Video Preventing or treating Nosema in Honey Bees
The are two very distinct strains of Nosema
Nosema Apis you get staining on the frames and also the front of the hive caused by dysentery. This will cause the hive to dwindle away if left untreated going in to winter and could result in the death of the colony , In the spring time the hive may not build up.
Nosema ceranae There are no real signs your bees are infected but the effects are the same as above
Two Nosema species have been identified in honey bees in the UK, Nosema apis and more recently the Asian species Nosema ceranae. Both are highly specialised parasitic Microsporidian fungal pathogens. Nosema spp. invade the digestive cells lining the mid-gut of the bee, there they multiply rapidly and within a few days the cells are packed with spores, the resting stage of the parasite. When the host cell ruptures, it sheds the spores into the gut where they accumulate in masses, to be later excreted by the bees. If spores from the excreta are picked up and swallowed by another bee, they can germinate and once more become active, starting another round of infection and multiplication.
The video here shows a very effective treatment that i have used to good effect for many years