European foulbrood

European foulbrood is a highly contagious infection caused by the melissococcus pluton bacteria. It can remain without visible signs for a long period.

Age of brood affected

Unsealed brood of 3–5 days old in their ‘curled up’ phase are most vulnerable to infection.

Some sealed brood may be affected.

Infection method

Bacteria is introduced to the larvae through infected honey. All bees may be affected by European foulbrood.

Symptoms

• discoloured larvae, from glistening pearly white to:
• yellow
• light brown
• dark brown
• discoloured gutline in larvae, from golden brown/yellow to chalky white with yellow/white bands
• sticky larvae liquid with a pasty consistency, instead of watery
• dried dead larvae, which can be easily removed from the cell wall once they are fully dried (this is a difference between European and American foulbrood)
• a sour or foul odour, which may develop in the brood if there is heavy infection.

Treatment

Follow these steps to minimise the effects of European foulbrood:

1. Re-queen regularly from disease-resistant stock.
2. Replace 2 or more brood nest combs annually with white combs or foundation. New hive material will help reduce the concentration of disease causing organisms.
3. Move bees at night to reduce heat production and associated stress on the hive.
4. Ensure honey and pollen are of good quality. Use artificial feeding if these aren’t available.

Antibiotics can be requested from a PIRSA Inspector, but should only be used during a severe infection. Antibiotic residue in honey may affect market access.

Diagnosing European foulbrood

European foulbrood can be diagnosed by the Apiary Unit through samples of:

• diseased larvae smears on a microscope slide
• sections of comb (sent in a waterproof container).

Send samples to: