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.

The heterophyid trematode Metagonimus romanicus (Ciurea, 1915) (Digenea) is redescribed on the basis of type material from domestic dogs (Canis familiaris) in Romania, vouchers from experimentally infected cats (Felis catus) and adults recovered from golden hamsters (Mesocricetus auratus) infected with metacercariae from scales of chub (Squalius cephalus) and common nase (Chondrostoma nasus) (Cypriniformes: Leuciscidae) in Hungary. This trematode, endemic to Europe and neighbouring regions (northwestern Türkiye), was previously misidentified as M. yokogawai (Katsurada, 1912), a zoonotic parasite of humans in East Asia. However, the two species differ considerably both genetically and morphologically, e.g., in the position of the ventral sucker, the presence of the prepharynx, the anterior extent of the vitelline follicles and the posterior extent of the uterus. Metagonimus ciureanus (Witenberg, 1929) (syn. Dexiogonimus ciureanus Witenberg, 1929), described from domestic cats and dogs in Israel, is a valid species distributed in the Middle East and Transcaucasia, which is also confirmed by molecular data. It differs from all Metagonimus species, including M. romanicus, in having symmetrical testes instead of the oblique testes of the other congeners. The zoonotic significance of M. romanicus and M. ciureanus is unclear, but appears to be low in Europe, mainly because raw or undercooked, whole fish with scales are generally not consumed. Accidental infection of fishermen by metacercariae in the scales when cleaning fish is more likely, but has never been reported. Remains of cyprinoids with scales infected with metacercariae of Metagonimus spp. can be an important natural source of infection for dogs, cats, and other carnivores, which can serve as a reservoir for these parasites.
UNASSIGNED: Petits trématodes intestinaux du genre Metagonimus (Digenea : Heterophyidae) en Europe et au Moyen-Orient : revue de parasites à potentiel zoonotique.
UNASSIGNED: Le trématode Heterophyidae Metagonimus romanicus (Ciurea, 1915) (Digenea) est redécrit sur la base de matériel type provenant de chiens domestiques (Canis familiaris) en Roumanie, de vouchers issus de chats (Felis catus) infectés expérimentalement et d’adultes collectés chez des hamsters dorés (Mesocricetus auratus) infectés par des métacercaires provenant d’écailles de chevesne commun (Squalius cephalus) et de nase commun (Chondrostoma nasus) (Cypriniformes : Leuciscidae) de Hongrie. Ce trématode, endémique d’Europe et des régions voisines (nord-ouest de la Turquie), avait été précédemment identifié à tort comme étant M. yokogawai (Katsurada, 1912), un parasite zoonotique des humains en Asie de l’Est. Cependant, les deux espèces diffèrent considérablement sur le plan génétique et morphologique, par exemple par la position de la ventouse ventrale, la présence du prépharynx, l’étendue antérieure des follicules vitellins et l’étendue postérieure de l’utérus. Metagonimus ciureanus (Witenberg, 1929) (syn. Dexiogonimus ciureanus Witenberg, 1929), décrite chez des chats et des chiens domestiques en Israël, est une espèce valide répartie au Moyen-Orient et en Transcaucasie, ce qui est également confirmé par des données moléculaires. Cette espèce diffère de toutes les espèces de Metagonimus, y compris M. romanicus, par ses testicules symétriques au lieu des testicules obliques des autres congénères. L’importance zoonotique de M. romanicus et M. ciureanus n’est pas claire, mais semble faible en Europe, principalement parce que les poissons n’y sont généralement pas consommés crus ou insuffisamment cuits et entiers avec les écailles. L’infection accidentelle des pêcheurs par des métacercaires présents dans les écailles lors du nettoyage du poisson est plus probable mais n’a jamais été signalée. Les restes de poissons cyprinoïdes avec les écailles, infectés par des métacercaires de Metagonimus spp. peuvent être une source naturelle importante d’infection pour les chiens, les chats et autres carnivores, qui peuvent servir de réservoir à ces parasites.

