The Prevalence and Control of Ectoparasitesin Irish Cattle Herds

Infestations of ectoparasites are known to cause significant welfare issues, production and economic losses within livestock herds globally either directly by causing irritation and skin damage to the animal or indirectly through the transmission of pathogens and diseases. In order to effectively target and control ectoparasite infestations within livestock herds, good knowledge and awareness of the types of ectoparasites that are present on individual farms and the risks associated with infestations are essential. This study aimed to investigate the prevalence of two major ectoparasites, lice and ticks, and the tick-borne pathogens Anaplasma phagocytophilum and Babesia divergens in cattle farms in Ireland. Moreover, we aimed to investigate how these parasites are managed on cattle farms and farmers’ attitudes and perceptions regarding the importance of ectoparasites and their control. Following a thorough review of the literature (chapter 1), we investigated the prevalence of lice on 18 cattle farms, the methods that were used to control louse infestations and the presence of insecticide-tolerant lice (chapter 2). The results showed that while lice were common on the cattle farms, infestations were generally well managed. However, we also found indications that insecticide resistance, particularly to the synthetic pyrethroid chemical class, was present on some farms. The 3rd chapter describes a blanket-dragging survey of 53 cattle farms across the country carried out to determine the prevalence of the hard tick Ixodes ricinus on farmland and tick-infection rates with the ruminant pathogens A. phagocytophilum and B. divergens. Our results suggested that the prevalence of I. ricinus was relatively low which is probably attributable to the improvement of grazing on farms in recent decades. Moreover, laboratory analysis of questing ticks collected from farms showed that considerably more ticks were infected with A. phagocytophilum than B. divergens. However, interestingly, data collected from farmer questionnaire surveys on the incidence of the tick-borne diseases associated with these pathogens showed the exact opposite. Whilst Irish farmers were generally well informed with regard to the occurrence of lice and ticks in their herds, more work is required to publicize the emergence of ectoparasiticide resistance and to develop guidelines for the sustainable management of ectoparasites.