Avian schistosomatids are blood flukes parasitizing a wide spectrum of aquatic birds. However, its research in the Neotropics is ongoing with several putative new taxa pending description. Although waterfowl represent the most important avian hosts for these flukes, only a small proportion of these birds have been assessed for schistosomatids. This study aimed to describe avian schistosomatids from two native ducks from the Southern Cone of South America. A total of 24 Chiloe wigeon (Mareca sibilatrix) and three Cinnamon teals (Spatula cyanoptera) from different localities in Chile and Argentina were dissected to retrieve schistosomatids. The retrieved worms were described through an integrative approach considering morphology (staining and SEM) and molecular tools (PCR: COI, 28S rRNA genes). The new schistosomatid: Trichobilharzia kulfu sp. nov. was recovered from the viscera of Chiloe wigeon. It was closely related to other undescribed Trichobilharzia taxa from the United States, also from Mareca ducks. The new species was morphologically and molecularly different from other Trichobilharzia species, and it was included in the clade Q. In addition, SEM imaging proved to be an important tool to describe unnoticed traits on the tegument of worms. This new species represents the second Trichobilharzia taxon from the Neotropics described through an integrative approach. Furthermore, the Cinnamon teals harboured Trichobilharzia querquedulae. Considering there are several avian schistosomatids described only through morphological or molecular tools, there is a clear need to include a comprehensive approach in the description of avian schistosomatids, considering the remarkable richness of schistosomatids in Neotropics.

This study examined the metacercariae of trematodes in cnidarian jellyfish around Japan to demonstrate the importance of the jellyfish as the second intermediate or paratenic hosts. Trematodes were sampled from cnidarian jellyfish in seven coastal regions of Japan between 2024 and 2025. Trematodes (adults and metacercariae) were also obtained from marine fish and arrow worms and included for data comparisons. DNA barcoding was used for the species identification of metacercariae in the jellyfish and for elucidating their partial life cycles. Eight cnidarian species (245 individuals) were sampled, with metacercarial infection detected in seven host species. Based on morphological and molecular analyses, the metacercariae were classified into nine species belonging to three families, Accacoeliidae, Hemiuridae, and Lepocreadiidae. Six of these species were identified as the same species of adults isolated from fish hosts around Japan, although species names of two of the six remained unclear. The remaining three trematode species were assumed to belong to Lepocreadiidae, a major group of fish trematodes. These findings indicate that cnidarian jellyfish are important intermediate or paratenic hosts of fish trematodes in Japanese waters, as has been reported in other areas in previous studies. Moreover, a metacercaria occasionally detected in an arrow worm was identified as the same species as those in jellyfish, suggesting predator–prey relationships between these hosts. The study also synonymised Tetrochetus hamadai Fukui and Ogata, 1935, T. aluterae (Hanson, 1955), and T. mitenevi Zubchenko, 1978, with T. coryphaenae Yamaguti, 1934, based on molecular and morphological data.

Based on morphological and molecular data, we describe a new species of Diaphorocleidus parasitizing the nasal cavities of Tetragonopterus argenteus from the Lima Campos weir, municipality of Icó, state of Ceará, Brazil. Diaphorocleidus radius n. sp. resembles other congeners in the morphology of the accessory piece, all by having a bifurcated accessory piece (pincer-shaped), composed of two subunits articulated. However, the new species can be easily distinguished from all congeners by the morphology of the sclerotized structures of the haptor (ventral anchor with well-developed superficial root, ornamented deep root, recurved blade, elongated and lightning-shaped tip; and ventral bar robust, plate-shaped, truncated in lateral ends). Phylogenetic analyses of LSU rDNA and COI mtDNA sequences, conducted using Bayesian Inference and Maximum Likelihood, placed Diaphorocleidus radius n. sp. within Diaphorocleidus, grouping it with species parasitizing acestrorhamphid hosts. Genetic distances between Diaphorocleidus radius n. sp. and other congeneric species such as D. armillatus and D. forficata showed clear differentiation. Both molecular markers support the distinctiveness of Diaphorocleidus radius n. sp., consistent with its recognition as a new taxon.

China accounts for over 90% of global alveolar echinococcosis (AE) cases caused primarily by Echinococcus multilocularis. If left untreated, AE can have a 10-year mortality rate of 94%. Understanding its epidemiological patterns is essential for targeted control strategies. Surveillance data from 2006 to 2020 were obtained from the Public Health Scientific Data Center, and spatial and temporal trends were analyzed using spatial autocorrelation, hot spot analysis, and centroid migration techniques. A total of 51,403 echinococcosis cases were reported from 2006 to 2020, with an average annual incidence of 0.25 per 100,000. Most cases (71.33%) occurred in individuals aged 20–60 years. High-incidence areas centred in western/northwestern provinces, including Qinghai, Xinjiang, Xizang, Gansu, and Ningxia. Incidence and cases increased until 2017, then declined steadily. Spatial autocorrelation revealed persistent High-High clusters in Gansu and Ningxia (2008–2018) and Xizang (2010–2020), while Low-Low clusters persisted in central/eastern China. Hotspot analysis confirmed sustained high-risk zones in western/northwestern regions. Trend surface and centroid migration showed a southward disease shift within Qinghai. Echinococcosis remains endemic in western/northwestern China, with a trend of southward expansion. Strengthened, tailored interventions are urgently needed, particularly in high-burden areas like Xizang and Qinghai.

Preserving viable infective stages of chicken ascarids under laboratory conditions facilitates the maintenance of characterized nematode strains for research purposes. We investigated the survivability of Ascaridia galli eggs exposed to low temperatures and the cryoprotectant dimethyl sulfoxide (DMSO). Two egg developmental stages (unembryonated or fully embryonated) were stored at 4°C, –20°, or –80°C in sterile water or with 5% and 10% DMSO for 1, 2, 4, or 8 weeks. Egg survival was assessed by morphology following post-storage incubation in 0.1 N H2SO4 at 26°C for unembryonated eggs or with a viability dye exclusion test of hatched larvae for the embryonated eggs. The results revealed that neither DMSO nor the hardy chitinous eggshell protected eggs from freezing damage, and not a single egg survived even for 1 week of storage at –20° or –80°C. DMSO at 10% significantly reduced (P < 0.0001) overall egg survival and embryonation capacity with increasing storage time at 4°C compared to water alone. For both egg developmental stages, egg survival was maintained in 5% DMSO at a rate similar to that in water alone. Unembryonated A. galli eggs survived refrigeration better than embryonated eggs with larval viability declining linearly at almost a double rate in the latter (9.75%/week) compared to the former (5.64 %/week). We conclude that DMSO is unlikely to provide cryoprotection for A. galli eggs and also causes concentration-dependent toxicity with increasing exposure time. Furthermore, survival during refrigeration is better for unembryonated than embryonated eggs.