Vibrio (V.) parahaemolyticus is a leading seafood-borne human pathogen frequently detected in shellfish. While accumulation and depuration dynamics have been extensively studied in oysters, comparable data for blue mussels (Mytilus edulis) are limited. This study investigated the accumulation and depuration of two V. parahaemolyticus strains (clinical and environmental) and virulence genotype (tdh+ vs. trh+) under controlled closed laboratory conditions. For the accumulation trials, mussels were exposed to 104 to 107 CFU V. parahaemolyticus/mL for 48 h. Depuration trials were conducted for 72h after 18 h exposure to 105 or 107 CFU/mL. Accumulation in mussel tissue was significantly affected by dose (F = 23.24, p < 0.001) and exposure time (F = 9.39, p < 0.001), while no strain effect was detected (F = 1.01, p = 0.315). Tissue concentrations of approximately 3–4 log10 MPN/g were already detected within 5 min after exposure. Comparable final tissue concentrations of approximately 4–5 log10 MPN/g were observed for both strains after 48 h. In contrast, depuration differed markedly between strains. The RIMD strain (tdh+) declined to below the detection limit (LOD) when exposed to 105 CFU/mL but remained detectable at 107 CFU/mL, while the VPILSH strain (trh+) remained detectable after 72 h of depuration at both exposure levels. Depuration in mussel tissue was significantly affected by strain (F = 82.67, p < 0.001) and dose (F = 110.18, p < 0.001), while time was not significant (F = 0.39, p = 0.81). These findings reveal dose- and time-dependent accumulation but strain-dependent depuration, highlighting enhanced persistence of the environmental VPILSH strain in blue mussels.
