Rastrelliger brachysoma (Bleeker, 1851), the short mackerel, is a dietary staple and of significant economic demand in Southeast Asia and Thailand. However, the demand for short mackerel has precipitated an overfishing crisis, leading to a depletion of fish stocks. Overfishing, coupled with parasitism, may result in a decline in the population of R. brachysoma. Digenetic trematode infection is prevalent in marine fish and has a considerable impact on the overall health of the fish. Here, to identify digenetic trematodes infecting R. brachysoma, we aim to determine the identity, prevalence, and intensity of digenean infections in R. brachysoma from the Gulf of Thailand. A total of 194 short mackerel were obtained from Chon Buri Province, where digeneans were isolated and identified. The molecular identity of the digeneans was confirmed using the nuclear 28S rRNA gene. Of the 194 short mackerel, 100% were found to be infected with digeneans, comprising of Lecithocladium, Prodistomum, Opechona, and Aphanurus. Lecithocladium was the most prevalent (98%) and had the highest intensity of infection (37 mean intensity), followed by Prodistomum (75% prevalence and 17 mean intensity). Our study thus presents the first evidence of digeneans infecting the economically important short mackerel from the Gulf of Thailand. The high infection rate of digenetic trematodes may have implications on the health of R. brachysoma, further driving their population decline. These data underscore the importance of safeguarding fisheries resources in the Gulf of Thailand, and downstream conservation efforts are crucial for evidence-based management decisions to safeguard the long-term sustainability of fish resources.

UNASSIGNED: The potential of plants as anthelmintics is very large, but there is still very little research conducted in the search for effective, safe, easily obtained, and affordable anthelmintic candidates. Palem putri (Veitchia merrillii) is an ornamental plant that is interesting to study because it is included in the areca nut group which is reported to have strong abilities as anthelmintics. The study aims to evaluate the anthelmintic efficacy of Veitchia merrillii against trematode worms such as Paramphistomum spp. and Fasciola hepatica.
UNASSIGNED: This research employs both in vitro and computational techniques. An anthelmintic in vitro test was carried out on Paramphistomum spp. worms at concentrations of 10%, 25%, and 40% (gr/v), assessing mortality index as the observable outcome, followed by a histopathological investigation of the deceased worms for tissue and cellular damage evaluation. Seventeen compounds from V. merrillii seeds were studied in silico for their anthelmintic activity against F. hepatica worms using the quantitative structure-activity relationship technique, molecular docking, and Lipinski\'s rule analysis for orally administered medication.
UNASSIGNED: About 25% and 40% extracts of V. merrillii damaged the tegument organs in the worms. Seventeen compounds in V. merrillii seed extract, on average, yielded a higher anthelmintic index on F. hepatica than praziquantel. Eleven of the 17 compounds exhibit stronger affinity than praziquantel, with routine and gallic acid being the top two ligands (∆Gbinding values: -11.65 kcal/mol and -11.07 kcal/mol, respectively). According to Lipinski\'s rule analysis, only routine compounds cannot be orally administered.
UNASSIGNED: The seeds of V. merrilli have potential as an anthelmintic agent for Paramphistomum spp. at concentrations of 25%-40% (gr/v).

BACKGROUND: Biological invasions pose risks to the normal functioning of ecosystems by altering the structure and composition of several communities. Molluscs stand out as an extensively studied group given their long history of introduction by either natural or anthropogenic dispersal events. An alien population of the lymnaeid species Orientogalba viridis was first sighted in 2009 in southern Spain. In its native range (Australasian), this species is one of the main intermediate hosts of Fasciola hepatica, a major worldwide trematode parasite largely affecting humans, domestic animals and wildlife.
METHODS: We collected field populations of O. viridis from its native (Malaysia) and invaded (Spain) ranges. We performed detailed morphoanatomical drawings of the species and screened for natural infection of parasites. Individuals were molecularly characterized using ITS2 for comparison with existing sequences in a fine phylogeography study. We founded experimental populations at two different conditions (tropical, 26 °C and temperate, 21 °C) to study the life-history traits of exposed and non-exposed individuals to different F. hepatica isolates.
RESULTS: We found a 9% natural prevalence of trematode infection (98% similarity with a sequence of Hypoderaeum conoideum [Echinostomatidae]) in the Spanish field population. The haplotypes of O. viridis found in our study from Spain clustered with Australian haplotypes. Experimental infection with F. hepatica was successful in both experimental conditions but higher in tropical (87% prevalence) than in temperate (73%). Overall lifespan, however, was higher in temperate conditions (mean 32.5 ± 7.4 weeks versus 23.3 ± 6.5) and survivorship remained above 70% during the first 20 weeks. In parasite-exposed populations, life expectancy dropped from an overall 37.75 weeks to 11.35 weeks but still doubled the time for initial cercariae shedding. Cercariae shedding started at day 23 post-exposure and peaked between days 53 and 67 with an average of 106 metacercariae per snail.
CONCLUSIONS: Whether O. viridis will succeed in Europe is unknown, but the odds are for a scenario in which a major snail host of F. hepatica occupy all available habitats of potential transmission foci, ravelling the epidemiology of fasciolosis. This research provides a comprehensive understanding of O. viridis biology, interactions with parasites and potential implications for disease transmission dynamics, offering valuable insights for further research and surveillance.

