this is from the ABJ, Jan 1955. I thought it was of interest re: Nosema

According to Fyg, in Germany, when a queen becomes infected, egg production is reduced, and those eggs which are laid may fail to develop. Farrar, in the U. S., has noted that infected queens may stop laying suddenly and immediately become sluggish. Both workers report, as would be expected, that queen supersedure follows.

Infection with Nosema apis, according to Farrar, "restricts the production of all classes of colonies." Although there is no evidence of the actual infection in the brood itself, it is brood production which suffers, and as a result of the poor brood production the colony becomes weakened. Most frequently this is due to the fact that the infected workers are unable to care for the brood. 

Furthermore, when the queen is infected, the resulting supersedure further delays brood production. Farrar reported in 1942 as high as 18 percent supersedure of queens, most of which due to nosema disease. Barnes of the U. S. Department of Agriculture estimated in 1946 that over half of queen losses in package bees that year were due to nosema disease.

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