Trematode Infections

Rare liver diseases in Egypt: Clinical and epidemiological characterization

Illnesses that afflict a tiny number of individuals are referred to as rare diseases (RDs), sometimes called orphan diseases. The local healthcare systems are constantly under financial, psychological, and medical strain due to low incidence rates, unusual presentations, flawed diagnostic standards, and a lack of treatment alternatives for these RDs. The effective management of the once widely spread viral hepatitis B and C has altered the spectrum of liver diseases in Egypt during the last several years. The detection of uncommon disorders such as autoimmune, cholestatic, and hereditary liver diseases has also been made easier by the increasing knowledge and greater accessibility of specific laboratory testing. Finally, despite Egypt's large population, there are more uncommon liver disorders than previously thought. This review article discusses the clinical and epidemiological characteristics of a few uncommon liver disorders and the information currently accessible concerning these illnesses in Egypt.

[Non-viral infections of the liver]

Non-viral infections of the liver are rare to very rare compared to viral infections. They can be caused by various bacteria, helminths, protozoa, and fungi, often leading to liver involvement during dissemination. Some of these infections affect in particular immunocompromised individuals, while others need to be considered in the differential diagnostic work-up in patients returning from tropical countries. In cases where the infection occurs through oral ingestion of eggs, such as in cystic and alveolar echinococcosis, the liver is often the most commonly affected organ. Due to the diversity of non-viral liver infections and their varied clinical manifestations, a comprehensive discussion of all potential pathogens and their effects is not within the scope of this article. Therefore, only a few of these conditions will be discussed in more detail.

The Detection of Circulating Antigen Glutathione S-Transferase in Sheep Infected with Fasciola hepatica with Double-Antibody Sandwich Signal Amplification Enzyme-Linked Immunosorbent Assay

Fasciolosis is a global zoonotic parasitic disease caused by F. hepatica infection that is particularly harmful to cattle and sheep. A biotin-streptavidin signal amplification ELISA (streptavidin-ELISA/SA-ELISA) based on circulating antigens can allow for the early detection of F. hepatica-infected animals and is suitable for batch detection. It is considered to be a better means of detecting F. hepatica infection than traditional detection methods. In this study, using the serum of sheep artificially infected with F. hepatica, the cDNA expression library of F. hepatica was screened, 17 immunodominant antigen genes of F. hepatica were obtained, and glutathione s-transferase (GST) was selected as the candidate detection antigen. Firstly, the GST cDNA sequence was amplified from F. hepatica, followed by the preparation of recombinant protein GST (rFhGST). Then, monoclonal and polyclonal antibodies against rFhGST were prepared using the GST protein. Afterward, the immunolocalization of the target protein in the worm was observed via confocal microscopy, and it was found that the GST protein was localized in the uterus, intestinal tract, and body surface of F. hepatica. Finally, a double-antibody sandwich SA-ELISA based on the detection of circulating antigens was established. There was no cross-reaction with positive sera infected with Dicrocoelium lanceatum (D. lanceatum), Haemonchus contortus (H. contortus), Neospora caninum (N. caninum), or Schistosoma japonicum (S. japonicum). Forty serum and fecal samples from the same batch of sheep in Nong'an County, Changchun City, Jilin Province, China were analyzed using the established detection method and fecal detection method. The positive rate of the SA-ELISA was 17.5%, and the positive rate of the fecal detection method was 15%. The detection results of this method were 100% consistent with commercial ELISA kits. A total of 152 sheep serum samples were tested in Nong'an County, Changchun City, Jilin Province, and the positive rate was 5.92%. This study laid the foundation for the development of serological detection preparations for F. hepatica infection based on the detection of circulating antigens.

Paragonimiasis

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species. Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex. Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 6.1).

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.

