Association between body size and reservoir competence of mammals bearing Borrelia burgdorferi at an endemic site in the northeastern United States

Abstract

BackgroundThe reservoirs for the Lyme disease agent, Borrelia burgdorferi, are dominated by several different small to medium sized mammals in eastern North America.FindingsTo experimentally assess the competence of different mammalian species to transmit this pathogen to ticks, we carried out quantitative species-specific PCR of individual nymphal Ixodes scapularis ticks, which had been collected as replete larvae from animals captured at a field site in eastern Connecticut and then allowed to molt in the laboratory. The mammals, in order of increasing body mass, were the white-footed mouse, pine vole, eastern chipmunk, gray squirrel, Virginia opossum, striped skunk, and common raccoon. The prevalence of infection in the nymphs and the counts of spirochetes in infected ticks allometrically scaled with body mass with exponents of −0.28 and −0.29, respectively. By species, the captured animals from the site differed significantly in the mean counts of spirochetes in the ticks recovered from them, but these associations could not be distinguished from an effect of body size per se.ConclusionsThese empirical findings as well as inferences from modeling suggest that small mammals on the basis of their sizes are more competent as reservoirs of B. burgdorferi in this environment than medium-to large-sized mammals.

Borrelia burgdorferiInfection and Lyme Disease in North American Horses: A Consensus Statement

“…They are maintained in a 2‐year enzootic life cycle that involves mammals and Ixodid ticks: Ixodes scapularis in eastern North America and Ixodes pacificus on the North American west coast . The white‐footed mouse in the east and gray squirrels in the west serve as common reservoir hosts for the spirochete and provide a source of spirochetes for Ixodes larvae and nymph infection with a continuation of the infection in adult ticks, whereas deer or other large wild mammals help maintain the adult Ixodes tick . Borrelia burgdorferi is transferred from the tick gut to animals during blood meals.…”

“…32 The whitefooted mouse in the east and gray squirrels in the west serve as common reservoir hosts for the spirochete and provide a source of spirochetes for Ixodes larvae and nymph infection with a continuation of the infection in adult ticks, whereas deer or other large wild mammals help maintain the adult Ixodes tick. [33][34][35][36] Borrelia burgdorferi is transferred from the tick gut to animals during blood meals. After tick attachment, several hours are believed to be required to successfully transfer the organism to a mammalian host.…”

The ecology of Lyme borreliosis risk : interactions between lxodes ricinus, rodents and Borrelia burgdorferi sensu lato

“…A correlation between host body size versus infectivity and spirochaete burden in feeding ticks has not been tested for I. ricinus. However, this correlation was negative at host species level for I. scapularis (Barbour et al 2015). These authors suggested that this was caused by a difference in time between inoculation and putative threshold for infectiousness.…”

Infection resistance and tolerance in Peromyscus spp., natural reservoirs of microbes that are virulent for humans

“…Figure 1 illustrates the white-footed mouse’s greater competency in comparison with some other mammals existing in the same environment. The figure shows the ranges for B. burgdorferi numbers in nymphal ticks that had been feeding as larvae on captured P. leucopus or different medium-sized mammals [24, 25]. …”