Adult Flukes Research Articles

Ultra-structure, genetic characterization and Immunological approach of fish borne zoonotic trematodes (Family: Heterophyidae) of a redbelly tilapia

Fish-borne zoonotic trematodes (FBZT) are highly significant zoonotic trematodes that can infect humans by eating raw or undercooked fish harboring active metacercaria. In this investigation, FBZT was found in samples of widely cultivated redbelly tilapia (Tilapia zillii) obtained from the Fayum governorate. Encysted metacercaria (EMC) infection was identified in fish belonging to the heterophyid family morphologically. The prevalence of heterophyid EMC was 30.5%. EMC was identified and implemented in a subsequent study on domestic pigeons (Columba livia domestica) carried out to allow adult flukes of Pygidiopsis (P.) genata; P. summa; and Ascocotyle (A.) pindoramensis species in their small intestine. This study presents the first report that combines ultra-structure, molecular approach of three species of heterophyid flukes, ultra-structure using transmission electron microscope in P. genata, and the study of host immunological responses and associated cytokines during Pygidiopsis species infection of pigeons in Egypt. Using Quantitative Real-time PCR (qRT- PCR), the gene expression levels of six cytokines (IL-1, IL-2, IL-6, IL-10, IFN-γ and TGF-β3) were assessed. The molecular confirmation of P. genata, P. summa, and A. pindoramensis have a registration in the GenBank under accession number MT672308.1, OR083433.1, and OR083431.1, respectively. Throughout the infection, the gut produced cytokines in considerably variable amounts. As a result of the Pygidiopsis species infection in pigeons, our data showed distinctive cytokine alterations, which could aid in figuring out the immunological pathogenesis and host defense mechanism against this infection. This study focused on different types of fish-borne trematodes, particularly the zoonotically important ones.

Epidemiological Investigation of Yak (Bos grunniens) Fascioliasis in the Pastoral Area of Qinghai–Tibet Plateau, China

The objective of this investigation was to understand the epidemiology of fascioliasis in yaks in the alpine pastoral areas of the Qinghai–Tibet Plateau, China. The prevalence of Fasciola hepatica infection was estimated by examining eggs in the feces of yaks and by autopsy after the slaughter. Yaks were sampled from a total of 16 representative counties in Qinghai province, and risk factors were assessed based on regional and age characteristics. Fecal samples were obtained from 1542 yaks aged 0–1 (<1 year old), 1–2 (≥1 year old and <3 years old), and over 3 years (≥3 years old). In addition, 242 yaks over 3 years old who had not undergone fecal examinations were randomly selected for autopsy. A total of 267 fecal samples were positive for Fasciola spp. eggs. The average infection rate was 17.32% (0–60.61%), and the average infection intensity was 51.9 eggs per gram (epg) of feces, with intensities ranging from 18 to 112 epg. In Maduo, Dari, Zhiduo, Chengduo, and Datong counties, the Fasciola spp. eggs infection rate was zero. Fasciola spp. adult flukes were detected in 66 out of 242 yaks at autopsy, with a total infection rate of 27.27% and an average infection intensity of 21.2 (adult worms), with intensities ranging from 3 to 46 worms. Logistic regression model analysis showed that age was a significant risk factor for yak infection with Fasciola spp. In addition, the risk varied between regions: Haiyan, Gangcha, Duran, and Wulan were all high-risk areas for yak infection with Fasciola spp. The spatial distribution of the Fasciola spp. infection rate in each region showed a very weak negative correlation (Moran’s I = −0.062), Duran formed a spatial distribution of high–low clusters with surrounding areas, and Datong formed a low–high clustering distribution characteristic with the surrounding areas. This investigation revealed that the infection rate of Fasciola spp. in yaks was higher on the Qinghai–Tibet Plateau. Increasing age was a risk factor for infection with Fasciola spp.; different regions also have a different risk of Fasciola spp. infection. Only two regions showed clustering characteristics in the spatial distribution of infection rates. These findings extend the epidemiological information on Fasciola spp. infection in yaks and provide baseline data for the execution of control measures against Fasciola spp. infection.

Species identity and phylogeny of Paramphistomoidea Fischoeder, 1901 occurring in cattle and sheep in North Cameroon.

