Assessment of the insecticidal activity of afoxolaner against Aedes aegypti in dogs treated with NexGard^®

Abstract

Twelve healthy dogs were studied in this parallel group, blinded, randomised, and negative controlled efficacy study. On Day -1, the 12 dogs included were ranked within sex in descending order of individual pre-treatment (Day -5) fed mosquito counts and randomly allocated by blocks of two dogs to the untreated control group or the afoxolaner-treated group. NexGard® (Merial, now part of Boehringer Ingelheim Animal Health) was administered orally on Day 0 in accordance with the European label instructions. On Days 1, 7, 14, 21 and 28, all dogs were exposed for a duration of 1 hour to 50 ± 5 unfed Aedes aegypti females. After each exposure, mosquitoes were collected after 1 hour and assessed for viability during collection and at 24 ± 2 hours. The arithmetic (and geometric) mean values of live fed mosquito counts at 24 hours after the exposure periods for the negative control group ranged from 33.7 (32.3) to 49.8 (49.7), indicating that this was a vigorous mosquito strain. There was no significant difference between control and treated groups in the number of live and fed mosquitoes at each 1 hour post-exposure collection time. Based on arithmetic and geometric mean values at 24 hours after each exposure, significantly fewer live fed mosquitoes were recorded in the treated group, compared to the negative control group, throughout the study (p < 0.001). The afoxolaner insecticidal efficacy against A. aegypti varied from 98% (Day 2) to 75.3% (Day 29) based on arithmetic means, and 98.7% (Day 2) to 89.8% (Day 29) based on geometric means.

Insecticidal efficacy of afoxolaner against bedbugs, Cimex lectularius, when administered orally to dogs

“…There are limited data on the infestation of dogs and cats by C. lectularius bedbugs. They are thought to bite pets, but the frequency remains unknown [ 1 , 17 ]. The fact that bedbugs are maintained in the laboratory using weekly feeding on rabbits provides initial evidence that mammals other than humans may be functional hosts [ 4 ].…”

“…Sarcoptes scabiei , Demodex canis , Otodectes cynotis ) [ 2 , 3 , 5 ], and has demonstrated insecticidal activity against hematophagous flying insects (i.e. sandflies, Phlebotomus perniciosus , and mosquitoes, Aedes aegypti ) through the treatment of dogs [ 17 , 21 ]. Recently, an insecticidal effect of afoxolaner and fluralaner has also been demonstrated in treated dogs against kissing bugs ( Triatoma infestans ), the vector of Chagas disease [ 15 , 18 ].…”

Assessment of the insecticidal activity of oral afoxolaner against Phlebotomus perniciosus in dogs

“…At the end of each 1-h exposure period, sandflies were smoothly vacuumed from the enclosure, categorized (male/female), counted and assessed for viability status (live/dead). As classically performed for insects and acarians, moribund sandflies were counted as live, which is more restrictive in the assessment of effectiveness [22]. Sandflies were also categorized as either fed or unfed, separated, and transferred to containers.…”

“…More recently, the insecticidal activity of afoxolaner against Aedes aegypti mosquitoes at 24 h postexposure was demonstrated. It showed that A. aegypti mosquitoes ingested a lethal dose of afoxolaner during their blood meal [22]. Based on these results, we hypothesized that afoxolaner could also kill sandflies that feed on afoxolaner treated dogs [13].…”

Recent Advancements in the Control of Cat Fleas

“…Mosquitoes readily fed on the dogs indicating that the treatment was not repellent. At 24 h after feeding, 98 and 75.3% of the female mosquitoes were killed when exposed to dogs on day 2 and 29 after the dogs were dosed, respectively [ 94 ].…”