BACKGROUND: Gills monogenean infestation causes significant mortalities in cultured fishes as a result of respiratory manifestation. Medicinal plants are currently being heavily emphasized in aquaculture due to their great nutritional, therapeutic, antimicrobial activities, and financial value.
METHODS: The current study is designed to assess the effect of garlic (Allium sativum) and onion (Allium cepa) extracts as a water treatment on the hematological profile, innate immunity, and immune cytokines expression besides histopathological features of gills of Nile tilapia (Oreochromis niloticus L.) infected with gills monogenetic trematodes (Dactylogyrus sp.). Firstly, the 96-hour lethal concentration 50 (96 h-LC50) of garlic extract (GE) and onion extract (OE) were estimated to be 0.4 g/ L and 3.54 g/ L for GE and OE, respectively. Moreover, the in-vitro anti-parasitic potential for (GE) was found between 0.02 and 0.18 mg/mL and 0.4 to 1.8 mg/mL for OE. For the therapeutic trial, fish (n = 120; body weight: 40-60 g) were randomly distributed into four groups in triplicates (30 fish/group, 10 fish/replicate) for 3 days. Group1 (G1) was not infected or treated and served as control. G2 was infected with Dactylogyrus spp. and not exposed to any treatment. G3, G4 were infected with Dactylogyrus sp. and treated with 1/10 and 1/5 of 96 h LC50 of OE, respectively. G5, G6 were infected with Dactylogyrus sp. and treated with 1/10 and 1/5 of 96 h LC50 of GE, respectively.
RESULTS: No apparent signs or behaviors were noted in the control group. Dactylogyrus spp. infected group suffered from clinical signs as Pale color and damaged tissue. Dactylogyrus spp. infection induced lowering of the hematological (HB, MCH, MCHC and WBCs), and immunological variables (lysozyme, nitric oxide, serum Anti- protease activities, and complement 3). the expression of cytokine genes IL-ß and TNF-α were modulated and improved by treatment with A. sativum and A. cepa extracts. The obtained histopathological alterations of the gills of fish infected with (Dactylogyrus spp.) were hyperplasia leading to fusion of the gill filament, lifting of epithelial tissue, aneurism and edema. The results indecated that G4 and G5 is more regenarated epithelium in compare with the control group.
CONCLUSIONS: A. sativum and A. cepa extracts enhance the blood profile and nonspecific immune parameters, and down-regulated the expression level of (IL-1β and TNF-α).

We show that the globally invasive, human-infectious flatworm, Haplorchis pumilio, possesses the most physically specialized soldier caste yet documented in trematodes. Soldiers occur in colonies infecting the first intermediate host, the freshwater snail Melanoides tuberculata, and are readily distinguishable from immature and mature reproductive worms. Soldiers possess a pharynx five times absolutely larger than those of immature and mature reproductives, lack a germinal mass, and have a different developmental trajectory than reproductives, indicating that H. pumilio soldiers constitute a reproductively sterile physical caste. Neither immature nor mature reproductives showed aggression in in vitro trials, but soldiers readily attacked heterospecific trematodes that coinfect their host. Ecologically, we calculate that H. pumilio caused ~94% of the competitive deaths in the guild of trematodes infecting its host snail in its invasive range in southern California. Despite being a dominant competitor, H. pumilio soldiers did not attack conspecifics from other colonies. All prior reports documenting division of labor and a trematode soldier caste have involved soldiers that may be able to metamorphose to the reproductive stage and have been from nonhuman-infectious marine species; this study provides clear evidence for an obligately sterile trematode soldier, while extending the phenomenon of a trematode soldier caste to freshwater and to an invasive species of global public health concern.

