Prevalence of Paenibacillus larvae in Apis mellifera in The Netherlands

Paenibacillus larvae is the causative agent responsible for American Foulbrood (AFB), a brood disease affecting Western honey bees ( Apis mellifera ). After policy changes in AFB control in the Netherlands in 2005, a prevalence study in 2008 reported a low presence of P. larvae . As this was the last such study and reported AFB outbreaks have remained rare, we aimed to assess the current prevalence of P. larvae in the Netherlands. In the summer of 2023, 623 brood comb honey samples from 224 apiaries across the country were collected and tested for P. larvae using real-time PCR. Samples were pooled per apiary, resulting in 223 pooled samples. One pool tested positive, indicating an apiary-level prevalence of 0.4% (95% CI: 0.02–2.9%). When the individual samples from this pool were tested, two of the three were positive, corresponding to a colony-level prevalence of 0.3% (95% CI: 0.06–1.3%). These results confirm that the prevalence of P. larvae in Dutch A. mellifera colonies remains very low, consistent with the study in 2008 and the very few to no reported outbreaks of clinical AFB reported annually.