Effect of Temperature on Host Preference in Two Lineages of the Brown Dog Tick, Rhipicephalus sanguineus

Abstract

Rhipicephalus sanguineus is a species complex of ticks that vector disease worldwide. Feeding primarily on dogs, members of the complex also feed incidentally on humans, potentially transmitting disease agents such as Rickettsia rickettsii, R. conorii, and Ehrlichia species. There are two genetic Rh. sanguineus lineages in North America, designated as the temperate and tropical lineages, which had occurred in discrete locations, although there is now range overlap in parts of California and Arizona. Rh. sanguineus in Europe are reportedly more aggressive toward humans during hot weather, increasing the risk of pathogen transmission to humans. The aim of this study was to assess the impact of hot weather on choice between humans and dog hosts among tropical and temperate lineage Rh. sanguineus individuals. Ticks in a two-choice olfactometer migrated toward a dog or human in trials at room (23.5°C) or high temperature (38°C). At 38°C, 2.5 times more tropical lineage adults chose humans compared with room temperature, whereas temperate lineage adults demonstrated a 66% reduction in preference for dogs and a slight increase in preference for humans. Fewer nymphs chose either host at 38°C than at room temperature in both lineages. These results demonstrate that risk of disease transmission to humans may be increased during periods of hot weather, where either lineage is present, and that hot weather events associated with climatic change may result in more frequent rickettsial disease outbreaks.

Predicting the northward expansion of tropical lineage Rhipicephalus sanguineus sensu lato ticks in the United States and its implications for medical and veterinary health

“…sanguineus s.l. becomes more aggressive and has a higher affinity for humans as temperatures increase [ 12 , 13 ]. However, in the laboratory the tropical lineage attaches more readily to a host than the temperate lineage [ 14 ].…”

New records of Rhipicephalus linnaei infected by Rickettsia massiliae from Central Mexico

“…For this reason, strategies must be implemented to reduce the risk of tick infestation on dogs, such as the use of collars with repellent agents, as well as acaricidal treatment within the home and around the home, coupled with integrated tick control to prevent family members from being exposed to the microorganism. One aspect that should be highlighted is that R. linnaei exhibited more marked anthropophilic habits than R. sanguineus s.s. (Backus et al., 2021). Evaluation of the vectorial competence and clarification of the prevalence in the study area would help reveal the impact of this Rickettsia in the centre of the country.…”

Potential Shared Disease Risk Among Dogs and Coyotes (Canis Latrans) Exemplified by the Ecology of Rickettsiosis in a Rocky Mountain Spotted Fever-Epidemic Region in Northern Mexico

“…Finally, the lack of ticks on the coyotes may be explained by sample size and weather. All of our samples were taken before the heat of summer, and the brown dog tick has increased overall activity and decreased host specificity with increasing temperature (Parola et al 2008; Backus et al 2021). Surveys later in the summer may have yielded more ticks or more infected blood samples.…”