Abstract
BackgroundAcaricides are used to treat and prevent tick infestations, and a common clinical scenario is to administer an acaricide on observing an attached tick. Consequently, immediate acaricidal efficacy (onset of activity and speed of kill) results are clinically valuable. This study evaluated the immediate efficacy of four commercially available acaricides against adult Rhipicephalus sanguineus (sensu lato).MethodsForty dogs were blocked on hair length and tick carrying capacity, then randomly assigned to receive one of four treatments (fluralaner, sarolaner, imidacloprid + permethrin, or afoxolaner) or left untreated as controls. All dogs were challenged with 50 adult R. sanguineus (s.l.) ticks 48 h prior to treatment. After treatment, in situ tick thumb counts were conducted at 2, 4, 8, 12 and 24 h; thereafter ticks were removed and counted at 48 h.ResultsImidacloprid + permethrin had the earliest onset of activity at 2 h (36.9% efficacy) followed at 4 h by fluralaner (60.2% efficacy) and sarolaner (48.2% efficacy), and lastly afoxolaner at 8 h (90.8% efficacy). Three oral treatments had an 8 h speed of kill (>90% efficacy) threshold; with corresponding efficacies as: fluralaner (99.6%), sarolaner (94.7%) and afoxolaner (90.8%). Fluralaner and sarolaner achieved 100% efficacy at 12, 24 and 48 h; afoxolaner achieved 100% efficacy at 48 h. Imidacloprid + permethrin achieved 80.1% efficacy at 48 h, therefore, failing to attain the speed of kill 90% efficacy threshold.ConclusionThe systemically distributed isoxazolines performed much better than cutaneously distributed imidacloprid + permethrin and are optimal treatment choices against attached ticks based on the combination of earlier onset of activity and speed of kill. Fluralaner had a 4 h onset of activity, an 8 h speed of kill and achieved 100% efficacy at 12 h.
Highlights
Acaricides are used to treat and prevent tick infestations, and a common clinical scenario is to administer an acaricide on observing an attached tick
Total live ticks attached to treated dogs declined over the 48 h period in all treatment groups and reached 0 in all treated groups except for the imidacloprid + permethrin group (Table 3)
The potential clinical impact of these efficacy differences is illustrated by comparing the total live tick counts on all dogs from each group at 8 h when there were: 113 attached live ticks counted on the imidacloprid + permethrin group dogs; 21 live ticks on the afoxolaner group dogs; 12 live ticks on the sarolaner group dogs; and one live tick on the fluralaner group dogs (Table 3)
Summary
Acaricides are used to treat and prevent tick infestations, and a common clinical scenario is to administer an acaricide on observing an attached tick. This study was designed to measure the immediate efficacy, defined as efficacy against ticks potentially attached at the time of treatment [5], of four different acaricides. ‘Onset of activity’ is used to refer to the earliest time that significant parasite killing activity can be shown after treatment administration [6] and is the first treatment threshold reached. ‘Speed of kill’ refers to the time required to achieve a defined efficacy threshold (usually > 90% for ticks) and can be measured at any elapsed time point after treatment administration, the elapsed time after treatment should be specified with the result [7]. A third measurement often included in approved product labels in Europe - is the ‘onset of effect’, which refers to the longest time required to reach the speed of kill efficacy level (90% efficacy for ticks) during the recommended treatment interval [8]. ‘Onset of effect’ is not usually a characteristic of immediate treatment efficacy because speed of kill is likely to be slowest toward the end of the treatment interval
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
