A PCR-RFLP assay for the distinction between Fasciola hepatica and Fasciola gigantica

An overview of fasciolosis in Nepal: epidemiology, diagnosis, and control strategies

Fasciolosis, caused by Fasciola hepatica and Fasciola gigantica, is a globally prevalent vector-borne disease that affects livestock and humans, with significant economic and zoonotic implications. In Nepal where livestock contributes to 11.5% of the GDP, fasciolosis poses a significant threat to the agriculture sector. The country's diverse geographical and climatic conditions contribute to the widespread prevalence of the disease. Domestic ruminants, including buffalo, cattle, goats, and sheep are extensively affected, with a prevalence rate ranging from 10.25% in goats to 68% in buffalo. The disease also impacts high-altitude regions, affecting even yaks in the Himalayas. Human infections are also on the rise, highlighting the zoonotic nature of the disease. This review provides a comprehensive and in-depth analysis of fasciolosis in Nepal, emphasizing its pathogenesis, epidemiology, and diagnosis. The review also assesses the strategies for controlling fasciolosis in Nepal, including anthelmintic treatments, vector control, and farm management practices. The challenges and limitations of these methods are discussed, underscoring the need for alternative strategies to prevent drug resistance and enhance disease management. Additionally, this paper proposes future directions for the management of fasciolosis in Nepal to provide a comprehensive and effective approach for controlling and managing the disease in the country.

Comparative evaluation of real-time PCR and ELISA for the detection of human fascioliasis

Fascioliasis is a zoonotic parasitic infection caused by Fasciola species in humans and animals. Despite significant advances in vaccination and new therapeutic agents, little attention has been paid to validating methods for the diagnosis of fascioliasis in humans. Serological techniques are convenient assays that significantly improves the diagnosis of Fasciola infection. However, a more sensitive method is required. The aim of this study was to compare the Real-Time PCR technique with the indirect-ELISA for the detection of Fasciola hepatica in human. Using a panel of sera from patients infected with Fasciola hepatica (n = 51), other parasitic infections (n = 7), and uninfected controls (n = 12), we optimized an ELISA which employs an excretory-secretory antigens from F. hepatica for the detection of human fascioliasis. After DNA extraction from the samples, molecular analysis was done using Real-Time PCR technique based on the Fasciola ribosomal ITS1 sequence. Of 70 patient serum samples, 44 (62.86%) samples were identified as positive F. hepatica infection using ELISA and Real-Time PCR assays. There was no cross-reaction with other parasitic diseases such as toxoplasmosis, leishmaniasis, taeniasis, hydatidosis, trichinosis, toxocariasis, and strongyloidiasis. The significant difference between the agreement and similarity of the results of patients with indirect ELISA and Real-Time PCR was 94.4% and 99.2%, respectively (Cohen's kappa ≥ 0.7; P = 0.02). Based on the Kappa agreement findings, the significant agreement between the results of ELISA and Real-Time PCR indicates the accuracy and reliability of these tests in the diagnosis of F. hepatica in humans.

Fasciolosis: pathogenesis, host-parasite interactions, and implication in vaccine development

Fasciola hepatica is distributed worldwide, causing substantial economic losses in the animal husbandry industry. Human fasciolosis is an emerging zoonosis in Andean America, Asia, and Africa. The control of the disease, both in humans and animals, is based on using anthelmintic drugs, which has resulted in increased resistance to the most effective anthelmintics, such as triclabendazole, in many countries. This, together with the concerns about drug residues in food and the environment, has increased the interest in preventive measures such as a vaccine to help control the disease in endemic areas. Despite important efforts over the past two decades and the work carried out with numerous vaccine candidates, none of them has demonstrated consistent and reproducible protection in target species. This is at least in part due to the high immunomodulation capacity of the parasite, making ineffective the host response in susceptible species such as ruminants. It is widely accepted that a deeper knowledge of the host-parasite interactions is needed for a more rational design of vaccine candidates. In recent years, the use of emerging technologies has notably increased the amount of data about these interactions. In the present study, current knowledge of host-parasite interactions and their implication in Fasciola hepatica vaccine development is reviewed.

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.

Molecular Characterization of Fasciola hepatica in Sheep Based on DNA Sequences of Ribosomal ITS-1

Introduction

World Health Organization (WHO) considers Fascioliasis as a neglected tropical disease that requires global efforts for disease control. Data from the genetic characterization of Fasciola population shed light on the spread of infections among animals which could help in the development of effective parasite control. The aim of the present work was to genetically characterize Fasciola adult worms isolated from sheep in Saudi Arabia by sequence analysis of ITS-1 region.

Methods

A total of 12,653 slaughtered sheep in Jeddah city, Saudi Arabia were examined for the presence of Fasciola spp. adult worms. The ITS-1 region of all parasites was amplified and sequenced.

Results

Overall, 12 variants DNA sequences were obtained. The variance of isolates ranged from 0.00771 to 0.34405. BLAST search showed that all obtained sequences were Fasciola hepatica and had >99.3% similarity with F. hepatica isolates from Spain and USA (from different hosts other than sheep). Phylogenetic analysis showed that Fasciola isolates were closely related to isolates from different countries.

Discussion

The current study showed that F. hepatica was the only spp. isolated from sheep in Jeddah. Further studies from different localities in Saudi Arabia are needed to help in the development of disease control.

New perspectives for fascioliasis in Upper Egypt's new endemic region: Sociodemographic characteristics and phylogenetic analysis of Fasciola in humans, animals, and lymnaeid vectors

BACKGROUND

Fascioliasis is a significant vector-borne disease that has emerged in numerous tropical and subtropical countries causing severe health problems. Egypt is one of the fascioliasis endemic regions; however, the current situation in Upper Egypt is understudied, with only sporadic human cases or outbreaks. This study aims to highlight the sociodemographic characteristics of human fascioliasis in a newly emerged endemic area in Upper Egypt, along with risk factors analysis and the molecular characteristics of the fasciolid population in humans, animals, and lymnaeid snails.

METHODOLOGY/PRINCIPAL FINDINGS

The study reported Fasciola infection in patients and their close relatives by analyzing the risk of human infection. Morphological and molecular characterization was performed on lymnaeid snails. Multigene sequencing was also used to characterize fasciolids from human cases, cattle, and pooled snail samples. The study identified asymptomatic Fasciola infection among family members and identified the presence of peridomestic animals as a significant risk factor for infection. This is the first genetic evidence that Radix auricularia exists as the snail intermediate host in Egypt.

CONCLUSIONS/SIGNIFICANCE

This study revealed that Assiut Governorate in Upper Egypt is a high-risk area for human fascioliasis that requires additional control measures. Fasciola hepatica was the main causative agent infecting humans and snail vectors in this newly emerged endemic area. In addition, this is the first report of R. auricularia as the snail intermediate host transmitting fascioliasis in Upper Egypt. Further research is required to clarify the widespread distribution of Fasciola in Egypt's various animal hosts. This provides insight into the mode of transmission, epidemiological criteria, and genetic diversity of fasciolid populations in Upper Egypt.\.

