Head Swiss Bee Research Centre Berne, Bern, Switzerland
In Switzerland, European foulbrood (EFB) is a notifiable disease which should be controlled according to the Animal Epidemic Regulation. After being under control during more than 30 years, cases have recently been reported with increasing frequency. From 1970 until 1998, 20 to 50 EFB cases per year were reported to the veterinary authorities. Since 1999, an increase in cases has been observed, with a peak of almost 1000 affected apiaries in 2010, which represented an incidence rate of 5.7%. Since then, the number of cases has steadily decreased to 159 EFB cases in 2021. Little is known on the pathogenesis of EFB and until today only the application of costly and laborious control measurements limits the spread of the disease. A better understanding of the disease would be necessary to develop more specific and effective control strategies. I will present hypotheses on the causes for this huge fluctuation of EFB cases in Switzerland. In particular, I will discuss the variation in virulence of Melissococcus plutonius isolates/strains in in vitro infections assays of honey bee larvae with the pathogen. Using the multilocus sequence typing technique (MLST), we have searched for genetic subtypes of M. plutonius in Switzerland. I will also present more practical aspects of the sanitary measures with the aim to control EFB outbreaks in Switzerland and worldwide.
