Evaluation of permethrin and imidacloprid for prevention of Borrelia burgdorferi transmission from blacklegged ticks (Ixodes scapularis) to Borrelia burgdorferi-free dogs

Abstract

Lyme borreliosis is an infectious disease caused by the spirochete Borrelia burgdorferi. The vector tick, Ixodes scapularis is infected during larval tick feeding. Transstadial transmission occurs in the tick, which may result in infection of a mammalian host during feeding as a nymph or adult. The disease is of significance as both dogs and people are susceptible to Lyme borreliosis. The aim of this study was to evaluate the ability of a product containing imidacloprid and permethrin (K-9 Advantix^TM) to prevent transmission of B. burgdorferi to dogs. Adult Beagle dogs confirmed to be free from B. burgdorferi exposure via IFA testing, were randomly assigned to two groups (treated and nontreated control) of 8 animals each and housed separately in a BL-2 facility. K-9 Advantix^TM was applied to one or several sites the dorsal midline of all 8 treated dogs. Field caught adult Ixodes scapularis with an average infectivity rate of 57.6% were used as source of B. burgdorferi organisms. One week post treatment 100 ticks per dog were placed on the backs of the dogs and encouraged into the hair coat. Serum antibody titers to B. burgdorferi were obtained for weeks 2 through 13. By week 6 all nontreated control dogs had seroconverted and all treated dogs continued to remain antibody negative. There was total agreement between the ELISA and IFA antibody results. Skin punch biopsies were obtained for PCR testing and these results are still pending. The results of this study show that K-9 Advantix^TM is effective 7 days after treatment in the prevention of transmission of Lyme borreliosis from infected I. scapularis ticks to dogs.