Prevalence and Risk Factors of Ovine and Caprine Fasciolosis in the Last 20 Years in China: A Systematic Review and Meta-Analysis

Fasciolosis is a significant zoonotic and common parasitic disease for animals and humans, creating public health concerns worldwide. This study retrieved articles related to the occurrence of Fasciola hepatica and Fasciola gigantica in sheep and goats in China by searching five databases: PubMed, ScienceDirect, the Chinese National Knowledge Infrastructure (CNKI), Wanfang Data, and the VIP Chinese Journal Database. A total of 60 valid articles were captured. The pooled prevalence of ovine and caprine fasciolosis was 26.00%. It was also found to be higher in the subgroups of Northwest China and Shaanxi Province, as well as in areas with a high altitude, rainfall of ≥800 mm, and temperature ranging between 10 °C and 20 °C. Analysis of the type of season and sampling years showed significant (p < 0.05) difference. In other subgroups, sheep (34.74%), hosts aged over 2 years (32.26%), females (48.33%) and free-range animals (26.83%) showed a higher disease prevalence. These results indicated that ovine and caprine fasciolosis was widely distributed, especially in Northwest China. The sampling years and the type of season are risk factors for the prevalence of ovine and caprine fasciolosis. Therefore, strategies for ovine and caprine fasciolosis control should be developed based on these epidemic risk factors, which will reduce the prevalence of fasciolosis in China.

The First Case of Human Hepatic Fasciolosis Presented as Hepatic Pseudotumor Histopathologically Diagnosed in Romania-A Case Report

Human hepatic fasciolosis has been reported in 81 countries, some of which are endemic areas. In Europe, case reports from humans were published in Portugal, Spain, France, and Italy. Regarding Romania, we do not have any data on the prevalence of this parasitosis, with the exception of two cases of twins that were born in Romania and diagnosed in the last 37 years in Italy after joining their mother that lived there. We report the case of a patient diagnosed in Romania with chronic fasciolosis, presented as a hepatic pseudotumor that was diagnosed during the histopathological examination of the hepatic lesion. The patient received oral treatment with triclabendazole, two doses of 10 milligrams (mg) per kilogram (kg) of body weight, given 12 h apart, with no side effects during or after the treatment. The evolution of the patient was favorable. In conclusion, even in areas free of human fasciolosis, the presence of an anemic syndrome especially in children, abdominal pain in the upper quadrants, associated or not with other digestive manifestations, even more so associated with eosinophilia in the acute phase, should be carefully evaluated for ruling out a parasitosis such as fasciolosis even in countries where this diagnosis seems unlikely.

Prevalence of Human and Animal Fasciolosis in Butajira and Gilgel Gibe Health Demographic Surveillance System Sites in Ethiopia

Fasciolosis is regarded as a major challenge to livestock productivity worldwide, but the burden of disease in humans has only started to receive some attention in the past three decades. The aim of this study was to determine the prevalence of human and animal fasciolosis and its determinant factors in the Gilgel Gibe and Butajira Health and Demographic Surveillance System (HDSS) sites in Ethiopia. A study was undertaken among 389 households across the two sites. Face-to-face interviews were conducted to investigate the knowledge, attitudes and practices of households with regard to fasciolosis. Stools from 377 children aged 7–15 years, and 775 animals (cattle, goats and sheep) were analyzed using a proprietary Fasciola hepatica (F. hepatica) coproantigen ELISA kit. The prevalence of fasciolosis in children was 0.5% and 1% in Butajira and Gilgel Gibe HDSS sites, respectively. The overall prevalence of animal fasciolosis was 29%, 29.2%, and 6% among cattle, sheep, and goats, respectively. More than half of the respondents from Gilgel Gibe (59%, n = 115) did not know that humans can be infected with F. hepatica. The majority of respondents in Gilgel Gibe (n = 124, 64%) and Butajira (n = 95, 50%) did not know the transmission route for fasciolosis. Grazing animals were 7 times more likely to be infected with fasciolosis than animals in cut-and-carry production systems (adjusted odds ratio [AOR] = 7.2; 95% confidence interval [CI]: 3.91–13.17). The findings indicated a lack of knowledge amongst local populations about fasciolosis. Thus, there is a need for public health awareness campaigns about fasciolosis in the study areas.

