Human Fascioliasis: Current Epidemiological Status and Strategies for Diagnosis, Treatment, and Control

Demographic Characteristics and Low Iron Status Markers Are Associated with Hemoglobin Levels and Anemia among Children Living at High Elevation in Cusco, Peru

Anemia is a complex condition associated with diet, chronic infections, and blood loss. Children living at high altitudes have higher absolute hemoglobin levels due to hypoxemia. However, they are exposed to repeated infections and dietary limitations. We conducted a cross-sectional study to identify factors affecting the hemoglobin concentration in children living in high-altitude rural communities in the Anta province of Peru. All children 3-16 years of age attending public schools were invited to participate. We enrolled children 3-16 years old in schools and visited their homes to collect demographic, socioeconomic, medical history, and anthropometric data. Children provided blood and stool samples for complete blood counts, iron status markers, and helminth infection testing. Among the 2,000 children enrolled, the mean age was 9.9 (±3.4) years, 1,004 (50.2%) were female, and the median residence altitude was 3,398 (interquartile range 3,35-3,497) meters. The mean hemoglobin level was 15 (±1.15) mg/dL; 320 (16%) had anemia as defined by WHO. Children with anemia were more likely to have lower serum iron levels (odds ratio [OR] 2.8 [95% CI 2.2-3.6], P <0.001) and serum transferrin saturation (OR 2.8 [95% CI 2-3.9], P <0.001). Younger age (OR 0.85 [95% CI 0.82-0.89], P <0.001), stunting (OR 0.68 [95% CI 0.59-0.79], P <0.001), education of the mother (OR 0.94 [95% CI 0.91-0.98], P <0.005), and low eosinophils (OR 0.49 [95% CI 0.26-0.9], P = 0.022) were associated with anemia. Helminth infections were not associated with anemia. Anemia among children at high altitude is multifactorial, but iron deficiency is a contributing factor. Further studies are needed to evaluate iron status and anemia in children living at high altitudes.

Digenean infections in snails (cercariae stage) in Can Gio Mangrove Biosphere Reserve, Ho Chi Minh City, Vietnam

Foodborne zoonotic trematodiasis is a public health problem in many countries. A study on digenean larvae (cercariae stage) obtained from snails in all ten main small canals and two rice fields was carried out in Can Gio Mangrove Biosphere Reserve, Ho Chi Minh city, Vietnam to identify the snail composition and digenean prevalence in snails. The snails were sampled in the dry season (January 2022) and the wet season (June 2022). In the ten canals, 23 snail species belonging to 16 genera, 10 families from the samplings were found; however, there were no cercariae in these 23 snail species. In the two rice fields, 11 snail species in 11 genera and 7 families were collected. In which, Bithynia siamensis in Ly Nhon rice field and Thiara scabra in Binh Khanh rice field infected xiphidio cercariae. For Bithynia siamensis, the prevalence in the dry season (5.6%) was higher than in the wet season (4.6%) (P > 0.05). In Binh Khanh rice field, only one Thiara scabra infected cercariae in the wet season. Further research on digenean infection in different months and in other water bodies in Can Gio Mangrove Biosphere Reserve should be done to contribute to the control of digeneans and reserve the biodiversity.

Uncovering the diversity of pathogenic invaders: insights into protozoa, fungi, and worm infections

Post COVID-19, there has been renewed interest in understanding the pathogens challenging the human health and evaluate our preparedness towards dealing with health challenges in future. In this endeavour, it is not only the bacteria and the viruses, but a greater community of pathogens. Such pathogenic microorganisms, include protozoa, fungi and worms, which establish a distinct variety of disease-causing agents with the capability to impact the host's well-being as well as the equity of ecosystem. This review summarises the peculiar characteristics and pathogenic mechanisms utilized by these disease-causing organisms. It features their role in causing infection in the concerned host and emphasizes the need for further research. Understanding the layers of pathogenesis encompassing the concerned infectious microbes will help expand targeted inferences with relation to the cause of the infection. This would strengthen and augment benefit to the host's health along with the maintenance of ecosystem network, exhibiting host-pathogen interaction cycle. This would be key to discover the layers underlying differential disease severities in response to similar/same pathogen infection.

