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  • Publication
    Distribution and prevalence of Borrelia burgdorferi sensu latu genospecies, Anaplasma phagocytophilum and Babesia divergens in Irish questing nymphal ticks
    (University College Dublin. School of Veterinary Medicine, 2020)
    Ixodes ricinus is an important vector of various pathogens of medical and veterinary importance in western Europe, including bacteria, protozoa and viruses. In Ireland, there has never been a national survey of ticks or tick-borne diseases. I. ricinus is the only exophilic tick present on the island, and it is the primary vector of borreliosis, babesiosis, anaplasmosis and Louping ill. This study aimed to optimise molecular assays and employ them to investigate the distribution and prevalence of different Borrelia species, Babesia divergens and Anaplasma phagocytophilum in I. ricinus nymphs collected from woodland sites and farms throughout Ireland between 2017 and 2019. Chapter 1 summarised the most important tick species worldwide and in Ireland, their life cycle and the most important tick-borne diseases. It also describes the most recent molecular assays used to investigate tick-borne pathogens and microbiomes and discusses strategies used to control ticks and tick-borne diseases. Chapter 2 investigated the distribution and prevalence of different B. burgdorferi s.l. genospecies in Irish I. ricinus nymphs using TaqMan and nested PCRs. In agreement with previous reports from Ireland we found a higher prevalence of Borrelia spp in woodland sites compared to farms which may be due to higher numbers of potential reservoir hosts in the former. Chapter 3 investigated the distribution and prevalence of Babesia divergens and Anaplasma phagocytophilum using optimised molecular assays. The results also showed a higher prevalence of A. phagocytophilum in woodland ticks compared to those collected from farm sites. In contrast the prevalence of B. divergens was higher in ticks collected farms confirming that cattle are the primary hosts for B. divergens. It is suggested for future research to investigate the presence of other pathogens not included in this study and to examine the role of different potential reservoir hosts to get a better understanding of tick-borne pathogens and their enzootic cycles in Ireland.
  • Publication
    Update on the presence of Ixodes ricinus at the western limit of its range and the prevalence of Borrelia burgdorferi sensu lato
    It is often suggested that due to climate and environmental policy changes, the risk from tick-borne disease is increasing, particularly at the geographical limits of the vector distribution. Our project aimed to determine whether this was true for the risk of Lyme borreliosis in Ireland which is the western-most limit of Ixodes ricinus, the European vector of Borrelia burgdorferi sensu lato. The availability of a historical data set of tick infection rates compiled in the 1990s represented a unique opportunity as it provided a baseline against which current data could be compared. Following construction of a spatial predictive model for the presence and absence of I. ricinus based on data from 491 GPS locations visited between 2016 and 2019, 1404 questing nymphs from 27 sites were screened for the presence of Borrelia spp. using a TaqMan PCR aimed at the 23S rRNA gene sequence. All positive ticks were further analysed by nested PCR amplification and sequence analysis of the 5 S–23 S intergenic spacer. The model indicated that areas with the highest probability of tick presence were mostly located along the western seaboard and the Shannon and Erne river catchments, coinciding with historical high incidence areas of bovine babesiosis, while the infection rate of questing nymphs with B. burgdorferi s.l. and the prevalence of the various genospecies have remained surprisingly stable over the last 3 decades. Clear communication of the potential disease risk arising from a tick bite is essential in order to allay undue concerns over tick-borne diseases among the general public.
      239Scopus© Citations 12