Peter (Dillon) questioned my statement that AFB is easy to diagnose
accurately in the field.

> I suggest that for those who are used to seeing AFB in all its forms the
chance
> of a correctly diagnosing is quite high.

Not sure what you mean by 'all its forms'.  My understanding is as follows:
AFB affects only sealed brood, the larvae die under the cappings which then
sink.  Cappings may appear darker or greasy and will be perforated when the
bees nibble a hole in them.  At the sunken cappings stage the remains of the
larvae become slimy and will 'rope' (the matchstick test); later they become
tacky and dry to a scale which is difficult to remove.
So, if we suspect AFB at the earliest possible stage, i.e. when there is
just one cell affected, the capping must have changed in appearance (or we
would not have noticed anything wrong) and a matchstick test should confirm
our suspicions.  If the disease has progressed further then there will be
more cells in various stages so we have plenty of material on which to base
our judgement.

> But, for those who may have limited experience - it is conversely, easy to
confuse AFB
> with EFB and larval/pupal deaths due to viral infection associated with
elevated V.d. mite
> levels.

EFB is a disease of unsealed brood and does not produce any of the symptoms
of AFB, except for a general appearance of patchy or 'pepperpot' brood and,
in a few cases, perforated cappings where the larva has died after capping
(however, in these cases the remains will not 'rope' as with AFB).
Whilst I might agree that EFB could be confused with larval deaths due to
viral infection associated with elevated varroa levels, I know of none that
cause the same symptoms as AFB.  If anyone knows otherwise then it would be
interesting to have that information.  Even here, it is very easy to dissect
a larva in the field to check the colour of the gut (EFB shows a white gut
full of bacteria).

> I would be most interested to read how you easily confirm AFB in the
field - when the classic symptoms are not present. This might occur if only
a few cells are infected.

What symptoms would there be then?

I would certainly agree that experience is useful.  Mine is based on 3 cases
of AFB in 1984 and a dozen or so of EFB from 2000 to 2002 - clear so far
this year, touch wood! - but I have also attended many excellent courses run
by our National Bee Unit (NBU) where it has been possible to handle many
diseased
combs, make microscope slides etc and talk to expert staff.

However, my real point was that, in the demonstration that I watched, the
test kit did not work until the third attempt - and, in my opinion, at £5
per kit few beekeepers will want to test for AFB (and EFB if they are not
sure?).  Even fewer will run the test 3 times just to be sure (how many
negative results do you need to be sure?), especially when it costs nothing
to call out your Seasonal Bee Inspector who will provide free diagnosis and
treatment.

Of course, the most important task is to educate beekeepers so that they
recognise when brood is not healthy and then ask for assistance if they are
not sure about the cause.  In the UK the NBU have taken a proactive step
towards this by asking associations to appoint voluntary Disease Liaison
Co-ordinators (DLCs), who have then been trained in disease recognition by
the NBU and are able to offer advice to their local membership.

Peter Edwards
[log in to unmask]
www.stratford-upon-avon.freeserve.co.uk/

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