Understanding the role of wild ruminants in anthelmintic resistance in livestock.

Wild ruminants are susceptible to infection from generalist helminth species, which can also infect domestic ruminants. A better understanding is required of the conditions under which wild ruminants can act as a source of helminths (including anthelmintic-resistant genotypes) for domestic ruminants, and vice versa, with the added possibility that wildlife could act as refugia for drug-susceptible genotypes and hence buffer the spread and development of resistance. Helminth infections cause significant productivity losses in domestic ruminants and a growing resistance to all classes of anthelmintic drug escalates concerns around helminth infection in the livestock industry. Previous research demonstrates that drug-resistant strains of the pathogenic nematode Haemonchus contortus can be transmitted between wild and domestic ruminants, and that gastro-intestinal nematode infections are more intense in wild ruminants within areas of high livestock density. In this article, the factors likely to influence the role of wild ruminants in helminth infections and anthelmintic resistance in livestock are considered, including host population movement across heterogeneous landscapes, and the effects of climate and environment on parasite dynamics. Methods of predicting and validating suspected drivers of helminth transmission in this context are considered based on advances in predictive modelling and molecular tools.

Grazing cattle exposure to neighbouring herds and badgers in relation to bovine tuberculosis risk.

Bovine tuberculosis (bTB) can be spread between and among cattle and wildlife hosts e.g. European badger (Meles meles). The majority of cattle in the UK and Ireland are grazed during the summer, potentially exposing them to Mycobacterium bovis. 18 farms were surveyed (39% dairy, 61% beef; fields n = 697) for one grazing season (May-November 2016, n = 148,461 field days) to quantify the co-occurrence of cattle with badger setts and latrines and adjacency to neighbouring cattle herds. 3% (n = 24) of the fields had a badger sett or latrine recorded, dairy cattle were significantly more likely to co-occur with badger setts and latrines than beef cattle. Most farms (89%) grazed cattle adjacent to a neighbouring herd, which accounted for 18% of the grazing season. Potential exposure to neighbouring herds did not differ between production systems but did vary between life stages. A significant positive association between the proportion of time cattle spent grazing fields with setts present and the historic 1-, 3- and 5- year bTB status (p = 0.007, p = 0.013 and p = 0.013 respectively) was found. However, when cattle were grazed in fields with latrines, a significant negative association was found between the proportion of time cattle spent grazing fields with latrines present and the historic 3- and 5- year bTB status (p = 0.033 and p = 0.012 respectively). Historic bTB status and percentage of days spent beside a neighbouring herd was unrelated. Idiosyncrasies at farm-level and between risk factors indicated that individual farm assessments would be beneficial to understand potential exposure risk.

Trends in Salmonella serovars and antimicrobial resistance in pigs and poultry in Northern Ireland between 1997 and 2016.

BACKGROUND: In the EU, salmonellosis is the second most commonly reported zoonosis. This pattern is reflected in Northern Ireland. Historically, foodborne salmonellosis has largely been attributed to the consumption of poultry products, and as such a number of legislative measures have been introduced by the EC. These policies focus mainly on five target Salmonella serovars. METHODS: Here the authors present a descriptive analysis of 20 years of data from the Northern Ireland National Reference Laboratory for Salmonella. RESULTS: The study's results show, for poultry submissions, a large decrease in the detection of four of the five targeted Salmonella serovars over the study period, with the fifth serovar undetected throughout the study. Additionally, there was an increase in the detection of a number of other non-regulated serovars. In pigs, S Typhimurium, which is among the most common causes of human salmonellosis, was the most commonly isolated serovar. When comparing levels of antimicrobial resistance in S Typhimurium between livestock groups, the authors found a decrease over time in poultry, but an increase in pigs, highlighting the potential significance of pigs in addressing public health concerns. CONCLUSION: The authors conclude that continued surveillance is important in the assessment of control measures at a national and transnational scale.