How common is American foulbrood in honey?

Checking for American foulbrood: A beekeeper inspecting a beehive in a protective suit.

Although we know we can transmit American foulbrood from one hive to another via contaminated honey, how often does this actually happen? Good question.

Honey can transmit AFB between colonies

We frequently warn beekeepers not to feed honey from untrusted sources to their colonies because it can carry the spores of American foulbrood (AFB). Furthermore, we know the spores of AFB can withstand standard pasteurization methods because they are highly resistant to heat. Pressure cooking at 250° F (121° C) for three minutes at 15 pounds pressure will kill the spores, as will other combinations of temperature, pressure, and time, but shortcuts don’t work.

However, as “saving the bees” has become a popular activity for many people, non-beekeepers frequently write to me and explain how they do their part to save the bees by feeding them honey. For many reasons, these individuals cannot become—or do not want to become—beekeepers, yet they want to help the honey bees.

Feeding honey to feral bees can be risky

When they write, I always take the time to explain the hazards of feeding honey, but of course, I don’t know if they heed the warning or not. But more problematic are all the folks who don’t write, don’t ask, don’t know, and assume they are doing the best thing for the bees. For every person who writes into a blog and asks, thousands don’t. And since I get a lot of e-mails about this, I assume the number of people feeding bees is staggering.

I have a picture in my mind of a scrupulous beekeeper, carefully tending his bees, taking precautions against the worst diseases, and doing everything by the book, while a neighbor down the road blithely buys imported honey from the grocery stores and fills a dozen feeders. It’s an uncomfortable thought.

How frequently is foulbrood transferred in honey?

So I began to wonder how often contaminated honey actually transmits AFB. We hear the warnings all the time, but I’ve never actually heard of a case where contaminated honey was thought to be the cause. So how common is American foulbrood in honey? Come to think of it, how common is American foulbrood in honey bee colonies?

The only time I ever saw American Foulbrood was in the hive of a friend, and that was many years ago. I seldom get mail asking about it. I’ve heard of a few recent cases of European foulbrood, but not AFB. Nearly all the mail I get is about varroa mites, deformed wing virus, nosema, CCD, chalkbrood, tracheal mites, and hive beetles, but nary a word about AFB.

The risk is real but the data is scarce

So how common is AFB? How big of a problem are AFB spores in honey? Should we worry about scores of people feeding grocery store honey to any honey bee that wanders by? Or is foulbrood in honey not a worry?

I’m curious to hear your thoughts and experience.

Honey Bee Suite

About Me

I backed my love of bee science with a bachelor’s degree in Agronomic Crops and a master’s in Environmental Studies. I write extensively about bees, including a current column in American Bee Journal and past columns in Two Million Blossoms and Bee Craft. I’ve endured multiple courses in melittology and made extensive identifications of North American bees for iNaturalist and other organizations. My master beekeeper certificate issued from U Montana. I’m also an English nerd. More here.


  • I saw two confirmed cases of AFB on Cape Cod (Mass.) this fall. It’s rare, but it does happen. And yes, both cases were related as the nucs both come from the same apiary.

  • Good golly, there are actually people feeding honey to bees?
    Last I looked, it was $7.5lb, a bit pricey for wildlife feeding — and are there really such things as “bee feeders”? (Seems a waste in the winter, aren’t the bees all in bed?!)
    They’d be better off planting bee-favorite wildflowers, which would help NATIVE bee populations, the truly endangered ones.


    • Eddy,

      “They’d be better off planting bee-favorite wildflowers, which would help NATIVE bee populations, the truly endangered ones.”

      That’s the perfect answer.

  • I don’t have a clue. Nor have I heard any beekeepers discuss AFB. A university might have the most accurate answer.

  • In the UK our bee inspectors keep AFB incidence reports, which give an idea of how common it is here: http://www.nationalbeeunit.com/public/BeeDiseases/diseaseIncidenceMaps.cfm

    You can also see a trends graph which may be more helpful: http://www.nationalbeeunit.com/public/BeeDiseases/trendDiseaseChart.cfm – the numbers are small, under 70 colonies confirmed with AFB from around 40,000 inspected each year.

    We have different legal procedures for treating AFB than the U.S., as colonies confirmed to have AFB must be burnt and destroyed. We’re also not allowed to use antibiotics to prevent AFB. This may cut down on how common it is here.

    • Oops just to add it’s early morning here and in a bit of a rush – think under 70 per 40,000 inspected is me getting the graph wrong as it shows regional figures. So under 70 per region but you’d need to add up the figures per region to get the national total.

    • Emily,

      Interesting. It raises another question: since preventive treatment is allowed here in the US, I wonder how many beekeepers do it. I know that AFB developed lots of resistance to terramycin and they’ve moved on to other antibiotics, tylosin, I think. But just like AFB itself, I never hear anything about prophylactic treatments.