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.

Advances in diagnostic approaches to Fasciola infection in animals and humans: An overviews

Fasciolosis, caused by Fasciola hepatica and F. gigantica, is an impediment to the livestock industry’s expansion and has a massively negative socio-economic impact due to its widespread prevalence in livestock. It is a waterborne zoonosis affecting human populations in the countries where rural economies are associated with livestock rearing. Conventional diagnosis of Fasciola infection is done by detecting parasite eggs in the faeces of infected animals or by immunological methods. Accurate and quick immunodiagnosis of Fasciola infection in animals and humans is based on the detection of antibodies and specific antigens expressed in the prepatent stage of the parasite. Both molecular and serodiagnostic tests developed thus far have enhanced the reliability of Fasciola diagnosis in both man and animals but are not widely available in resource-poor nations. A pen-side diagnostic test based on a lateral flow assay or a DNA test like loop-mediated isothermal amplification (LAMP) would be simple, fast, and cost-effective, enabling clinicians to treat animals in a targeted manner and avoid the development of drug resistance to the limited flukicides. This review focuses on the recent advances made in the diagnosis of this parasite infection in animals and humans.

Fasciola spp. in Southeast Asia: A systematic review

BACKGROUND

Fasciolosis is an emerging public health threat in a number of regions worldwide. To date, we lack an overview of both its occurrence and distribution in Southeast Asia across all actors involved in the life cycle, which impedes the development of disease control measures. Therefore, our objective was to collect recent information on the distribution and the prevalence of Fasciola spp. and the associated risk factors for infection in humans, animals, snails and plant carriers in Southeast Asia.

METHODOLOGY

Bibliographic and grey literature databases as well as reference lists of important review articles were searched for relevant records published between January 1st, 2000, and June 30th, 2022. The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for reporting systematic reviews. A total of 3,887 records were retrieved, of which 100 were included in the final analysis.

PRINCIPAL FINDINGS

The studies focused mainly on one host species (96.0%), with Fasciola spp. infection in animals being the most studied (72.0%), followed by humans (21.0%). Based on the used inclusion and exclusion criteria, reports were retrieved describing the presence of Fasciola spp. infection in seven out of 11 countries in Southeast Asia. Depending on the diagnostic tool applied, the prevalence of Fasciola spp. infection ranged between 0.3% and 66.7% in humans, between 0% and 97.8% in animals, and between 0% and 66.2% in snails. There were no studies reporting the presence of metacercariae on plant carriers.

CONCLUSIONS/SIGNIFICANCE

Our study reconfirms that Fasciola spp. infections are widespread and highly prevalent in Southeast Asia, but it remains difficult to accurately assess the true occurrence of Fasciola spp. in absence of well-designed surveys covering all hosts. As next steps we propose to assess the occurrence of the infection across all actors involved in the transmission, to identify associated risk factors and to estimate the burden of the disease to support national and international decision makers.

[Climate Crisis: What Gastrointestinal Complications of this Medical Emergency Should We Be Aware Of?]

INTRODUCTION

The climate crisis has serious consequences for many areas of life. This applies in particular to human health - also in Europe. While cardiovascular, pneumological and dermatological diseases related to the climate crisis are often discussed, the crisis' significant gastroenterological consequences for health must also be considered.

METHODS

A literature search (Pubmed, Cochrane Library) was used to identify papers with relevance particularly to the field of gastroenterology in (Central) Europe. Findings were supplemented and discussed by an interdisciplinary team.

RESULTS

The climate crisis impacts the frequency and severity of gastrointestinal diseases in Europe due to more frequent and severe heat waves, flooding and air pollution. While patients with intestinal diseases are particularly vulnerable to acute weather events, the main long-term consequences of climate change are gastrointestinal cancer and liver disease. In addition to gastroenteritis, other infectious diseases such as vector-borne diseases and parasites are important in the context of global warming, heat waves and floods.

