Trichinella spiralis (T. spiralis) is a zoonotic parasitic worm that has a significant impact on both public health and the livestock industry. It is widely used in experimental studies because of several unique features of its life cycle that can be completed in a single host, including distinct intestinal and muscular phases of infection, and it can be easily maintained in laboratory animals. These characteristics make T. spiralis a valuable model for evaluating the efficacy of new drugs and vaccines against parasitic infections. The current work aims to evaluate the procedures used for Trichinella larval counting in experimental studies by comparing the magnetic stirring digestion method (MSDM) with individual muscle digestion and compression techniques under standardised, controlled conditions to assess their effectiveness and applicability. Fifteen male Swiss albino mice were orally infected with T. spiralis and sacrificed on day 35 post-infection. They were divided into three groups: group 1—MSDM for total larval count; group 2—individual digestion of masseter, diaphragm, gastrocnemius, and tongue muscles; and group 3—slide compression method of the same muscles. MSDM yielded the highest larval counts, with individual muscle digestion and compression methods generally producing significantly lower results, except tongue digestion, while correlation and concordance analyses identified gastrocnemius compression as an alternative despite overall poor agreement with the reference method. Therefore, MSDM is the most accurate method for larval counting in experimental studies, compared to individual muscle digestion or compression methods.

Anurans are bioindicators and key components of ecosystem functions. Although South America harbors more than 4,000 identified anuran species, fewer than 10% have been analyzed regarding their trematode fauna. When tadpoles are considered, the paucity of studies becomes even more evident. Considering the ability of digeneans to serve as indicators of ecosystem health, it is evident that there is a gap in the knowledge of trematodes occurring in anuran biodiversity hotspots. Herein, we provide an ecological and morphological analysis of the trematode component community recovered in tadpoles and adult anurans. During a long-term herpetological and helminthological study conducted in a Cerrado fragment in Brazil, 569 anurans from 17 species were necropsied. Eleven species were common to both adults and tadpoles, and six species occurred only in adults. The total prevalence was 61% (352/569), in separate analyses, 65% (192/296) for adult anurans, and 58% (160/273) for tadpoles. A total of 12,397 trematodes belonging to 16 taxa were recovered. The component community was composed mostly of metacercariae. We provided a brief morphological description for each trematode taxa recovered. Additionally, statistical analysis was performed to elucidate the differences between tadpoles and adult anurans trematode communities. The trematode community analyzed in our study revealed 24 new host records and was the first to include tadpoles in such an analysis, highlighting the importance of faunistic inventories for a better understanding of parasitism in their hosts, as well as providing a foundation for further research.

It is assumed that the biology and ecology of commercial fish species are relatively well-known, given that many of these parameters are key for stock assessment in fisheries management. Surprisingly (or not), several new parasite species are described annually from fish that are of commercial and cultural importance. Haddock (Melanogrammus aeglefinus) is an important commercial fish species in the North Atlantic with more than 50 parasite species having been reported from it. Despite its commercial importance in Icelandic waters, only 11 parasite species have been reported from Icelandic haddock. In February and March 2023, 26 haddock were sampled, including 16 and 10 from the north and south of Iceland, respectively. Fish were examined for parasites, with a focus on macroparasites (large, usually visible to the eye). Parasites were identified morphologically with identifications of helminths confirmed using DNA barcoding (Sanger sequencing). Overall, 19 different parasite species were recovered with 17 being shared between haddock sampled from the north and south of Iceland. Of these, eight represent new geographical records for parasites of haddock in Icelandic waters. Our study indicates that monitoring for parasites remains important, regardless of how well a species has been studied. Furthermore, reporting parasites per organ and per region, especially when areas are known to be influenced by different abiotic and physical features, is important in the context of parasites as biological tags for stock identification. Despite a small sample size, our study suggests that some parasites might act as potential biological tags for stock identification of haddock in Icelandic waters.

Nematode records and specimens from the South Australian Museum, Australian Museum, CSIRO Wildlife Collection, Queensland Museum, Western Australian Museum, and Natural History Museum, London, of 1107 individuals of Rattus fuscipes were examined. The nematode community comprised 19 families, 36 genera, and 44 identified species. Mastophorus muris and unidentified heligmonellids were recovered from 4 individuals of R. f. fuscipes. Rattus f. assimilis was infected with 40 identified species of nematode from 955 individuals; R. f. coracius 18 species from 107 individuals; and R. f. greyii 8 species from 28 individuals. Rattus fuscipes harboured 18 species in Northern Queensland, 27 species in Southern Queensland, 27 species in New South Wales, 19 species in Victoria, and 8 species in South Australia. A bootstrap analysis of the R. f. greyii nematode community indicated that 91.3% of species had been found. No core species were revealed. The Trichostrongylidae dominated with Nippostrongylus magnus, and Odilia emanuelae occurring in all the populations. Nippostrongylus magnus, 43% prevalence, in Victoria and Physaloptera troughtoni, 42% prevalence, in South Australia were secondary species. Sorensen’s indices indicated that R. f. assimilis and R. f. coracius had the most similar nematode communities, 54.8%. Overall, the Northern and Southern Queensland populations were most similar (77.3%) and the New South Wales and South Australian populations least similar (22.9%). The identifications of Heterakis spumosa, Physaloptera troughtoni, Rictularia mackerrasae, and Pterygodermatites pearsoni were confirmed. The species composition of the nematode community of R. fuscipes suggested a scenario of coevolution, host switching, recently acquired and occasional infections in a community of cosmopolitan, regional, and indigenous species. Species throughout the component communities of R. fuscipes indicated that climate and habitat were also determinants of species composition.