Food- and vector-borne parasitic zoonoses: Global burden and impacts

Around 25% of the global population suffer from one or more parasitic infections, of which food- and vector-borne parasitic zoonotic diseases are a major concern. Additionally, zoonoses and communicable diseases, common to man and animals, are drawing increased attention worldwide. Significant changes in climatic conditions, cropping pattern, demography, food habits, increasing international travel, marketing and trade, deforestation, and urbanization play vital roles in the emergence and re-emergence of parasitic zoonoses. Although it is likely to be underestimated, the collective burden of food- and vector-borne parasitic diseases accounts for ∼60 million disability-adjusted life years (DALYs). Out of 20 neglected tropical diseases (NTDs) listed by the World Health Organization (WHO) and the Centres for Disease Control and Prevention (CDC), 13 diseases are of parasitic origin. There are about 200 zoonotic diseases of which the WHO listed eight as neglected zoonotic diseases (NZDs) in the year 2013. Out of these eight NZDs, four diseases, namely cysticercosis, hydatidosis, leishmaniasis, and trypanosomiasis, are caused by parasites. In this review, we discuss the global burden and impacts of food- and vector-borne zoonotic parasitic diseases.

Survey on Limnic Gastropods: Relationships between Human Health and Conservation

The present work aimed to study ecological aspects related to the distribution pattern of medically important and native freshwater mollusks, found in a rural municipality in the state of Minas Gerais, Brazil. Malacological captures were carried out in aquatic environments (lentic and lotic) from 46 locations between October 2018 and September 2019. The collected specimens were subjected to taxonomic identification and evaluation for infection with trematode larvae. Qualitative data were used to analyze the similarity and the odds ratios between the environmental variables. In total, 1125 specimens were sampled, belonging to the following species: Biomphalaria glabrata, B. tenagophila, B. straminea, B. kuhniana, B. cousini, Biomphalaria sp., and Drepanotrema cimex (Planorbidae), Stenophysa marmorata (Physidae), Omalonyx sp. (Succineidae), Pseudosuccinea columella (Lymnaeidae), and Pomacea sp. (Ampullaridae). Echinostome, strigeocercaria, and xiphidiocercaria types of larval trematodes were detected in S. marmorata and D. cimex. Of note was the similarity in the distribution of S. marmorata, a supposedly endangered species, with that of the medically important Biomphalaria species, with the two sharing environments. This complex scenario led us to reflect on and discuss the need for the control of important intermediate hosts, as well as the conservation of endangered species. This relevant issue has not yet been discussed in detail, in Brazil or in other countries that recommend snail control.

Study of the migration of Fasciola hepatica juveniles across the intestinal barrier of the host by quantitative proteomics in an ex vivo model

Fasciola hepatica is a trematode parasite that infects animals and humans causing fasciolosis, a worldwide-distributed disease responsible for important economic losses and health problems. This disease is of growing public health concern since parasite isolates resistant to the current treatment (triclabendazole) have increasingly been described. F. hepatica infects its vertebrate host after ingestion of the encysted parasite (metacercariae), which are found in the water or attached to plants. Upon ingestion, newly excysted juveniles of F. hepatica (FhNEJ) emerge in the intestinal lumen and cross the intestinal barrier, reach the peritoneum and migrate to the biliary ducts, where adult worms fully develop. Despite the efforts made to develop new therapeutic and preventive tools, to date, protection against F. hepatica obtained in different animal models is far from optimal. Early events of host-FhNEJ interactions are of paramount importance for the infection progress in fasciolosis, especially those occurring at the host-parasite interface. Nevertheless, studies of FhNEJ responses to the changing host environment encountered during migration across host tissues are still scarce. Here, we set-up an ex vivo model coupled with quantitative SWATH-MS proteomics to study early host-parasite interaction events in fasciolosis. After comparing tegument and somatic fractions from control parasites and FhNEJ that managed to cross a mouse intestinal section ex vivo, a set of parasite proteins whose expression was statistically different were found. These included upregulation of cathepsins L3 and L4, proteolytic inhibitor Fh serpin 2, and a number of molecules linked with nutrient uptake and metabolism, including histone H4, H2A and H2B, low density lipoprotein receptor, tetraspanin, fatty acid binding protein a and glutathione-S-transferase. Downregulated proteins in FhNEJ after gut passage were more numerous than the upregulated ones, and included the heath shock proteins HSP90 and alpha crystallin, amongst others. This study brings new insights into early host-parasite interactions in fasciolosis and sheds light on the proteomic changes in FhNEJ triggered upon excystment and intestinal wall crossing, which could serve to define new targets for the prevention and treatment of this widespread parasitic disease.

