American foulbrood disease (AFB) is a disease of honey bee larvae and pupae caused by the bacterium Paenibacillus larvae. It is the most serious honey bee disease in New Zealand and has a major impact on bee populations.
AFB spores can survive outside a honey bee colony for more than 35 years, are able to withstand very high temperatures, and are resistant to many disinfectants.
Management in New Zealand of AFB differs from other countries in that the use of drugs to control it is illegal under NZ law. Therefore prevention through good bee keeping practices is vital here.
The big goal is to completely eliminate AFB from New Zealand.
Symptoms are usually found in the worker larvae and pupae. Visual symptoms can range from colour of cell capping colour, to shape and colour of brood. The most reliable symptom to diagnose AFB is the presence of a pupal tongue. When the pupae dies from AFB a thin thread can be seen stretched across the face of the cell. Larvae and pupae infected with AFB can also exhibit a characteristic foul smell similar to dead fish.
Diagnosis can be difficult, as it is also not always an easy task to distinguish between the symptoms of AFB and other brood diseases and conditions in the hive.
Identifying the subtle differences between symptoms of various bee requires both experience and regular refreshers. Fortunately, there are also laboratory tests that can be used to confirm a visual AFB diagnosis.
Unlike other countries, New Zealand is choosing not to treat AFB with drugs. Instead when a hive is found to be infected the hive needs to be completely destroyed within 7 days. This is done by burning the hive. Before burning the AFB hive, a hole should be dug. The hole will contain the fire, and will also ensure that any infected material not completely destroyed by burning will be buried so that foraging bees will not find it.