Peter Dillon rightly queried if it was right to say EFB was apparently very
infectious and also that equipment  apparently remains infective for 40
years.  The best written support I can find (listed below) is inconclusive.
However, estimates of the infective period will only be anecdotal, as it is
unlikely any scientist would seal away EFB infected combs and test at
periods up to 40 years later.
MAFF pamphlet:  Foul brood disease .., 1996: "It appears that  infection can
develop over a period of months or years, debilitating but not killing the
colony . During this time, signs of the disaese may become more or less
severe or disappear altogether.  ..Eventually the disease is likely to reach
a stage where a high proportion of the brood  is affected and the colony
will be weakened and ultimately killed".   So "infection persists for years"
.
Bailey & Ball, Honey Bee Pathology, 1991:p43 " .The bacteria are discharged
with the faeces and deposited on the walls of the brood-comb cells.  The
deposits occur mainly on the base and cappings of the cell and M. pluton in
them remains infective, possibly for several years".   So, several years.
Bailey, Honey Bee Pathology, 1991:p1963: p28 " S. pluton remains alive in
dry smears . for at least three years.  p136 "As S. pluton stays alive in a
dormant state for several years it is obvious that  equipment  , especially
combs, will carry infection. If it is not destroyed, it should be
sterilised.  Fumes of ascetic acid .for between 5 and 15 minutes ...  Combs
with dead brood  or sealed brood  should be destroyed..."  So, "several
years and at least 3 years".
Hooper, Guide to Bees and Honey , 2nd edn 1983 p199, on AFB: " Infection can
be carried over a great number of years by equipment  and combs, certainly
for as long as thirty-five years ."  So at least 35 years for AFB - but no
equally firm statement for EFB.  So I was incorrect when lumping the two
togther.

However, as equipment is not normally out of use for over 3 years, In feel
we can say that in practice all equipment has to be destroyed or sterilised
when EFB has been found.   As OTC merely inhibits the bacteria while OTC is
in bee's stomachs - and does not clean the combs - it is difficult to
understand why beekeepers use it regularly.  The symptoms of EFB disappear
naturally when the brood peak is passed - but return again next year ,
worse, if the combs remain.

Robin Dartington

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