The epidemiology of Brachyspira species in Ontario layer chicken flocks
Avian intestinal spirochetosis is a disease of poultry caused by the spirochete bacterium Brachyspira, and is characterized by increased mortality, reduced egg production, weight loss, diarrhoea, and fecal staining of egg shells, which leads to downgrading of eggs. The presence of Brachyspira species in Ontario layer chicken flocks and its association with downgrades for dirty eggs was explored. Further, farm interviews were conducted to determine risk factors associated with the presence of Brachyspira species. The prevalence of Brachyspira species was significantly higher in flocks with a higher proportion of dirty eggs (dirty flocks) compared to those with a lower proportion of dirty eggs (clean flocks). Brachyspira pilosicoli was the only pathogenic species detected. Risk factors associated with the presence of Brachyspira species were flock age, barn age, multi-age farms, and housing type. Based on these findings, recommendations were suggested to control the occurrence of Brachyspira species and the associated dirty egg problem.