Potential Hybridization of Fasciola hepatica and F. gigantica in Africa-A Scoping Review

The occurrence of Fasciola gigantica and F. hepatica in Africa is well documented; however, unlike in Asia, there is a paucity of information on the existence of hybrids or parthenogenetic species on the continent. Nonetheless, these hybrid species may have beneficial characteristics, such as increased host range and pathogenicity. This study provides evidence of the potential existence of Fasciola hybrids in Africa. A literature search of articles published between 1980 and 2022 was conducted in PubMed, Google Scholar, and Science Direct using a combination of search terms and Boolean operators. Fasciola species were documented in 26 African countries with F. hepatica being restricted to 12 countries, whilst F. gigantica occurred in 24 countries, identified based on morphological features of adult Fasciola specimens or eggs and molecular techniques. The co-occurrence of both species was reported in 11 countries. However, the occurrence of potential Fasciola hybrids was only confirmed in Egypt and Chad but is suspected in South Africa and Zimbabwe. These were identified based on liver fluke morphometrics, assessment of the sperms in the seminal vesicle, and molecular techniques. The occurrence of intermediate host snails Galba truncatula and Radix natalensis was reported in Ethiopia, Egypt, South Africa, Tanzania, and Uganda, where F. hepatica and F. gigantica co-occurrences were reported. The invasive Pseudosuccinea columella snails naturally infected with F. gigantica were documented in South Africa and Egypt. In Zimbabwe, P. columella was infected with a presumed parthenogenetic Fasciola. This suggests that the invasive species might also be contributing to the overlapping distributions of the two Fasciola species since it can transmit both species. Notwithstanding the limited studies in Africa, the potential existence of Fasciola hybrids in Africa is real and might mimic scenarios in Asia, where parthenogenetic Fasciola exist in most Asian countries. In South Africa, aspermic F. hepatica and Fasciola sp. have been reported already, and Fasciola hybrids have been reported? in Chad and Egypt. Thus, the authors recommend future surveys using molecular markers recommended to identify Fasciola spp. and their snail intermediate hosts to demarcate areas of overlapping distribution where Fasciola hybrids and/or parthenogenetic Fasciola may occur. Further studies should also be conducted to determine the presence and role of P. columella in the transmission of Fasciola spp. in these geographical overlaps to help prevent parasite spillbacks.

Development of a colloidal gold immunochromatographic strip for the rapid detection of antibodies against Fasciola gigantica in buffalo

Background

Fasciola gigantica, a tropical liver fluke, infects buffalo in Asian and African countries, causing significant economic losses and posing public health threats. The diagnostic of buffalo fascioliasis caused by F. gigantica is vital in fascioliasis control and preventation. The 22nd gel filtration chromatography fraction of F. gigantica Excretory-Secretory Products (FgESP), namely Fasciola 22 (F22), which was used as a diagnostic antigen in indirect ELISA, has demonstrated great potential for fascioliasis diagnosing. In the absence of rapid diagnostic methods, the use of a colloidal gold immunochromatographic strip based on F22 was applied to detect F. gigantica infection in buffalo.

Methods

In the present study, the 22nd gel filtration chromatography fraction of FgESP (F22) was used as an antigen to establish the colloidal gold-based immunochromatographic strip (ICS). The nitrocellulose membrane was incubated with F22 at the test line (T line) and goat anti-mouse secondary antibody at the control line (C line). The mouse anti-buffalo secondary antibody 2G7 conjugated to colloidal gold particles was used as the detection system for line visualization. The strip was assembled and developed by optimizing reaction conditions. The sensitivity, specificity, stability, and early diagnostic value of the strip were evaluated employing buffalo-derived sera.

Results

An immunochromatographic strip for the rapid detection of antibodies against F. gigantica-FgICS was developed. The strip demonstrated high sensitivity and specificity. Sensitivity tests confirmed positive results even when the positive reference serum was diluted 4,096 times. Except for one Schistosoma japonicum-positive serum that tested positive via FgICS, specificity tests confirmed no cross-reactivity with other positive sera of Schistosoma japonicum and Babesia bovis. The strip remained stable after storage at 4°C for up to 3 months. In infected buffalo, antibodies could be detected as early as 14–21 days post-infection. The detection of 17 positive sera yielded an 82.4% positive rate via FgICS vs. a 100.0% positive rate via ELISA based on FgESP. For FgICS, the 95% confidence interval of sensitivity was 84.8–95.4%, while specificity was 4.2–14.7%.

Conclusion

The immunochromatographic strip FgICS developed in this study provides a simple and rapid method of F. gigantica antibody detection and infected buffalo monitoring in the field.

Identification and Genetic Characterization of Fasciola hepatica Isolated from Cattle in Jeddah, Saudi Arabia Based on Sequence Analysis of Mitochondrial (COI) Gene

Background

In Saudi Arabia, more than US$ 0.2 million annual losses are caused by liver condemnations due to fascioliasis. Data obtained from the genetic characterization of Fasciola population sheds light on parasite transmission which could eventually help in development of effective parasite control measures. So, the aim of this study was to investigate the genetic diversity of Fasciola spp. isolated from cattle in Saudi Arabia by sequence analyses of COI gene.

Materials and Methods

A total of 325 cows slaughtered at the central municipal abattoir in Jeddah city, Jeddah Province, Saudi Arabia were examined for fascioliasis in the period from 1^st of June to 1^st of July 2020. DNA was extracted from adult Fasciola worms and used for PCR and DNA sequence using a primer pair targeting COI gene. Analysis of the obtained sequences was done using BLAST search and phylogenetic analysis.

Results

Bovine fascioliasis was diagnosed in 18 out of 325 cattle (5.5%). Forty-eight flukes were extracted from infected animals and DNA was successfully amplified from all flukes. Overall 12 different DNA sequences were obtained. BLAST search showed that all obtained sequences were F. hepatica and had >97% similarity with F. hepatica isolates from Tanzania, Europe and Iran. Phylogenetic analysis of the obtained sequences showed that Fasciola isolates from the current study were clustered in one subclade closely related to isolates from North and South Africa and Italy.

Conclusion

Reports on the molecular characterization of Fasciola spp. in Saudi Arabia are limited. In the current study, our findings showed that F. hepatica was the only Fasciola species parasitizing cattle in Jeddah city, Saudi Arabia. Further studies using a large number of samples from different localities in Saudi Arabia are needed to provide data that will help the development of control measures against fascioliasis.

Molecular Identification of Fasciola Isolated from the Liver of Meat Animals in Fars Province, Iran

Background

Fasciola hepatica and Fasciola gigantica are flatworms that infect animals and humans. Fasciola is the parasite of the liver or bile ducts and intestines of mammals, where such animals are known as their “definite hosts.” The study aims to detect the genotype of Fasciola spp. from the livers of meat animals by using RFLP-PCR in samples collected from Fars province.

Methods

Sixty Fasciola spp. samples were collected from infected slaughtered animals in three counties of Fars province, Iran (Jahrom, Nourabad Mamasani, and Kazeroun).Genomic DNA was extracted by the conventional phenol-chloroform method. For the study, PCR-RFLP and sequence analysis of the first nuclear ribosomal internal transcribed spacer (ITS1) region from Fasciola species were used to conduct the study.

Results

The fragment of about 700 bp in all the Fasciola samples was amplified. In total, 43 samples of Fasciola gigantica and 17 samples of Fasciola hepatica were identified.

Conclusion

The dominant Fasciola species in this region is Fasciola gigantica. Hence, it seems that hygienic policies should be developed to prevent and control fascioliasis because of the dominant species, Fasciola gigantica.

Describing the intestinal microbiota of Holstein Fasciola-positive and -negative cattle from a hyperendemic area of fascioliasis in central Colombia

The ability to identify compositional changes in the intestinal microbiota of parasitized hosts is important for understanding the physiological processes that may affect animal productivity. Within the field of host–parasite interactions, many studies have suggested that helminths can influence the microbial composition of their hosts via their immunomodulatory effects. Bovine fascioliasis is a helminthiasis widely studied by immunologists, but with little information available regarding gut microbial communities. Thus, we aimed to describe the composition of the intestinal microbiota of Holstein Fasciola-positive and -negative cattle using parasitological methods and ELISA (enzyme-linked immunosorbent assay). Bovine fecal samples (n = 65) were obtained from livestock slaughter plants in the Cundi-Boyacense Colombian highlands (a hyperendemic region for bovine fascioliasis) and studied by amplicon-based next-generation 16S-rRNA and 18S-rRNA gene sequencing. From these samples, 35 were Fasciola hepatica-negative and, 30 were F. hepatica-positive in our detection analysis. Our results showed a reduction in the relative abundance of Bacteroidetes and Ascomycota in the Fasciola-positive samples, along with decreased relative abundances of the commensal taxa previously associated with fermentation and digestion processes. However, metabolomic approaches and functional analyzes of the intestinal microbiota are necessary to support these hypothesis. These findings are a small first step in the development of research aimed at understanding how microbial populations in bovines are modulated in liver helminth infections.

