Vibrio vulnificus in aquariums is a novel threat to marine mammals and public health.

Vibrio vulnificus is a Gram-negative, curved, obligate halophilic marine bacterium that exclusively exists in coastal seawaters. Previous studies revealed that V. vulnificus is one of the most dangerous foodborne zoonotic pathogens for human beings. However, it remains unknown whether marine mammals can be infected by V. vulnificus. In May 2016, a captive spotted seal (Phoca largha) died due to septicemia induced by V. vulnificus. Upon post-mortem examination, V. vulnificus was isolated, identified, and named as BJ-PH01. Further analysis showed that BJ-PH01 belongs to biotype 1 and the Clinical genotype. Furthermore, we performed an epidemiological investigation of V. vulnificus in six aquariums in northern China. As a result, V. vulnificus was successfully isolated from all investigated aquariums. The positive rates ranged from 20% to 100% in each investigated aquarium. During the investigation, 12 strains of V. vulnificus were isolated, and all 12 isolates were classified into biotype 1. Eleven of the 12 isolates belonged to the Clinical genotype, and one isolate belonged to the Environmental genotype. All 12 isolated V. vulnificus strains showed limited antibiotic resistance. Overall, our work demonstrated that V. vulnificus is frequently distributed in aquariums, thus constituting a threat to captive marine mammals and to public health.