| dc.description.abstract | The European badger (Meles meles) is a member of the Mustelid Family and Ireland?s
largest terrestrial carnivore. Since the identification of badgers as wildlife reservoirs of bovine tuberculosis (bTB), extensive research has been conducted in the field of badger ecology in the ROI and badgers have become the focus of a reactive culling strategy. As badgers are a protected species in the ROI, culling has only been used as an interim control in the absence of a viable, effective vaccine. Research has now shown, in both controlled and field studies, that a low dose of liquid encapsulated Bacillus Calmette-Gu?rin (BCG) vaccine is effective at promoting a powerful immune response by triggering the T-helper 1
(Th1) arm of the adaptive immune system. A strong immune response is thereby essential
for both the host?s ability to control pathogenesis of bTB and the efficacy of the BCG.
One factor that has been identified as disrupting the immune response to tuberculosis
infection is an underlying helminth infection. Helminths are a diverse group of large,
multicellular parasitic worms. Some species have been found to live for many years - even
decades - within a living host. To enable them to survive, many use highly effective
mechanisms of immune subversion. This not only allows helminths to evade expulsion by
the immune system but has also been shown to result in ?spill over suppression? of routine
vaccinations and reduced control of mycobacterial infections.
To date, only 5 studies across the badgers? Eurasian range have described the helminth
community of badgers, none of which occur in the ROI. To fill this knowledge gap, a total of
289 badgers were collected from western and eastern counties and examined for the
presence of helminth parasites. Infection was diagnosed using a combination of gross organ
dissection and faecal egg/larval counts. Access to data from both methods of detection is
rare and this offered the unique opportunity to evaluate the efficacy of coprological analysis
in comparison to adult worm burden. My results show that for hookworm (Uncinaria
criniformis), an individual was more likely to be diagnosed incorrectly than correctly for a
helminth infection. In contrast, for lungworm (Aelurostrongylus falciformis), neither adult
worm burden nor faecal larval counts were sensitive for diagnosing infection. However,
when infection was present, coprological analysis was an effective indicator of intensity of
infection.
iv
The helminth community consisted of 8 nematodes and included 4 identified to species, 1
identified to genus and 3 unknown - Aelurostrongylus falciformis; Crenosoma melesi.;
Eucoleus aerophilus; Uncinaria criniformis; ?Species A?; Strongyloides spp. and two
unidentifiable but morphologically distinct nematodes (nematode 1 and 2). U. criniformis
infection was found to be endemic throughout the badger population and A. falciformis and
Strongyloides spp. were common. Interestingly, all helminths described here belong to the
Nematoda group and the majority of the known species exhibit direct life cycles.
It is hoped the results from this study will serve as a baseline of badger health surveillance,
as well as illuminating the helminth community, in the Irish badger, as an important
comparator for other countries across the badgers? range. Additionally, as the ROI is now
moving towards a vaccination-led strategy for the control of bTB, it is imperative that work
is continued to investigate the effect of underlying helminth infection on both bTB
pathology and vaccination efficacy, in light of the helminth endemicity reported here and
the well documented immunological effects of helminth infection. | en |
