Persistent Salmonella typhimurium PT 104 infection in a dairy herd
Sharp, M.W.; Rawson, B.C.
Veterinary Record 131(16): 375-376
1992
ISSN/ISBN: 0042-4900 PMID: 1441160 Document Number: 402056
In May 1991, 11 of 68 (16%) Friesian type dairy cows in one herd presented with pyrexia and diarrhoea; a 30% reduction in saleable milk was recorded 3 days after the start of the outbreak. S. typhimurium infection was diagnosed; positive faecal culture from 8 affected animals confirmed the diagnosis. Cultural examination of an in line milk filter yielded S. typhimurium PT104. The clinical situation improved quickly and no new cases were recorded. Milk filters were collected and cultured weekly; filters collected in the next 2 weeks were negative but positive results were subsequently recorded on 8 consecutive occasions. During further investigations in August, milk from the recording jar was screened; S. typhimurium PT104 was isolated from 2 cows. One of these cows was dried off during the following week and was not available. The second cow was excluded from the lactating group and dried off; following calving in January 1992, S. typhimurium PT104 was isolated from milk samples and from rectal swabs taken from the cow and her calf. The cow was culled from the milking herd.