Fasciola hepatica, a liver parasite, infects a wide variety of hosts, mostly ruminants. Ruminant infections with this parasite cause economic losses worldwide, mainly in livestock. Given its importance, much research has been carried out on this parasite, a lot of which has focused on its ability to alter the immune responses of its host. However, little is known about the numerous other interactions it has with the host and how they might affect the host’s intestinal microbiota. Here, we observed a reduction in the abundance of microorganisms associated with the fermentation and digestion of vegetable fiber, two important processes in animal health and productivity. Therefore, it is possible that F. hepatica, in addition to the previously documented liver alterations, also generates changes in the intestinal microbiota that may impact its bovine host. These findings are a small first step in the research of microbial populations in cattle infected with liver helminths which open the door to further research aimed at identifying alternative treatments for parasites such as F. hepatica.

Dicrocoelium spp. in cattle from Wa, Ghana: prevalence and phylogeny based on 28S rRNA

Dicrocoeliosis is a trematode infection in cattle, sheep and goats caused by the small liver fluke, Dicrocoelium spp. Though endemic in Ghana, its disease situation is poorly understood. In the present study, the prevalence, distribution and worm load of Dicrocoelium spp. in cattle at slaughter in Wa were determined. A total of 389 cattle were screened during meat inspection for liver flukes, and polymerase chain reaction accompanied by DNA sequencing of the 28S rRNA gene was used to identify Dicrocoelium spp. Generally, prevalence of bovine dicrocoeliosis (small liver fluke) stood at 19.54 % with prevalence in males and females being 17.62 % and 21.43 %, respectively. Animals under 2 years suffered more infection than older ones (23.08 % vs. 16.80 %). Dicrocoelium infection was recorded in animals from all the communities where slaughtered cattle came from. On average, 31 flukes per infected animal were recorded. A molecular confirmatory test on seven flukes identified them as D. hospes. This preliminary study highlights the importance of bovine dicrocoeliosis in Ghana and has identified D. hospes as a causal agent. The data provides basis for further studies to appraise the trematode disease situation in animals and phylogeny of Dicrocoelium spp. circulating in Ghana.

Morphological and molecular characterization of Fasciola hepatica and Fasciola gigantica phenotypes from co-endemic localities in Mpumalanga and KwaZulu-Natal provinces of South Africa

Fasciolosis is a food- and water-borne disease caused by digenean trematode species, Fasciola hepatica and F. gigantica. They are widely distributed and infect a wide range of definitive hosts, causing enormous economic loss due to reduced productivity in domestic ruminants. The two species have been previously reported to be co-endemic in KwaZulu-Natal and Mpumalanga provinces of South Africa. Hybridization between the two species has been reported elsewhere. Despite the overlap of the two species in two provinces, there has been no attempt to determine the presence of the intermediate forms or hybrids. Therefore, this study aimed at morphological and molecular characterization of Fasciola spp. collected from cattle slaughtered at abattoirs located in the two provinces of South Africa, where two species are endemic. A total of 71 fluke specimens were collected cattle from abattoirs in Enhlazeni and Nelspruit in Mpumalanga province and Pietermaritzburg in KwaZulu-Natal province of South Africa, and Zimbabwe (Bulawayo abattoir). Fasciola gigantica specimen collected from Zimbabwe where it has been confirmed as the only species occurring and this was used as control in the morphological and molecular assessment of the collected specimens. Of the 71 specimens collected, 37 were classified as F. hepatica, 12 as F. gigantica and 22 as Fasciola spp using morphological characters. Of these species, 11 of 37 F. hepatica and 6 of 22 Fasciola sp were found to be aspermic or having very scanty sperm. Fifteen flukes which were spermatic were all identified morphologically as F. gigantica whilst 5 flukes which were aspermic were identified morphologically as F. hepatica. Molecular analysis of the same 15 spermatic specimens confirmed the presence of F. hepatica (n = 9) and F. gigantica (n = 6) using the CO1 marker and as F. hepatica (n = 4), F. gigantica (n = 7) and Fasciola sp. (n = 1) for the same specimens using the ITS-1/5.8S/ITS-2 marker. The remaining 4 aspermic flukes (one did not resolve) were all identified morphologically as F. hepatica and molecular analysis confirmed them as F. hepatica (n = 4) by both CO1 and ITS-1/5.8S/ITS-2. Phylogenetic analysis based on both CO1 and ITS-1/5.8S/ITS-2 showed that F. hepatica species formed a moderately supported monophyletic clade with F. gigantica. Their ancestral history was further confirmed by haplotype network, which formed novel haplotypes that corresponded with the structure of the phylogenetic tree. Results from this study showed that morphological characters alone have limitations in identifying F. hepatica and F. gigantica in areas where the two species occur, although both methods confirmed the presence of F. gigantica occurring in Zimbabwe, F. hepatica in KwaZulu-Natal, and both species occurring in Mpumalanga province. Therefore, the use of morphological techniques, complemented by molecular techniques are recommended, especially in endemic areas where the two species are co-endemic.

Molecular characterization revealed Fasciola specimens in Ecuador are all Fasciola hepatica, none at all of Fasciola gigantica or parthenogenic Fasciola species

All 225 Fasciola flukes obtained from domestic animals (73 cattle, 7 sheep and 1 pig) of 18 distinct geographic areas in Ecuador-South America, were identified as Fasciola hepatica, based on molecular analyses of nuclear pepck and pold genes, and mitochondrial nad1gene as well as the morphological observation of sperm within the seminal vesicles. Fasciola gigantica and parthenogenic Fasciola forms endemic to Asian countries were not found in this study, although zebu cattle and water buffalos have introduced into South America from Asia; this could be due to the absence of suitable intermediate host snails. The results of pepck analysis using multiplex PCR developed previously showed that 32 of the flukes could not be confirmed as F. hepatica, suggesting that the method is unreliable for the accurate discrimination of F. hepatica, and that pepck gene of the species consists of multiple loci, not a single locus. The results of genetic diversity, phylogenetic, and network analyses based on mitochondrial nad1 sequences suggest that F. hepatica populations in South America, including Ecuador, formed from the ancestral F. hepatica individuals introduced into the continent along with anthropogenic movement of livestock infected with the species.

Fascioliasis and fasciolopsiasis: Current knowledge and future trends

Food-borne zoonotic trematodiases are classified as neglected diseases by the World Health Organization. Among them, fascioliasis is caused worldwide by Fasciola hepatica and F. gigantica, and represent a huge problem in livestock production and human health in endemic areas. Fasciolopsis buski, restricted to specific regions of Asia, causes fasciolopsiasis. The incidence of these trematodiases is underestimated due to under-reporting and to the lack of sensitive and widely accepted tool for their diagnosis. This, together with a rising trend in reporting of drug resistance and the need for an effective vaccine against these parasites, pose a challenge in the effective control of these diseases. Here, the latest reports on fascioliasis outbreaks between 2000 and 2020 and the most recent advances in their epidemiology, diagnosis, treatment and control are revised. Finally, future needs in the field of fascioliasis and fasciolopsiasis are presented, which could be addressed based on current knowledge and by means of new emerging technologies.

Effectiveness of Fasciola gigantica excretory-secretory and recombinant cathepsin L antigens for rapid diagnosis of human fascioliasis using immunochromatographic devices

Fascioliasis, a food- and water-borne trematodiasis, has been identified as a public health threat by the World Health Organization, with millions of people estimated to be infected or at risk of infection worldwide. We developed an immunochromatographic test (ICT) as a point-of-care (POC) tool for the rapid serodiagnosis of human fascioliasis caused by Fasciola gigantica and evaluated their diagnostic ability. Two tests were developed using antigens from adult F. gigantica excretory-secretory (ES) product and recombinant F. gigantica cathepsin L (rFgCL). Sera from 12 patients with parasitologically proven fascioliasis caused by F. gigantica, 18 with clinically suspected fascioliasis, 65 with other parasitic infections, and 30 healthy controls were used. Using a cutoff of > 0.5 for antibody detection, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the ES-based ICT method were 100%, 98.9% 96.8%, 100%, and 99.2%, respectively, and those of the rFgCL-based ICT method were 86.7%, 93.7%, 81.3%, 95.7%, and 92.0%, respectively. The concordance between the two methods was 91.2%. Tests using F. gigantica ES and rFgCL antigens can be employed quickly and easily as POC diagnostic tools. They can be used to support the clinical diagnosis of human fascioliasis gigantica and in large-scale surveys in endemic areas throughout tropical regions without necessitating additional facilities or ancillary supplies.

