Hi Al and Everyone,
Good thread with many good posts but I have a couple of comments below:

Al wrote in part
"AFB is more difficult to take out. It reproduces by forming spores, millions
of them. Another well known spore forming bacteria would be Anthrax.  The
"parent" bacteria are killed by antibiotic but the spores are not touched.
These spores are picked up by bees cleaning up the brood cells and get into
everything. They get into the honey, wax and propolis and onto the wooden
ware. As soon as you stop the antibiotic treatment the spores that are
picked up will start to survive and reproduce again. Now you have a hive
that is a infection source for every hive in a two to three mile radius, or
more!

Move a frame from this hive to a clean hive and you have sealed its fate.
Let it get weak and robbed out and a dozen others are gone. The spores get
into the guts of field bees and if they drift to another hive empty their
nectar, along with spores into the new hive. Each of these hives now
requires you to start antibiotic treatment. These treatments will never end.
The spores will outlive the beekeeper."

First I would like to try to correct some misconception regarding the AFB bacteria.  Bacteria do not reproduce by producing spores.  Bacterial spores are part of the life cycle of spore forming bacteria that allow the bacteria to survive unfavorable environmental conditions.  One bacterial cell produces one spore maybe a fine point here but when you see those big numbers of spores in a single AFB scale everyone of them came from a different bacterial cell that reproduces by fission or cell division.  TM or OTC prevents the germination of the spores and so prevent the disease as well as production of more spores.  That's the biology lesson.

The interaction between the host bee colony and the disease is much more complex that the simple if there are AFB spores present the colony breaks down with AFB.  Colonies also have resistance mechanisms that have to be overcome to induce disease.  There are also mechanisms by which a colony can remove the disease or spores from the hive.  As Allen points out taking colonies off treatment does not necessary result in an outbreak of AFB.  I know of a case here a commercial outfit had a major outbreak of resistant AFB and the beekeeper by culling and replacing diseased combs has turned the situation around as far as active disease is concerned.  He may be using antibiotics but a sample of his honey from the extractor taken this fall - note one small sample from a large commercial outfit - was sent in for AFB spore testing and came back negative ( no spores found - limits of the test are about 100 spores per oz of honey ).   With the disease levels in this outfit 5 years ago one would have expected some spores to be found in the honey but the test did not find any.  Now before you get excited about drawing conclusions from one small sample in a large outfit inspections of many colonies showed the same result just like before TM resistance this beekeeper knows how to keep his colonies AFB free.  If he stops all treatments will AFB show up - probably in some hives but not likely to be anywhere near the numbers of 5 years ago.  In the field drug treatment along with culling of combs with disease or scale results in healthy colonies of bees for years in the same equipment.  Dr Spivak has also shown that not all colonies that are exposed to large numbers of spores ( comb with AFB scales ) ever show any symptoms of AFB and some that show a few cells can clean it up without drugs.  I think the evidence is there that Allen is right - properly used drug treatment can cure honey bee colonies of AFB.  Proper treatment is the key and culling of any visibly diseased combs.

One little note:  Do I used TM?  Not any more used to but now don't but only have 4 colonies and know how to identify disease.  Can afford the time to check those few colonies for disease a few times each year.  Would I use TM if operating many more colonies - certainly managing AFB is cheaper and easier with drugs than without but would still be alert for disease and destroy diseased combs as quickly as found and may even just burn whole hives instead of spending the time to treat properly diseased colonies - time that would then not be available for managing the other colonies.

FWIW

Thanks to all for a very interesting thread.

blane

******************************************
Blane White
MN Dept of Agriculture
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