Paramphistomidae and Gastrothylacidae are parasitic flatworms occurring in wild and domestic ruminants in different parts of the world especially in Asia and Africa. In Central Africa, few studies have been done using molecular techniques to resolve taxonomical groupings and understand the epizootiology of these parasites. In this study, we molecularly characterized two hundred adult flukes collected from the fore stomachs of cattle and sheep in the Adamawa region of the northern Cameroon. PCR and sequencing of the nuclear ITS-2 of the ribosomal DNA gene and a portion of the mitochondrial cox-1 locus revealed the presence of at least nine species belonging to the genera of Cotylophoron, Calicophorn, Orthocoelium and Carmyerius. In Zebu cattle, we identified Ca. microbothrium, Ca. clavula, Ca. phillerouxi, Co. cotylophorum, Co. fuelleborni, O. scoliocoelium, Car. gregarius, Car. graberi and Car. mancupatus and one yet unknown Paramphistomoidea sp, whereas in sheep, only Ca. microbothrium was found. The present study also strongly suggests cross-hybridization between the two Cotylophoron species coexisting in cattle. These results have implications for the diagnosis and control of rumen flukes in the region and point to the need for accurate species identification to understand parasite distribution and population genetics.

First morphometric and molecular characterization of Fasciola spp. in Northwest Tunisia.

The aim of this study was to characterize the Tunisian Fasciola spp. flukes by morphometric and molecular analyses. Flukes were collected from livers of sheep slaughtered in Sejnane slaughterhouses (Bizerte gouvernorate, Northwest Tunisia) between January and March 2021.Five morphometric parameters were determined for all the liver flukes, as follows: (i) total body length (BL), (ii) distance between ventral sucker and the tail (VS-T), (iii) distance between oral sucker and ventral sucker (OS-VS), (iv) abdomen diameter (AD), (v) tail diameter (TD) and the body length to width ratio (BL/BW). Molecular identification of the fluke specimens was carried out by polymerase chain reaction, restriction fragment polymorphism (PCR-RFLP) of a 680 bp sequence of the internal transcribes spacer 1 (ITS1) gene and by amplification, sequencing, and phylogenetic analysis of a 500 bp sequence of the ITS2 gene. Morphometric measurements showed that the mean of the total body length of the adult flukes was 21.1 ± 2.7 mm with minimum and maximum lengths of 13 and 31 mm, respectively. The PCR-RFLP analysis revealed a single profile consisting of three bands of approximately 370, 100, and 60 bp. Fasciola sequences described in the present study (GenBank numbers: OQ457027 and OQ457028) showed 99.58-100% identity to Fasciola hepatica. In conclusion, the results of this study show that molecular and phylogenetic analyses confirm the presence of a single species of F. hepatica in the Sejnane region Northwest of Tunisia. However, further studies are needed to identify the occurrence of Fasciola species in other Tunisian regions.

Review of Recent Prevalence of Urogenital Schistosomiasis in Sub-Saharan Africa and Diagnostic Challenges in the Field Setting.

Human schistosomiasis is one of neglected tropical diseases that remain highly prevalent in sub-Saharan Africa (SSA). Human schistosomiasis is mainly caused by two species, Schistosoma haematobium and S. mansoni, leading to urogenital and intestinal schistosomiasis, respectively. The World Health Organization (WHO) recommends mass drug administration (MDA) with praziquantel as the primary method of global intervention. Currently, MDA with praziquantel covers over half of the target population in endemic SSA countries. However, an accurate diagnosis is crucial for monitoring and evaluating the effectiveness of MDA. The standard diagnosis of both urogenital and intestinal schistosomiasis relies on the microscopic identification of eggs. However, the diagnostic sensitivity of this approach is low, especially for light or ultra-light infections. This is because Schistosoma eggs are laid inside of the venous plexus of the urinary bladder or mesenteric vein, where the adult flukes live. Approximately half of the eggs circulate in the blood vessels or are packed in neighboring tissues, while the remaining half are expelled into the lumen of the urinary bladder or intestine intermittently when the blood vessels are ruptured. In the field setting, the accuracy of any diagnostic method is critical for proper management of the intervention. The present article reviews the recent prevalence of urogenital schistosomiasis in SSA and highlights the practical limitations of diagnostic methods such as urine microscopy, urine reagent strips, molecular diagnosis, and ultrasound scanning in the field setting. Despite continuous global efforts to eliminate schistosomiasis over the past 20 years, many areas still remain endemic in SSA. No single diagnostic approach achieves acceptable sensitivity and specificity in the field setting. Therefore, any field survey should employ a combination of these methods based on the purpose of the study to accurately monitor and evaluate urogenital schistosomiasis. Based on diagnostic values and a cost-benefit analysis, a urine reagent strip test can replace urine microscopy in the field setting. The WHO criteria by ultrasound diagnosis should be updated including the echogenic snow sign and contour distortion.

