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Objective: Assess the variability of Mannheimia haemolytica isolates obtained from fatal cases of bovine respiratory disease (BRD) in the USA and Australia using repetitive sequence-based PCR (REP-PCR) and sequencing of the 16S ribosomal RNA (rRNA) gene., Methods: We examined 22 isolates from the USA and 36 isolates from Australia using (GTG)5 and BOX-A1R REP-PCR primers, as well as sequencing a 700-base pair length of the 16S rRNA gene. The discriminatory ability of each typing method was assessed and correlation coefficients were calculated to assess concordance between the results of each approach., Results: All methods appeared to discriminate among isolates, with BOX-A1R being the most sensitive and sequencing the least sensitive. Modest to moderate diversity was seen among the isolates, with as much variation within a continent as between the two., Conclusions: Using samples from diverse origins may permit extrapolation even to isolates with distant geographic and temporal relationships. Further, this information can serve as a baseline in assessing whether M. haemolytica is an opportunistic pathogen or if there are notable features that distinguish commensal isolates from those more likely to be associated with disease., (© 2014 Australian Veterinary Association.)

The 1970 National Health Interview Survey included questions on respiratory disease and smoking habits. The new data were released in July 1974. Data consisted of information on approximately 116,000 persons from 37,000 households selected randomly from 357 primary sampling units. To test a hypothesis about familial clustering of chronic respiratory disease in households, we selected as index households those having an adult (aged 35-54 years) reporting a diagnosis of asthma, bronchitis, or emphysema and also having first order relatiaves less than age 35. Index households were matched with households from the same neighbourhood having an adult aged 35-54, of the same sex as the diseased person in the index household, without disease and with all other adults 35-54 without disease, and which had first order relatives less than 35 living in the same household. Analysis was carried out using Cochran's d-test to compare frequency of respiratory disease in persons less than 35 in each group. There was a strong association (P less than .001) between persons over 35 with chronic respiratory diseases and the disease rate in their first order relatives. The association could not be explained by differences in demographic variables and smoking habits.