Nosemosis will be held on


There are 2 nosema species.

  1. Nosema apis
  2. Asian species Nosema ceranae

They are highly specialised parasitic Microsporidian fungal pathogens. Invading invade the digestive cells lining in the mid-gut of the bee, they multiply rapidly.  Within a few days the cells are packed with spores.  This is the resting stage of the parasite. When the host cell ruptures, the spores are shed into the gut where they accumulate in masses.  They are later excreted by the bees.

Nosema apis (Dave Cushman)

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.

In a highly infected colony, the disease can spread quickly and can have fatal ramifications.

Although there are no outward symptoms, dysentery is often associated with nosema apis infections.  This manifests itself as “spotting” at the entrance or down the front of the hive.   If this presents itself and is then followed by prolonged confinement in the hive during bad weather, the situation can get worse and the bees are forced to defecate in the hive.  This just makes things worse still!

Nosema ceranae is less obvious; however typically characterised by a reduction in the number of bees and productivity.  Other secondary diseases may also present themselves including chalk brood and AFB (American Foul Brood).  There does not appear to be evidence of dysentery in cases of Nosema ceranae.

Nosema can be quickly spread through the continued use of comb and or contaminated come.  The spores are viable for up to 1 year.  Transfer of comb between colonies is to be avoided at all cost!

Diagnosis and Treatment

The simplest method to confirm Nosema apis and /or ceranae is by microscopic examination.  The best time to test is in the very early spring – March.

They appear as white/green rice shaped bodies under a microscope and an expert can distinguish them apart.

You cannot treat nosema apis or Nosema ceranae with any sort of medicine.

Treatment of Nosemosis is by applying good husbandry practices.   This includes strong well fed colonies with young prolific queens.

Two manipulations could include

Bailey Comb exchange
Shook Swarm

TESTING for Nosemosis will be held on