Effect of per- and polyfluoroalkyl substances (PFAS) levels on helminth infections in small mammals

The potential interactions between per- and polyfluoroalkyl substances (PFAS) and helminth infection in terrestrial mammals remain largely unexplored. This study investigated the relationship between PFAS accumulation in the tissues of two small mammal species, Apodemus flavicollis and Myodes glareolus, collected from northwestern and southeastern Bohemia (Czech Republic), and their gastrointestinal parasite burden. PFAS were analysed in liver and kidney tissues from 71 individuals, of which 23 (32.4 %) were infected with intestinal helminths. Extraction followed the QuEChERS protocol and quantification was performed by LC-MS/MS. The method was validated for 20 PFAS compounds, including several newer-generation substances (e.g., HFPO-DA, HFPO-TA, HFPO-TeA, ADONA, F-53B). None of the GenX compounds or PFOA were detected, while six legacy PFAS (PFOS, PFDA, PFDoDA, PFNA, PFUnDA, PFTrDA) were present in varying concentrations. PFOS was the most prevalent, detected in 99 % of samples (70/71), ranging from 0.09 to 125.51 ng/g (w/w). A. flavicollis exhibited significantly higher concentrations of PFDoDA, PFTrDA, and PFUnDA compared with M. glareolus, whereas no sex-related differences were observed. Importantly, animals infected with helminths had significantly higher PFOS levels as well as higher total PFAS concentrations than uninfected individuals. These findings demonstrate a possible association between helminth infections and increased PFAS body burden in small mammals. This relationship may reflect interactions between PFAS exposure, parasite susceptibility, and immune system function, supporting the relevance of PFAS immunotoxicity in shaping host-parasite dynamics.