|  | Survey 2 |  |
---|
 |  | Positive | Negative | Total |
---|
Survey 1 | Positive | 27 | 77 | 104 |
Negative | 60 | 283 | 343 |
 | Total | 87 | 360 | 447 |
- Status of Scottish farms (positive or negative) during Survey 1 (SEERAD, 1998-2000) and Survey 2 (IPRAVE, 2002-2004). A positive farm was one in which at least one faecal pat tested positive by Immuno-magnetic separation (IMS) for the presence of E. coli O157.