Amphistomes, commonly referred to as \'stomach\' or \'rumen\' flukes because of the localization of these flukes in the stomach of ruminants, are digenetic trematodes distinguished by the absence of an oral sucker and the position of the ventral sucker or acetabulum at the posterior end of the body. The body is characterized by a leaf-like fleshy structure, pink or red with a large posterior sucker. Amphistomes are an important group of parasites since they cause \'amphistomiasis\' (variously known as paramphistomosis/amphistomosis), a serious disease of great economic importance in ruminants worldwide. These parasites have a broad spectrum of definitive hosts together with a wide geographical distribution. Though they form a continuous evolutional lineage from fishes to mammals, amphistomes mainly inhabit the rumen and reticulum of ruminant mammals, while some species occur in the large intestine or parenteric sites of ruminants, pigs, equines and man.

The systematic review and meta-analysis were conducted to determine the estimates of the prevalence and infection rates of natural and experimental infections of amphistome species in intermediate host snails (IHs) across different continents. A search of peer-reviewed literature on natural and experimental infections of freshwater snails with amphistome species was conducted from four electronic databases from 1984 to 2023. The estimates of the prevalence and/or infection rates were based on 36 eligible peer-reviewed articles, which met the inclusion criteria and reported on natural and experimental infections of amphistome species in freshwater snails. The results showed that a total of 1,67,081 snail species from the peer-reviewed articles were examined for natural infections and 7,659 snail species for experimental infections. The overall pooled prevalence of amphistome infections from naturally infected snails was 2% (95% CI: 0-4), while the overall pooled prevalence of amphistome infections from infections was 40% (95% CI: 18-64). The highest pooled prevalence of natural infection was 3%, which was recorded in Europe (95% CI: 1-7%). The highest overall prevalence of naturally infected amphistome was 6% (95% CI: 0-20%) for Paramphistomum epiclitum. The Americas had the highest pooled prevalence of experimental amphistome infection among freshwater snails (66%; 95% CI: 26-96%). The highest pooled infection rate of 65% (95% CI: 12-100%) was recorded for Paramphistomum cervi in experimental infections. Galba truncatula was the only snail that qualified for meta-analysis for natural infection with Calicophoron daubneyi, with a pooled prevalence of 3% (95% CI: 1-8%). Galba truncatula infected with C. daubneyi and P. cervi, and Bulinus tropicus infected with Calicophoron microbothrium in the experimental infection qualified for the meta-analysis, with an overall infection rate of 66% (95% CI: 34-92%) and 30% (95% CI: 0-74%), respectively. The pooled prevalence of amphistome species infection in the intermediate host (IH) snails based on detection techniques was higher with PCR compared to the dissection and shedding of cercariae. The results from the quality effects model revealed a high heterogeneity and publication bias between studies. This meta-analysis provided valuable insights into the prevalence and infection rates of amphistome species in snail IHs across different geographical regions.

This study aimed at determining the identity of freshwater snails collected from selected water habitats frequented by wildlife as source of drinking water in the Matebeleland region of Zimbabwe and further screening the identified snails for natural infections with amphistomes using PCR. A total of 487 freshwater snails were collected from six areas in the Matebeleland region of Zimbabwe for identification and screening of amphistome infection. Eight freshwater snail species were morphologically identified and Biomphalaria pfeifferi, Bul. tropicus, Bul. truncatus, Bul. globosus, and L. (R.) natalensis were confirmed using the COI gene. Bulinus tropicus and Phy. acuta were the most abundant species at 33.9% (165/487) and 31.2% (155/487), respectively. DNA of amphistome was detected in 11.9% (58/487) of the collected snails. The highest infection rate was detected in Bul. globosus (44.4%). West Nicholson recorded the highest infection rate (33.9%), and infection was not detected in L. (R.) natalensis, Phy. acuta, and Bellamya spp. Amphistome DNA from M. tuberculata was successfully sequenced and identified as Calicophoron microbothrium. An additional band was detected in M. tuberculata, Bul. tropicus, and Bul. trancatus, which showed a 96.42% similarity to Paragonimus sp. sequence in the GenBank.

