Comparison of Listeria serotypes and phage types isolated from sheep, other animals and humans.

A total of 814 different faecal, nasal, vaginal and milk samples of 50 healthy cotted sheep was investigated for Listeria during an epidemic-free summer season. Forty ewes and 5 tegs excreted Listeria strains; 18.1% of all samples were positive. A total of 151 Listeria monocytogenes strains belonging to serotypes 1/2, 4, 5, 6 and unknown were identified and phage typed. On the basis of the serotype and phage type of the excreted strains the animals could be divided into 7 groups. Characters of strains isolated from the cotted sheep were compared with those cultivated from 68 dead animals received from 44 distinct settlements. Also properties of 10 Listeria strains originating from 8 ill patients infected in the same region from where the carcasses of the animals were sent to the laboratory were studied. Two human Listeria strains were identical in serotype and phage type with some animal strains.