Genotypic mutations indicative of pesticide resistance in temperate and tropical Rhipicephalus sanguineus sensu lato ticks in a Rocky Mountain spotted fever endemic area of Arizona

Tuesday, November 12, 2024

2:24 PM – 2:36 PM MST

Location: Phoenix Convention Center, 221 C, PCC

Presenting Author(s)

Maureen Brophy (she/her/hers)

Epidemiologist
Centers for Disease Control and Prevention
Phoenix, Arizona

Co-Author(s)

NS

Nathan Stone

Senior Research Coordinator
Northern Arizona University
Flagstaff, Arizona
ND

Naomi Drexler

Epidemiologist
Centers for Disease Control and Prevention
Atlanta, Georgia
CP

Christopher Paddock

Medical Officer
Centers for Disease Control and Prevention
Atlanta, Georgia
GK

Gilbert Kersh

Rickettsial Zoonoses Branch Chief
Centers for Disease Control and Prevention
Atlanta, Georgia
HB

Harty Bendle

San Carlos Apache Tribe
San Carlos, Arizona
DW

David L. Wagner

Northern Arizona University
Flagstaff, Arizona
WN

William Nicholson

Centers for Disease Control and Prevention
Atlanta, Georgia
JS

Johanna Salzer

Epidemiology Team Lead
Centers for Disease Control and Prevention
Atlanta, Georgia

Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) refers to a species complex that is found throughout the world in domestic or peridomestic settings, where it has regular access to its primary host, domesticated dogs. While the taxonomy of this group has not been resolved, it is generally accepted that there are two major lineages, the temperate and tropical, which occupy distinct ecologic niches. The ecologic ranges have been reported to overlap in more than one region, including central Arizona, where the tick is the primary vector for Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever (RMSF). The disease has become endemic on multiple tribal reservations with large populations of free-roaming dogs. Application of broad-spectrum peridomestic pesticides and tick control products for dogs are part of an integrated approach to RMSF prevention that has been employed by some impacted communities for over a decade to treat and control infestations of Rh. sanguineus. Sodium and para-sodium channel mutations associated with target site insensitivity to synthetic pyrethroids have been reported in various populations of Rh. sanguineus and other Rhipicephalus species across the world. Additionally, dieldrin/fipronil resistance is associated with GABA-gated chloride channel mutations of Drosophila spp. and Rh. microplus. We evaluated the distribution of the two major lineages of Rh. sanguineus ticks and the prevalence of genetic mutations indicative of pesticide resistance within an RMSF-endemic area in Arizona. Identifying potential pesticide resistance in Rh. sanguineus populations is critical to ensure continued success in reducing risk of this severe and potentially fatal disease.