Effects of company and season on blood fluke (Cardicola spp.) infection in ranched Southern Bluefin Tuna: preliminary evidence infection has a negative effect on fish growth.

Aporocotylid blood flukes Cardicola forsteri and C. orientalis are an ongoing health concern for Southern Bluefin Tuna (SBT), Thunnus maccoyii, ranched in Australia. Therapeutic application of praziquantel (PZQ) has reduced SBT mortalities, however PZQ is not a residual treatment therefore reinfection can occur after the single treatment application. This study documents the epidemiology of Cardicola spp. infection in ranched SBT post treatment over three ranching seasons (2018, 2019 and 2021). Infection prevalence (percentage of SBT affected) and intensity (parasite load) was determined by adult fluke counts from heart, egg counts from gill filaments and the use of specific quantitative polymerase chain reaction (qPCR) for detection of C. forsteri and C. orientalis ITS-2 DNA in SBT hearts and gills. SBT Condition Index decreased as intensity of Cardicola spp. DNA in SBT gills increased, suggesting blood fluke infection had a negative effect on SBT growth (Spearman's r = -0.2426, d.f. = 138, p = 0.0041). Prevalence and intensity of infection indicated PZQ remained highly effective at controlling Cardicola spp. infection in ranched SBT, 10 years after PZQ administration began in this industry. Company A had the highest prevalence and intensity of Cardicola spp. infection in 2018, and Company G had the highest in 2019. No consistent pattern was seen in 2021. Overall, intensity of infection did not increase as ranching duration increased post treatment. Results from this study improve our knowledge of the biology of blood flukes and helps the SBT industry to modify or design new blood fluke management strategies to reduce health risks and improve performance of SBT.

Activity of cumin essential oil to control fascioliasis: Efficacy and changes in the tegument of Fasciola hepatica

Fasciola hepatica, the liver trematode, infects ruminants and causes economic loss. Because parasites are developing resistance to commercial drugs, the negative effects of parasitism are increasing. In this study, we aimed to evaluate the efficacy of cumin (Cuminum cyminum) essential oil against F. hepatica eggs and adults. The eggs were incubated with eight concentrations of the essential oil (0.031125–4.15 mg/mL), and viable eggs were counted after 14 days and classified as embryonated or non-embryonated. Adult flukes were incubated in Roswell Park Memorial Institute medium to ensure their viability and then incubated in essential oil. They were observed for 24 h after treatment. The adults were assessed with the two lowest effective oil concentrations used in the ovicidal test. Three controls were used for both tests: nitroxynil, a negative control, and Tween®80. After incubation in oil, the adult specimens were processed for histological analysis and stained with hematoxylin-eosin. In addition, the oil was tested for cytotoxicity using Madin–Darby bovine kidney cells to assess any possible effect on them. The oil was effective in ovicidal and adulticidal inhibition of the trematode, with statistically significant results. All concentrations assessed in the ovicidal test were 100% effective. The adult test was effective within 15 h and inactivated all the specimens at the highest concentration evaluated (0.06225 mg/mL). Histological analysis showed that cumin essential oil resulted in marked areas of vacuolization. The spines showed no structural changes but were surrounded by microvesicles. These findings indicated that cumin oil could be a potential compound in the control of fasciolosis.

Modified Hederagenin Derivatives Demonstrate Ex Vivo Anthelmintic Activity against Fasciola hepatica.

