Abstract
Since 2010, outbreaks of haemorrhagic septicaemia (HS) caused by Pasteurella (P.) multocida capsular type B (PmB) emerged in Germany. In 2017, we noticed a close spatiotemporal relationship between HS outbreak sites and wolf (Canis lupus) territories. Thus, the main objectives of our study were to investigate the molecular epidemiology of German PmB-HS-isolates and to assess the role of wolves as putative vectors of this pathogen. We collected 83 PmB isolates from HS outbreaks that occurred between 2010 and 2019 and sampled 150 wolves, which were found dead in the years 2017 to 2019, revealing another three PmB isolates. A maximum-likelihood-based phylogeny of the core genomes of 65 PmB-HS-isolates and the three PmB-wolf-isolates showed high relatedness. Furthermore, all belonged to capsular:LPS:MLST genotype B:L2:ST122RIRDC and showed highly similar virulence gene profiles, but clustered separately from 35 global ST122RIRDC strains. Our data revealed that German HS outbreaks were caused by a distinct genomic lineage of PmB-ST122 strains, hinting towards an independent, ongoing epidemiologic event. We demonstrated for the first time, that carnivores, i.e., wolves, might harbour PmB as a part of their oropharyngeal microbiota. Furthermore, the results of our study imply that wolves can carry the pathogen over long distances, indicating a major role of that animal species in the ongoing epidemiological event of HS in Germany.
Highlights
Haemorrhagic septicaemia (HS) is an OIE listed disease of cattle and buffaloes characterised by an acute, highly fatal septicaemia with high morbidity and mortality, causing major economic losses especially in Asian and African countries [1]
All 86 P. multocida capsular type B (PmB) isolates obtained from HS outbreaks and wolves harboured the HS-specific DNA fragment KTT72/KTSP61
With our study we have demonstrated for the first time that carnivores, i.e., wolves, might harbour PmB as a component of their oral microbiota
Summary
Haemorrhagic septicaemia (HS) is an OIE listed disease of cattle and buffaloes characterised by an acute, highly fatal septicaemia with high morbidity and mortality, causing major economic losses especially in Asian and African countries [1]. Besides domestic and wild ruminants [2,3,4,5,6,7], domestic pigs and wild boar might be affected [7,8,9,10,11]. HS is caused by the Gram-negative, facultative anaerobic bacterium Pasteurella (P.). Based on serological or DNA-based typing methods P. multocida isolates can be classified into 5 capsular types (A, B, D, E and F) [12], 16 serotypes HS cases in Asia and Europe are commonly associated with serovar B:2, while serovar E:2 isolates have so far been limited to outbreaks in Africa. Two MLST schemes are available for P. multocida typing, namely the RIRDC and the multi-host scheme, both hosted at the P. multocida MLST website
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