Dermatologic Changes Induced by RepeatedIxodes scapularisBites and Implications for Prevention of Tick-Borne Infection

Abstract

Previous studies in rodents and people have demonstrated that repeated tick exposure is associated with reduced Borrelia burgdorferi transmission but the mechanism of prevention remains unclear. We examined the acute histopathologic reactions to initial and repeated Ixodes scapularis bites in BALB/c mice and in people. Skin biopsies of BALB/c mice infested for the first time by I. scapularis nymphs revealed vascular dilatation and an accumulation of inflammatory cells adjacent to the bite site but absent at the site of tick attachment. Such changes would enhance tick-borne pathogen transmission. Mice reexposed to I. scapularis nymphs experienced a decrease in vascular dilatation and a marked increase in inflammatory cells at the site of tick attachment. Skin biopsies of people with attached I. scapularis nymphs revealed similar histologic patterns. These results indicate that cellular changes at the tick-dermal interface following I. scapularis attachment are likely to allow for successful transmission of tick-borne pathogens in non-tick-immune hosts and to inhibit tick-borne pathogen transmission in hosts that have developed tick immunity.

Vaccination against Lyme disease: past, present, and future

“…It is then plausible that the salivary proteome changes to meet feeding phase-specific requirements (Figure 3). Histopathological and molecular examination of the dermis at the tick bite site also showed differences in the composition of the inflammatory milieu that accumulates in the early and late stages of feeding (Krause et al, 2009; Heinze et al, 2012). During the final rapid feeding phase, I. scapularis ticks have been shown to secrete a protein that facilitates release of histamines from neutrophils, mast cells and possibly basophils to increase vasodilation and accelerate the flow of blood to the bite site (Dai et al, 2010).…”

Characterization of the early local immune response to Ixodes ricinus tick bites in human skin

“…For example, natural tick bites elicit an inflammatory response in human skin, including the accumulation of eosinophils at the tick bite site (5). Because Ixodes ticks feed for several days, they must overcome the host's hemostatic, inflammatory, and immunologic responses during this time.…”

Partial pathogen protection by tick-bite sensitization and epitope recognition in peptide-immunized HLA DR3 transgenic mice

“…Prolonged feeding usually is associated with increased pathogen transmission in tick-bite naïve hosts, while extended feeding on a tick sensitized host occurs due to an inability to obtain a proper bloodmeal. Primed host immune defenses decrease vascular size and recruit neutrophils and lymphocytes to the tick bite site creating a hostile environment for blood uptake and pathogen transmission 10,19 . However, unlike ATR typically seen in other non-natural tick hosts, there was no significant difference in the amount of blood ingested by tick-bite sensitized HLA DR3 tg mice compared to tick naïve HLA DR3 or tick naïve or sensitized B6 controls ( Table 1 ).…”

“…Altered tick feeding, either shortened or prolonged, is indicative of host anti-tick responses. Grooming due to a heightened itch response contributes to abbreviated tick feeding 10 . Prolonged feeding usually is associated with increased pathogen transmission in tick-bite naïve hosts, while extended feeding on a tick sensitized host occurs due to an inability to obtain a proper bloodmeal.…”