Foodborne trematodiases (FBTs) are a group of trematodes targeted for control as part of the World Health Organization (WHO) road map for neglected tropical diseases from 2021 to 2030. Disease mapping; surveillance; and capacity, awareness, and advocacy building are critical to reach the 2030 targets. This review aims to synthesise available data on FBT prevalence, risk factors, prevention, testing, and treatment.
We searched the scientific literature and extracted prevalence data as well as qualitative data on the geographical and sociocultural risk factors associated with infection, preventive/protective factors, and methods and challenges of diagnostics and treatment. We also extracted WHO Global Health Observatory data representing the countries that reported FBTs during 2010 to 2019.
One hundred and fifteen studies reporting data on any of the 4 FBTs of focus (Fasciola spp., Paragonimus spp., Clonorchis sp., and Opisthorchis spp.) were included in the final selection. Opisthorchiasis was the most commonly reported and researched FBT, with recorded study prevalence ranging from 0.66% to 88.7% in Asia, and this was the highest FBT prevalence overall. The highest recorded study prevalence for clonorchiasis was 59.6%, reported in Asia. Fascioliasis was reported in all regions, with the highest prevalence of 24.77% reported in the Americas. The least data was available on paragonimiasis, with the highest reported study prevalence of 14.9% in Africa. WHO Global Health Observatory data indicated 93/224 (42%) countries reported at least 1 FBT and 26 countries are likely co-endemic to 2 or more FBTs. However, only 3 countries had conducted prevalence estimates for multiple FBTs in the published literature between 2010 to 2020. Despite differing epidemiology, there were overlapping risk factors for all FBTs in all geographical areas, including proximity to rural and agricultural environments; consumption of raw contaminated food; and limited water, hygiene, and sanitation. Mass drug administration and increased awareness and health education were commonly reported preventive factors for all FBTs. FBTs were primarily diagnosed using faecal parasitological testing. Triclabendazole was the most reported treatment for fascioliasis, while praziquantel was the primary treatment for paragonimiasis, clonorchiasis, and opisthorchiasis. Low sensitivity of diagnostic tests as well as reinfection due to continued high-risk food consumption habits were common factors.
This review presents an up-to-date synthesis on the quantitative and qualitative evidence available for the 4 FBTs. The data show a large gap between what is being estimated and what is being reported. Although progress has been made with control programmes in several endemic areas, sustained effort is needed to improve surveillance data on FBTs and identify endemic and high-risk areas for environmental exposures, through a One Health approach, to achieve the 2030 goals of FBT prevention.

Fish is a great nutritious food and provides quality protein and a variety of vitamins and minerals. This contributes significantly to the economy and food security in Iran. However, there are safety concerns related to the presence of zoonotic parasites.
The objective of this study is, therefore, to review fish-borne zoonotic parasites in Iran.
Keywords such as fish-borne, parasites, zoonotic, Iran, and some names of fish-borne zoonotic parasites were searched in databases including PubMed, Science Direct, Elsevier, SID, Magiran, Irandoc, Google Scholar and the World Health Organization.
The most common fish-borne parasites with zoonotic potential identified in reports in the literature were the protozoa Balantidium spp., Myxobolus spp. and Sarcosystis sp.; the trematodes Heterophyes heterophyes and Clinostomum complanatum; the cestodes Ligula intestinalis and Diphyllobothrium latum; the nematodes Pseudoterranova sp., Anisakis spp., Contracaecum spp., Raphidascaris spp., Eustrongylides spp. and Capillaria sp.; and the acanthocephal Corynosoma spp.
The potential risk factors for the transmission of fish-borne zoonotic parasites to humans are consumption of raw or undercooked infected fish, contact with contaminated water and contact with infected fish. There is a need for epidemiological surveillance of fish for parasites with zoonotic potential and of occurrence of infections in humans to better understand the public health significance and design prevention programs.