Molecular characterization and immunodiagnostics of Dicrocoelium dendriticum species isolated from sheep of north-west Himalayan region

Despite its extensive presence among grazing ruminants, dicrocoeliosis, also known as 'small liver fluke' disease, is poorly known and often underestimated by researchers and practitioners in many countries. The accurate identification and prepatent diagnosis of Dicrocoelium dendriticum infection is an essential prerequisite for its prevention and control. In the present study, the morphologically identified specimens isolated from the bile ducts of sheep (Ovis aries) were validated through molecular data. The sequence analysis of the second internal transcribed spacer (ITS-2) of our isolates showed a high degree of similarity with D. dendriticum using the BLAST function of the National Center for Biotechnology Information (NCBI). The phylogenetic analysis of our isolates showed a close relationship with previously described D. dendriticum isolates from different countries. The antigenic profiles of somatic and excretory/secretory (E/S) antigens of D. dendriticum were revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting using sera from sheep naturally infected with D. dendriticum. By SDS-PAGE, 16 distinct bands were revealed from crude somatic fraction. Immunoblotting analysis of these proteins with positive sera exhibited six seroreactive bands ranging from 27 to 130 kDa. Among these, the 84 and 130 kDa bands were quite specific, with high diagnostic specificity and sensitivity. The E/S fraction comprised nine distinct bands, as revealed by SDS-PAGE analysis. Immunoblotting analysis of these proteins with positive sera exhibited five antigenic bands ranging from 27 to 130 kDa. Among these, the 130 kDa band was found to be quite specific, with high diagnostic specificity and sensitivity. The present study concludes that the protein bands of 84 and 130 kDa in somatic fraction and 130 kDa in E/S fraction can be used for the immunodiagnostic purpose for this economically important parasite, which may also encourage further studies regarding their vaccine potential.

Fasciola hepatica and Fasciola gigantica coexistence in domestic ruminants in Nigeria: application of a PCR-based tool

The distinction between Fasciola hepatica and Fasciola gigantica has been traditionally based on morphological criteria, although accurate recognition of the two flukes is usually difficult because of substantial variations in morphological features. The main aim of this study was to develop a PCR-based assay for discrimination between both species collected in sheep and cattle from Nigeria. A total of 47 animals, 33 cattle and 14 sheep, were sampled, and a single adult fluke was collected from each animal. DNA was extracted from flukes, and primers were designed based on mitochondrial DNA sequences to amplify a 304 bp fragment for the identification of F. hepatica and 752 bp for F. gigantica. PCR products from 12 flukes were sequenced for phylogenetic analysis. A total of 29 out of 47 flukes were identified as F. hepatica and 18 as F. gigantica. Within each host, the percentage of each fluke species was as follows: In cattle, 18/33 (54.5%) and 15/33 (45.5%) were F. hepatica and F. gigantica, respectively. In sheep, 11/14 (78.6%) were F. hepatica and 3/14 F. gigantica (21.4%). The phylogenetic analysis confirmed these results. Although the number of flukes collected in sheep was limited, it seems that F. hepatica is more prevalent in sheep than F. gigantica, whereas the percentage of each species was similar in cattle. This study confirms the presence of F. hepatica in Nigeria.

Which species is in the faeces at a time of global livestock movements: single nucleotide polymorphism genotyping assays for the differentiation of Fasciola spp

Fasciolosis, caused by Fasciola hepatica and Fasciola gigantica, is a globally distributed zoonotic disease of livestock. While F. hepatica and F. gigantica have temperate and tropical distributions, respectively, parasite sympatry occurs in parts of Asia and Africa. A growing protein demand has the potential to facilitate the translocation of parasites from endemic to non-endemic areas, via associated international livestock movements. Such is the case in Southeast Asia, where livestock trade from F. hepatica-endemic countries into China and Vietnam may account for detection of F. hepatica hybrid/introgressed forms. Of particular importance is Lao People's Democratic Republic, which acts as a major livestock thoroughfare for the region. Our ability to understand the impacts of livestock-associated Fasciola spp. movements on local animal and human health is hindered by a lack of ante-mortem diagnostic tools allowing species differentiation. Molecular tools have been developed for Fasciola spp. differentiation, however those rely on access to pure DNA from adult specimens, limiting their application to post-mortem use. Our aim was to detect and differentiate F. hepatica from the endemic F. gigantica in local smallholder cattle in a region of Southeast Asia with frequent livestock trafficking. To do this we designed and validated ante-mortem molecular assays for Fasciola spp. differentiation targeting single-nucleotide polymorphisms (SNPs) within ITS1 and lsrRNA. We then deployed these SNP genotyping assays to diagnose Fasciola spp. infection in 153 local cattle from 27 villages in Northern Laos. We demonstrate the presence of F. hepatica DNA, confirmed by qualitative Sanger and quantitative Illumina amplicon sequencing of ITS1 and lsrRNA, and highlight the shortfalls of Sanger sequencing for Fasciola spp. identification due to the preferential amplification of F. gigantica nucleotides in mixed DNA samples. The outlined protocol enables rapid surveillance of faecal samples for the presence of Fasciola species eggs, their co-infection and/or infection with F. hepatica/F. gigantica hybrids.

Multilocus approach reveals discordant molecular markers and corridors for gene flow between North African populations of Fasciola hepatica

Fasciolosis is a foodborne trematodosis characterised by a worldwide distribution. Various approaches have been developed for the study of the causative agents of this parasitic infection: Fasciola hepatica, Fasciola gigantica and the aspermic intermediated forms (hybrid and introgressed). In the present study, novel and common molecular markers (pepck and pold, ITS, CO1, ND1 and CO1-trnT-rrnL) were used to characterise Fasciola flukes from the Tunisian-Algerian border, to estimate the gene flow between these populations and to evaluate the reliability of different molecular markers. All nuclear and mitochondrial markers, apart from pepck, supported the monophyly of the studied flukes identified as F. hepatica. Multiplex PCR for pepck revealed three different genotypes corresponding to F. hepatica (pepck-Fh), F. gigantica (pepck-Fg) and the aspermic Fasciola flukes (pepck-Fh/Fg). Sequence analysis of pepck revealed high polymorphism, length variation, within this intronic marker. The observed inconsistencies were due to the position of the forward primer within the intronic region. Pepck sequences showed different level of heterozygosity and homozygosity with length polymorphisms in the introns. Pepck multiplex PCR patterns could not differentiate between Fasciola species. All studies based on only pepck multiplex PCR with mitochondrial markers should be revised. Nuclear and mitochondrial markers revealed an important gene flow between Tunisian and Algerian populations of F. hepatica. The combination of nuclear and mitochondrial sequence analysis is still the best method to distinguish these taxa. Effective measures are needed in order to better control cross-country illegal trade of vector.

