# Detection of Zoonotic Photobacterium damselae Subspecies damselae in a Razorbill ( Alca torda ): The First Report of a Potential Cross‐Species Transmission in Birds

## TL;DR

A razorbill bird in Italy was found dead with a rare marine bacterium, suggesting it can spread between species and highlighting risks to wildlife and human health.

## Contribution

This is the first report of Photobacterium damselae subsp. damselae in a migratory bird, indicating potential cross-species transmission.

## Key findings

- Pdd was isolated from a dead razorbill, confirmed via MALDI-TOF MS, PCR, and gene sequencing.
- The presence of the hlyAch gene suggests a pathogenic strain affecting birds.
- Histopathology showed severe inflammation and hemorrhages, linking Pdd to the bird's death.

## Abstract

A razorbill (
Alca torda
) was found dead in Bacoli, Italy, on January 16, 2023, during an exceptional irruptive event. Post‐mortem examination revealed coelomitis with severe congestion of the liver, lungs, kidneys, and myocardium. Bacterial isolation, MALDI‐TOF MS analysis and PCR confirmed the presence of
Photobacterium damselae
subsp. damselae (Pdd), supported by 16S rDNA gene sequencing and detection of the ureC gene. PCR screening for virulence factors identified the hlyAch gene in lung samples, suggesting a potentially pathogenic strain in avian species. Histopathological examination showed severe inflammatory infiltrates and widespread haemorrhages with mild and multifocal lymphocytic infiltrates in tissues analysed. These findings suggest a significant role of Pdd in the observed lesions. Pdd is an emerging pathogen affecting a wide range of marine animals, including invertebrates, fish, and cetaceans. Here, we report the first isolation of Pdd in a razorbill and more importantly, the first detection in a migratory bird. We report a potential new cross‐species transmission of Pdd, underscoring its zoonotic potential and the need for further research. Given the role of migratory birds in pathogen spread and the impact of climate change on marine ecosystems, a preventive approach is essential to mitigate risks to wildlife, aquaculture, and human health.

The first isolation of
Photobacterium damselae
subsp. damselae in a razorbill highlights a new cross‐species transmission of this new emerging zoonotic bacterium. Given the role of migratory birds in pathogen spread and the impact of climate change on marine ecosystems, further research and a preventive approach are essential to mitigate risks to wildlife, aquaculture, and human health.