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Surveillance and improved control of American foulbrood in Saskatchewan honey bees through the detection of Paenibacillus larvae spores in pooled, extracted honey



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The North American beekeeping industry is heavily reliant on antimicrobial metaphylaxis to prevent and control outbreaks of the destructive bacterial disease, American foulbrood (AFB). The infectious endospores (spores) of the causative agent, Paenibacillus larvae, are incredibly resilient to environmental extremes and are impervious to antimicrobials licensed for use against AFB (1–3). Consequently, non-curative antibiotic use fosters dependency and sustained, indiscriminate use to ensure industry profitability. In the face of growing international concern regarding antimicrobial resistance (AMR) and the emergence of strains of P. larvae with AMR, North American beekeepers are inadequately prepared to reduce their reliance on antimicrobials without risk of significant economic losses to AFB (2,4–11). Current methodology to guide evidence-based antimicrobial use through AFB risk assessment relies on the sampling and testing of individual hives and is logistically impossible for large-scale, commercial beekeeping operations to implement (12–21). To address this issue, we evaluated the use of spore detection in conveniently collected, pooled, extracted honey to determine AFB risk at a yard or operation level within antibiotic-reliant apiculture. Large-scale, commercial honey bee operations in Saskatchewan, Canada, with a history of antimicrobial use and recent outbreaks of AFB were clinically characterized and opportunistically sampled to compare the detection of spores and predictive ability of pooled, extracted honey to the current standard of samples collected from individual hives. We demonstrated that pooled honey was predictive of the spore contamination identified through individual hive testing and appeared to have prognostic value in assessing the risk of AFB at the yard or operation level. Accordingly, we expanded our testing of pooled honey to 116 Saskatchewan beekeepers representing approximately 75% of the province’s 110,00 registered colonies during the study period. By correlating spore concentrations to the incidence of AFB, we established reliable prognostic thresholds at 2 and 100 spores per gram of honey to determine a beekeeper’s future risk of disease. Additionally, we highlighted management practices related to a higher risk of AFB that could represent key targets for improved biosecurity to mitigate risk. Given their expertise in herd-health management and biosecurity, veterinarians should play an integral role in a beekeeper’s health management team in the prevention and control of AFB. Together, beekeepers who are at low risk of AFB through the testing of their pooled honey and are simultaneously incorporating low-risk management practices through the help of their health management team may temporarily cease antimicrobial metaphylaxis. Improved, judicious antimicrobial use in apiculture will reduce the threat of AMR and will help to ensure the sustainability of the North American industry.



American foulbrood, AFB, Paenibacillus larvae, apiculture, microbiology, risk assessment, herd health



Master of Science (M.Sc.)


Veterinary Pathology


Veterinary Pathology


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