DISCUSSION

Adaptation strategies must be consistently developed and implemented for vulnerable groups. Patients at risk should be informed about measures that can be implemented individually, such as avoiding heat, ensuring appropriate hydration and following hygiene instructions. Recommendations for physical activity and a healthy and sustainable diet are essential for the prevention of liver diseases and carcinomas. Measures for prevention and the promotion of resilience can be supported by the physicians at various levels. In addition to efforts fostering sustainability in the immediate working environment, a system-oriented commitment to climate protection is important.

Visceral larva Migrans in a Young Italian Patient: A Diagnostic Dilemma

BACKGROUND

The association of fever, focal hepatic lesions and peripheral hyper-eosinophilia (FHLH) can be observed in both infectious and non-infectious conditions. Fascioliasis, capillariasis, toxocariasis, all causes of visceral larva migrans (VLM), represent most of the former, whilst lymphomas, eosinophilic leukemias and mastocytosis belong in the non-infectious conditions.

METHODS

We prospectively followed a young patient presenting with FHLH in the Tuscany region of Italy.

RESULTS

The patient was subject to serological and parasitological examination in an attempt to clarify the origin of the lesions. Serologies for both Fasciola hepatica and Toxocara spp. were positive, with the latter presenting a higher index. We opted for treatment with a prolonged course of albendazole due to the serological results and being toxocariasis more frequent in our setting. The patient was then subject to radiological follow-up. The patient responded to treatment with albendazole as shown by a decrease in eosinophils, seronegativization for Toxocara spp., clinical and radiological improvement. Toxocariasis was hence considered the most likely diagnosis.

CONCLUSIONS

Parasitic infections cannot be disregarded in the presence of FHLH. Differential diagnosis between these parasitic infections can be challenging due to the presence of similar clinical presentations and serological cross-reactions, and follow-up of the patient is needed to ensure optimal treatment outcomes.

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.

Emerging Human Fascioliasis: A Retrospective Study of Epidemiological Findings in Dali, Yunnan Province, China (2012-2021)

BACKGROUND Human fascioliasis is an emerging zoonotic disease caused by the trematodes, or flatworms, Fasciola hepatica and Fasciola gigantica, also known as liver flukes. This retrospective study aimed to report the epidemiological findings in 95 cases of human fascioliasis in Dali, Yunnan Province, southwestern China, diagnosed between 2012 and 2021. MATERIAL AND METHODS The epidemiologic and clinical data of 95 patients diagnosed with human fascioliasis in Dali area from January 2012 to December 2021 were collected and retrospectively analyzed. The diagnosis of fascioliasis was based on the Chinese National Standard of Diagnosis of Fascioliasis (WS/T566-2017). RESULTS The mean age of patients was 38.54±15.68 years, and there were more female patients than male (61.05% vs 38.95%). The high-incidence seasons were identified as summer and autumn. The patients with human fascioliasis lived in pastoral areas or were infected F. gigantica by consuming contaminated vegetables or water containing metacercaria. Meanwhile, human fascioliasis was diagnosed by positive serologic tests (1: 640), and Fasciola eggs (144-180×73-96 μm) were detected in stool samples of 6 patients. The most common clinical features were abdominal pain (70.53%), accompanied by elevated eosinophils in 89.5% of these patients. Antiparasitic treatment with triclabendazole at 10 mg/kg/day for 2 days led to symptom relief in all patients. CONCLUSIONS The findings from this observational epidemiological study have highlighted the importance of recognizing, diagnosing, and managing fascioliasis, which is an emerging zoonosis associated with increased human proximity to plant-eating domestic and farmed animals.

