These agents are considered secondary or opportunistic pathogens, they are incapable of transplacental infection unless the placenta is damage or the cow is immuno-compromised. They cause sporadic abortion; however, their presence in the tissues of an aborted foetus should not be considered as definitive evidence that they caused the abortion.
Table 2.4: Combined frequency of detection of selected abortion agents on routine foetal culture.
| Coliforms |
379 |
| Streptococcus spp |
83 |
| Staph. spp |
18 |
| Bacillus spp |
14 |
| Pseudomonas spp |
11 |
| Yeasts and Fungi |
10 |
| Listeria spp |
4 |
| Histophilus somnus |
1 |
| Pasteurella multocida |
1 |
| Yersinia pseudotuberculosis |
1 |