No abstract

Repellency is a highly desirable attribute for an acaricide that protects dogs against the Australian paralysis tick (Ixodes holocyclus). A bite from a single tick of this species can be fatal and carries the risk of transmission of vector-borne diseases. A randomised, controlled study was conducted to confirm the repellency sensu stricto and sensu lato (expellency) of a 10 % imidacloprid/4.5 % flumethrin collar (Seresto ® , Bayer) on dogs, against artificial infestations of I. holocyclus. Based on a novel protocol, dogs treated with Seresto ® , or a placebo collar, were sedated and placed in infestation chambers for 1 h at varying time points up to 6 months after treatment. Ticks were released alongside the dogs, and allowed to approach and/or attach. Treating dogs with a Seresto ® collar resulted in significantly (p < 0.001) more residual ticks being found in the infestation chambers (repellency sensu stricto) compared to the placebo treated dogs for the 168-day duration of the study (range 67.5% to 90.2 %). Repellency sensu lato (expellency) was reflected in significantly (p <0.002) fewer ticks being found attached to treated dogs throughout the study. Comparative decrease in ticks attached exceeded 95 % for 84 days, when assessed after 6 h. When assessed after 24 h, there was a > 95 % comparative decrease in ticks attached until Day 84, > 90 % on Days 112 and 140 then > 95 % to Day 168. Efficacy (killing effect) of the Seresto ® collar based on total live tick counts was > 95 % 6 h after tick challenge throughout the 6 month study period. This study demonstrated the excellent repellency effect of the Seresto ® collar against I. holocyclus in dogs. S146Ectopar asitEs

Background: An investigation aimed to confirm whether immunisation with the “benign” buffeli genotype of Theileria orientalis could reduce the parasitosis of the virulent ikeda genotype. Methods: Calves were inoculated intravenously or subcutaneously with bovine blood containing merozoites of T.orientalis buffeli. When recipients became positive, they and control animals were challenged with unfed nymphs of Haemaphysalis longicornis ticks infested as larvae with T.orientalis ikeda. Results: All calves became positive for the challenge within 12 days after tick application. In the immunised calves, the first wave of parasitosis with T.orientalis ikeda from 4-6 weeks was reduced significantly by >80% before the infestation declined into the carrier state by 9 weeks. Conclusions: The results confirm the field experience with theileriosis in endemic zones where the carrier state appears to prevent clinical disease despite repeated, seasonal tick infestations with virulent genotypes of the parasite. This method offers a means to reduce the severity of the first wave of theilerial parasitosis after tick challenge and recover associated production losses.