Zoonotic transmission of intestinal helminths in southeast Asia: Implications for control and elimination

Intestinal helminths are extremely widespread and highly prevalent infections of humans, particularly in rural and poor urban areas of low and middle-income countries. These parasites have chronic and often insidious effects on human health and child development including abdominal problems, anaemia, stunting and wasting. Certain animals play a fundamental role in the transmission of many intestinal helminths to humans. However, the contribution of zoonotic transmission to the overall burden of human intestinal helminth infection and the relative importance of different animal reservoirs remains incomplete. Moreover, control programmes and transmission models for intestinal helminths often do not consider the role of zoonotic reservoirs of infection. Such reservoirs will become increasingly important as control is scaled up and there is a move towards interruption and even elimination of parasite transmission. With a focus on southeast Asia, and the Philippines in particular, this review summarises the major zoonotic intestinal helminths, risk factors for infection and highlights knowledge gaps related to their epidemiology and transmission. Various methodologies are discussed, including parasite genomics, mathematical modelling and socio-economic analysis, that could be employed to improve understanding of intestinal helminth spread, reservoir attribution and the burden associated with infection, as well as assess effectiveness of interventions. For sustainable control and ultimately elimination of intestinal helminths, there is a need to move beyond scheduled mass deworming and to consider animal and environmental reservoirs. A One Health approach to control of intestinal helminths is proposed, integrating interventions targeting humans, animals and the environment, including improved access to water, hygiene and sanitation. This will require coordination and collaboration across different sectors to achieve best health outcomes for all.

The Lesser Antillean Iguana (Iguana delicatissima) on St. Eustatius: Genetically Depauperate and Threatened by Ongoing Hybridization

The Lesser Antillean Iguana (Iguana delicatissima) is an endangered species threatened by habitat loss and hybridization with non-native Green Iguanas (Iguana iguana). Iguana delicatissima has been extirpated on several islands, and the Green Iguana has invaded most islands with extant populations. Information is essential to protect this species from extinction. We collected data on 293 iguanas including 17 juveniles from St. Eustasius, one of the few remaining I. delicatissima strongholds. Genetic data were leveraged to test for hybridization presence with the Green Iguana using both mitochondrial and nuclear genes, including 16 microsatellite loci. The microsatellites were also analyzed to estimate genetic diversity, population structure, and effective population size. Using molecular and morphological data, we identified 286 I. delicatissima individuals captured during our first fieldwork effort, and 7 non-native iguanas captured during a second effort, showing hybridization occurs within this population. Comparing homologous microsatellites used in studies on Dominica and Chancel, the I. delicatissima population on St. Eustatius has extremely low genetic diversity (HO = 0.051; HE = 0.057), suggesting this population is genetically depauperate. Furthermore, there is significant evidence for inbreeding (FIS = 0.12) and weak spatial genetic structure (FST = 0.021, P = 0.002) within this population. Besides immediate threats including hybridization, this population's low genetic diversity, presence of physiological abnormalities and low recruitment could indicate presence of inbreeding depression that threatens its long-term survival. We conclude there is a continued region-wide threat to I. delicatissima and highlight the need for immediate conservation action to stop the continuing spread of Green Iguanas and to eliminate hybridization from St. Eustatius.

Molecular Characterization and Immunodiagnostic Potential of Various Antigenic Proteins of Fasciola Gigantica Species Isolated from Sheep of North West Himalayan Region

The control of the digenetic trematode Fasciola gigantica has been the major challenge in both cattle and small ruminants as there is a paucity of an effective and commercial vaccine. Thus, the accurate identification and prepatent diagnosis of F. gigantica is an essential prerequisite for its successful prevention and control. In the present study, the morphologically identified specimens isolated from the liver and bile ducts of sheep (Ovis aries) were validated through molecular data. The sequence analysis of ITS2 of our isolates showed high degree of similarity with F. gigantica and F. hepatica using BLAST function of NCBI. The phylogenetic analysis of our isolates showed a close relationship with previously described F. gigantica and F. hepatica isolates from different countries. The antigenic profile of somatic and E/S antigens of F. gigantica were revealed by SDS-PAGE and immunoblotting using sera from sheep naturally infected with F. gigantica. By SDS-PAGE, 20 distinct bands were revealed from crude somatic fraction. Immunoblotting analysis of these proteins with positive sera exhibited 8 sero-reactive bands ranging from 14 to 97 kDa. Among these 38 and 44 kDa bands were quite specific with high diagnostic specificity and sensitivity. The E/S fraction comprised 7 distinct bands, as revealed by SDS-PAGE analysis. Immunoblotting analysis of these proteins with positive sera exhibited 6 antigenic bands ranging from 23 - 54 kDa. Among these 27 and 33 kDa were found to be quite specific with high diagnostic specificity and sensitivity. The present study concludes that the protein bands of 38 and 44 kDa in somatic fraction and 27 and 33 kDa in E/S fraction can be used for the immunodiagnostic purpose for this economically important parasite, which may also entice further studies regarding their vaccine potential.

Fasciola spp. in Armenia: Genetic diversity in a global context

Fasciolosis, a food- and waterborne infection caused by the trematodes Fasciola hepatica and F. gigantica, is recognized by WHO as a neglected zoonotic disease. Whereas F. hepatica is distributed worldwide in cooler climates, F. gigantica occurs mainly in the tropics of Africa and Asia. The southern Caucasus, with Armenia, is one of the most northern regions where both species occur and may produce hybrids. In this study, livestock in central Armenia was surveyed for fasciolosis, the causative species were determined and the genetic diversity of both species was estimated. Total prevalence in sheep (1794), cattle (324) and goats (9) was 21.2%, 15.7% and 44.4%, respectively. After morphological identification and sequencing of a mitochondrial (nad1) and a nuclear marker gene (28S rRNA), 62 collected specimens were allocated to F. hepatica (n = 55) and F. gigantica (n = 7). Intraspecific diversity was evaluated for the complete nad1 gene, resulting in 29 haplotypes of F. hepatica and six haplotypes of F. gigantica. Diversity was higher among F. gigantica than F. hepatica in the Armenian sample set, a difference that was confirmed analyzing available sequences for both species worldwide. Maximum genetic distance between haplotypes in global networks was 49 nucleotide steps for F. gigantica compared to 15 for F. hepatica. In the available sample sets, F. hepatica showed higher diversity in western Asia and the Middle East compared to Europe and eastern Asia, while for F. gigantica loosely structured clusters comprising mainly western/southern Asian and African haplotypes could be identified. A distinct clade comprising haplotypes from Zambia was basal in the phylogenetic tree. Biogeographical implications of these data are discussed.

Fascioliasis

Fascioliasis is a major parasitic disease caused by the digenetic trematodes Fasciola hepatica and Fasciola gigantica. The disease is a well-known veterinary problem of worldwide distribution. Fascioliasis is the vector-borne parasitic disease presenting the widest latitudinal, longitudinal, and altitudinal distribution known at present. In the last two decades, many surveys have shown it to be an important public health problem as well, including estimations of 2.4 million, up to 17 million people, or even higher depending on the hitherto unknown situations mainly in several regions of Asia and Africa. In recent years, the increasing number of human case reports in many countries of the five continents and the results of studies on pathogenicity and immunity, mainly regarding the chronic period of the disease, were the reasons why it was decided to no longer consider fascioliasis merely a secondary zoonotic disease but an important human parasitic disease. In this chapter, we review the most relevant features in relation to fascioliasis, including from the most traditional to the most innovative aspects.

Identification of Fasciola Species Isolates from Nghe An Province, Vietnam, Based on ITS1 Sequence of Ribosomal DNA Using a Simple PCR-RFLP Method

Fascioliasis—a disease caused by Fasciola spp. (Platyhelminthes: Trematoda: Digenea)—is considered as the most important helminthic infection of bovine, sheep, and buffalo in Vietnam. The aim of this study is to detect the genotype of Fasciola spp. isolated from bovine and buffalo in the Nghe An province, central Vietnam, using PCR-RFLP and sequence analysis of the first nuclear ribosomal internal transcribed spacer (ITS1). Adult Fasciola spp. were isolated from bile ducts of bovine and buffalo in Nghe An province, Vietnam. Overall, 96 adult flukes from livers of slaughtered animals were collected from abattoirs of different areas. They included 7 samples from infected bovine and 89 samples from infected buffalo. 96/96 samples were identified as Fasciola species by ITS1 of rDNA. In this study, a PCR-RFLP method was used to distinguish between F. hepatica and F. gigantica in ITS1 of rDNA (680 bp) with RsaI restriction enzyme. RFLP pattern with RsaI produced a consistent pattern of 360, 100, and 60 bp fragments in F. hepatica, whereas F. gigantica worms had a profile of 360, 170, and 60 bp in size, respectively. The results showed that using PCR-RFLP based on the first internal transcribed spacers (ITS1) of the ribosomal RNA revealed that 93 out of 96 isolates were of Fasciola gigantica type, whereas three isolates presented an intermediate Fasciola. In the present study, F. gigantica and intermediate form were coexisting in bovine and buffalo in the Nghe An province of central Vietnam, whereas F. hepatica was not detected.

