FellowshipS Seminar 2016

Oral ABSTRACTS
A diagnostic and control programme for
Johne’s disease on Irish dairy farms
Aideen E. Kennedy 1,2 , Noel Byrne 1 , Jim O’Mahony 2 , Ríona G. Sayers 1
1 Animal & Grassland Research and Innovation Centre, Teagasc, Moorepark, Fermoy, Co. Cork
2 Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Co. Cork
Johne’s disease (JD) is an enteritis of ruminants with potential zoonotic implications. JD diagnosis and control present
difficulties given JDs prolonged subclinical nature. In order to improve JD control in Ireland, PhD aims included
conducting a national survey documenting high-risk husbandry practices employed on Irish farms, thereby targeting
areas for improved management. As JD has been associated with on-farm economic losses internationally, this
research programme aimed to analyse production losses associated with testing JD ELISA positive. Clinical cases of
JD are rare in Ireland and studies of potential cross-protection by annual bovine tuberculosis (bTB) testing were also
investigated. Finally, a longitudinal study was conducted to assess if successful JD control can be achieved using
gold-standard management. Across all investigations, 312 farms were recruited, samples were collected from 4500
cows, and 10000 test results were generated (ELISA, PCR, faecal culture). However, no significant associations were
identified between JD ELISA positivity and production parameters, an important consideration in promoting on-farm JD
control for Irish farms engaged in high-risk management practices facilitating JD transmission. Annual bTB testing was
associated with an increased prevalence of JD ELISA positive results and indicates that sampling for the purposes of
JD surveillance should be avoided for 71 days post-TB test administration. Coupled to increased antibody responses,
interferon-γ production was also significantly increased post-bTB testing. As cell-mediated immunity is particularly
important in the control of JD systemically, bTB testing may be contributing to the low levels of clinical JD in Ireland
and warrants further investigation. Finally, on-farm sero-prevalence was decreased by implementation of gold standard
protocols. Eradication was not achieved, however, highlighting the long-term commitment required for effective JD
control. This research programme has greatly contributed to the work of Animal Health Ireland’s JD technical working
group and immensely improves understanding of practical measures necessary to control JD.
15