It is not the fresh and pure honey which makes the bees sick.
The common cause of dysentery is fermented honey or syrup.
How to avoid fermentation.
1. All the stores have to be capped, otherwise moisture goes into the cells and dilute the honey.
2. The honey should not crystallize or only slightly. When the sugar goes into solid state the remaining solution is thin, not enough to prevent the activity of yeasts and bacteria. There is difference between honey and honey. Some of them practically does not crystallises (black locust) others quite quickly (sunflower). The worst is honey dew especially willow honey dew. High fructose content is good to delay crystallisation.
Since we don't always know what kind of honey is in the combs, it is safer to give white sugar (sucrose) for winter. The bees use their enzymes to invert it (split into glucose and fructose) if they have enough time.