Sarcocystosis is an emerging disease in yaks, and Sarcocystis infection creates a health threat to humans and animals. During a recent study, Sarcocystis infection was detected in yaks by means of morphological observation using hematoxylin and eosin, Giemsa, and acridine orange staining. The species of Sarcocystis isolated from yaks were analyzed and identified phylogenetically. To establish the best model for culturing sarcocystosis isolated from yaks in vitro, four different cell lines—PAMs, Pk15, HeLa, and Vero cells—were used. The effects of sarcocystosis isolated from yaks on the MAPK signaling pathway in Vero cells were detected using Wes automatic Western blot and RT-qPCR. The results from the phylogenetic tree indicate that the sequences of Sarcocystis obtained from yaks in this study were grouped within the Sarcocystis cruzi clade. Results also have shown that S. cruzi had a higher proliferation rate in Vero cells, suggesting that Vero cells are more suitable for the long-term culturing of S. cruzi in vitro. Results also indicate that S. cruzi infecting Vero cells could cause the activation of ERK1/2 pathway, while inhibiting the ERK1/2 pathway could suppress S. cruzi infection in Vero cells. Therefore, the study and exploration of Sarcocystis-host relationships can effectively provide certain theoretical knowledge and the basis for the treatment of clinical diseases and the development of Sarcocystis drugs.

The genus Scalithrium is one of the most poorly known genera of rhinebothriidean tapeworms. It currently houses 10 morphologically heterogeneous species hosted by stingrays and guitarfishes. This study aimed to expand our understanding of this genus. Two new species, Scalithrium healyae n. sp. and Scalithrium johnvolini n. sp., are described from the giant guitarfish, Glaucostegus typus, off Australia and the lesser guitarfish, Acroteriobatus annulatus, off South Africa, respectively. The microtriches of members of this genus are characterized using scanning electron microscopy for the first time. Existing generic membership is critically assessed in the context of the morphology of the type species of the genus, Scalithrium minutum. As a result, Scalithrium bilobatum, Scalithrium smitii, and Scalithrium trygonis are considered species inquirenda owing to the limited amount of available information and material of both species. Scalithrium palombii and Scalithrium rankini are considered incertae sedis given the numerous morphological differences that exist between these species and the type and six other species in the genus. These differences include a greater length, more proglottids, and a much greater number of testes, the distribution of which extends to the ovary, rather than being restricted to the region anterior to the genital pore. The diagnosis of the genus is revised to accommodate these modifications in membership. We anticipate that the more cohesive concept of Scalithrium developed here will help advance future work circumscribing several of the other problematic genera of rhinebothriideans.

Trophically transmitted parasites have complex life cycles that incorporate multiple hosts at different developmental stages. As part of a study quantifying parasite diversity in the Indian River Lagoon, Florida, we documented immature acanthocephalan cystacanths in the mesentery of the frillfin goby, Bathygobius soporator. Sequencing of a 626-base-pair region of the mitochondrial cytochrome c oxidase subunit I gene yielded a 100% match to Southwellina hispida, a generalist parasite with a worldwide distribution. As a paratenic host for S. hispida, frillfin gobies bridge the trophic gap between first-intermediate (crustaceans) and definitive hosts (piscivorous birds). Frillfin gobies in our system consume a variety of potentially infected prey; however, crustaceans accounted for 87% of all identifiable stomach contents. In turn, gobies are likely preyed upon by multiple species of migratory piscivorous wading birds, which S. hispida uses to complete its life cycle. This is the second confirmed record of a member of the Gobiidae serving as a paratenic host for S. hispida. Our study adds to the limited but expanding knowledge of metazoan parasite diversity in B. soporator.

Bat flies (Diptera: Hippoboscoidea) are highly specialized ectoparasites only associated with bats (Mammalia: Chiroptera). These pupiparous flies are born as larvae but immediately pupate. The puparia have not been described for most species. We report new findings of bat fly puparia in Asia, with descriptions of the puparium of highly distributed species Nycteribia quasiocellata Theodor, 1966 from Siberia and adjacent territories and Eucampsipoda sundaicum Theodor, 1955 from Southeast Asia with a key to the determination of puparia of Eurasian nycteribiid flies known so far.

