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Date: | Wed, 9 May 2018 10:13:05 -0600 |
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Dr. Jochai Weiss, who worked for decades in extension work in Israel
until the 1980s, presented a useful concept based on his experience:
AFB is not a disease of the bees, but of the comb. The main source of
infective risk to a colony lies in the wax of brood cells since AFB
produces very persistent spores which can accumulate to highly
infective doses in brood cells. Beyond this primary point
source clearly other factors play supporting roles: hygienic removal by
workers, incoming spores from robbed colonies, spores on woodenware, or
treatment by antibiotics. On the latter, Dr. Weiss insisted that
treatment just masks temporarily the disease by interrupting the cycle
of infection, yet the primary source of infection remains in the comb
even after treatment. Hence the effectiveness of burning comb.
The apparent reduction in AFB in the US in the last two decades is
intriguing. Some have speculated that it has to do with a major
improvement in hygienic activity. It is also possible that increased
mortality from varroa (and mothing out of comb) is producing a lot of
comb turnover, especially in operations with no treatment, which are
likely the ones more prone to infection and robbing.
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