Clinical characteristics of human fascioliasis in Egypt

There is a lack of epidemiological data on fascioliasis in Egypt regarding disease characteristics and treatment outcomes across different governorates. We aimed to identify the demographic, epidemiologic, clinical, laboratory, and radiological characteristics and treatment outcomes of patients diagnosed with fascioliasis in Egypt. Data on human fascioliasis were collected retrospectively from patients' medical records in the period between January 2018 and January 2020. The study included 261 patients. More than 40% of enrolled patients were in the age group of 21-40 years old. Geographically, 247 (94.6%) were from Assiut Governorate with 69.3% were from rural areas. The most frequent symptoms were right upper quadrant pain (96.9%), and fever (80.1%). Eosinophilia was found in 250 cases (95.8%). Hepatic focal lesions were detected in 131 (50.2%); out of them 64/131 (48.9%) had a single lesion. All patients received a single dose of 10 mg/kg of triclabendazole, 79.7% responded well to a single dose, while in 20.3% a second ± a third dose of treatment was requested. After therapy, there was a reduction in leucocytes, Fasciola antibodies titer, eosinophilic count, bilirubin, and liver enzymes with an increase in hemoglobin level. According to our findings, a high index of suspicion should be raised in cases with fever, right upper abdominal pain, and peripheral eosinophilia, and further imaging workup is mandated to detect hepatic focal lesions. Prompt treatment by triclabendazole can serve as a standard-of-care regimen even for suspected cases.

Genetic variation and population structure of Fasciola hepatica: an in silico analysis

Fasciola hepatica is a trematode leading to heavy economic setbacks to the livestock sector globally. The population's genetic information and intimate kinship level are frequently assessed using analysis of mitochondrial DNA. In this analysis, we retrieved cox1 (n = 247) and nad1 (n = 357) sequences of F. hepatica from the NCBI GenBank database and aligned the sequences with the respective reference sequences using MEGA software. The median joining network was drawn using PopArt software while neutrality and diversity indices were estimated with the help of DnaSp software. Neighbor-joining phylogenetic tree was constructed using the MEGA software package. A total of 46 and 98 distinctive haplotypes were observed for cox1 and nad1 genes, respectively. Diversity indices indicated high haplotype and nucleotide diversities in both genes. Positive Tajima's D and Fu's Fs values were found for the entire population of both the genes under study. The cox1 and nad1 gene segments in this study showed high Tajima's D values, suggesting a low likelihood of future population growth. The Tajima's D value of the nad1 gene sequence is lower (2.14910) than that of the cox1 gene sequence (3.40314), which suggests that the former is growing at a slower rate. However, the region-wise analysis revealed that both the cox1 and nad1 genes showed deviation from neutrality suggesting a recent population expansion as a result of an excess of low-frequency polymorphism. Furthermore, the overall host-wise analysis showed positive and significant Tajima's D values for the cox1 and nad1 gene sequences. To the best of our knowledge, this is the first attempt to provide insights into genetic variations and population structure of F. hepatica at a global scale using cox1 and nad1 genes. Our findings suggest the existence of specific variants of F. hepatica in different parts of the world and provide information on the molecular ecology of F. hepatica. The results of this study also mark a critical development in upcoming epidemiological investigations on F. hepatica and will also contribute to understanding the global molecular epidemiology and population structure of F. hepatica.

ON LIVER FLUKE (FASCIOLA HEPATICA) IN CAPTIVE VICUÑAS (VICUGNA VICUGNA) AT KNOWSLEY SAFARI, PRESCOT, UNITED KINGDOM

Knowsley Safari (KS), Prescot, United Kingdom houses a variety of captive exotic ungulates. As part of their animal welfare plan, a prospective coprological survey was undertaken for liver fluke. In June 2021, 330 fecal samples, representative of 18 exotic ungulate species, were processed by sedimentation and filtration, with examination by coproscopy. Finding fascioliasis in all five vicuña alone, with fecal egg counts ranging from one to eight eggs per gram, anthelminthic treatment was attempted twice, with three coprological reviews. While the first anthelminthic treatment (oxyclozanide) was equivocal, the second anthelminthic treatment (triclabendazole) was proven effective upon two later follow-ups. An initial malacological survey of 16 freshwater sites in KS, first found Galba truncatula at two sites in June 2021, then upon more extensive searching subsequently within the vicuña's enclosure. It appears that F. hepatica was locally acquired, being the first report of fascioliasis within captive vicuñas in the United Kingdom. To develop a better fluke-management plan, regular coprological and malacological surveillance is justified, perhaps with molecular xenomonitoring of snails, alongside prompt administration of appropriate flukicide as required.

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.\.