Leucochloridium spp. have been established in Taiwan since the 1930s, with five species listed: Leucochloridium turdi, Leucochloridium passeri, Leucochloridium muscularae, Leucochloridium sime, and Leucochloridium taiwanese listed until now. Because of the similar morphology among the adults of the Leucochloridiidae family, the taxonomic status of most of them should be reconsidered. Broodsacs are the most distinct characteristic shared by Leucochloridium flukes, and L. passeri is, by far, the only one whose broodsacs have been described. In this study, broodsacs collected from an infected Succinea sp. (amber snails) in Taiwan were morphologically compared to previous descriptions and sequenced using both nuclear and mitochondrial genetic markers for identification. Our samples resembled broodsacs of L. passeri previously described in northern Taiwan and those recently collected in Okinawa, Japan. The conspecific status of the broodsacs collected in Taiwan and Okinawa was supported by the identical DNA sequences identified in this study. Broodsacs have rarely been reported in tropical and subtropical regions, although some Leucochloridium spp. have been recorded. In such cases, genetic markers will be crucial to link Leucochloridium broodsacs in snails (intermediate host) with their corresponding adult stage in birds (definitive host).

With a long coastline stretching from tropical to subtropical climate zones, and an immense exclusive economic zone with over 4000 islands, the Vietnamese marine waters support a rich and biodiverse parasite fauna. Although the first parasitological record was in 1898, systematic studies of the parasite fauna have increased during the last 50 years. This comprehensive review covers the current state of knowledge of marine fish parasites in Vietnam and lists 498 species found in 225 fish species, and their geographical distribution. In addition, 251 marine parasite species have newly been added to the already known fauna of 247 species since 2006 (more than two-fold increase). The most speciose group was the Digenea, which accounted for 43% of the total parasite species biodiversity, followed by Monogenea (23.5%), Crustacea (11.6%), Nematoda, and Acanthocephala (8.0% each). The shallow and muddy Gulf of Tonkin showed a rich parasite fauna, accounting for 66.3% of the whole marine parasite fauna of Vietnam, with Digenea accounting for 51% of the regional total parasite richness, followed by Monogenea (27%), Acanthocephala (8.8%), and Nematoda (5.8%). Only a few species belonged to Hirudinea, Myxozoa, and Cestoda, suggesting that these taxa may be understudied. Despite significant progress in studies of marine fish parasites in Vietnam since 2006, only about 12% and 13% of the total fish species have been examined for parasites in the whole country and the Gulf of Tonkin, respectively.
UNASSIGNED: Parasites des poissons marins du Vietnam : synthèse complète et mise à jour des listes d’espèces, des hôtes et de la distribution zoogéographique.
UNASSIGNED: Avec un long littoral s’étendant des zones climatiques tropicales à subtropicales et une immense zone économique exclusive incluant plus de 4 000 îles, les eaux marines vietnamiennes abritent une faune parasitaire abondante et riche en biodiversité. Le premier signalement parasitologique remonte à 1898 et les études systématiques de la faune parasitaire se sont multipliées au cours des 50 dernières années. Cette synthèse complète couvre l’état actuel des connaissances sur les parasites des poissons marins au Vietnam et répertorie 498 espèces trouvées dans 225 espèces de poissons et leur répartition géographique. De plus, 251 espèces de parasites marins ont été nouvellement ajoutées à la faune déjà connue de 247 espèces depuis 2006 (soit une augmentation de plus du double). Le groupe le plus riche en espèces était les Digenea, qui représentaient 43% de la biodiversité totale des espèces de parasites, suivis des Monogenea (23,5 %), des Crustacea (11,6 %), des Nematoda et des Acanthocephala (8,0 % chacun). Le golfe peu profond et boueux du Tonkin a montré une riche faune parasitaire, représentant 66,3 % de l’ensemble de la faune parasitaire marine du Vietnam, avec les Digenea représentant 51 % de la richesse parasitaire totale régionale, suivi des Monogenea (27 %), Acanthocephala (8,8 %) et Nematoda (5,8 %). Seules quelques espèces appartenaient aux Hirudinea, Myxozoa et Cestoda, ce qui suggère que ces taxons pourraient être sous-étudiés. Malgré des progrès significatifs dans les études sur les parasites des poissons marins au Vietnam depuis 2006, seulement 12 % et 13 % des espèces de poissons ont été examinées, respectivement pour les parasites de l’ensemble du pays et du golfe du Tonkin.

