<i>Brucella ceti</i> in Common Dolphins (<i>Delphinus delphis</i>) in Portugal—Characterization of First Isolates
2025
Sandra Cavaco | Miguel L. Grilo | Ricardo Dias | Mónica Nunes | Pedro Pascoal | Marcelo Pereira | Catarina Fogaça | Ana Beatriz Costa | Sofia Pardal | Ana Cristina Ferreira
This study investigates <i>Brucella ceti</i> infection in marine mammals stranded along the Lisbon and Tagus Valley coast between 2022 and mid-2024, marking the first report of <i>Brucella</i> presence in Portuguese waters. Out of 59 examined marine mammals, <i>B. ceti</i> was isolated in three common dolphins (5.1%), a prevalence rate consistent with previous studies from other coastlines. PCR-based detection indicated a higher infection rate (23.7%), suggesting an underestimation of the prevalence of <i>B. ceti</i> infection in this population. Multi-locus Sequence Typing (MLST) and Multiple-Locus Variable-Number Tandem-Repeat Analysis (MLVA) revealed distinct genetic profiles and close relationships to <i>B. ceti</i> strains from the Atlantic, supporting the hypothesis of specific host-adapted lineages in dolphins. Virulence genes, including those for host interaction (<i>bsp</i>E, <i>btp</i>B) and intracellular survival (<i>vir</i>B7, <i>vce</i>A), were consistent across isolates, highlighting the pathogenic potential. Additionally, antimicrobial resistance (AMR) genes, such as <i>mpr</i>F and efflux proteins (<i>bep</i>C-G), were also identified. These findings underscore the need for further research and surveillance to understand <i>B. ceti</i> transmission, host range, and impacts on Atlantic cetaceans, as well as to develop effective diagnostic and management strategies to mitigate infection risks in marine environments.
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