Samples of milk from 1501 cows with mastitis were negative for Campylobacter jejuni. The faeces of 74 healthy Friesian cows were screened for C. jejuni: 13% of the samples were positive during the summer when the cows were on pasture, and 51% were positive in the winter when the cows were housed. Positive samples contained on average 1 × 104 campylobacters per g faeces.
It is concluded that faecal contamination rather than udder infection is the means by which campylobacters enter milk and thereby infect man.