The causative organism of European foulbrood is the non spore forming Gram-positive bacterium Melissococcus plutonius. Larvae become infected by ingesting contaminated food and the bacteria multiply within the midgut of the infected larvae competing with the larva for food. Infected larvae usually die prior to cell capping due to starvation rather than invasion of the body tissues by the bacterium in some cases larvae may die after capping, sometimes the larvae survive to pupation, producing undersized adults.
European foulbrood (EFB) is well distributed across every continent that honey bees inhabit (Matheson 1993) and in many cases has not been considered a problem for apiculture. However, it appears to have increased in importance more recently, particularly for example in the UK (1002 cases in 2012 – figures available on National Bee Unit website nationalbeeunit.com), Switzerland (cases increasing 10 fold in 10 years (Roetschi et al., 2008) with 796 outbreaks in 2009 (Genersch 2010) and more recently in Norway. In Norway EFB was first reported in 2009 and in winter 2011 (1250 cases in 2011) an eradication campaign was instigated, costing an estimated 1.5M€ in compensation (Sorum et al., 2012 (York COLOSS meeting)). The status of EFB varies across Europe, being a notifiable disease (i.e. its suspected presence must be reported to the relevant authorities) in some Member states, (e.g. UK and Switzerland) and not in others (e.g. The Netherlands). The treatment of EFB also varies across Europe, ranging from destruction or
shook swarm (destroying the infected combs and shaking the bees onto clean foundation and boxes) or by feeding the colony with the antibiotic oxytetracycline (OTC) (Coloss Foulbrood survey- unpublished).