Infection with Fasciola hepatica (liver fluke) causes fasciolosis (or fascioliasis) and poses a considerable economic as well as welfare burden to both the agricultural and animal health sectors. Here, we explore the ex vivo anthelmintic potential of synthetic derivatives of hederagenin, isolated in bulk from Hedera helix. Thirty-six compounds were initially screened against F. hepatica newly excysted juveniles (NEJs) of the Italian strain. Eleven of these compounds were active against NEJs and were selected for further study, using adult F. hepatica derived from a local abattoir (provenance unknown). From these eleven compounds, six demonstrated activity and were further assessed against immature liver flukes of the Italian strain. Subsequently, the most active compounds (n = 5) were further evaluated in ex vivo dose response experiments against adult Italian strain liver flukes. Overall, MC042 was identified as the most active molecule and the EC50 obtained from immature and adult liver fluke assays (at 24 h post co-culture) are estimated as 1.07 μM and 13.02 μM, respectively. When compared to the in vitro cytotoxicity of MDBK bovine cell line, MC042 demonstrated the highest anthelmintic selectivity (44.37 for immature and 3.64 for adult flukes). These data indicate that modified hederagenins display properties suitable for further investigations as candidate flukicides.

FISH BORNE TREMATODE INFECTION IN THAC BA LAKE – NORTHERN VIETNAM: HYPERENDEMIC ISSUE AND VARIETY ASOCIATED RISK FACTORS.

A cross sectional survey was conducted in three communes including An Phucommune of Luc Yen district, and Bao Ai and Mong Son communes in Yen Binh districtnear by Thac Ba lake of Yen Bai Province in August and September, 2019 to investigatethe FZTs (liver fluke C. sinensis and intestinal flukes included H. pumilio, H. taichui, H.yokogawai, Procerovum varium and C. formosanus) infection status in the area and todetermine the associated risk factors of the diseases using Formaline ether concentrationtechnique and interview by questionnaire.1214 individuals with an average age of 41 years old were involved in the presentstudy, among the participants, 47.5% were infected with FBT. By univariate analysis, thefactors were at the most significant risk of getting infected were persons who were men,ate raw fish, prepared raw dish with fish from the lake, drank whisky with raw dish, livedin Luc Yen District, lived next to the lake (< 500 m from house to the lake, and their age(age of 20 – 39); breeding dog & cat, feeding dog & cat with raw fish were associated tothe FBT as well. There was no relationship between house characteristics (having hygienelatrine or fish pond) and FBT infection.Identification of recovered trematodes: 757 adult flukes were expelled from 6 willingpatients (R2=0.803) in the two districts, of which 20 flukes were randomly selected forcarmine stain. All stained flukes were identified as C. sinensis by the most typicalmorphology traits: the tandem and dendritic testes overlap the caeca laterally and site inthe posterior third of the body.We need conduct a prevention and control program at the Thac Ba lake for not onlyhuman but also animal cat, dog, fish and snail asap.

Histopathology and antibody responses describe the seasonal pattern of dicrocoeliosis in small ruminants in the Himalayan ranges of Pakistan

In some parts of the world, Dicrocoelium spp. lancet flukes cause significant production loss in pastoral livestock, and accurate diagnosis of infection is important. The aims of the present study were to describe the histopathology and to investigate the transmission patterns of Dicrocoelium amongst ten sheep and goat farms in Khyber Pakhtunkhwa and Gilgit Baltistan, Pakistan. The liver histology and indirect enzyme-linked immunosorbent assay (ELISA) analyses followed standard procedures. The liver histopathology showed intensive tissue destruction and biliary hyperplasia associated with presence of adult flukes, severe inflammatory cell infiltration, congestion of blood vessels, damaged hepatocytes, and sinusoids in the infected areas. The time of onset of infection was investigated by ELISA detection of antibodies in sheep (n = 164) and goats (n = 152). Colostral transfer of Dicrocoelium antibodies from seropositive mothers was detected in sheep and goats up to 16 weeks of age. In both sheep and goats, the estimated time of infection differed between farms and years. Infection was seen in both sheep flocks and goat herds, with high variation between flocks and herds, and the highest infection rate in lambs. Dicrocoelium infection was most prevalent in sheep and goats in September (n = 84) and August (n = 63) respectively. This study concluded Dicrocoelium causes severe inflammation and necrosis of liver tissues in sheep and goats. Colostral transfer of antibodies can be detected up to about ten weeks of age. Higher infection rates are observed during August and September in sheep than in goats, putatively due to effects of different grazing and browsing behaviors on the ingestion of ants. The results will aid in the development of effective disease control strategies to ensure optimal growth and productivity of sheep and goats.

