Occurrence and Distribution of Vibrio alginolyticus in Shellfish

V. alginolyticus (VAlg) is one of the three Vibrio species causing human vibriosis. Its presence in shellfish constitutes a potential health risk. Thus, this investigation aimed to determine the prevalence and distribution of VAlg in 18,544 shellfish across geographies using standard protocols and random intercepts/mixed-effects regressions. The global VAlg prevalence in shellfish was 19.70% (95% CI: 13.54-27.75). VAlg pooled prevalence was significantly different (p < 0.0001) by shellfish type (χ202 = 238.48), species (χ742 = 440.34), genus (χ512 = 414.37), VAlg detection methods (χ102 = 150.43), nation (χ302 = 632.27), and continent (χ42 = 33.81). Europe and South America showed the highest pooled VAlg contaminated rates in shellfish (27% and 32%, respectively) but Asia had a low rate (~4%). By shellfish type, gastropods (snails) topped the list with 50%, followed by bivalves (29%). Among shellfish species, the VAlg rate declined from 67% to 5% (k ≤ 6), but with a more stable prevalence in Litopenaeus vannamei (19.02%, k = 11) and Crassostrea gigas (15.18%, k = 9). Edible oysters and clams had lower VAlg pooled rates (4-15%). Targeted culture with MALDI-TOF or species-specific qPCR detected VAlg in 100% of tested shellfish samples. By contrast, conventional phenotypic tests detected less VAlg in shellfish yielding 20% by general biochemical/API tests, 8.8% by generic PCR, and near-zero (0.3-3%) by multiplex PCR or MALDI-TOF/PCR. Both the multiplicative (β0=-3.28±3.76, F54;125 = 3.01, p = 0.001) and additive (β0=-1.89±1.47, F31;148 = 3.83, p = 0.001) interactions of nation and sample size explained 73.14% and 58.04% of the true variance in VAlg prevalence in shellfish. Other factors include detection techniques (R2 = 46.59%, β0=-1.63±0.83, F10;169=11.16, p = 0.001), nation (R2=37.72 = 1.89, p = 0.006), medium R2 = 19.42%, β0=2.24±1.85, F15;164 = 1.69, p = 0.03), shellfish type (R2 = 16.99%, β0=-3.90±1.32, F20;159 = 1.34, p = 0.12), and continent (R2 = 15.29%, β0=-1.81±0.41, F4;175 = 5.90, p = 0.001). In conclusion, the study reveals substantial occurrence of VAlg in shellfish worldwide, with notable regional and species-specific hotspots. Harmonized and molecular-based surveillance of VAlg in shellfish linked to food safety criteria will be essential to manage its emerging threat.