      • I have sometimes come across U.S. beekeepers on forums who use antibiotics prophylatically, but if you never hear anything about it perhaps the number of people doing that are small.

  • Here in the UK, if your colony tests positive for EFB, the bees, comb and honey are destoyed by burning as it is a notifiable disease – as is AFB. I presume this means that the honey is regarded as being contaminated so I would imagine the same would be for AFB. Therefore I would be rather concerned about using honey from an infected colony to feed other bees in case this spreads the disease (s).

    I’ve not heard about dogooders using supermarket honey to feed bees over here – honey is far too expensive!!!!!

  • Hi Rusty,

    A more experienced beekeeper once told me that colonies can be carriers of foul brood without experiencing any negative consequences. Now I don’t know what the veracity is of this claim, perhaps you can shine a light.

    We had a short outbreak of AFB here in the Netherlands during the last season. There were about 5 reported cases, I think the policy here is still to exterminate the entire apiary so I don’t know how keen beekeepers are to report cases of foul brood.

    That same beekeeper told me that there is a way to free a colony of foul brood. You should shake the bees of the frames into an case you can seal (obviously with mesh). Get rid of the hive then keep the bees enclosed until they begin to die from starvation and then place them a clean hive. He said that the foul brood is in the honey and you should make sure that the bees have consumed all the honey in their system, after which they should be free of foul brood.

    Again, I don’t know if there is any truth to this method.

    • Hey Andrew,

      I believe the first is true: you can have carriers that have no symptoms. As far as that method of ridding a colony of foul brood, I’ve never heard of anything working other than destroying the whole colony. But I don’t know . . . maybe it works.

      • If that worked, surely a researcher would have written a paper about it and that would be included in the recommendations that I see all the time, which simply say burn baby burn everything!

  • Rusty

    This is the first I have heard of well-intentioned persons feeding random honey to bees, Around here, it’s all “Take action to save the bees! Sign our petition!” To give them credit, they seem to prefer to eat the honey, to buy it locally and know their beekeeper. And my response is always the same: Folks, signing a petition is not “action.” If you want to take real action, sow white clover in your lawns.

    So there’s two good suggestions.
    Thanks, I’ll keep an ear out.
    Northern Kenrucky

  • I imagine you try and steer these people towards the sugar patties instead of honey? Or do you try to get them to cook the honey to attempt to pasteurize it and make it safer?

  • Hi Rusty, I live in Mill Bay British Columbia and the 2nd Apiary inspector was by to see about the health of my hive. I have a single colony. And there is AFB. I am devastated as I must now kill the bees and burn everything. An email went out to beeks within a 3 kilometre radius to inform them as well. I’m so sad!

  • Hi Rusty, I suspect it was brought to me by either drifting bees from the area, or two beekeepers who came to visit to mentor me as I am (or was) a 2nd year beek. Two years ago I aquired 2 nucs from a supplier which the inspector himself inspected and stated they were the best managed bees he had ever seen. So I very much doubt that was the source. I have never visited any other hives in the area. My neighbour set up hives after I did using used equipment and perhaps there were spores in there. Who knows for sure, but here we are 🙁

  • You state pressure cooking at 250 for 3 minutes will kill any AFB in honey, but that there are other combinations of time, temp, and pressure also. I would like to know the best way to do this. We do structure hive removals and relocations. We would like a pasteurization method that will kill AFB so that we can feed it to our bees safely. Thanks in advance.

  • First I am not Mr R Sole but fear/knowing how the NZ AFB [miss]management agency will track me down and audit the daylights out of me at NZ$265/hr/person, for telling it as it is, I am very cautious.

    In the wild west [New Zealand] Manuka madness/greed has seen registered hives go from 400K to over 1M in a few years . AFB in many of these recent “Instant Gold Rush” honey harvesters is rampant , one [who folded taking an investment of NZ$80M] using cheep imported asian man power – had a fire pit burning all day truck after truck AFB infected gear [on that fire we observed ]. Never reported ONE AFB hive in their annual AFB return.

    A land owner [Lawyer] no bee experience purchased 200 hives from NZ South Island shipped then to his North Island site, just about all with AFB that took a couple of years of burning to reduce this problem.

    I am a very small bee keeper [on my remote isolated property], yet took my 2016/7 harvest to an export approved extractor, 3 drums [900kg/NZ$36K] put my wets back, NO problems until I spring split my hives, zero to 100% AFB in 6 weeks. Burnt all my 20 hives BIG FIRE – rang the extractor – “Yea no problem the guy after you through the extraction plant, has his outfit full of AFB”????

    So my opinion:

    1/. AFB is bad in NZ – BUT is even worst in Australia, where antibiotics use for EFB gets to incidentally accidently mask AFB. The USA must be bad due to extensive antibiotics use there.

    2/. AFB is not destroyed at 121C for 3mins / try NZ standard 160C for 10mins / or EU standard 140C for 10mins / see published science on this.

    3/. AFB spores were able to survive 50 years in the soil – now it is 70 years? See the science here also.