Genetic characterisation of Fasciola gigantica from Ghana

Fasciola hepatica and Fasciola gigantica are the causal agents of the zoonotic food-born disease fascioliasis. Africa is primarily endemic to F. gigantica, although sympatric presence of F. hepatica is known for some countries. The present situation of fascioliasis in western Africa, and Ghana in particular, is still poorly understood, and studies including molecular identification of species and variants are lacking. In this explorative study we genotyped 19 Fasciola isolates obtained by opportunistic sampling in the Upper East and Upper West Regions of Ghana. All isolates were identified as F. gigantica based on a partial sequence of the 28S rRNA (548 bp) gene. In addition, the complete mtDNA nad1 (903 bp) gene was employed to infer intraspecific microvariation among isolates. Six nad1 haplotypes were identified that clustered into two West African haplogroups when compared with previous records from Nigeria. These preliminary data suggest that fascioliasis in Ghana is (at least) mainly caused by F. gigantica, and that transmission may be principally autochthonous. However, the small number of isolates prevents firm conclusions, and this study is intended to stimulate molecular surveys on this neglected disease in a neglected region.

Scrambled eggs: A highly sensitive molecular diagnostic workflow for Fasciola species specific detection from faecal samples

BACKGROUND

Fasciolosis, due to Fasciola hepatica and Fasciola gigantica, is a re-emerging zoonotic parasitic disease of worldwide importance. Human and animal infections are commonly diagnosed by the traditional sedimentation and faecal egg-counting technique. However, this technique is time-consuming and prone to sensitivity errors when a large number of samples must be processed or if the operator lacks sufficient experience. Additionally, diagnosis can only be made once the 12-week pre-patent period has passed. Recently, a commercially available coprological antigen ELISA has enabled detection of F. hepatica prior to the completion of the pre-patent period, providing earlier diagnosis and increased throughput, although species differentiation is not possible in areas of parasite sympatry. Real-time PCR offers the combined benefits of highly sensitive species differentiation for medium to large sample sizes. However, no molecular diagnostic workflow currently exists for the identification of Fasciola spp. in faecal samples.

METHODOLOGY/PRINCIPAL FINDINGS

A new molecular diagnostic workflow for the highly-sensitive detection and quantification of Fasciola spp. in faecal samples was developed. The technique involves sedimenting and pelleting the samples prior to DNA isolation in order to concentrate the eggs, followed by disruption by bead-beating in a benchtop homogeniser to ensure access to DNA. Although both the new molecular workflow and the traditional sedimentation technique were sensitive and specific, the new molecular workflow enabled faster sample throughput in medium to large epidemiological studies, and provided the additional benefit of speciation. Further, good correlation (R2 = 0.74-0.76) was observed between the real-time PCR values and the faecal egg count (FEC) using the new molecular workflow for all herds and sampling periods. Finally, no effect of storage in 70% ethanol was detected on sedimentation and DNA isolation outcomes; enabling transport of samples from endemic to non-endemic countries without the requirement of a complete cold chain. The commercially-available ELISA displayed poorer sensitivity, even after adjustment of the positive threshold (65-88%), compared to the sensitivity (91-100%) of the new molecular diagnostic workflow.

CONCLUSIONS/SIGNIFICANCE

Species-specific assays for sensitive detection of Fasciola spp. enable ante-mortem diagnosis in both human and animal settings. This includes Southeast Asia where there are potentially many undocumented human cases and where post-mortem examination of production animals can be difficult. The new molecular workflow provides a sensitive and quantitative diagnostic approach for the rapid testing of medium to large sample sizes, potentially superseding the traditional sedimentation and FEC technique and enabling surveillance programs in locations where animal and human health funding is limited.

Human fascioliasis by Fasciola hepatica: the first case report in Nepal

BACKGROUND

Fascioliasis is a zoonotic disease caused by Fasciola species. Patient may be asymptomatic or presents with jaundice and biliary colic or right hypochondriac pain due to bile duct obstruction with gastrointestinal symptoms.

CASE PRESENTATION

We report a case of human fascioliasis in a 45 years old female presented to Tribhuvan University Teaching Hospital (TUTH), Kathmandu, Nepal on August, 2015 with fever, right hypochondriac pain, jaundice and occasional vomiting with anorexia for 4 months whose alkaline phosphatase was elevated and peripheral blood smear revealed eosinophilia. The patient also gives the history of consumption of water-cress. Endoscopic Retrograde Cholagiopancretography (ERCP) showed the presence of a flat worm resembling Fasciola hepatica and stool routine examination revealed ova of F. hepatica. The patient was treated with nitazoxanide by which she got improved. Repeat stool examination 2 weeks after treatment revealed no ova of F. hepatica.

CONCLUSIONS

Patient with fascioliasis can be simply diagnosed with stool routine microscopy and treated with nitazoxanide. So patient with right hypochondriac pain, sign and symptoms of obstructive jaundice, eosinophilia and history of water-cress consumption should be suspected for fascioliasis and investigated and treated accordingly.

Molecular characterization of Fasciola flukes using mitochondrial 28S rRNA gene in Naimi Saudi sheep

Fasciolosis is a parasitic disease of medical and economic importance. This retrospective study was conducted on 110 Fasciola flukes collected from livers of 14 infected Naimi sheep slaughtered at Riyadh abattoir in Saudi Arabia during winter season of 2016. Collected specimens were analyzed for their species identification on the basis of partial sequences of mitochondrial 28S rRNA gene. Results have shown the presence of both Fasciola hepatica (F. hepatica) and Fasciola gigantica (F. gigantica) species. Where Fasciola hepatica was predominate (80%). Both intra-species and interspecies genetic distance was studied and results showed that the intraspecific variability among individuals of both species i.e., F. hepatica and F. gigantica, ranging between 0 and 1% while the interspecific diversity between F. hepatica and F. gigantica was only 1%. In conclusion, mitochondrial 28S rRNA gene is a proved as a good marker in identifying Fasciola of different species. Where, the F. hepatica and F. gigantica are present in sheep breed in Riyadh region, Saudi Arabia.

A review of bovine fasciolosis and other trematode infections in Nigeria

Trematode infections cause serious economic losses to livestock worldwide. Global production losses due to fasciolosis alone exceed US$3 billion annually. Many trematode infections are also zoonotic and thus a public health concern. The World Health Organization has estimated that about 56 million people worldwide are infected by at least one zoonotic trematode species, and up to 750 million people are at risk of infection. Fasciolosis caused by the fluke Fasciola gigantica is endemic in Nigeria and is one of the most common causes of liver condemnation in abattoirs. Total cattle losses from Fasciola infection in Nigeria have been estimated to cost £32.5 million. Other trematode infections of cattle, including paramphistomosis, dicrocoeliasis and schistosomiasis, have all been reported in various parts of Nigeria, with varying prevalence. Most publications on trematode infections are limited to Nigerian local and national journals, with very few international reports. This paper therefore summarized the current data on distribution, control and zoonotic trematode infections in Nigeria and other African countries. We also identified research gaps and made recommendations for future research and areas for funding for policy/planning.