This paper is a bibliographical survey of records of bat parasites in France (including Corsica) between 1762 and 2018. In total, 237 scientific publications were analysed. They show that bats are infected with a large diversity of endoparasites and ectoparasites. A total of 113 parasite taxa were identified from 27 host species; in addition, six bats were not identified to the species-level. The helminth fauna of bats comprises three species of Cestoda, 15 of Trematoda, and 13 of Nematoda. Acari parasites include 53 species (in addition to 22 invalid species). Finally, insect parasites comprise 13 species of Diptera (bat flies), 12 of Siphonaptera (fleas), 3 of Hemiptera (bugs), and 1 Anoplura species. Bat taxa reported with parasites were Barbastella barbastellus, Eptesicus serotinus, Hypsugo savii, Miniopterus schreibersii, Myotis bechsteinii, M. blythii, M. capaccinii, M. dasycneme, M. daubentonii, M. emarginatus, M. myotis, M. mystacinus, M. nattereri, M. punicus, Nyctalus lasiopterus, N. leisleri, N. noctula, Pipistrellus kuhlii, P. nathusii, P. pipistrellus, Plecotus auritus, P. austriacus, Rhinolophus euryale, R. ferrumequinum, R. hipposideros, R. mehelyi, Tadarida teniotis, Eptesicus sp., Myotis sp., Pipistrellus sp., Plecotus sp., Rhinolophus sp. and the species complex Pipistrellus pipistrellus/kuhlii/nathusii. As regards E. nilssonii, Vespertilio murinus (Particoloured Bat), M. alcathoe, M. escalerai, P. macrobullaris and P. pygmaeus, no records were found. These published field data originated from 72 of the 96 departments in metropolitan France. The most commonly cited were Ardèche, Ariège, Bouches-du-Rhône, Haute-Savoie, Maine-et-Loire, Moselle, Meurthe-et-Moselle, Pyrénées-Orientales, Sarthe, Haute-Corse and Corse-du-Sud.
BACKGROUND: Les parasites des Chiroptères (Acari, Anoplura, Cestoda, Diptera, Hemiptera, Nematoda, Siphonaptera, Trematoda) en France (1762–2018) – état des lieux bibliographique et contribution à une liste des espèces.
UNASSIGNED: Cet article est une étude bibliographique des signalements de parasites de chauves-souris en France (y compris la Corse) entre 1762 et 2018. Au total, 237 publications scientifiques ont été analysées. Elles montrent que les chauves-souris sont infectées par une grande diversité d’endoparasites et d’ectoparasites. Un total de 113 taxons parasites ont été identifiés parmi 27 espèces hôtes (en outre, six chauves-souris n’ont pas été identifiées au niveau de l’espèce). La faune helminthique des chauves-souris comprend trois espèces de Cestodes, 15 de Trématodes et 13 de Nématodes. Les Acariens parasites comprennent 53 espèces (en plus de 22 espèces invalides). Enfin, les insectes parasites comprennent 13 espèces de Diptères, 12 de Siphonaptères (puces), 3 d’Hémiptères (punaises) et 1 espèce d’Anoploure. Les taxons de chauves-souris signalés avec des parasites étaient Barbastella barbastellus, Eptesicus serotinus, Hypsugo savii, Miniopterus schreibersii, Myotis bechsteinii, M. blythii, M. capaccinii, M. dasycneme, M. daubentonii, M. emarginatus, M. myotis, M. mystacinus, M. nattereri, M. punicus, Nyctalus lasiopterus, N. leisleri, N. noctula, Pipistrellus kuhlii, P. nathusii, P. pipistrellus, Plecotus auritus, P. austriacus, Rhinolophus euryale, R. ferrumequinum, R. hipposideros, R. mehelyi, Tadarida teniotis, Eptesicus sp., Myotis sp., Pipistrellus sp., Plecotus sp., Rhinolophus sp. et le complexe d’espèces cryptiques Pipistrellus pipistrellus/kuhlii/nathusii. Aucun signalement n’a été trouvé pour E. nilssonii, Vespertilio murinus, M. alcathoe, M. escalerai, P. macrobullaris et P. pygmaeus. Ces données de terrain publiées proviennent de 72 des 96 départements de France métropolitaine. Les plus cités sont l’Ardèche, l’Ariège, les Bouches-du-Rhône, la Haute-Savoie, le Maine-et-Loire, la Moselle, la Meurthe-et-Moselle, les Pyrénées-Orientales, la Sarthe, la Haute-Corse et la Corse-du-Sud.

