Ticks Infesting Humans in North-Western Italy and Associated Pathogens: A Cross-Sectional Study in a Three-Year Period (2017-2019) in North-Western Italy.

Abstract

Abstract Background. Tick-borne diseases are widespread in many European Countries and high incidence has been reported in the past few years. Ticks are able to transmit several pathogens to the host while feeding and are considered the most important vectors of infectious agents worldwide together with mosquitos. As tick-bite events has remarkably increased in North-Western Italy and information about the prevalence of tick-borne pathogens in ticks removed from humans in Italy are scarce, this study aimed to identify the species of ticks biting humans and the tick-borne pathogens they can transmit.Methods. Ticks collected from bitten humans during 2017-2019 were morphologically identified and screened by biomolecular essays. A total of 1,290 ticks were analysed. Most of the ticks belonged to the Ixodes genus: 1,009 ticks (78.0%) were classified as Ixodes ricinus. Some Ixodes ticks (n = 158; 12.3%) were identified only at genus level due to lack of morphological features. Overall, 500 ticks were PCR tested for the presence of Rickettsia spp., Borrelia spp., and Anaplasma spp. in at-risk population (elderly and children). Pathogen identity was confirmed by Sanger sequencing. Results. The overall prevalence was 22.8%; (n = 114; 95%CI 19.19-26.73%), meaning that at least one pathogen was detected. Molecular analysis was carried out on a subset of 500 ticks showing the presence of R. helvetica (n=31), R. monacensis (n=35), R. slovaca (n=3), R. aeshlimannii (n=1), Rickettsia spp. (n=6); B. afzelii (n=11), B. burgdorferi sensu stricto (n=1), B. garinii (n=3), B. lusitaniae (n=4), and B. valaisiana (n=2), Borrellia spp. (n=11); Anaplasmaphagocytophilum(n=6).Conclusions. These data highlight the importance of surveillance to assess the epidemiology of TBDs that pose a threat to human health by the implementation of control strategies for both tick infestations and their associated pathogens.