Twenty-two of the 25 swarms and 21 of the mother colonies were positive for P. larvae at the time of swarming. There was a significant correlation between the spore loads of the daughter swarms and mother colonies at the time of swarming.
..... None of the swarms showed any clinical disease symptoms at any time. This indicates that the amount of spores needed to produce clinical disease are not transmitted by swarms, or at least that
they are not readily available to the larvae. If clinical symptoms appear, it is on a non-detectable level