Investigation of an atypical case of European foulbrood in France
Abstract
An apiary with 26 colonies of Western honey bees in Central France presented in 2017 a high prevalence (58%) of European foulbrood (EFB). Microbiological analyses and a global audit of beekeeping practices were carried out. Certain stress factors, food- and weather-related, as well as certain risky beekeeping practices, may have exacerbated this epizootic. Despite the sanitary measures implemented (euthanasia, transfer to a clean hive, clinical follow-up), the disease became enzootic with 15% and 14% diseased colonies in 2018 and 2019, respectively. In addition to its recurrence, significant damage to the capped brood was observed, which is quite rare in EFB. This atypical finding could not be explained by the microbiological studies, and may be the result of differential virulence among strains of Melissococcus plutonius, the causative agent of the disease.