As I mentioned in the last blog post the last meeting of Puget Sound Beekeepers was especially informative.  Over the next few blog posts I’ll be going over some of the nasty diseases and pests we talked about so you can familiarize yourself with these yucky things and in doing so hopefully prevent them from becoming a problem in your hive.

Today’s topic is American Foulbrood.

The Basics

American Foulbrood (AFB) causes hive to die over winter usually.  You can treat for it and it’s easy to detect by odor.  AFB is caused by a spore (this is different from European which does not have a spore stage) which makes it highly contagious as the spores can remain viable for 40 years in comb and honey!

Affects all types of larvae including queen, drone and worker larvae.  In general every hive has spores in your but with a healthy and hygienic hive it’s  just not usually a problem.  AFB is the main reason people don’t recommend using old, used equipment when you begin beekeeping.

Signs of AFB

Signs include spotty capped brood pattern.  Cappings are sunk in rather than bubbled out as usual.  Larvae become infected in less than 2 ½ days.  They get infected by swallowing spores present in their food.  Older larvae are not susceptible.  Death usually happens after cell is capped during the last two days of the larval stage or first two days of pupal stage.  Each infected larvae when dead contains as many as 100 million AFB spores.

One way to tell AFB besides spotty brood is the rope like structure of dead brood.  Using a match stick on one of the sunken brood can help you determine if it’s AFB.

AFB treatment

There is no natural treatment for AFB.  To treat when you have an active breakout you must use Terramycin and can purchase at any feed store.  You will mix with powdered sugar and sprinkle the top bar of each brood super.  This does not kill the spores only the bacteria in the active phase.  If a bad infestation burn your equipment.

As a final note most everyone will tell you that you must burn your equipment if you get an AFB outbreak and certainly this is recommended however some will treat instead.  We do not recommend this but are still presenting this information for your benefit.  Also some treat for AFB before an outbreak occurs to prevent a possible outbreak.  As with all chemical treatments it’s possible that doing this will lead to more robust strains of AFB that are resistant to treatment as has happened with different treatments for Varroa mites.  For more information about antibiotic resistance of AFB please see this excellent article from the USDA.

Have you ever had an outbreak or seen an outbreak of AFB?

Photo by Virginia Williams courtesy of the USDA

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