Serological evidence for historical and present-day exposure of North American bison to Mycoplasma bovis

Background

Mycoplasma bovis causes mastitis, otitis, pneumonia and arthritis in cattle and is a major contributor to bovine respiratory disease complex. Around the year 2000, it emerged as a significant threat to the health of North American bison. Whether healthy bison are carriers of M. bovis and when they were first exposed is not known. To investigate these questions we used a commercially available ELISA that detects antibodies to M. bovis to test 3295 sera collected from 1984 through 2019 from bison in the United States and Canada.

Results

We identified moderately to strongly seropositive bison from as long ago as the late 1980s. Average seroprevalence over the past 36 years is similar in the United States and Canada, but country-specific differences are evident when data are sorted by the era of collection. Seroprevalence in the United States during the pre-disease era (1999 and prior) was significantly higher than in Canada, but was significantly lower than in Canada during the years 2000–2019. Considering individual countries, seroprevalence in the United States since the year 2000 dropped significantly as compared to the years 1985–1999. In Canada the trend is reversed, with seroprevalence increasing significantly since the year 2000. ELISA scores for sera collected from free-ranging bison do not differ significantly from scores for sera from more intensively managed animals, regardless of the era in which they were collected. However, seroprevalence among intensively raised Canadian bison has nearly doubled since the year 2000 and average ELISA scores rose significantly.

Conclusions

Our data provide the first evidence that North American bison were exposed to M. bovis many years prior to the emergence of M. bovis-related disease. Patterns of exposure inferred from these results differ in the United States and Canada, depending on the era under consideration. Our data further suggest that M. bovis may colonize healthy bison at a level sufficient to trigger antibody responses but without causing overt disease. These findings provide novel insights as to the history of M. bovis in bison and will be of value in formulating strategies to minimize the impact of mycoplasmosis on bison health and production.

Surgical treatment of supracondylar humerus fractures in children

PURPOSE OF THE STUDY

Surgical techniques for the treatment of supracondylar fractures in children are repeatedly the subject of discussion. The aim of the present study was to compare experience with the technique of crossed Kirschner wires at our own hospital with current literature.

PATIENTS AND METHODS

In the period from 2000-2006 a total of 86 children aged 1.7 to 12.7 years were treated by means of crossed K-wire osteosynthesis. Follow up was conducted at an average of 32 months. Outcomes were evaluated based on von Laer's criteria.

RESULTS

Reported complications were migration of the K-wires in 7% of cases and secondary dislocation and re-operation in 4% of cases. Lesion of the radial nerve was diagnosed postoperatively in two cases. Hospital stay was 1.5 days on average. Postoperative immobilization in an upper arm splint and implant removal after 6 weeks on average. 57% of the children received physiotherapy during the course of treatment. Slight varization was found in 11% of children and an unsatisfactory range of motion in 13%. Satisfactory outcomes were recorded for 83% of patients.

CONCLUSION

K-wire osteosynthesis is associated with a low complication rate and continues to be a safe standard procedure for the stabilization of supracondylar humerus fractures. Key words: supracondylar humerus fracture, Kirschner wires, paediatric fractures.