    4/. There are at least THREE types of AFB – type 1 mainly in NZ North Island – type 2 in NZ South Island.

    5/. The PCR Lab detection processes developed by NZ government scientists [MPI] are now starting to be used to detect AFB in retail honey – WATCH THIS SPACE.

    6/. Nectar flow is 6 – 10 weeks in my local, bees need big honey stores to survive, [OR pesky sugar feeding] – NZ hive numbers need to reduce by about 50% to be in sync with the available nectar amount.

  • Recently a colleague diagnosed one of her hives with AFB. She is aware of the need to burn the equipment (we have no irradiation available). She has euthanized the hive. However, I saw that she removed honey from that hive. Is that even a good idea?

    • Sharon,

      The honey is perfectly fine for human consumption because humans and other mammals are not affected by foulbrood. The only caveat is she shouldn’t feed it to her bees because they could catch it from the honey.

  • I personally feel you should not feed your bees in most situations. Especially if there are natural sources of food for them. In San Diego, there are sources all year round. I am about to rescue a hive in Vancouver BC that is in a compost bin. Since it is the end of August, there aren’t a lot of sources for food for the bees. I am considering supplementing. I am trying to decide if I should use sugar water, coconut nectar, or raw honey. I personally believe that giving bees sugar water isn’t the best for them. Has anyone used any natural nectar sources to feed their bees? I also don’t want to cause a robbing issue by putting in honey. As you can see, I am torn. If I rescued this hive sooner, I wouldn’t be feeding them at all. I just want them to last the winter.

    • Todd,

      Overwintering bees in the north is different than overwintering them in San Diego. The biggest difference is that bees in the north cannot get out for cleansing flights for months at a time. Too many solids in the feed (i.e. things like coconut nectar) can cause honey bee dysentery. And honey from an unknown source should never be fed because it can carry foulbrood spores. The safest feed for overwintering is sugar syrup.

  • Help! 3 of our 4 hives had foul brood and died. When we discovered something was wrong we contacted our local bee person and he sold us some Tylan and had us give it to the sick hives once a week for 3 weeks. The hives still died. ? The forth hive is still hanging on, but I assume it must be diseased also?

    What should we do with the honey from the dead foul brood hives?
    What should we do with all of the frames and boxes? Do we really need to destroy it all?
    Should we try and keep the 4th hive alive or is it contaminated also? Does it need to be destroyed?

    Thank you so much for your help!

    • Tina,

      In the US, which includes Utah, it is illegal to use Tylan on a honey bee colony without a prescription or veterinarian feed directive. The EPA website says:

      “On December 11, 2013, The U.S. Food and Drug Administration (FDA) implemented a plan to help phase out the use of medically important antimicrobials in food animals for food production purposes, such as to enhance growth or improve feed efficiency. The plan would also phase in veterinary oversight of the remaining appropriate therapeutic uses of such drugs.

      Implementation will require a beekeeper to get a prescription or veterinarian feed directive (VFD) from a veterinarian who has a “Veterinarian-client-patient relationship (VCPR)” with the beekeeper in order to purchase and feed antibiotics to honey bees for the prevention and control of American and European foulbrood diseases. A list of drugs affected by this plan has been published:

      It should be noted that the list includes oxytetracycline (Terramycin), lincomycin (Lincomix) and tylosin (Tylan) which were over the counter drugs labeled for controlling American foulbrood (AFB) in honey bee colonies. Oxytetracycline was also labeled for preventing AFB, and for the control and prevention of European foulbrood.”

      The changes were implemented in response to people using these drugs in incorrect ways, thus making them less efficacious when they were truly needed.

      The first question I would ask was who and how was the AFB diagnosed and who provided the treatment? Based on your statement, it doesn’t sound like this was all above board. AFB is a serious brood disease, and once it gets established it can be hard to get rid of.

      Unfortunately, Tylan will often suppress the symptoms, but it cannot kill the spores. So as soon as the treatment stops, the disease can reappear. If you don’t burn, or at least scorch, your equipment, any bees you put in there can easily contract the disease. The spores can last upwards of 50 years.

      So by all means, burn the equipment or have it treated with ozone or whatever they do these days. The honey is safe for human consumption but it’s not safe to feed bees because the spores can persist in honey.

      If the fourth colony is still alive, have it tested for AFB by your local extension agent or by someone who knows what they are doing. If it has AFB, it too should be destroyed.

  • I attended a webinar where the researcher, I wish I could remember their name, said AFB spores are in a lot more hives and honey than anyone thought. Their research found AFB spores in 20% of the hives tested. It also found 50% of the honey in stores has AFB spores in it. The higher number is apparently because honey from infected hives is mixed with other honey contaminating it.

    • Mark,

      Yes, there are high background levels of AFB nearly everywhere honey bees are kept. This is why we should never feed honey to bees from unknown hives and why sharing brood combs is risky.

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