Due to anthropogenic mechanisms, global freshwater biodiversity is declining, and non‐indigenous species are consistently cited as a major threat to native ecosystems. In particular, exotic freshwater gastropods and their parasites have invaded ecosystems through deliberate introductions and/or accidental transfer. In many cases, introduced hosts experience parasite escape in their non‐indigenous range by leaving behind some of their native parasite load during introduction. We investigated whether the Japanese mystery snail, Heterogen japonica, may be exhibiting signatures of parasite escape in non‐indigenous populations in the mid‐Atlantic U.S.A. by comparing the prevalence and diversity of trematode parasites in H. japonica and co‐occurring indigenous snails. Because trematodes can severely impact snail host reproduction, they are an important parasite group to investigate using comparative parasite analyses. Finally, we used genetic data to elucidate whether host switching of trematode lineages had occurred among the indigenous and non‐indigenous snails. Six locations from Richmond, Virginia to Washington, D.C. were surveyed for non‐indigenous and indigenous snails in 2018 and 2019. A random subset of each species was measured, dissected, sexed, and examined for parasite diversity. Brooding embryos were also counted in non‐indigenous snails. Among all snails, native species had a higher diversity of trematode (digenean and aspidogastrean) parasites than the invasive mystery snail, and infection was also influenced by site. Although H. japonica was uninfected at the majority of sites, it had moderate prevalence (up to 34%) of aspidogastrean trematodes at two sites. Female H. japonica infected with aspidogastreans had significantly fewer brooding embryos than uninfected snails. We found additional associates such as ciliates, nematodes, and the oligochaete Chaetogaster sp. in indigenous snails; of these, only ciliates and nematodes were found in association with H. japonica at comparatively low prevalence. While H. japonica has escaped several trematode species, specific populations still had high prevalence of aspidogastreans, the highest of which was found where H. japonica co‐occurred with the indigenous snail Elimia virginica. Genetic data found at least two cryptic lineages of aspidogastreans, and one was shared between H. japonica and E. virginica, suggesting that host‐switching has occurred. Parasites can play powerful roles in interspecific relationships, influence species interactions, and even impact ecosystem functioning. The ability of parasites to host switch could further influence community interactions in this system, particularly if H. japonica continues to spread in North America. Further research is needed to evaluate how parasites (or lack thereof) may mediate the interactions and demographics of indigenous and non‐indigenous species in invaded ranges.