Phylogenetic Characteristics of Fasciola hepatica Isolated from a Korean Patient

Fascioliasis is a parasitic infection caused by liver flukes. Although several cases have been reported in Korea, phylogenetic analysis of isolates is lacking. In this study, a 66-year-old woman with right upper quadrant (RUQ) abdominal pain was diagnosed as fascioliasis involving abdominal muscle by imaging study. She received praziquantel treatment, but symptoms were not improved. Lateral movement of the abscess lesion was followed. Trematode parasite was surgically removed from the patient’s rectus abdominis muscle. The fluke was identified as Fasciola hepatica based on sequence analysis of 18S rDNA. To determine the phylogenetic position of this Fasciola strain (named Korean Fasciola 1; KF1), the cox1 gene (273 bp) was analyzed and compared with the genes of 17 F. hepatica strains isolated from cows, sheep, goats, and humans from various countries. Phylogenetic analysis showed that KF1 was closely related with the isolates from China goat.

Fasciolosis in sheep and goats slaughtered at abattoirs in Central Ethiopia and associated financial losses

Fasciolosis is a serious animal health problem in Ethiopia where livestock is crucial for the domestic economy. A study was conducted in two Ethiopian abattoirs to estimate the prevalence of Fasciola infection in goats and sheep, and the monetary losses resulting from liver condemnation. Post-mortem examination of 925 animals (424 sheep and 501 goats) were examined by incision of the liver parenchyma for presence of the liver fluke, Fasciola. The direct financial losses were calculated based on the estimated prevalence, the market price of the liver, and the average number of sheep and goats slaughtered annually. The overall prevalence of fasciolosis was 10.4% (20.7% sheep and 1.6% goats). Among the studied variables, species of the study animal and age in sheep showed a statistically significant association with infection (p < 0.05). Based on the annual average of 89,054 sheep and 76,374 goats slaughtered, the annual average economic loss due to the condemned liver was estimated at 3700 US$ (185,232 ETH Birr) for sheep and 245 US$ (12,220 ETH Birr) for goats.

This study revealed that the prevalence of fasciolosis was higher in sheep than in goats, and substantial economic losses occur for the sheep and goat industry. Hence, considering the irrigations schemes in the country, strategic control programs targeting Fasciola infection and intermediate hosts are warranted.

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20.7% of 424 sheep and 1.6% of 501 goats were infected with fasciolosis.

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Young sheep were more commonly affected than adults.

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Sheep and goat livers condemned annually were valued at $3700 US and $245 US, respectively.

Biochemical Evaluation of Antioxidant Enzyme Activities and Lipid Peroxidation Level Associated with Liver Enzymes in Patients with Fascioliasis

Fascioliasis, which is caused by infection with Fasciola gigantica and Fasciola hepatica, is a zoonotic disease with a global distribution. This comparative study aimed to investigate antioxidant enzyme activities and oxidative status of chronic fascioliasis patients. In this study, 20 patients were compared with 10 controls and the levels of superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GPX), catalase (CAT), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzymes were evaluated. The results showed that MDA, CAT, AST, and ALT levels were higher in patients than in controls, while SOD and GPX levels were higher in controls than in patients (P≤0.05). Moreover, the enzyme MDA showed a positive correlation with SOD and GPX in the infected group. The enzyme SOD had an indirect correlation with CAT and a direct correlation with GPX. The positive correlation between ALT and AST was shown to be extremely significant (P≤0.05). The significant decrease in antioxidant enzymes and an increase in serum lipid peroxidation in the red blood cells of patients with fascioliasis indicated the presence of oxidative stress, which showed inflammation and oxidative stress, the pathogenesis of which was indicative of the stage of infection.

Liver Abscess due to Fasciola hepatica: A Case Report of the North of Iran

One of the rare manifestations of fascioliasis is liver abscess. In this paper, we report the case of a 38-year-old woman with a liver abscess caused by Fasciola hepatica (F. hepatica). The patient was referred to the clinic with recurrent fever, right upper quadrant (RUQ) pain, and a large abscess in her liver. Despite the consumption of an antibiotic drug, she still had symptoms. The symptoms began to disappear upon starting the consumption of triclabendazole (TCBZ). Fascioliasis can manifest itself with unusual symptoms that provide no specific clue for its diagnosis. Therefore, it is important to consider F. hepatica in the differential diagnosis of liver abscess, especially in endemic regions.

