Two obvious differences between American Foulbrood and European Foulbrood:
 
Amercian Foulbrood:
 
1)  The infected larvae normally die after the cell has been capped over.
 Look for concave brood cappings.  They may be punctured and/or wet.
 
2)  Dead brood will be "ropey".  Poke a twig into some cells with concave
cappings.   If  the twig, a thread of larva comes with it (sort of like a
string of rubber cement), that is a considered a positive ID for American
Foulbrood.   Note that the twig test is done on capped larvae.
 
European Foulbrood:
 
1)  The infected larvae generally die young, hence they are not capped over
by the workers.
 
2) You will not be able to pull a thread of dead larva with the twig test.
 The dead larva will normally come out of a cell in discreet pieces.
 
The USDA-Beltsville lab will test comb for American Foulbrood.   Send a piece
of suspect brood comb about 3" x 5" to:
 
     U. S. Department of Agriculture
     Bee Research Laboratory
     Building 476, BARC-East
     Beltsville, MD 20705
 
Include in your cover letter that you suspect the sample has American
Foulbrood.  Expect an answer in about two weeks.
 
If you have American Foulbrood, you should destroy the infected colony
immediately.  The Maryland custom is to destroy the colony on a positive
"twig test", then send a comb sample to the USDA lab for confirmation.  We
also seal up all openings to the colony with duck tape; this includes joints
between boxes.  Bees must not get access to any equipment that is suspected
of being contaminated with American Foulbrood.   Hive tools may be
disinfected by washing and cleaning; but disinfecting woodenware and combs
requires special equipment.   Your State Apiary Inspector (or other
appropriate government agency) can tell you what is available in your area.
 Gloves can also be a problem.
 
The American Foulbrood bacteria does not affect humans, but whether or not
you can use the honey from the hive will depend on how the colony was
destroyed.   In Maryland, an insecticide is normally used which will require
disposing of the honey on the colony.  I just take the contaminated frames to
the local landfill.   If you extract the honey, remember that your extraction
equipment will become contaminated and need to be disinfected.
 
Treatment:
 
European Foulbrood can be handled by ensuring your colonies have young,
vigorous queens.  Requeen if needed.
 
American Foulbrood colonies are traditionally destroyed, as no treatment will
completely eradicate the bacteria without also killing the bees.   Some
people use Terramycin powder as a control.   If you elect to go that route,
be aware that although Terramycin will kill the bacteria, it won't kill the
bacteria's spores, and for all intents and purposes those spores have an
inifinte "shelf life".   Accordingly, once you start using Terramycin, you
are stuck having to use it on all your colonies forevermore (or get your
equipment properly decontaminated).  Active AFB will reappear the instant you
discontinue Terramycin.
 
W. G. Miller
Gaithersburg, MD