Prevention of Babesia canis in dogs: efficacy of a fixed combination of permethrin and fipronil (Effitix®) using an experimental transmission blocking model with infected Dermacentor reticulatus ticks

BACKGROUND: Two experimental studies using a transmission blocking model with Dermacentor reticulatus ticks infected with Babesia canis were performed to test the ability of Effitix® to prevent the transmission of babesiosis in dogs. METHODS: Four groups of seven dogs (experiment 1) and one group of eight dogs (experiment 2) were treated topically with a novel combination of fipronil and permethrin in a spot-on formulation (Effitix®, Virbac) respectively 28, 21, 14 and 7 days (experiment 1) and 2 days (experiment 2) prior to tick infestation. In each study, a control group of seven dogs (experiment 1) and eight dogs (experiment 2) remained untreated. On day 0, all dogs were infested with adult D.reticulatus ticks harboring B. canis. An efficacy failure (successfully infected) was regarded as a dog in the treated groups that was tested serologically positive for B.canis antibodies, using an indirect fluorescent antibody (IFA) assay and tested positive for B.canis by DNA-assay using PCR analysis. RESULTS: B.canis was transmitted by D.reticulatus to all untreated dogs (experiment 1) and six untreated dogs out of eight (experiment 2) as confirmed by IFA and PCR assays. The large majority of treated dogs (92.9% in experiment 1 and 100% in experiment 2) remained sero-negative over the challenge period. CONCLUSIONS: The treatment of dogs with Effitix® applied 2 to 28 days prior to infestation with D. reticulatus harboring B.canis, successfully prevented the transmission of canine babesiosis.