A 1932 study showed a minimum infective dose for AFB of 50 million 
spores per litre. (Sturtevant, A.P. 1932. Relation of commercial 
honey to the spread of American foulbrood.)
A 1994 study showed 5 million spores per litre.

A problem though is the sensitivity of any testing method used to 
determine the presence of spores. The sensitivity of the Honey 
Culture Test (HCT) pioneered by Hansen and further developed by 
Hornitsky is around 20 million spores per litre (mainly due to a very 
low level of germination rate of AFB spores)

>> You may find the following study of interest:
>> http://pub.epsilon.slu.se/1053/1/Avhandling.pdf

> ANY EVIDENCE THAT MOST HIVES HAVE SOME AFB SPORES, OR THAT BEES CAN
> TOLERATE A LOW LEVEL, WOULD BE GREATLY APPRECIATED.

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]

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html

Guidelines for posting to BEE-L can be found at:
http://honeybeeworld.com/bee-l/guidelines.htm