Robert Brenchley wrote:

>     My 1924 edition of Cowan's book describes two forms of foul brood,
> strong-smelling foul brood, which is clearly EFB, and odourless foul brood,
> which is AFB. Things may possibly have been clearer on the other side of the
> Atlantic, but it seems that the information necessary to identify the disease
> has been available to UK beekeepers for less than a century.

Both efb and afb can have or not have odors, so it is not a distinction.
When thy do smell, efb smells sour and afb smells like a "glue pot"
(ABC+XYZ of Beekeeping). Having smelled afb and not smelled anything
observing efb, I can only attest that afb just smells bad.

The Hive and the Honey Bee says the efb smell may be from other
bacteria. In any case, they can both stink or be near odorless.

Bill Truesdell
Bath, Maine