Using an epidemiological framework and bovine spongiform encephalopathy investigation questionnaire to investigate suspect bovine spongiform encephalopathy cases: an example from a bovine spongiform encephalopathy case in Ireland in 2015

O’Connor, Jarlath T; Byrne, Justin P; More, Simon J; Blake, Martin; McGrath, Guy; Tratalos, Jamie A; Mcelroy, Maire C; Kiernan, Paul; Canty, Mary J; O’Brien-Lynch, Chris; Griffin, John M

The identification of BARB cases is not unprecedented, but continues to be challenging from an epidemiological perspective. The epidemiological framework and BSE investigation questionnaire overcome some of these challenges, in particular the use of methodology to facilitate data collection that is comprehensive and consistent. Further, the framework and questionnaire are underpinned by best available science. Nonetheless, several challenges remain that contribute to the difficulty in attributing cause to recent BSE cases. By its nature, a case study does not allow definite conclusions to be drawn on the source of disease. Further, the role of any specific putative source cannot be directly tested as no information is available on suitable controls. Finally, because of the passage of time between exposure and the development of clinical signs, there are inevitable information gaps that hamper attribution of the source of the BSE agent. Ireland's 2015 BSE case was identified through existing surveillance mechanisms, and the investigation provided evidence that all BSE controls are operating as intended. Based on the investigation, no definitive source of infection with the BSE agent was identified.