Troglocephalinae n. subfam. is proposed for Spinuris Doran, 1953, Neoheterocotyle Hargis, 1955, Anoplocotyloides Young, 1967, Troglocephalus rhinobatidis Young, 1967 (previously incertae sedis), Nonacotyle pristis Ogawa, 1991, Mehracotyle insolita Neifar, Euzet & Ben Hassine, 2002, Scuticotyle cairae n. gen. et sp., and Brancheocotyle imbricata n. gen. et sp. All members of the proposed new subfamily are gill parasites of shovelnose rays of the order Rhinopristiformes. The subfamilies Heterocotylinae Chisholm, Wheeler & Beverley-Burton, 1995, and Dasybatotreminae Bychowsky, 1957, are amended to exclude Spinuris, Nonacotyle, Neoheterocotyle, and Anoplocotyloides and Mehracotyle, respectively. Heterocotylinae includes gill parasites of members of the orders Myliobatiformes and Torpediniformes. Dasybatotreminae includes parasites of the gills and pharyngeal cavity of members of the orders Myliobatiformes and Rajiformes. A revised phylogeny of the Monocotylidae Taschenberg, 1879 is presented and discussed, based on 28S rDNA sequences, including new sequences for Myliocotyle pteromylaei Neifer, Euzet & Ben Hassine, 1999, Heterocotyle tokoloshei Vaughan & Chisholm, 2010, Neoheterocotyle robii Vaughan & Chisholm, 2010, and the two newly proposed species and genera. Additional locality records are also provided for Monocotylidae from off South Africa.

UNASSIGNED: Parasite-mediated selection is considered one of the potential mechanisms contributing to the coexistence of asexual-sexual complexes. Gibel carp (Carassius gibelio), an invasive fish species in Europe, often forms populations composed of gynogenetic and sexual specimens.
UNASSIGNED: The experimental infection was induced in gynogenetic and sexual gibel carp using eye-fluke Diplostomum pseudospathaceum (Trematoda), and the transcriptome profile of the spleen as a major immune organ in fish was analyzed to reveal the differentially expressed immunity-associated genes related to D. pseudospathaceum infection differing between gynogenetic and sexual gibel carp.
UNASSIGNED: High parasite infection was found in gynogenetic fish when compared to genetically diverse sexuals. Although metacercariae of D. pseudospathaceum are situated in an immune-privileged organ, our results show that eye trematodes may induce a host immune response. We found differential gene expression induced by eye-fluke infection, with various impacts on gynogenetic and sexual hosts, documenting for the majority of DEGs upregulation in sexuals, and downregulation in asexuals. Differences in gene regulation between gynogenetic and sexual gibel carp were evidenced in many immunity-associated genes. GO analyses revealed the importance of genes assigned to the GO terms: immune function, the Notch signaling pathway, MAP kinase tyrosine/threonine/phosphatase activity, and chemokine receptor activity. KEGG analyses revealed the importance of the genes involved in 12 immunity-associated pathways - specifically, FoxO signaling, adipocytokine signaling, TGF-beta signaling, apoptosis, Notch signaling, C-type lectin receptor signaling, efferocytosis, intestinal immune network for IgA production, insulin signaling, virion - human immunodeficiency virus, Toll-like receptor signaling, and phosphatidylinositol signaling system.
UNASSIGNED: Our study indicates the limited potential of asexual fish to cope with higher parasite infection (likely a loss of capacity to induce an effective immune response) and highlights the important role of molecular mechanisms associated with immunity for the coexistence of gynogenetic and sexual gibel carp, potentially contributing to its invasiveness.

Introduced species have a major impact on freshwater ecosystems, particularly on islands. Numerous fish species have been introduced in Corsica (Mediterranean island, southern France) as part of planned programs or clandestinely. The introduction of non-native freshwater fish species can have a range of impacts on the recipient ecosystem, including through the co-introduction of its pathogens. A sample of introduced perch Perca fluviatilis Linnaeus, 1758 from the artificial reservoir of Padula was examined following a report of parasites by an angler. The analyses revealed the occurrence of Eustrongylides sp. (Nematoda) and Clinostomum complanatum (Digenea), two zoonotic parasites in P. fluviatilis. Both parasites are reported for the first time in France. Eustrongylides sp. and C. complanatum may have been introduced with their fish intermediate hosts or through their final bird hosts. The occurrence of the two parasites raises concerns from both a veterinary and human health perspective as they can use a wide range of amphibians as intermediate hosts and can be acquired in humans through the consumption of raw or undercooked fish.

