Sympatric Ixodes-tick species: pattern of distribution and pathogen transmission within wild rodent populations

Abstract

The generalist tick Ixodes ricinus is the most important vector for tick-borne pathogens (TBP), including Borrelia burgdorferi sensu lato, in Europe. However, the involvement of other sympatric Ixodes ticks, such as the specialist vole tick I. trianguliceps, in the enzootic circulations of TBP remains unclear. We studied the distribution of I. ricinus and I. trianguliceps in Central Finland and estimated the TBP infection likelihood in the most common rodent host in relation with the abundance of the two tick species. Ixodes trianguliceps was encountered in all 16 study sites whereas I. ricinus was frequently observed only at a quarter of the study sites. The abundance of I. ricinus was positively associated with open water coverage and human population density around the study sites. Borrelia burgdorferi s. l.-infected rodents were found only in sites where I. ricinus was abundant, whereas the occurrence of other TBP was independent of I. ricinus presence. These results suggest that I. trianguliceps is not sufficient, at least alone, in maintaining the circulation of B. burgdorferi s. l. in wild hosts. In addition, anthropogenic factors might affect the distribution of I. ricinus ticks and, hence, their pathogens, thus shaping the landscape of tick-borne disease risk for humans.

Relationships between landscape structure and the prevalence of two tick-borne infectious agents, Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato, in small mammal communities

“…Consequently, a lower local extinction probability of their parasites (including small mammal specialist tick species like I. trianguliceps and I. acuminatus), and of the infectious agents they could transmit is expected (H1). (Agoulon et al 2012;Li et al 2012;Cayol et al 2018). However, in previous studies, no relationship was observed between the abundance of I. ricinus nymphs and B. burgdorferi s.l.…”

Effect of rodent density on tick and tick-borne pathogen populations: consequences for infectious disease risk

“…An alternative explanation for this non-linear association might be that I. ricinus is not a main vector of this parasite. Previous studies proposed I. trianguliceps, a nidicolous rodent tick species as the main vector [63][64][65]. It indicates that B. microti circulates in the, so called 'cryptic cycle' between specialist ticks and rodents, while I. ricinus sporadically becomes infected and perhaps acts as an occasional bridge vector to other host species [63].…”

Human Bartonellosis: An Underappreciated Public Health Problem?

“…in Europe. This is because I. ricinus is an important vector for tick-borne diseases in Europe [81]. I. ricinus have been collected in the larval, nymphal, and adult stages in Austria [82].…”