Small mammals and stray cats were trapped in two areas of North Zealand, Denmark, and their blood cultured for hemotrophic bacteria. Bacterial isolates were recovered in pure culture and subjected to 16S rDNA gene sequencing. Bartonella species were isolated from five mammalian species: B. grahamii from Microtus agrestis (field vole) and Apodemus flavicollis (yellow-necked field mouse); B. taylorii from M. agrestis, A. flavicollis and A. sylvaticus (long-tailed field mouse); B. tribocorum from A. flavicollis; B. vinsonii subsp. vinsonii from M. agrestis and A. sylvaticus; and B. birtlesii from Sorex vulgaris (common shrew). In addition, two variant types of B. henselae were identified: variant I was recovered from three specimens of A. sylvaticus, and B. henselae variant II from 11 cats; in each case this was the only B. henselae variant found. No Bartonella species was isolated from Clethrionomys glareolus (bank vole) or Micromys minutus (harvest mouse). These results suggest that B. henselae occurs in two animal reservoirs in this region, one of variant I in A. sylvaticus, which may be transmitted between mice by the tick Ixodes ricinus, and another of variant II in cats, which may be transmitted by the cat flea (Ctenocephalides felis). To our knowledge, this is the first report of the occurrence of B. henselae and B. tribocorum in Apodemus mice.

At autopsy of 230 adult stray cats, 120 from backyards and 110 from gardens, the intestinal tract was scrutinized for helminths. The prevalence of Toxocara cati, Taenia taeniaeformis and Dipylidium caninum was found to be 79%, 11% and 14%, respectively. Comparisons were made with the results of previous Danish investigations. The prevalence of Toxocara cati was found to be independent of time of collection and the sex and habitat of the cats and identical in cats with or without Taenia. This indicates that paratenic hosts do not play an important epizootiological role in the transmission of T. cati. The intensity of Toxocara per cat followed a negative binomial pattern. The high prevalence of T. cati combined with most cats having a low wormload shows that the cat population generally possesses a high degree of resistance against superimposed infections. The intensity of male Toxocara increases with the size of the worm population. This we consider to be an expression of increasing susceptibility of the cats. The prevalence of T. taeniaeformis was significantly higher in garden cats, due to their greater opportunity for catching mice. D. caninum, however, was significantly more frequent in backyard cats, probably owing to better living condition for the flea larvae in backyards. For both T. taeniaeformis and D. caninum a higher frequency was found in female cats, which is thought to be associated with their care for the kittens.

Whether the presence of M. paratuberculosis is connected to the inflammatory bowel disease or is a mere coincidence cannot be stated. We find this presence interesting and encouraging for further investigations.