Fasciola hepatica infections in cattle and the freshwater snail Galba truncatula from Dakhla Oasis, Egypt

Infection by Fasciola species was investigated in seven districts of Dakhla Oasis, Egypt, through abattoir inspection of cattle livers for adult worms and sedimentation of faecal samples from local cattle to detect Fasciola eggs. In addition, lymnaeid snails collected from the study area were examined microscopically for developmental stages of Fasciola spp. Abattoir inspection revealed that 51 out of 458 cattle livers (11.1%) contained adult flukes, which were identified morphologically as Fasciola hepatica. Examination of the cattle faecal samples revealed that 142 out of 503 (28.2%) contained Fasciola eggs. The collected snails, identified as Galba truncatula and Radix natalensis, showed larval stages of Fasciola in 71 out of 731 (9.7%) G. truncatula, while R. natalensis showed no infection. Specific duplex polymerase chain reaction (PCR) targeting the mitochondrial cox1 gene of F. hepatica and Fasciola gigantica was carried out on DNA extracted from pooled infected snails and adult worms. The F. hepatica size amplicon (1031 bp) was obtained from both the infected G. truncatula and the adult worms isolated from cattle livers from different districts. The amplicon sequences were identical to the published sequences of F. hepatica mitochondrial cox1 gene. In conclusion, the zoonotic importance of Fasciola infection and appropriate hygienic measures must be taken into consideration in Dakhla Oasis, Egypt.

Morphological and molecular identification of Explanatum explanatum in domestic water buffalo in Pakistan

More than 70 species of the family Paramphistomatidae, have been identified in ruminants in different parts of the world. Most are pathogenic, causing amphistomosis. Adult flukes of this Family have a predilection for the rumen, liver or bile duct of ruminants where they may cause damage to the epithelium. Identification of adult paramphistomes to the species level based on morphology alone requires specialized knowledge, whereas, molecular genetic marker analysis is more precise and transferable. In the present study, we performed both morphological and molecular characterization of fifteen adult flukes collected from the liver of domesticated buffalo in the Punjab province of Pakistan. The morphology of five of these flukes was examined in detail and on this basis these were identified as either Explanatum explanatum or Explanatum bathycotyle. PCR and sequencing of the ITS-2 rDNA region from these 5 flukes, plus 10 others, revealed a single haplotype in all cases. This differed by just a single nucleotide polymorphism from a previously described E. explanatum ITS-2 rDNA sequence. Phylogenetic comparison of these E. explanatum ITS2-rDNA sequences with those from other Paramphistomatidae, Fasciola and Dicrocoelium species was performed to assess within and between species variation and validate the use of ITS-2 rDNA as a robust species-specific marker for E. explanatum. This work provides a validated species-specific marker of E. explanatum and the first report of this parasite species from Pakistan.

Molecular characterization of Fasciola gigantica in Delhi, India and its phylogenetic relation to the species from South Asian countries

The aim of this study was to phylogenetically analyze Fasciola gigantica (F. gigantica) from mainland India and to reveal the expansion history of F. gigantica in the Indian subcontinent. We analyzed 40 Fasciola flukes that were collected from Delhi, in the Indian mainland, and identified them as F. gigantica by using nucleotide analyses of the nuclear phosphoenolpyruvate carboxykinase (pepck) and DNA polymerase delta (pold) genes. Based on the nucleotide sequence of mitochondrial NADH dehydrogenase subunit 1 (nad1) gene, the flukes had 18 haplotypes. The haplotypes were classified under haplogroup A, which is predominant in the F. gigantica of South Asia. The population genetics of haplogroup A revealed that Delhi population showed higher π value than eastern India population. These results suggest that F. gigantica of haplogroup A might have spread from the west to the east in India along with the artificial migration of the domestic Zebu cattle, Bos indicus.

DNA sequence analyses reveal co-occurrence of novel haplotypes of Fasciola gigantica with F. hepatica in South Africa and Zimbabwe

The aim of this study was to identify and determine the genetic diversity of Fasciola species in cattle from Zimbabwe, the KwaZulu-Natal and Mpumalanga provinces of South Africa and selected wildlife hosts from Zimbabwe. This was based on analysis of DNA sequences of the nuclear ribosomal internal transcribed spacer (ITS1 and 2) and mitochondrial cytochrome oxidase 1 (CO1) regions. The sample of 120 flukes was collected from livers of 57 cattle at 4 abattoirs in Zimbabwe and 47 cattle at 6 abattoirs in South Africa; it also included three alcohol-preserved duiker, antelope and eland samples from Zimbabwe. Aligned sequences (ITS 506 base pairs and CO1 381 base pairs) were analyzed by neighbour-joining, maximum parsimony and Bayesian inference methods. Phylogenetic trees revealed the presence of Fasciola gigantica in cattle from Zimbabwe and F. gigantica and Fasciola hepatica in the samples from South Africa. F. hepatica was more prevalent (64%) in South Africa than F. gigantica. In Zimbabwe, F. gigantica was present in 99% of the samples; F. hepatica was found in only one cattle sample, an antelope (Hippotragus niger) and a duiker (Sylvicapra grimmia). This is the first molecular confirmation of the identity Fasciola species in Zimbabwe and South Africa. Knowledge on the identity and distribution of these liver flukes at molecular level will allow disease surveillance and control in the studied areas.

Molecular characterization of veterinary important trematode and cestode species in the mithun Bos frontalis from north-east India

Helminth infections in the mithun Bos frontalis, including the liver fluke Fasciola gigantica, hepato-gastric amphistomes Explanatum explanatum, Paramphistomum epiclitum and Calicophoron calicophorum, and the cestodes Echinococcus granulosus and E. ortleppi were studied in north-east India over a 2-year period from 2012 to 2014. Cystic echinococcosis caused by E. granulosus and E. ortleppi was found to be highly prevalent in the mithun, with E. ortleppi being reported for the first time. Molecular markers, including the internal transcribed spacer 2 (ITS-2), 28S rDNA and mitochondrial NADH dehydrogenase sub-unit1 (nad1) were used to confirm the identification of the trematode and cestode species.

Molecular phylogenetic analysis of Fasciola flukes from eastern India

Fasciola flukes from eastern India were characterized on the basis of spermatogenesis status and nuclear ITS1. Both Fasciola gigantica and aspermic Fasciola flukes were detected in Imphal, Kohima, and Gantoku districts. The sequences of mitochondrial nad1 were analyzed to infer their phylogenetical relationship with neighboring countries. The haplotypes of aspermic Fasciola flukes were identical or showed a single nucleotide substitution compared to those from populations in the neighboring countries, corroborating the previous reports that categorized them in the same lineage. However, the prevalence of aspermic Fasciola flukes in eastern India was lower than those in the neighboring countries, suggesting that they have not dispersed throughout eastern India. In contrast, F. gigantica was predominant and well diversified, and the species was thought to be distributed in the area for a longer time than the aspermic Fasciola flukes. Fasciola gigantica populations from eastern India were categorized into two distinct haplogroups A and B. The level of their genetic diversity suggests that populations belonging to haplogroup A have dispersed from the west side of the Indian subcontinent to eastern India with the artificial movement of domestic cattle, Bos indicus, whereas populations belonging to haplogroup B might have spread from Myanmar to eastern India with domestic buffaloes, Bubalus bubalis.

Molecular evidence shows that the liver fluke Fasciola gigantica is the predominant Fasciola species in ruminants from Pakistan

Fascioliasis is an important disease affecting livestock, with great costs to producers worldwide. It has also become a serious issue for human populations in some endemic areas as an emerging zoonotic infection. There are two Fasciola species of liver fluke responsible for this disease, which occur worldwide, Fasciola hepatica and Fasciola gigantica. Identifying these two species on the basis of adult or egg morphology requires specialist knowledge due to the similarity of characters, and may misidentify putative intermediate or hybrid forms. In this study we sequenced the internal transcribed spacer 2 (ITS-2) rDNA of liver flukes collected from multiple species of hosts from seven localities in the Punjab and Baluchistan provinces of Pakistan, to determine the distribution of these two species. All 46 flukes processed in this study, collected from seven sites, showed the rDNA ITS-2 genotype corresponding to F. gigantica, contradicting previous reports, based on adult and egg morphology, that both species are present in Pakistan, with F. hepatica being the more common.

