> > With AFB you  have to get hundreds of million spores to a colony to get it
> most likely with symptoms.
>
> And if a million spores will fit on the head of a pin?

Then you need 50 pins per litre of honey to have a minimal infective dose
(MID).  :-)

MID = 50,000,000 spores per litre.

I'm too lazy to dig out and cite the references but this has been researched
back in the '50s (I think) and confirmed by further work in the '90s.

From memory I think the number of spores in one scale is around 2.5 billion!.

However it's important to remember that the brood becomes infected by being
fed infectious material with at least the MID.  It's unlikey that these
spores just fall into the mouth of the waiting larvae from "blowing around"
in the hive.  This concentration of spores must therefore find its way into
the food fed to the larvae.  Infectious honey is by far and away the most
common source.

The biggest problem beekeepers have in determining the AFB source is
establishing cause and effect.  Where small scraps of MID honey are covered
over by fresh honey, it may be several seasons before the hive gets down to
the dregs - and up pops AFB - with no apparent cause in sight.  Add
suppression of symptoms with drugs into this mix, and you may never be sure
where it came from.

One observation we made, is that syrup feeding enables the hvies to be run on
much lower reserves/safety margins of honey (that could be MID), so cause and
effect becomes more immediate and therefore more apparent.

At this point the simple rules for emliminating AFB become more obvious.
1.  Beekeepers spread most (nearly all) AFB
2.  Finding more than you're spreading = reducing levels.
3.  Never remove anything from a beehive (brood, honey) without checking for
AFB - if nothing else, inspect hives at honey harvest time!

Regards,
Peter Bray
_________________________________________________________
Airborne Honey Ltd., Pennington St, PO Box 28, Leeston,
New Zealand Fax 64-3-324-3236,  Phone 64-3-324-3569
http://www.airborne.co.nz  [log in to unmask]

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