Badger Ecology, Bovine Tuberculosis, and Population Management: Lessons from the Island of Ireland

Pathology of new world camelids in Ireland: 13 years of disease surveillance and the significance of bovine tuberculosis in alpaca

Causes of New World Camelid (168 alpacas; 7 llamas) mortality in Ireland based on review of passive surveillance findings of the Irish Veterinary Laboratory Service from 2010 till 2023 were analysed. The most frequently submitted age group were adults (58.8 %), followed by juveniles (20.6 %), crias (16.6 %), and aborted foeti (4 %). Regardless of age, 96 % were suitable for investigation, with identified aetiology in 77.4 % of cases. The pathology was systemic (30.9 %) or involving the alimentary (39.3 %), respiratory (8.9 %), urogenital (4.9 %), musculoskeletal and lymphatic (2.2 % each), integument (1.8 %), cardiocirculatory (1.3 %), nervous (0.9 %) system; 7.6 % were inconclusive. The aetiology was bacterial (44.4 %), parasitic (24.3 %), nutritional/metabolic/toxic (6.4 %), traumatic/mechanical (3.2 %), congenital (1.6 %), and neoplastic (0.5 %), while 19.6 % had unknown aetiology. The diagnostic rate was highest in crias (79.3 %) and lowest in the abortion group (0 %). Crias had mainly systemic and alimentary tract diseases (43.3 % and 26.6 %, respectively); juveniles had mainly alimentary illness and systemic diseases (51.3 % and 30.7 %, respectively); similarly for adults (40.2 % and 25.5 %, respectively). The primary aetiology detected was bacterial (45.5 %, 35.1 %, and 48.7 % for crias, juveniles and adults, respectively). Mycobacterium bovis was identified in 27.4 % of submissions, 25 % of which had lesions localised to a single organ (mainly lung), whilst 75 % had generalised tuberculosis, where the lung and liver were the most and second most commonly affected organs, respectively. Fasciola hepatica infection represented the second most common cause or co-cause of mortality. To the authors' knowledge, this is the most extensive published case series of M. bovis pathology in alpacas.

Can badger vaccination contribute to bovine TB control? A narrative review of the evidence

In parts of Europe, the European badger Meles meles acts as a wildlife host for Mycobacterium bovis, the causative agent of bovine tuberculosis (bTB). Options for reducing the risk of transmission of M. bovis from badgers to cattle include biosecurity measures, culling, and vaccination of badgers using the BCG vaccine. The use of vaccination as a control measure for tuberculosis (TB) in badgers has increased in recent years, with large-scale deployment in Ireland, and increasing use in England alongside a gradual phasing out of badger culling. Here we review evidence relating to the use of badger vaccination as a tool for controlling TB in badgers and cattle. Vaccination reduces the severity and progression of TB in badgers experimentally infected with M. bovis in laboratory studies, and significantly decreases the likelihood of naturally-acquired infection in free-living badgers in field trials. Modelling studies evaluating different strategies for controlling TB in badgers predict that badger vaccination will reduce TB prevalence in badger populations and lead to corresponding reductions in cattle herd disease incidence. While large scale field trials have not been undertaken to quantify the level of impact of badger vaccination on cattle bTB incidence in the UK, field studies in Ireland suggest that in some situations badger vaccination can result in beneficial disease outcomes in cattle which are comparable to those from badger culling. Attitudes to badger vaccination vary among stakeholder groups. Although members of the public are relatively positive about the benefits of vaccination, farmers are generally negative, due to concerns about practicality and effectiveness, along with a view that badger populations need to be controlled. The evidence published to date indicates that badger vaccination has the potential to contribute to the control of TB prevalence in wild badger populations and to form part of a wider strategy for controlling bTB. Future research should focus on investigating the effect of badger vaccination on bTB in cattle, along with understanding the impacts of vaccination in badgers in a broader range of ecological settings. Further understanding of the drivers of negative attitudes towards vaccination will nonetheless be crucial for incentivising and increasing the deployment of badger vaccination.