Microorganisms associated with a pneumonic epizootic in Rocky Mountain bighorn sheep (Ovis canadensis canadensis).

A comprehensive study of a pneumonic epizootic was initiated when the first signs of disease were noted in a metapopulation of bighorn sheep inhabiting Hells Canyon, bordering Idaho, Oregon, and Washington. A total of 92 bighorn sheep were tested for etiologic agents during the following 6-mo study period. The study population included bighorn sheep believed to be the subpopulation in which disease was first noted, and these sheep were translocated to a holding facility in an effort to contain the disease (group A1, n = 72); bighorn sheep in other subpopulations (group A2) with evidence of clinical disease were captured, sampled, given antibiotics, and released (n = 8) and those that were found dead were necropsied (n = 12). Samples, including oropharyngeal and nasal swabs, and lung and liver tissue were collected from the bighorn sheep identified above. Tissue was collected at necropsy from 60 group A1 bighorn sheep that died following translocation, and samples were cultured for bacteria and viruses. Blood samples were tested for antibodies against known respiratory viruses, and histopathology was conducted on tissue samples. The major cause of death in both group A1 and group A2 bighorn sheep was a rapidly developing fibrinous bronchopneumonia. Multiple biovariants of Pasteurella were isolated from oropharyngeal and nasal samples from both groups, and Mycoplasma ovipneumonia was isolated from five group A1 oropharyngeal samples. Organisms isolated from lung tissue included Pasteurella multocida multocida a and Pasteurella trehalosi, both of which differentiated into multiple strains by restriction enzyme analysis, and parainfluenza-3 virus (PI-3). Paired serum samples revealed > fourfold increases in titers against PI-3 and bovine respiratory syncytial viruses. It was concluded that this epizootic resulted from a complex of factors including multiple potential respiratory pathogens, none of which were identified as a primary pathogen, and possible stress factors.

Sharing of Pasteurella spp. between free-ranging bighorn sheep and feral goats.

Pasteurella spp. were isolated from feral goats and free-ranging bighorn sheep (Ovis canadensis canadensis) in the Hells Canyon National Recreation Area bordering Idaho, Oregon, and Washington (USA). Biovariant 1 Pasteurella haemolytica organisms were isolated from one goat and one of two bighorn sheep found in close association. Both isolates produced leukotoxin and had identical electrophoretic patterns of DNA fragments following cutting with restriction endonuclease HaeIII. Similarly Pasteurella multocida multocida a isolates cultured from the goat and one of the bighorn sheep had D type capsules, serotype 4 somatic antigens, produced dermonecrotoxin and had identical HaeIII electrophoretic profiles. A biovariant U(beta) P.haemolytica strain isolated from two other feral goats, not known to have been closely associated with bighorn sheep, did not produce leukotoxin but had biochemical utilization and HaeIII electrophoretic profiles identical to those of isolates from bighorn sheep. It was concluded that identical Pasteurella strains were shared by the goats and bighorn sheep. Although the direction of transmission could not be established, evidence suggests transmission of strains from goats to bighorn sheep. Goats may serve as a reservoir of Pasteurella strains that may be virulent in bighorn sheep; therefore, goats in bighorn sheep habitat should be managed to prevent contact with bighorn sheep. Bighorn sheep which have nose-to-nose contact with goats should be removed from the habitat.

Restriction endonuclease analysis using Hhal and Hpall to discriminate among group B Pasteurella multocida associated with haemorrhagic septicaemia.

The purpose of this study was to improve and standardise restriction endonuclease analysis (REA) for discriminating isolates of serogroup B Pasteurella multocida associated with haemorrhagic septicaemia in wild and domestic animals and to create a reference database that can be used for epidemiological studies. Two techniques for extraction and isolation of chromosomal DNA were compared, a DNAzol method and an enzymic lysis followed by a two-phase partition method. No differences were observed between DNA fingerprint profiles with either technique; however, the former technique was faster and easier to perform. P. multocida isolated from different animals in different countries representing serotypes B:2, B:3, B:3,4 and B:4 were subjected to REA with HhaI and HpaII endonucleases. Forty-eight fingerprint profiles were distinguished among 222 isolates when only HhaI was used. By combining the data from REA with HhaI and HpaII used separately, 88 different groups could be distinguished among the same isolates. Following digestion with HhaI and electrophoresis, the DNA of all serotype B:2 isolates produced fingerprint profiles characterised by two trailing bands at approximately 8.4-7.1 kb which have not been observed in any other serotypes of P. multocida. Passage of three serotype B:2 isolates on laboratory media or two serotype B:2 isolates through mice did not result in a change of DNA fingerprint profile detectable by REA. The findings with 59 isolates from Sri Lanka showed that REA was highly discriminative in determining the genetic diversity of serotype B:2 P. multocida in an area where haemorrhagic septicaemia is endemic.