzelii</i> and with <i>B. garinii</i>. Besides the risk of borreliosis and co-infections with different <i>Borrelia</i> species, physicians should also be aware of <i>B. miyamotoi</i> infections among patients.