Fasciolosis caused by the helminth parasite Fasciola hepatica is a serious health and economic problem worldwide. Treatment and prevention of this disease pose several drawbacks that have so far not been solved. The definition of suitable parasite molecular targets to overcome such drawbacks should be based on thoroughly deciphering host-parasite interactions, and in this regard most studies have focused on the adult stages of F. hepatica. Nevertheless, in this context, the study of the transient juvenile stages of this parasite could be of higher utility due to the importance of early interactions with the host for parasite migration and the successful establishment of infection. In this work, we set-up an ex vivo model and performed a quantitative proteomics approach to study the changes in F. hepatica juveniles upon gut passage. We found that the parasite tegument and somatic compartments experienced deep changes in their composition and showed that the host triggers the expression of specific molecules that are important for parasite migration and survival at this stage. The molecules described here could serve to better understand host-parasite interactions and to define new targets against fasciolosis.

The Differences in the Susceptibility Patterns to Triclabendazole Sulfoxide in Field Isolates of Fasciola hepatica Are Associated with Geographic, Seasonal, and Morphometric Variations

Triclabendazole (TCBZ) resistance is an emerging problem in fascioliasis that is not well understood. Studies including small numbers of parasites fail to capture the complexity of susceptibility variations between and within Fasciolahepatica populations. As the first step to studying the complex resistant phenotype−genotype associations, we characterized a large sample of adult F. hepatica with diverging TCBZ susceptibility. We collected parasites from naturally infected livestock slaughtered in the Cusco and Cajamarca regions of Peru. These parasites were exposed to TCBZ sulfoxide (TCBZ.SO) in vitro to determine their susceptibility. We used a motility score to determine the parasite’s viability. We titrated drug concentrations and times to detect 20% non-viable (susceptible conditions) or 80% non-viable (resistant conditions) parasites. We exposed 3348 fully motile parasites to susceptible (n = 1565) or resistant (n = 1783) conditions. Three hundred and forty-one (21.8%) were classified as susceptible and 462 (25.9%) were classified as resistant. More resistant parasites were found in Cusco than in Cajamarca (p < 0.001). Resistant parasites varied by slaughterhouse (p < 0.001), month of the year (p = 0.008), fluke length (p = 0.016), and year of collection (p < 0.001). The in vitro susceptibility to TCBZ.SO in wildtype F. hepatica was associated with geography, season, and morphometry.

R-praziquantel integrated population pharmacokinetics in preschool- and school-aged African children infected with Schistosoma mansoni and S. haematobium and Lao adults infected with Opisthorchis viverrini

Racemic praziquantel (PZQ) is the standard treatment for schistosomiasis and liver fluke infections (opisthorchiasis and clonorchiasis). The development of an optimal pediatric formulation and dose selection would benefit from a population pharmacokinetic (popPK) model. A popPK model was developed for R-PZQ, the active enantiomer of PZQ, in 664 subjects, 493 African children (2-15 years) infected with Schistosoma mansoni and S. haematobium, and 171 Lao adults (15-78 years) infected with Opisthorchis viverrini. Racemate tablets were administered as single doses of 20, 40 and 60 mg/kg in children and 30, 40 and 50 mg/kg in 129 adults, and as 3 × 25 mg/kg apart in 42 adults. Samples collected by the dried-blood-spot technique were assayed by LC-MS/MS. A two-compartment disposition model, with allometric scaling and dual first-order and transit absorption, was developed using Phoenix™ software. Inversely parallel functions of age described the apparent oral bioavailability (BA) and clearance maturation in children and ageing in adults. BA decreased slightly in children with dose increase, and by 35% in adults with multiple dosing. Crushing tablets for preschool-aged children increased the first-order absorption rate by 64%. The mean transit absorption time was 70% higher in children. A popPK model for R-PZQ integrated African children over 2 years of age with schistosomiasis and Lao adults with opisthorchiasis, and should be useful to support dose optimization in children. In vitro hepatic and intestinal metabolism data would help refining and validating the model in younger children as well as in target ethnic pediatric and adult groups.