High endemicity of Opisthorchis viverrini infection among people in northern Cambodia confirmed by adult worm expulsion

Opisthorchis viverrini infection is an emerging disease in Cambodia, especially in central and southeastern areas. However, its status in northern areas bordering Lao PDR has been relatively unknown. The present study was performed to investigate the status of O. viverrini infection among people in Preah Vihear and Stung Treng provinces through fecal examination to detect eggs and recovery of adult flukes from some of the egg-positive cases. Fecal examinations were performed on a total of 1101 people from 10 villages in the 2 provinces using the Kato-Katz thick smear technique. For recovery of adult flukes and other helminth parasites 10 volunteers positive for eggs of Opisthorchis viverrini and/or minute intestinal flukes (Ov/MIF), in Kampong Sangkae village, Preah Vihear province, were administered a single oral dose of 40 mg/kg praziquantel plus 5–10 mg/kg of pyrantel pamoate and purged with 40–50 g magnesium salts. Adult trematodes, together with nematodes and cestodes expelled in diarrheic stools were collected under a stereomicroscope or with the naked eye. The proportion of egg-positive cases for overall liver and intestinal helminths was high but not notably different between the 2 provinces, 65.5% in Preah Vihear versus 64.7% in Stung Treng. The average proportion of Ov/MIF egg-positive cases was 59.8%. A total of 315 adult specimens of O. viverrini were recovered from the 10 volunteers (4–98 specimens per individual; mean, 32). A smaller number of Haplorchis taichui adults, an intestinal fluke, were found mixed-infected in 7 (103 specimens in total; 1–31 per individual; mean, 15) of the 10 volunteers. Adult specimens of hookworms, Enterobius vermicularis, Trichostrongylus sp., and a Taenia tapeworm strobila were recovered in some cases. Based on the results, it has been confirmed that the surveyed areas in Preah Vihear and Stung Treng provinces, Cambodia, are highly endemic areas of O. viverrini infection with a low-grade mixed infection with H. taichui.

Cloning and expression of Fasciola hepatica enolase gene and efficacy of recombinant protein in the serodiagnosis of sheep fasciolosis

Fasciolosis caused by Fasciola hepatica is a disease of zoonotic importance that is common worldwide and can cause serious problems in farm animals, some wild animals and humans. The development of diagnostic kits for the correct diagnosis of fasciolosis in sheep is important in terms of preventing yield losses. With this study, it is aimed to clone and express the enolase gene to be isolated from adult F. hepatica and to determine the effectiveness of the recombinant antigen in the serodiagnosis of sheep fasciolosis. For this aim, primers were designed to amplify the enolase gene from the F. hepatica enolase sequence, mRNA was isolated from F. hepatica adult fluke obtained from an infected sheep followed by cDNA was obtained. Enolase gene was amplified by PCR and the product was cloned and then expressed. The efficiency of the purified recombinant protein was displayed by Western blot (WB) and ELISA using positive and negative sheep sera. As a result, the sensitivity and specificity rates of the recombinant FhENO antigen were 85% and %82.8 by WB while the rates were 90% and 97.14% by ELISA, respectively. At the same time, in sheep blood sera samples collected from the Elazig and Siirt provinces of Turkey, 100 (50%) of 200 sera were found to be positive by WB and 46 (23%) were found to be positive by ELISA. The most important problem in ELISA was the high cross-reaction rate of the recombinant antigen used, as in WB. In order to prevent the cross-reactions, it will be useful to compare the genes encoding the enolase protein of parasites from the closely related parasite family, and select the regions where there are no common epitopes, and clone them and test the purified protein.

Trematode metacercariae and adults in cyprinoid fish from Khun Thale Swamp in Surat Thani province, Thailand.

