A Discussion on Foulbrood

[Calum]

Colonies with AFB frequently get up to swarming strength and swarm if they go undetected, the 'dont feed a swarm for a couple of days' tip is a percentages thing, we may as well make it less likely that anything is passed from one generation to the next ( vertical transmission).

If you gather a swarm that is of unknown origin you have two choices to try and protect yourself from them bringing (possibly large levels of) FB spores with them.
1. Burn a sulphur strip in the swarm box after collection (with the bees still in it)
2. Starve them a bit

choice one is 100% sure to protect you
choice two is a percentages thing

[mbc]

If you gather a swarm that is of unknown origin you have two choices to try and protect yourself from them bringing (possibly large levels of) FB spores with them.
1. Burn a sulphur strip in the swarm box after collection (with the bees still in it)
2. Starve them a bit

choice one is 100% sure to protect you
choice two is a percentages thing

Lol, yes.

This linky:http://pub.epsilon.slu.se/1053/1/Avhandling.pdf is a paper I keep going back to to explode some myths about AFB, our own NBU seems scared to tread on this ground in case beekeepers twig their colonies need not necessarily be destroyed if they have AFB and they can rid themselves (sometimes !) of the infection given a fresh start on clean comb.

[Jon]

Great find that paper, MBC. First time I have seen it.
It certainly backs up what Calum suggested about not feeding a newly housed swarm.

Page 18

None of the swarms showed any clinical disease symptoms at any time. This indicates that the amount of spores
needed to produce clinical disease are not transmitted by swarms, or at least that they are not readily available to the larvae. If clinical symptoms appear, it is on a non-detectable level. It seems reasonable that a “no brood, no food” argument is
valid here, as well as in the artificial swarm case. Because the bees do not have
any stored food they will consume whatever contaminated honey they have in their
honey sac. Also, there are no larvae available to the swarm to which they can
transmit spores before most contaminated food carried from the mother colony is
consumed.

It also shows that there are AFB spores in a colony without symptoms necessarily being present.
Page 14

Twenty-two percent of the individual colonies
were clinically diseased. All samples from clinically diseased colonies were
positive. Of the remaining colonies, 77% were positive although they had no
visible symptoms of AFB. We found a significant relationship between the number
of clinically diseased cells in the colony and the number of colony-forming units
(cfu) in the laboratory cultures. Colony-forming units are the number of bacterial
colonies that grow on the agar plates.
Fifty-four percent of the apiaries contained clinically diseased colonies. In the
lab cultures, however, 70 % of the clinically healthy apiaries were positive for
AFB.