Fascioliasis complicated by acute necrotizing pancreatitis in an Ethiopian child - a case report on a rare complication of a rarely reported emerging disease

BACKGROUND

Fascioliasis is a zoonotic infection caused by Fasciola spp. (liver fluke). Although infrequently diagnosed, it is emerging as a helminth infection of public health importance in many parts of the world. There are few reports on human fascioliasis from Africa.

CASE REPORT

This article reports a case of a 12-year-old Ethiopian boy who presented with left-sided abdominal pain and a history of frequent consumption of leafy vegetables. His work-up showed leukocytosis with marked eosinophilia, and increased serum amylase and lipase, and imaging confirmed multiple subcapsular hepatic masses as well as acute necrotizing pancreatitis. Upon serological testing for helminths, he tested positive on Fasciola hepatica enzyme-linked immunosorbent assay.

CONCLUSIONS

Fascioliasis may present with acute pancreatitis, and should be considered as a possible diagnosis in people with acute biliary disease in endemic settings.

Molecular characterization of a novel GSTO2 of Fasciola hepatica and its roles in modulating murine macrophages

Fascioliasis is an important zoonotic helminthic disease caused by Fasciola hepatica and poses a serious threat to global public health. To evade the immune response of its host (humans or animals), F. hepatica secretes various antioxidant enzymes such as glutathione transferase (GST) to facilitate its invasion, migration and parasitism in vivo. To investigate the biological functions of a novel omega-class GST (GSTO), the molecular features of GSTO2 of F. hepatica were analyzed by online software, and the biochemical properties in vitro of recombinant GSTO2 (rGSTO2) were dissected. Then, the regulatory roles of rGSTO2 protein in murine macrophages in vitro were further explored. The results revealed that the GSTO2 gene encodes 254 amino acids, which harbor the characteristic N-terminal domain (βαβαββα) and C-terminal domain (α-helical) of the cytoplasmic GST superfamily. GSTO2 was mainly expressed in F. hepatica vitelline follicles, intestinal tract, excretory pores and vitelline cells, with thioltransferase and dehydroascorbate reductase activities. Moreover, rGSTO2 protein could be taken up by murine macrophages and significantly inhibit the viability of macrophages. In addition, rGSTO2 protein could significantly promote apoptosis and modulate the expression of cytokines in macrophages. These findings suggested that F. hepatica GSTO2 plays an important role in modulating the physiological functions of macrophages, whereby this protein might be involved in immunomodulatory and anti-inflammatory roles during infection. This study provided new insights into the immune-evasion mechanism of F. hepatica and may contribute to the development of a potential anti-inflammatory agent.

The Zoonotic Helminth Parasite Fasciola hepatica: Virulence-Associated Cathepsin B and Cathepsin L Cysteine Peptidases Secreted by Infective Newly Excysted Juveniles (NEJ)

Simple Summary

Fasciolosis, caused by the worm parasite Fasciola hepatica (liver fluke), is a global disease of farm animals and a neglected disease of humans. Infection arises from the ingestion of resistant metacercariae that contaminate vegetation. Within the intestine, the parasite excysts as an active larvae, the newly excysted juvenile (NEJ), that borrows through the intestinal wall to infect the host and migrates to the liver. NEJ release, tissue penetration and migration are facilitated by enzymes secreted by the parasite, namely, cathepsin B1 (FhCB1), cathepsin B2 (FhCB2), cathepsin B3 (FhCB3) and cathepsin L3 (FhCL3). While our knowledge of these enzymes is growing, we have yet to understand why the parasites require all four of them to invade the host. In this study, we produced functional recombinant forms of these enzymes and demonstrated that they vary greatly in terms of activity, optimal pH and substrate specificity, suggesting that, combined, these enzymes provide the parasite with an efficient digestion system for different host tissues and molecules. We also identified several compounds that inhibited the activity of these enzymes, but did not affect the ability of the larvae to excyst or survive. However, this does not exclude these enzymes as targets for development of drugs or vaccines.

