Abstract
BackgroundLyme borreliosis (LB) is the most common vector-borne disease in Europe. Monitoring changes in the prevalence of different Borrelia species in ticks may be an important indicator of risk assessment and of differences in pathogenicity in humans. The objective of our study was to assess the prevalence, co-infection and distribution of Borrelia and Babesia species in ticks removed from humans in a large sample collected during a study period of 4 years.MethodsThe ticks were collected throughout Poland from March to November over 4-year period from 2016 to 2019. All ticks (n = 1953) were morphologically identified in terms of species and developmental stage. Molecular screening for Borrelia and Babesia by amplification of the flagellin gene (flaB) or 18S rRNA marker was performed. Pathogen identity was confirmed by Sanger sequencing or PCR–restriction fragment length polymorphism analysis.ResultsThe ticks removed from humans in Poland during this study belonged to two species: Ixodes ricinus (97%) and Dermacentor reticulatus (3%). High Borrelia prevalence (25.3%), including B. miyamotoi (8.4%), was confirmed in Ixodes ricinus ticks removed from humans, as was the change in frequency of occurrence of Borrelia species during the 4-year study. Despite Babesia prevalence being relatively low (1.3%), the majority of tested isolates are considered to be pathogenic to humans. Babesia infection was observed more frequently among Borrelia-positive ticks (2.7%) than among ticks uninfected with Borrelia (0.8%). The most frequent dual co-infections were between Borrelia afzelii and Babesia microti. The presence of Borrelia was also confirmed in D. reticulatus (12.7%); however the role of these ticks in spirochete transmission to susceptible hosts is still unclear.ConclusionsAlthough the overall risk of developing LB after a tick bite is low in Europe, knowledge of the prevalence and distribution of Borrelia and Babesia species in ticks might be an important indicator of the risk of both these tick-borne diseases.Graphical abstract
Highlights
Lyme borreliosis (LB) is the most common vector-borne disease in Europe
Ixodes ricinus and D. reticulatus ticks Almost all ticks collected from humans in during the study period (2016–2019) were I. ricinus (97%), with the other tick species identified being D. reticulatus (3%)
The identification of different Borrelia species in our study revealed that B. afzelii was the most frequent species within the study period; these results are comparable to data on questing and engorged ticks from other European countries
Summary
Lyme borreliosis (LB) is the most common vector-borne disease in Europe. Monitoring changes in the prevalence of different Borrelia species in ticks may be an important indicator of risk assessment and of differences in pathogenicity in humans. With 85,000 cases reported annually, Lyme borreliosis (LB) is the most common vector-borne disease in Europe [1]. The estimated incidence of LB in Poland increased dramatically from 20.3 per 100,000 inhabitants in 2007 to Pawełczyk et al Parasites Vectors (2021) 14:348. At least five species of Borrelia, namely Borrelia burgdorferi (s.s.), B. garinii, B. afzelii, B. spielmanii and B. bavariensis, are known to be pathogenic to humans, with each of these species believed to be associated with different clinical manifestations. Borrelia miyamotoi disease (BMD) has been confirmed in an immunocompetent patient, and BMD concurrent with Lyme disease has been described [6]
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