The present study aimed to determine the infection status of trematode metacercariae and adults in cyprinoid fish from the Khun Thale Swamp in Surat Thani, Southern Thailand, with epidemiologic and faunistic viewpoints. In 2020, 577 fish in 15 species were collected in the summer (February-April) and rainy (September-November) seasons. Fish were individually examined for trematode metacercariae in the whole body and adults in the gastrointestinal tract using a stereomicroscope. Three species of digenetic trematode metacercariae, i.e., Haplorchis taichui, Haplorchoides mehrai, and Centrocestus formosanus, were detected in the muscle, fin, and/or scale of fish. Two species of adult flukes, including Rohdella siamensis and Helostomatis cyprinorum, were collected in the intestines. The prevalence of overall trematode infections was 32.4% (187/577 fish), which was higher in the rainy season (41.4%; 118/285) than in the summer season (23.6%; 69/292). The metacercariae of H. taichui and H. mehrai were detected in 7 fish species each, and those of C. formosanus were found only in Rasbora toneri. The aspidogastrean trematode R. siamensis (adult) was detected in Babonymus gonionotus. A digenean species, H. cyprinorum (adult), was found in Labiobarbus siamensis and Osteochilus vittatus. The present study has first confirmed that the metacercariae of heterophyid flukes, including H. taichui, H. mehrai, and C. formosanus, and adults of R. siamensis (Aspidogastrea) and H. cyprinorum (Digenea) are infected in some species of the cyprinoid fish from the Khun Thale Swamp in Surat Thani, Thailand.

Molecular characterization of Fasciola spp. from ruminants in Duhok province using the ITS1 ribosomal DNA marker

This study aimed to characterize and identify the genotypes of Fasciola spp. isolated from sheep, goats, and cattle in Duhok province based on the ITS1 region of rDNA. About 54 adult Fasciola flukes were individually isolated from the livers of naturally infected ruminants. After morphological identification, the genomic DNA of 54 isolated Fasciola spp. was successfully extracted, and the ITS1segment (518 bp) of rDNA was amplified. The amplicons were confirmed by gel electrophoresis and yielded mono cleared bands. Five amplicons from these samples (2 sheep, 2 cattle, and 1 goat) were selected for sequencing and then compared with NCBI-GenBank sequences for genotyping and phylogenetic analysis. Sequencing analysis and the BLAST results revealed that 3/5 of the resultant sequences were F. hepatica and 2/5 were F. gigantica. The ITS1 sequences were submitted to NCBI-GenBank with accession numbers: OM920533, OM920534, OM948733, OM948683, and OM918714. Alignment analysis of the current study and GenBank ITS1 sequences showed the presence of nucleotide variations between F. hepatica and F. gigantica species (interspecific), which were enough to separate them. At the same time, they were not observed within the same species of Fasciola (intraspecific). The pairwise identity percentage of intraspecific and interspecific Fasciola isolates was 100% and 99.2-99.6%, respectively. Phylogenetic analysis of the ITS1 sequences demonstrated that the Fasciola isolates of this study were clustered into two clades (hepatica and gigantica clades). The present study concluded that both Fasciola spp. (F. hepatica and F. gigantica) existed among the infected ruminants in Duhok province and are closely related to intraspecific Fasciola isolates from different countries in the Middle East, Asia, Europe, and Africa.

FOREGUT ULTRASTRUCTURE OF ADULT SANGUINICOLA VOLGENSIS (RAŠÍN, 1929) MCINTOSH, 1934 (DIGENEA: APOROCOTYLIDAE).