Techniques for the diagnosis of Fasciola infections in animals: room for improvement

The common liver fluke, Fasciola hepatica, causes fascioliasis, a significant disease in mammals, including livestock, wildlife and humans, with a major socioeconomic impact worldwide. In spite of its impact, and some advances towards the development of vaccines and new therapeutic agents, limited attention has been paid to the need for practical and reliable methods for the diagnosis of infection or disease. Accurate diagnosis is central to effective control, particularly given an emerging problem with drug resistance in F. hepatica. Traditional coprological techniques have been widely used, but are often unreliable. Although there have been some advances in establishing immunologic techniques, these tools can suffer from a lack of diagnostic specificity and/or sensitivity. Nonetheless, antigen detection tests seem to have considerable potential, but have not yet been adequately evaluated in the field. Moreover, advanced nucleic acid-based methods appear to offer the most promise for the diagnosis of current infection. This chapter (i) provides a brief account of the biology and significance of F. hepatica/fascioliasis, (ii) describes key techniques currently in use, (iii) compares their advantages/disadvantages and (iv) reviews polymerase chain reaction-based methods for specific diagnosis and/or the genetic characterization of Fasciola species.

Molecular and Morphological Characterization of Fasciola spp. Isolated from Different Host Species in a Newly Emerging Focus of Human Fascioliasis in Iran

The current study aimed to find out the morphometric and genotypic divergences of the flukes isolated from different hosts in a newly emerging focus of human fascioliasis in Iran. Adult Fasciola spp. were collected from 34 cattle, 13 sheep, and 11 goats from Kohgiluyeh and Boyer-Ahmad province, southwest of Iran. Genomic DNA was extracted from the flukes and PCR-RFLP was used to characterize the isolates. The ITS1, ITS2, and mitochondrial genes (mtDNA) of NDI and COI from individual liver flukes were amplified and the amplicons were sequenced. Genetic variation within and between the species was evaluated by comparing the sequences. Moreover, morphometric characteristics of flukes were measured through a computer image analysis system. Based on RFLP profile, from the total of 58 isolates, 41 isolates (from cattle, sheep, and goat) were identified as Fasciola hepatica, while 17 isolates from cattle were identified as Fasciola gigantica. Comparison of the ITS1 and ITS2 sequences showed six and seven single-base substitutions, resulting in segregation of the specimens into two different genotypes. The sequences of COI markers showed seven DNA polymorphic sites for F. hepatica and 35 DNA polymorphic sites for F. gigantica. Morphological diversity of the two species was observed in linear, ratios, and areas measurements. The findings have implications for studying the population genetics, epidemiology, and control of the disease.

Invasion biology meets parasitology: a case study of parasite spill-back with Egyptian Fasciola gigantica in the invasive snail Pseudosuccinea columella

The liver fluke Fasciola gigantica is a trematode parasite of ruminants and humans that occurs naturally in Africa and Asia. Cases of human fascioliasis, attributable at least in part to F. gigantica, are significantly increasing in the last decades. The introduced snail species Galba truncatula was already identified to be an important intermediate host for this parasite and the efficient invader Pseudosuccinea columella is another suspect in this case. Therefore, we investigated snails collected in irrigation canals in Fayoum governorate in Egypt for prevalence of trematodes with focus on P. columella and its role for the transmission of F. gigantica. Species were identified morphologically and by partial sequencing of the cytochrome oxidase subunit I gene (COI). Among all 689 snails found at the 21 sampling sites, P. columella was the most abundant snail with 296 individuals (42.96%) and it was also the most dominant species at 10 sites. It was not found at 8 sites. Molecular detection by PCR and sequencing of the ITS1-5.8S-ITS2 region of the ribosomal DNA (rDNA) revealed infections with F. gigantica (3.38%), Echinostoma caproni (2.36%) and another echinostome (7.09%) that could not be identified further according to its sequence. No dependency of snail size and trematode infection was found. Both high abundance of P. columella in the Fayoum irrigation system and common infection with F. gigantica might be a case of parasite spill-back (increased prevalence in local final hosts due to highly susceptible introduced intermediate host species) from the introduced P. columella to the human population, explaining at least partly the observed increase of reported fascioliasis-cases in Egypt. Eichhornia crassipes, the invasive water hyacinth, which covers huge areas of the irrigation canals, offers safe refuges for the amphibious P. columella during molluscicide application. As a consequence, this snail dominates snail communities and efficiently transmits F. gigantica.

Neurological and ocular fascioliasis in humans

Fascioliasis is a food-borne parasitic disease caused by the trematode species Fasciola hepatica, distributed worldwide, and Fasciola gigantica, restricted to given regions of Africa and Asia. This disease in humans shows an increasing importance, which relies on its recent widespread emergence related to climate and global changes and also on its pathogenicity in the invasive, biliary, and advanced chronic phases in the human endemic areas, mainly of developing countries. In spite of the large neurological affection capacity of Fasciola, this important pathogenic aspect of the disease has been pronouncedly overlooked in the past decades and has not even appear within the numerous reviews on the parasitic diseases of the central nervous system. The aim of this wide retrospective review is an in-depth analysis of the characteristics of neurological and ocular fascioliasis caused by these two fasciolid species. The terms of neurofascioliasis and ophthalmofascioliasis are restricted to cases in which the direct affection of the central nervous system or the eye by a migrant ectopic fasciolid fluke is demonstrated by an aetiological diagnosis of recovered flukes after surgery or spontaneous moving-out of the fluke through the orbit. Cases in which the ectopic fluke is not recovered and the symptoms cannot be explained by an indirect affection at distance may also be included in these terms. Neurofascioliasis and ophthalmofascioliasis cases are reviewed and discussed. With regard to fascioliasis infection giving an indirect rise to neurological affection, the distribution and frequency of cases are analysed according to geography, sex, and age. Minor symptoms and major manifestations are discussed. Three main types of cases are distinguished depending on the characteristics of their manifestations: genuine neurological, meningeal, and psychiatric or neuropsychic. The impressive symptoms and signs appearing in each type of these cases are included. Brain examination techniques and neuroimaging useful for the diagnosis of neurological cases are exposed. Within fascioliasis infection indirectly causing ocular manifestations, case distribution and frequency are similarly analysed. A short analysis is devoted to clarify the first reports of a human eye infection. The affection of related and close organs is discussed by differentiating between cases of the dorsal spine, pulmonary manifestations, heart and vessel affection, findings in blood vessels, skin and dermatologic reactions, cases of ectopic mature flukes, and upper body locations. The clinical complexity of the puzzling polymorphisms, the disconcerting multifocality of the manifestations, and their changes along the evolution of the disease in the same patient, as well as the differences between the clinical pictures shown by different patients, are highlighted. The many syndromes involved are enumerated. The pathogenic and physiological mechanisms underlying neurofascioliasis and ophthalmofascioliasis caused by ectopic flukes and the physiopathogenic processes indirectly affecting the central nervous system and causing genuine neurological, meningeal, psychiatric, and ocular manifestations are discussed. The diagnosis of neurological and ophthalmologic fascioliasis is analysed in depth, including clinical and paraclinical diagnosis, eosinophilia in the blood and cerebrospinal fluid, differential diagnosis from other parasitic infections such as helminthiases and myiases, an update of human fascioliasis diagnosis, and fluke and/or fluke egg recovery by surgery. Diagnostic analyses with faecal and blood samples for fascioliasis patients are updated. Therapy for patients with major neurological manifestations includes both antiparasitic treatments and anti-inflammatory therapeutics. Prognosis in fascioliasis patients with neurological manifestations is discussed, with emphasis on sequelae and fatal cases, and the care of patients with ophthalmologic manifestations is added. Conclusions indicate that neurological cases are overlooked in human fascioliasis endemic areas and also in developing countries in general. In remote zones, rural health centres and small hospitals in or near the human endemic areas do not dispose of the appropriate equipments for neurological analyses. Moreover, physicians may not be aware about the potential relationship between liver fluke infection and neurological implications, and such cases may therefore remain misdiagnosed, even in developed countries. Priority should henceforth be given to the consideration of neurological and ocular affection in human endemic areas, and efforts should be implemented to assess their characteristics and frequency. Their impact should also be considered when estimating the global burden of fascioliasis.