Volume 13, Number 12—December 2007
Research
Pig Herds Free from Human Pathogenic Yersinia enterocolitica1
Table
Herd no. (year established) | Serologic testing (1996–2007), no. pos/no. tested | Culture (2005–2006), no. pos./no. tested |
---|---|---|
1 (1996) | 10/397† | 0/20 |
2 (1999) | 0/150 | 0/20 |
3 (1997) | 1/61 | 0/21 |
4 (1997) | 0/19 | 0/20 |
5 (1998) | 0/30 | NA‡ |
6 (1999) | 0/34 | 0/20 |
7 (1999) | 0/20 | 0/20 |
8 (2000) | 0/60 | 0/20 |
9 (2001) | 0/30 | NA‡ |
10 (2002) | 1/61 | 0/20 |
11 (2002) | 0/20 | 0/20 |
12 (2003) | 0/30 | 0/22 |
13 (2003) | 0/51 | 0/18 |
14 (2004) | 15/30 | 11/24§ |
15 (2004) | 0/50 | 0/23 |
16 (2004) | 0/30 | 0/20 |
*SPF, specific pathogen–free. Herds 1 and 2 are nucleus herds. Herds 3–16 were established with gilts from 1 or both of the nucleus herds. A basic cut-off of optical density of 20% was used to maximize the specificity of the ELISA.
†During the first 5 years, 10 of 174 blood samples from pigs in herd 1 had a low level of antibodies against Y. enterocolitica O:3 (OD >20 but <31). None of the 223 blood samples taken from pigs in this herd from 2002 through 2007 was positive. The low-positive reactions from pigs in herd 1 might have been the result of nonspecific reactions because a few of these samples were from old sows, which might have more serologic interference.
‡NA, not applicable; no culture of feces.
§Positive for Y. enterocolitica O:3/biovar 4.
1Findings from this investigation were presented in part at the International Pig Veterinary Science Congress, July 16–19, 2006, Copenhagen, Denmark; and 9th International Symposium on Yersinia, July 10–14, 2006, Lexington, Kentucky, USA.