The northern fur seal (NFS), Callorhinus ursinus (Mammalia: Otariidae), is a marine mammal species included into the IUCN Red List as the vulnerable species which population is dramatically declining. A significant amount of parasitological data collected previously and our recent data allowed us to clarify the list of NFS metazoan parasites and to perform a comprehensive analysis of the gastrointestinal helminth community. Gastrointestinal tracts from 756 NFSs (3- to 4-year-old males) were collected during the annual Aleut subsistence harvests in July-August of 2011-2014 from five separate rookeries on St. Paul Island, Alaska. Totally, 27,625 specimens of helminths and approximately 1000 nasal mites were collected and identified. Detailed analysis of the previously published and newly obtained data revealed 32 species of metazoan parasites, including trematodes (6 species), cestodes (4), nematodes (9), acanthocephalans (9) and arthropods (4). The gastrointestinal helminth community of newly studied NFSs comprised 19 species including trematodes (4), cestodes (3), nematodes (5) and acanthocephalans (7). Temporal changes in the helminth community structure were small but statistically significant. Gastrointestinal helminth infracommunities comprised from 1 to 10 species (average of 4). Small but significant correlation was found between the abundances of acanthocephalans (Corynosoma similis and C. strumosum), nematodes (Contracaecum osculatum, Pseudoterranova spp.) and cestode Diphyllobothrium tetrapterum.

The use of molecular tools in the study of parasite taxonomy and systematics have become a substantial and crucial component of parasitology. Having genetic characterisation at the disposal of researchers has produced mostly useful, and arguably more objective conclusions. However, there are several groups for which limited genetic information is available and, coupled with the lack of standardised protocols, renders molecular study of these groups challenging. The Diplozoidae are fascinating and unique monogeneans parasitizing mainly freshwater cyprinid fishes in Europe, Asia and Africa. This group was studied from a molecular aspect since the turn of the century and as such, limitations and variability concerning the use of these techniques have not been clearly defined. In this review, all literature and molecular information, primarily from online databases such as GenBank, were compiled and scrupulously analysed for the Diplozoidae. This was done to review the information, detect possible pitfalls, and provide a \"checkpoint\" for future molecular studies of the family. Hindrances detected are the availability of sequence data for only a limited number of species, frequently limited to a single sequence per species, and the heavy reliance on one non-coding ribosomal marker (ITS2 rDNA) which is difficult to align objectively and displays massive divergences between taxa. Challenging species identification and limited understanding of diplozoid species diversity and plasticity are also likely restricting factors, all of which hamper the accurate taxonomic and phylogenetic study of this group. Thus, a more integrated taxonomic approach through the inclusion of additional markers, application of more rigorous morphological assessment, more structured barcoding techniques, alongside thorough capturing of species descriptions including genetypes, genophore vouchers and reference collections in open sources are encouraged. The pitfalls highlighted are not singular to the Diplozoidae, and the study of other groups may benefit from the points raised here as well.

Fish blood flukes (Digenea: Aporocotylidae) are important pathogens of fishes in aquaculture. Severe infections have been associated with mass mortality events in cultured marine species of teleosts in Australia, Asia and Europe, leading to significant socio-economic losses. Here we review recent advances towards understanding the biology and ecology of fish blood flukes, and the integral role molecular techniques have played in this development. Techniques include molecular matching of aporocotylid life stages using ITS-2 rDNA, and targeting ITS-2 rDNA to distinguish aporocotylid species using quantitative PCR (qPCR). These approaches have facilitated the elucidation of multiple life cycles for species of Cardicola infecting bluefin tunas Thunnus spp. cultured in Australia and Japan. Continued work to identify intermediate hosts of fish blood flukes is critical to improve understanding of their life cycles and help inform aquatic animal health management e.g. through site selection and/or separation of intermediate and definitive hosts. As praziquantel is the only known treatment option for infected fish, its continued efficacy will need to be monitored and other possible solutions may need to be identified as aquaculture continues to grow and diversify.