Herein, we use scanning and transmission electron microscopy to describe the foregut (mouth, pharyngeal canal, and associated epithelia and musculature) of an adult freshwater fish blood fluke, Sanguinicola volgensis (Rašín, 1929) McIntosh, 1934, infecting the blood of sabre, Pelecus cultratus Linnaeus, 1758 (Cypriniformes: Leuciscidae) from the Volga River, Russia. Our results indicate that S. volgensis has a pharynx and lacks an oral sucker and that its pharyngeal canal acts as a peristaltic pump that sucks blood into the esophagus, whereupon digestion commences with granules secreted from the esophageal epithelium. We saw no evidence of longitudinal muscle fibers beneath the pharyngeal canal epithelium, pharyngeal glands, or pharyngeal epithelial cells or muscle cells within the pharyngeal muscular complex; collectively indicating the presence of a pharynx rather than an oral sucker. The specialized epithelial lining associated with the mouth and pharyngeal canal evidently is unique among neodermatans; it is smooth, ∼40 nm thick anteriorly, and thickens (∼250-700 nm) posteriorly as the mouth cavity transitions into the pharyngeal canal. The pharyngeal canal epithelium has lumps of dense material resembling those of the basal lamina and fibrous coat of the tegument. The actin-like material within the pharyngeal cavity epithelium could provide structural support to the pharynx.

Review on Ruminant Fasciolosis in Ethiopia

Ethiopia possesses the largest livestock population in Africa. Ruminant Fasciolosis is a serious problem in animal production in different areas of the world especially in Ethiopia. It is a wide spread trematodal disease affecting ruminants (cattle, sheep and goats) and also other species of animals. F. hepatica and F. gigantica are the parasitic species belonging to Genus Fasciola under the phylum platyhelminths. The fasciola disease has three phases of clinical sign acute, sub-acute and chronic forms. Fasciolosis is more apparent in young ruminant and is usually chronic in nature. Adult flukes in the bile ducts cause inflammation, biliary obstruction, distraction of liver tissue and anemia. Snails of family Lymnaeidae are main intermediate hosts having great role on the transmission of the disease and the infection is acquired through grazing on swampy pasture. The disease mostly diagnosed by prior knowledge of the epidemiology of the disease in a given environment; observation of clinical signs, information on grazing history, seasonal occurrence and standard examination of feces in the laboratory. The affected cattle should be effectively treated with narrow spectrum anthelmintic such as Triclabendazole in addition to reducing the population of the intermediate host to control the disease. Now a days, fasciolosis is recognized as emerging human disease over the world even if only few case reports of human fascioliasis are available in Ethiopia, as the disease mostly affects animals in the country. The disease causes a significant economic loss in ruminant production by inflecting direct and indirect loss at different parts of Ethiopia. To control and prevent the disease, the strategic destruction of snail population should be implemented throughout the country to break down the life cycle of liver fluke.

A Study into the Identity, Patterns of Infection and Potential Pathological Effects of Rumen Fluke and the Frequency of Co-Infections with Liver Fluke in Cattle and Sheep

Rumen fluke (RF) are trematode parasites that have increased in prevalence within European ruminant livestock since the 1990s. Morbidity and mortality can result from the development of juvenile flukes in the duodenum, however, evidence for significant impacts of adult fluke in the rumen of the final host is equivocal. The presence of rumen fluke in Scotland had not previously been quantified, so the purpose of this study was to use historical coprological data collected between 2008 and 2018 at the School of Veterinary Medicine in Glasgow to evaluate the frequency of rumen fluke infection and to compare this with the presence of liver fluke. This analysis showed evidence of adult rumen fluke in 6.6% of samples submitted, with a substantial and significant increase in positive diagnoses from 2016, following which positive rumen fluke diagnoses equaled or slightly outnumbered those of liver fluke. A prospective post-mortem examination study was also carried out to determine the presence of rumen and liver fluke in cattle and sheep, to quantify adult rumen fluke burdens and to assess any pathological changes in the reticulorumen and proximal duodenum associated with infection. The presence of rumen fluke in post-mortem cases was 26.9% (n = 18/67), the majority (66.7%, n = 12/18) with burdens of less than 100 adult rumen flukes. There was no significant difference in mean ruminal papillar density and length in animals with and without adult rumen fluke and no significant gross pathology was observed in the rumen or reticulum. Examination of animals with adult rumen fluke provided no evidence of any consistent associations with acute or chronic inflammatory changes in the duodenum. All rumen fluke collected at necropsy were identified by PCR and sequencing as Calicophoron daubneyi.

Diagnosis of helminths depends on worm fecundity and the distribution of parasites within hosts.

