Efficacy of a new combination of fipronil and permethrin (Effitix ® ) against Phlebotomus perniciosus in dogs
Two controlled clinical trials were carried out to assess the anti-feeding and adulticidal effects of a spot-on combining fipronil and permethrin (Effitix(®), Virbac, Carros, France) against Phlebotomus perniciosus in dogs. The first study (Exp. A) was a dose-determination study in which 3 doses of permethrin (30 mg/kg, 60 mg/kg and 120 mg/kg) were compared. The second study (Exp. B) was an efficacy study using commercial dose of permethrin contained in Effitix(®) (the minimum dose of permethrin applied to dogs was 60 mg/kg). Twenty four and twelve Beagle dogs with equal sensitivity to sandflies were included in Exp. A and in Exp. B, respectively. Dogs were challenged with female sandflies (50 per dogs in Exp. A and 80 in Exp. B) for 60±5 min on Days - 7, 1, 7, 14, 21 and 28 (Day 0 being treatment day). Counts and engorgement determination of dead and alive sandflies were performed after each exposure to treated and untreated dogs. Dead sandflies were also counted 24 h after exposure. In Exp. A, the repellency induced by an administration of 30 mg/kg of permethrin to dogs was above 91% for the first two weeks and then dropped to 82.2, 83.1 and 81.1% on Days 14, 21 and 28, respectively. For dogs receiving 60 mg/kg of permethrin, the repellency was a bit higher with 95.8, 97.6, 92.1, 91.4, and 86.8%, for Days 1, 7, 14, 21 and 28, respectively. The repellency induced by 120 mg/kg of permethrin was significantly higher than that induced by 60 mg/kg of permethrin on Day 14 only. In Exp. B the anti-feeding effect of the spot-on formulation was 94.1, 97.8, 96.3, 90.8 and 87% on Days 1, 7, 14, 21 and 28, respectively. The mortality effect was 98.9, 99.1, 99.8, 97.0 and 89.7% on Days 1, 7, 14, 21 and 28, respectively. At each challenge point, the mortality and anti-feeding effects on sandflies were significantly different between control and treatment group (p<0.05). The results indicate that a monthly administration of this new combination of permethrin and fipronil could be used as an effective sandfly control strategy in dogs and therefore recommended for use in an integrated leishmaniosis prevention program.