Chalk brood is a mycosis caused by fungus “Ascosphaera apis”
Likes damp conditions
Prefers high levels of carbon dioxide
Mummification of sealed brood
Rarely killing a colony
Larvae ingest the spores with their food
Larvae die within two days of being sealed
The fungus grows best when the brood is chilled
Mostly spread by beekeepers, on clothing and tools
Chalkbrood is present on nearly all continents.
Chalkbrood will thrive in damp, shaded and lacking ventilation
Antibiotics or poor-quality artificial feed can increase your chances of chalkbrood.
Alkaline pH of the nectar makes chalkbrood more likely
Burning all contaminated comb and wooden frames can help prevent Chalkbrood
Replaceing Queens can help if she is spreading the fungus - but so can all the workers
So performing a Bailey comb change will help eliminate the spore and help prevent further spread of the Fungal spores - I think I would try this before replacing the Queen