Helminth transmission and morbidity are dependent on the number of mature parasites within a host; however, observing adult worms is impossible for many natural infections. An outstanding challenge is therefore relating routine diagnostics, such as faecal egg counts, to the underlying worm burden. This relationship is complicated by density-dependent fecundity (egg output per worm reduces due to crowding at high burdens) and the skewed distribution of parasites (majority of helminths aggregated in a small fraction of hosts). We address these questions for the carcinogenic liver fluke Opisthorchis viverrini, which infects approximately 10 million people across Southeast Asia, by analysing five epidemiological surveys (n = 641) where adult flukes were recovered. Using a mechanistic model, we show that parasite fecundity varies between populations, with surveys from Thailand and Laos demonstrating distinct patterns of egg output and density-dependence. As the probability of observing faecal eggs increases with the number of mature parasites within a host, we quantify diagnostic sensitivity as a function of the worm burden and find that greater than 50% of cases are misdiagnosed as false negative in communities close to elimination. Finally, we demonstrate that the relationship between observed prevalence from routine diagnostics and true prevalence is nonlinear and strongly influenced by parasite aggregation.

Assessment of antioxidant enzymes during the development of the digenetic trematode parasite Gastrothylax crumenifer, infecting the rumen of Indian water buffalo, Bubalus bubalis.

The presence of antioxidant enzymes in helminth parasites is well known. These enzymes help the parasites to survive in their hosts by detoxifying host-generated reactive oxygen species (ROS). The literature survey reveals that most of the studies related to antioxidant enzymes in helminth parasites are restricted to the adult stage while the larval stages are neglected. The present investigation is designed to evaluate the level of antioxidant enzymes in the adult and larval stages of rumen-infecting paramphistome parasites, Gastrothylax crumenifer. The larval stages include 0-day eggs, 4-day eggs, and eggs containing mature miracidia, cercariae, and metacercariae. Antioxidant enzyme assays were performed using standard assay protocols. Our findings revealed an increasing pattern in the level of Glutathione-S-Transferase (GST), Superoxide Dismutase (SOD), Glutathione Reductase (GR), and Glutathione Peroxidase (GPx) antioxidant enzymes during the development from 0-day eggs to the adult stage. Overall analysis shows that adult worms have higher antioxidant enzyme activity as compared to the larval stages, indicating that adult flukes are more adapted to oxidative stress. It can be concluded that the miracidia, cercarial, and metacercarial developmental stages of G. crumenifer possess a considerable level of antioxidant enzymes suitable to overcome the oxidative stress encountered during the development and help them in the completion of the life cycle and survival in the definitive host.

Molecular and cellular basis of praziquantel action in the cardiovascular system.

The anthelmintic drug praziquantel (PZQ) causes contraction of parasitic schistosomes as well as constriction of blood vessels within the mesenteric vasculature of the host where the adult blood flukes reside. The contractile action of PZQ on the vasculature is mediated by the activation of host serotonergic 5-HT2B receptors (5-HT2BRs). However, the molecular basis for PZQ interaction with these targets and the location of these 5-HT2B receptors in the vessel wall have not been experimentally defined. Evaluation of a PZQ docking pose within the 5-HT2BR orthosteric site, using both Ca2+ reporter and bioluminescence resonance energy transfer (BRET) assays, identified residues F3406.51 and F3416.52 (transmembrane helix 6, TM6) as well as L209EL2 (extracellular loop 2) as critical for PZQ-mediated agonist activity. A key determinant of PZQ selectivity for the 5-HT2B receptor over the 5-HT2A/2C receptors was determined by M2185.39 in transmembrane helix 5 (TM5) of the orthosteric site. Mutation of this residue to valine (M218V), as found in 5-HT2A and 5-HT2C, decreased PZQ agonist activity, whereas the reciprocal mutation (V215M) in 5-HT2C increased PZQ activity. Two-photon imaging in intact mesenteric arterial strips visualized PZQ-evoked Ca2+ transients within the smooth muscle cells of the vessel wall. PZQ also triggered cytoplasmic Ca2+ signals in arterial smooth muscle cells in primary culture that were isolated from mesenteric blood vessels. These data define the molecular basis for PZQ action on 5-HT2B receptors localized in vascular smooth muscle.