American foulbrood (AFB) is the most devastating honeybee disease.

AFB kills the infected colony. It's high virulence also means it can easily be spread to other colonies within foraging distance.

AFB infected comb showing perforated brood cells and a spoty brood pattern
Spotty brood pattern on a comb infected with AFB. Via Flickr.

Not only do you loose your bees, all comb and frames must be destroyed to prevent further infections. Even a small outbreak can be both heart breaking and expensive.

Identifying American foulbrood

The following video provides quick overview of:

  • the matchstick or 'ropiness' test
  • AFB scales
  • brood pattern symptoms

Being able to confidently diagnose AFB is critical. Spotting AFB in the early stages allows you to take immediate action and reduce the severity of impact to your apiary.

More information and illustrations can be found on the Ontario Ministry of Agriculture and Rural Affairs web site.

American foulbrood scale on comb
Infected comb with AFB scale and perforated brood cells. Via Flickr.

Responding to an AFB infection

Protocols for dealing with AFB vary vary slightly by region. Typically one must report the disease and burn infected equipment. Some areas do allow you to keep hive boxes as well as outer and inner covers if you scorch them with a blow torch to kill spores. You might even be able to save your comb if you are willing to pay to have them irradiated.

A few jurisdictions do permit you to try and save your bees using the shake method. While people have reported success with this method, areas that permit shaking bees with AFB almost always have a higher overall infection rate.

AFB scale
American foul brood scale removed from cell with toothpick. Via Flickr

Preventing American foulbrood

As a very basic precaution, it's useful to scorch hive tools before opening different hives. This can be done either with a propane torch or by placing your tool in a smoker. You want to see the propolis on your tool boil.

There is also some suggestion that poor nutrition can leave bees more susceptible to AFB. For example, a lack of lactic acid bacteria (LAB) found in honeybee's gut may diminish their ability to ward off the disease. In one experiment LAB levels were charted based on bee feed type (see pg. 15).

In some parts of the world antibiotics are fed to bees to mitigate the risk of contracting AFB. Unfortunately, this has given rise to strains of American foulbrood developing resistance to particular antibiotics.

A few other tips to help limit the spread of disease can be found here.