What is American Foulbrood?

Claire Waring looks at the disease and its consequences.

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There have been press reports of a serious outbreak of American foulbrood (AFB) near Guisborough, Middlesborough, North Yorkshire. With 32 confirmed infected colonies, this is the biggest recorded outbreak since one in Norfolk in 2014.

WHAT IS AFB?

AFB is caused by a sporeforming bacterium, Paenibacillus larvae subsp. larvae. Larvae are infected when fed larval food contaminated with spores. The spores germinate in the larval gut and then move into the tissues where they multiply quickly. The infected larva dies, usually after the cell is sealed. It contains millions of spores which can lie dormant for many years and then germinate. The spores are also very resistant to high temperatures and many available disinfectants. They are thus extremely hard to eliminate. The infection will eventually kill the colony.

Spores can be spread by beekeepers moving infected combs between colonies and by the bees themselves via robbing, swarming and drifting.