This review summarizes published records on the prevalence, species diversity, geographical distribution, mixed infections, co-infections with other trematodes and intermediate hosts (IHs) of amphistomes (rumen flukes) of wild ruminants in Africa. Literature search was conducted on Google Scholar, PubMed and JSTOR, using a combination of predetermined search terms and Boolean operators. Of the 54 African countries searched, results showed that occurrence of amphistome infections in wild ruminants have only been reported in 23 countries. A total of 38 amphistome species consisting of the following 11 genera were recorded, viz Bilatorchis, Calicophoron, Carmyerius, Choerecotyloides, Cotylophoron, Explanatum, Gastrothylax, Gigantocotyle, Leiperocotyle, Paramphistomum and Stephanopharynx. These were recorded in 39 wild ruminant species, belonging to the Bovidae family. The genus Carmyerius recorded the highest number of species (n = 13) across nine countries Africa. However, Calicophoron species (n = 9) were more widely distributed, occurring in 17 countries across all regions of Africa. Species of this genus collectively infected 27 wild ruminant species. However, at a species level, Cotylophoron cotylophorum infected the highest number of wild ruminant species. Prevalence of infection based on post-mortem examination ranged from 1.89% in African Buffalo to 100% in Defassa waterbuck from Egypt and Zambia, respectively. The most common mixed infections recorded were those between amphistomes of the same or different genus. Snail intermediate hosts (IHs) were described for 10/38 amphistome species, and these were predominantly species from Plarnobidae family. Despite the richness in diversity of amphistomes infecting wild ruminants in Africa, there is need to further confirm identity of snail IHs and the amphistome species using both morphological and molecular techniques. Furthermore, more studies are recommended to assess the burden of amphistomosis in commercially reared wildlife/game farming, mixed game and livestock farming systems in Africa.

UNASSIGNED: Parasitic diseases, including trematode invasions, result in losses to livestock in Indonesia, hindering the government\'s efforts to achieve meat self-sufficiency. This study aimed to estimate the prevalence of Amphistomes and Fasciola in large ruminants reared by smallholder farmers.
UNASSIGNED: Fecal samples from 199 buffalo and cattle were collected from the districts of East Lampung (Lampung Province) and Lebak (Banten Province). Fecal samples were examined for the presence of trematode eggs using a sedimentation technique.
UNASSIGNED: Parasite invasion rate was 48.2% (95% confidence interval [CI]: 41.3%-55.2%). Rate of invasion was 63.3% (95% CI: 52.7%-73.9%) in Lampung and 38.3% (95% CI: 29.6%-47.0%) in Lebak-Banten. The prevalence of multiple invasions of both Amphistomes and Fasciola was 20% in buffalo and local cattle, whereas invasion rate was 12.8% in crossbred cattle. Invasion rate of Amphistomes alone was 27.1%, and that of Fasciola was 4.5%. A higher invasion rate of Amphistomes (29.8%) occurred in crossbred animals. There were no significant differences between age groups for trematode invasion. The Chi-square test showed that the prevalence of trematode invasion in females was significantly higher than in males (51.5% and 30.0%, respectively). Amphistomes more commonly infected females than males (29.0% and 16.7%, respectively).
UNASSIGNED: All breeds were vulnerable to invasion by both trematode species and single invasions with different invasion rates. These findings contribute to determining the magnitude of the disease and provide a basis for studies on prevention and treatment of trematode invasion.

Rumen flukes in the genus Fischoederius are neglected foodborne parasites of cattle in Asia. Fischoederius elongatus, first described in 1883 from a sample collected in Indonesia is the type-species of the genus and is found from South to East Asia. In this study Fischoederius spp were collected from cattle in Thailand. The flukes resembled F. elongatus and images of 48 specimens were taken and their DNA was isolated. The mtDNA sequence of the cytochrome c oxidase subunit I (COX1) gene was amplified by PCR and used for restriction analysis with MseI. Nine restriction patterns (A-I) were observed and the COX1 mtDNA sequence for each pattern was determined. Phylogenetic analysis clustered the nine COX1 sequences into five groups with 4.6-9.6 % sequence differences between the groups. This is beyond intragenic variation observed for the COX1 gene in other organisms and suggested that the analyzed specimens represented several species. A comparative transcriptome analysis of specimens with COX1 MseI patterns A, C, E supported this finding. The observed median base differences, both absolute and relative, in the protein coding sequences of 999 orthologs were similar to those between distinct fruit fly species. It is proposed that the genus Fischoederius contains undescribed species that follow the classic description of F. elongatus.