BACKGROUND: Gastropods of the genus Biomphalaria (Family Planorbidae) are exploited as vectors by Schistosoma mansoni, the most common causative agent of human intestinal schistosomiasis. Using improved genomic resources, overviews of how Biomphalaria responds to S. mansoni and other metazoan parasites can provide unique insights into the reproductive, immune, and other systems of invertebrate hosts, and their responses to parasite challenges.
RESULTS: Using Illumina-based RNA-Seq, we compared the responses of iM line B. glabrata at 2, 8, and 40 days post-infection (dpi) to single infections with S. mansoni, Echinostoma paraensei (both digenetic trematodes) or Daubaylia potomaca (a nematode parasite of planorbid snails). Responses were compared to unexposed time-matched control snails. We observed: (1) each parasite provoked a distinctive response with a predominance of down-regulated snail genes at all time points following exposure to either trematode, and of up-regulated genes at 8 and especially 40dpi following nematode exposure; (2) At 2 and 8dpi with either trematode, several snail genes associated with gametogenesis (particularly spermatogenesis) were down-regulated. Regarding the phenomenon of trematode-mediated parasitic castration in molluscs, we define for the first time a complement of host genes that are targeted, as early as 2dpi when trematode larvae are still small; (3) Differential gene expression of snails with trematode infection at 40dpi, when snails were shedding cercariae, was unexpectedly modest and revealed down-regulation of genes involved in the production of egg mass proteins and peptide processing; and (4) surprisingly, D. potomaca provoked up-regulation at 40dpi of many of the reproduction-related snail genes noted to be down-regulated at 2 and 8dpi following trematode infection. Happening at a time when B. glabrata began to succumb to D. potomaca, we hypothesize this response represents an unexpected form of fecundity compensation. We also document expression patterns for other Biomphalaria gene families, including fibrinogen domain-containing proteins (FReDs), C-type lectins, G-protein coupled receptors, biomphalysins, and protease and protease inhibitors.
CONCLUSIONS: Our study is relevant in identifying several genes involved in reproduction that are targeted by parasites in the vector snail B. glabrata and that might be amenable to manipulation to minimize their ability to serve as vectors of schistosomes.

BACKGROUND: Digenetic trematodes, including blood flukes, intestinal flukes, liver flukes, lung flukes, and pancreatic flukes, are highly diverse and distributed widely. They affect at least 200 million people worldwide, so better understanding of their global distribution and prevalence are crucial for controlling and preventing human trematodiosis. Hence, this scoping review aims to conduct a comprehensive investigation on the spatio-temporal distribution and epidemiology of some important zoonotic digenetic trematodes.
METHODS: We conducted a scoping review by searching PubMed, Web of Science, Google Scholar, China National Knowledge Infrastructure, and Wanfang databases for articles, reviews, and case reports of zoonotic digenetic trematodes, without any restrictions on the year of publication. We followed the inclusion and exclusion criteria to identify relevant studies. And relevant information of the identified studies were collected and summarized.
RESULTS: We identified a total of 470 articles that met the inclusion criteria and were included in the review finally. Our analysis revealed the prevalence and global distribution of species in Schistosoma, Echinostoma, Isthmiophora, Echinochasmus, Paragonimus, Opisthorchiidae, Fasciolidae, Heterophyidae, and Eurytrema. Although some flukes are distributed worldwide, developing countries in Asia and Africa are still the most prevalent areas. Furthermore, there were some overlaps between the distribution of zoonotic digenetic trematodes from the same genus, and the prevalence of some zoonotic digenetic trematodes was not entirely consistent with their global distribution. The temporal disparities in zoonotic digenetic trematodes may attribute to the environmental changes. The gaps in our knowledge of the epidemiology and control of zoonotic digenetic trematodes indicate the need for large cohort studies in most countries.
CONCLUSIONS: This review provides important insights into the prevalence and global distribution of some zoonotic digenetic trematodes, firstly reveals spatio-temporal disparities in these digenetic trematodes. Countries with higher prevalence rate could be potential sources of transmitting diseases to other areas and are threat for possible outbreaks in the future. Therefore, continued global efforts to control and prevent human trematodiosis, and more international collaborations are necessary in the future.