What is AFB?
What is AFB and how is it caused?
American foulbrood disease is caused by the bacterium Paenibacillus larvae larvae. Until recently, the bacterium was known as Bacillus larvae, but scientists have now determined that the organism should be in its own unique genus (Paenibacillus).
Life cycle of AFB
The bacterium causing AFB exists in two forms (the spore form and the vegetative form), both of which are microscopic in size.
Bacterial spores can be thought of as seeds that assist the bacteria in spreading from one suitable host to another and resisting adverse conditions. Spores of Paenibacillus larvae larvae can survive outside a honey bee colony for more than 35 years, and are able to withstand very high temperatures, including boiling water.
The spores are also resistant to a range of disinfectants. AFB spores can survive more than 35 years, and withstand boiling water and many disinfectants.
A honey bee larva is usually infected by being fed AFB spores which contaminate the brood food placed in its cell by nurse bees. The larva eats the spores, which then germinate in the larval gut, and turn into the vegetative form of the bacterium.
The vegetative form is in the shape of rods. These rods penetrate the gut wall of the larva, where they multiply, consuming the larval tissues. Death of the developing bee usually occurs either in the pre-pupal stage or just after pupation. When the vegetative rods have consumed all of the larval tissues, they turn into spores again. A single diseased larva may contain more than 2.5 billion spores. House bees in the colony try to remove diseased larvae and pupae and in so doing become contaminated with spores. New larvae are infected when they are fed contaminated food.
Spores are the only form of the disease that can infect healthy larvae. As well, the spores can only increase in number by infecting a larva. They do not multiply in any other environment (e.g. honey or beekeeping equipment). AFB spores will only multiply inside a larva.
How well do you know what you need to know about AFB and beekeeping? Take our short quiz and find out.
Our videos cover everything from your legal obligations to how to recognise AFB, collecting cell and bee samples and more.
There’s a lot of good information here, telling you everything you need to know about recognising AFB: the visual symptoms, smell of AFB and more.
New Zealand beekeepers have a number of legal obligations that must be met regarding AFB disease. Read the shortened list in summary, here.
Most hives become infected because bees, honey or equipment have been put into a hive from another hive that is infected with AFB. Lower your chances of an AFB infection by reading this section.
Find out when the next AFB Recognition and Competency Courses, or Refresher Courses are available. These are held throughout the year in various New Zealand locations across the South Island and North Island.