Zygocotyle lunata inhabits the caecum of birds and mammals from the American continent. This amphistome parasite is easily maintained in the laboratory and serves as a model organism in life-cycle studies, but it has seldom been studied using molecular data. Neither the position of Z. lunata in the superfamily Paramphistomoidea nor the monophyly of the Zygocotylidae has been evaluated with molecular phylogenetic methods. In the present study, adult specimens of Z. lunata obtained experimentally in mice from Brazil were submitted to molecular studies. Partial sequences of nuclear (1261 bp of 28S and 418 bp of 5.8S-ITS-2) and mitochondrial (1410 bp of cytochrome c oxidase 1, cox1) markers were compared with published data. In the most well-resolved phylogeny, based on 28S sequences, Z. lunata clustered in a well-supported clade with Wardius zibethicus, the only other species currently included in the Zygocotylidae, thus confirming the validity of this family. Divergence of 28S sequences between these species was 2.2%, which falls in the range of intergeneric variation (0.9-5.6%) observed in the other two monophyletic groups in the 28S tree, i.e., representatives of Gastrodicidae and Neotropical cladorchiids (Cladorchiidae). Analysis of ITS-2 and two parts of the cox1 gene placed Z. lunata within poorly resolved clades or large polytomies composed of several paramphistomoid families, without clarifying higher-level phylogenetic relationships. The cox1 of a Brazilian isolate of Z. lunata is 99.6% similar to a Canadian isolate, confirming the pan-American distribution of the species. Finally, our phylogenetic reconstructions of Paramphistomoidea revealed a complex scenario in the taxonomic composition of some amphistome families, which highlights a need for further integrative studies that will likely result in rearrangements of traditional morphology-based classifications.

In the present study, Calicophoron clavula (Paramphistomidae), a parasite of rumina of sheep and cows, was collected from Taif region, KSA, to investigate its identity and the prevalence of infection in livestock. Specific identification was mainly achieved by ITS molecular technique and surface ultrastructure was studied by SEM. Adult C. clavula is described for the first time from Saudi Arabia. The infection rate is 1% in sheep and 10% in cows. Results indicated that this species isolate was genetically identical with other C. clavula isolates where matching reach 100%. The primary sequence of the rDNA ITS2+ region of the fluke produces amplicon of 647 bp. SEM results show that no observed papillae around its genital opening. Besides, it has very few scattered small papillae around its oral region with few randomly distributed acetabular papillae. These findings were compared with the same corresponding species in other previous works of literatures.

Amphistomes, commonly referred to as \'stomach\' or \'rumen\' flukes because of the localization of these flukes in the stomach of ruminants, are digenetic trematodes distinguished by the absence of an oral sucker and the position of the ventral sucker or acetabulum at the posterior end of the body. The body is characterized by leaf-like fleshy structure, pink or red in colour with a large posterior sucker. Amphistomes are an important group of parasites since they cause \'amphistomiasis\' (variously known as paramphistomosis/amphistomosis), a serious disease of great economic importance in ruminants worldwide. These parasites have a broad spectrum of definitive hosts together with a wide geographical distribution. Though, they form a continuous evolutional lineage from fishes to mammals, amphistomes mainly inhabit the rumen and reticulum of ruminant mammals, while some species occur in the large intestine or parenteric sites of ruminants, pigs, equines and man.

BACKGROUND: Fasciolosis, caused by the liver fluke Fasciola gigantica, and paramphistomosis are widespread in cattle in Tanzania, and the use of trematocides is encouraged by the Government livestock extension officers. However, reduced efficacy of oxyclozanide against Fasciola gigantica and amphistomes (rumen flukes), and albendazole against F. gigantica, has been reported in some regions. This study was conducted to assess the efficacy of different trematocides against F. gigantica and amphistome infections in cattle at Iringa Rural and Arumeru Districts.
METHODS: Cattle found with concurrent infection of F. gigantica and amphistomes were randomly grouped into six experimental groups. One control group was left untreated while five treatment groups were treated with one of five trematocides that include: albendazole, nitroxynil, oxyclozanide, closantel and triclabendazole. Post-treatment faecal sample collection was done on the day of treatment and again at 7, 14 and 28 days, from each cattle. The samples were processed by Flukefinder® method to recover and identify eggs. Assessment of the efficacy of the trematocides against F. gigantica and amphistomes was conducted using faecal egg count reduction (FECR) tests.
RESULTS: The findings of the present study in both districts indicate that nitroxynil, oxyclozanide, closantel and triclabendazole are effective against patent F. gigantica infection, as the calculated FECR% for each trematocide was 100% by day 14 post-treatment. However, albendazole found to have reduced efficacy of against F. gigantica, as FECR% was 49% in Arumeru District and 89% in Iringa Rural District by day 14 post-treatment. Oxyclozanide was the only trematocide found to be effective against amphistomes with FECR of 99%.
CONCLUSIONS: Albendazole had reduced efficacy against F. gigantica in cattle in Arumeru and Iringa Rural Districts, Tanzania. The reduced efficacy was prominent in Arumeru, where cattle are commonly treated with anthelmintics, than in Iringa Rural, where cattle are seldom treated.