Ticks secrete immunosuppressant proteins that modulate the host's immune system during blood feeding. Five putative genes encoding similar p36 immunosuppressant proteins from other tick species were cloned by sequencing randomly picked plaques from a complementary DNA library constructed from salivary glands of partially engorged Haemaphysalis qinghaiensis. The genes were designated Hq-p36-1, Hq-p36-2, Hq-p36-3, Hq-p36-4, and Hq-p36-5. By doing a Multiple Em for Motif Elicitation (MEME) tool search, 3 potential common motifs, which coincided with 3 conserved regions, were found among the 8 aligned tick p36 homologs. Antigenicity analysis suggested that most of these homologs might be satisfactory antigen candidates, and 2 common antigenic determinants were predicted from each of the 5 proteins, and they overlapped with 2 common motifs. Four out of the 5 Hq-p36 proteins might share a similar 3-dimensional model with an exposed big loop overlapped by the motif MEME-1 and a conserved antigenic region. The finding of the 5 H. qinghaiensis p36 protein homologs could expand our knowledge of tick immunosuppressant proteins and lay ground for future studies to determine their exact role in tick feeding process.

The freshwater leech genus Orientobdelloides Bolotov, Eliseeva & Kondakov, 2022, is reported for the first time in Indonesia. Morphological and mitochondrial DNA sequence data identified the specimens as Orientobdelloides tridens (Chiangkul, Trivalairat, Kunya & Purivirojkul, 2021), a species previously known only from Thailand. The external and internal morphological features of the Indonesian O. tridens are provided in detail here, and the species diagnosis is amended based on our observations.

Differences in parasite infection patterns between hosts can be influenced by numerous factors placed into 2 categories: encounter filters (precontact) and compatibility filters (postcontact). The influence of these factors in shaping the patterns of parasite infection was investigated in Lake Holiday, a 100-ha lake in northern Virginia, U.S.A. In total, 1,586 fish in the family Centrarchidae, encompassing 4 species—Lepomis macrochirus, Lepomis cyanellus, Lepomis auritus, and Micropterus salmoides—were collected and necropsied over a 7-yr period. The length, weight, age, stomach contents, and counts of 2 diplostomid parasites—Posthodiplostomum cf. centrarchi and Uvulifer cf. ambloplitis—were recorded. The prevalence and intensity of P. cf. centrarchi differed between host species, which was likely influenced by both encounter and compatibility filters. However, U. cf. ambloplitis infection showed significant correlations with the prevalence, but not the intensity, of infection. This indicates that encounter filters may play a larger role in shaping the infection patterns of U. cf. ambloplitis than compatibility filters. Furthermore, the infection pattern differences between host species exhibited by P. cf. centrarchi indicate that the parasite species complex are likely specialists, whereas U. cf. ambloplitis represents a true generalist parasite because there are no apparent differences in compatibility between hosts. In addition, P. cf. centrarchi infections follow distinct patterns in the tissues that they infect, thereby allowing single organ counts, particularly the liver, to be proxies for total parasite infection, whereas the correlations in U. cf. ambloplitis are less predictable and do not allow for single tissue infections to be reliable indicators for total parasite load.

The trematode currently recognized as Metagonimoides oregonesis primarily utilizes the Southern Black-bellied Salamander, Desmognathus amphileucus, as a second intermediate host in southern Appalachian streams. We investigated seasonal variation in relative intensity within larvae of this salamander species in the Broad River system of northeastern Georgia by counting metacercariae visible through the ventral body wall in February, May, August, and November of 2023. Summer hatching and metamorphosis by salamander larvae coupled with likely summer shedding time of trematode cercariae from the snail host explain much of the variation, which showed a peak relative intensity in November. However, this peak remained even after the effect of salamander size (and presumably age) had been removed. The seasonal pattern we observed may be subject to interannual variation.

Examination of the feces of an emydid turtle, a watersnake, and a passeriform bird for coccidian parasites yielded some new host and geographic distributional records. Oocysts of Eimeria cooteri McAllister and Upton, 1989, and Eimeria marginata (Deeds and Jahn, 1939) Pellérdy, 1974, occurred in an eastern river cooter, Pseudemys concinna concinna, from Arkansas, U.S.A., Eimeria hydrophis Wacha and Christiansen, 1974, was found in a plain-bellied watersnake, Nerodia erythrogaster, from Arkansas, and Isospora zimmermani McAllister and Hnida, 2023, was found in a barn swallow, Hirundo rustica, from Texas, U.S.A. Mensural data as well as new photomicrographs are provided for each coccidian.