Abstract

Fasciolosis caused by Fasciola hepatica is a major global disease of livestock and an important neglected helminthiasis of humans. Infection arises when encysted metacercariae are ingested by the mammalian host. Within the intestine, the parasite excysts as a newly excysted juvenile (NEJ) that penetrates the intestinal wall and migrates to the liver. NEJ excystment and tissue penetration are facilitated by the secretion of cysteine peptidases, namely, cathepsin B1 (FhCB1), cathepsin B2 (FhCB2), cathepsin B3 (FhCB3) and cathepsin L3 (FhCL3). While our knowledge of these peptidases is growing, we have yet to understand why multiple enzymes are required for parasite invasion. Here, we produced functional recombinant forms of these four peptidases and compared their physio-biochemical characteristics. Our studies show great variation of their pH optima for activity, substrate specificity and inhibitory profile. Carboxy-dipeptidase activity was exhibited exclusively by FhCB1. Our studies suggest that, combined, these peptidases create a powerful hydrolytic cocktail capable of digesting the various host tissues, cells and macromolecules. Although we found several inhibitors of these enzymes, they did not show potent inhibition of metacercarial excystment or NEJ viability in vitro. However, this does not exclude these peptidases as targets for future drug or vaccine development.

Population pharmacokinetic-pharmacodynamic model of oxfendazole in healthy adults in a multiple ascending dose and food effect study and target attainment analysis

Oxfendazole is a potent veterinary antiparasitic drug undergoing development for human use to treat multiple parasitic infections. Results from two recently completed Phase I clinical trials conducted in healthy adults showed that the pharmacokinetics of oxfendazole is nonlinear, affected by food, and, after the administration of repeated doses, appeared to mildly affect hemoglobin concentrations. To facilitate oxfendazole dose optimization for its use in patient populations, the relationship among oxfendazole dose, pharmacokinetics and hemoglobin concentration was quantitatively characterized using population pharmacokinetic-pharmacodynamic modeling. In fasting subjects, oxfendazole pharmacokinetics was well described by a one-compartment model with first-order absorption and elimination. The change in oxfendazole pharmacokinetics when administered following a fatty meal was captured by an absorption model with one transit compartment and increased bioavailability. The effect of oxfendazole exposure on hemoglobin concentration in healthy adults was characterized by a lifespan indirect response model in which oxfendazole has positive but minor inhibitory effect on red blood cell synthesis. Further simulation indicated that oxfendazole has a low risk of posing a safety concern regarding hemoglobin concentration, even at a high oxfendazole dose of 60 mg/kg once daily. The final model was further used to perform comprehensive target attainment simulations for whipworm infection and filariasis at various dose regimens and target attainment criteria. The results of our modeling work, when adopted appropriately, have the potential to greatly facilitate oxfendazole dose regimen optimization in patient populations with different types of parasitic infections.

Trematode Proteomics: Recent Advances and Future Directions

Trematodes cause disease in millions of people worldwide, but the absence of commercial vaccines has led to an over-reliance on a handful of monotherapies to control infections. Since drug-resistant fluke populations are emerging, a deeper understanding of parasite biology and host interactions is required to identify new drug targets and immunogenic vaccine candidates. Mass spectrometry-based proteomics represents a key tool to that end. Recent studies have capitalised on the wider availability of annotated helminth genomes to achieve greater coverage of trematode proteomes and discover new aspects of the host-parasite relationship. This review focusses on these latest advances. These include how the protein components of fluke extracellular vesicles have given insight into their biogenesis and cellular interactions. In addition, how the integration of transcriptome/proteome datasets has revealed that the expression and secretion of selected families of liver fluke virulence factors and immunomodulators are regulated in accordance with parasite development and migration within the mammalian host. Furthermore, we discuss the use of immunoproteomics as a tool to identify vaccine candidates associated with protective antibody responses. Finally, we highlight how established and emerging technologies, such as laser microdissection and single-cell proteomics, could be exploited to resolve the protein profiles of discrete trematode tissues or cell types which, in combination with functional tools, could pinpoint optimal targets for fluke control.