So, I think the honey pump had some good insight here on Nosema. In my world I look for the telltale stains, but its amazing what the spore-count can be and still have no visual, dependent on the nosema strain.
Snapshot of 3 hives over a 2 month period
Jan
Hive 1- 5 spores (~250,000 spores per honey bee)
Hive 2- 21 spores (~1,050,000 spores per honey bee)
Hive 3- 1 spores (~50,000 spores per honey bee)
Feb
Hive 1- 0 spores
Hive 2- 34 spores (~1,700,000 spores per honey bee)
Hive 3- 39 spores (~1,950,000 spores per honey bee)
And around 1,000,000 spores per honey bee is the thresh-hold. Granted we had a lot of rain this spring, and these should be dropping in the coming months unless its N. ceranae.