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 epidemiological framework and associated BSE investigation questionnaire were used to guide the investigation of a BSE suspect identified in Ireland in 2015. A number of data-gathering methods were used during this investigation. The index herd (the herd of residence of the case animal at time of diagnosis) was visited by DAFM staff to examine the farm, herd movement records and farm records. The field investigation began once a positive screening test result was received, noting the high specificity of these tests. 43 The likely infection window (encompassing the most likely period of infection of the case animal) was determined to be 2010, the year of birth. The case animal was born and died in the index herd. The identification of the cohort group, in line with DAFM protocols, took account of animals born in the index herd during 2010, and also those born in the previous (2009) and subsequent (2011) years. Data with respect to animal feed were gathered, including receipts and records in relation to animal feed and feeding systems. All feed business operators (FeBOs) that supplied proprietary feed to the index farm were contacted by DAFM to obtain details of all animal feed supplied to this farm during October to December (Q4) 2009 and throughout 2010. In addition, all questions in the BSE investigation questionnaire were completed, providing a summary of each line of investigation outlined in the epidemiological framework. Estimating the date and location of exposure Examination of DAFM's national bovine registration and movement data showed that the case animal was born in the index herd and had remained there throughout its life. The index herd was a dairy enterprise consisting mainly of Rotbunt animals. The index herd was situated in an area of mixed grazing (cattle and sheep) and tillage enterprises.