Distribution of bovine <em>Fasciola gigantica</em> (Cobbold, 1885) in the district des Savanes, northern Côte d'Ivoire

Fascioliasis, caused by an infection with liver flukes of the genus Fasciola, is an important disease of livestock in most parts of the world. However, little is known about the distribution of fascioliasis in sub-Saharan Africa. We report results of a cross-sectional study conducted in 2014 in the district des Savanes in the northern part of Côte d'Ivoire. We obtained 275 livers from bovine suspected with fascioliasis and 51 unsuspected livers from 24 slaughterhouses. Livers were dissected using a standard operating procedure and all Fasciola gigantica flukes were removed from the tissues of the liver and the biliary ducts. We found F. gigantica in 125 livers from bovines suspected with fascioliasis (45.5%) in 10 departments of the district des Savanes. Among the unsuspected livers, five were positive for F. gigantica (9.8%). The distribution of fascioliasis showed considerable spatial heterogeneity, both at regional (ranging from 18.0% to 52.3%) and departmental level (ranging from 14.3% to 64.0%). Poro region was the most affected (52.3%) with a relatively homogeneous distribution. The departments most affected by fascioliasis were M'Bengué (64.0%), Sinématiali (62.1%) and Ferkessédougou (52.9%). Our study confirms that fascioliasis is an important veterinary disease in the northern part of Côte d'Ivoire, and hence, high-risk areas need to be targeted for prevention and control measures.

In silico prediction of secretory proteins of Opisthorchis viverrini, Clonorchis sinensis and Fasciola hepatica that target the host cell nucleus

Liver flukes Fasciola hepatica, Opisthorchis viverrini and Clonorchis sinensis are causing agents of liver and hepatobiliary diseases. A remarkable difference between such worms is the fact that O. viverrini and C. sinensis are carcinogenic organisms whereas F. hepatica is not carcinogenic. The release of secretory factors by carcinogenic flukes seems to contribute to cancer development however if some of these target the host cell nuclei is unknown. We investigated the existence of O. viverrini and C. sinensis secretory proteins that target the nucleus of host cells and compared these with the corresponding proteins predicted in F. hepatica. Here we applied an algorithm composed by in silico approaches that screened and analyzed the potential genes predicted from genomes of liver flukes. We found 31 and 22 secretory proteins that target the nucleus of host cells in O. viverrini and C. sinensis, respectively, and that have no homologs in F. hepatica. These polypeptides have enriched the transcription initiation process and nucleic acid binding in O. viverrini and C. sinensis, respectively. In addition, other 11 secretory proteins of O. viverrini and C. sinensis, that target the nucleus of host cells, had F. hepatica homologs, have enriched RNA processing function. In conclusion, O. viverrini and C. sinensis have 31 and 22 genes, respectively, that may be involved in their carcinogenic action through a direct targeting on the host cell nuclei.

Autonomous Non Antioxidant Roles for Fasciola hepatica Secreted Thioredoxin-1 and Peroxiredoxin-1

Trematode parasites of the genus Fasciola are the cause of liver fluke disease (fasciolosis) in humans and their livestock. Infection of the host involves invasion through the intestinal wall followed by migration in the liver that results in extensive damage, before the parasite settles as a mature egg-laying adult in the bile ducts. Genomic and transcriptomic studies revealed that increased metabolic stress during the rapid growth and development of F. hepatica is balanced with the up-regulation of the thiol-independent antioxidant system. In this cascade system thioredoxin/glutathione reductase (TGR) reduces thioredoxin (Trx), which then reduces and activates peroxiredoxin (Prx), whose major function is to protect cells against the damaging hydrogen peroxide free radicals. F. hepatica expresses a single TGR, three Trx and three Prx genes; however, the transcriptional expression of Trx1 and Prx1 far out-weighs (>50-fold) other members of their family, and both are major components of the parasite secretome. While Prx1 possesses a leader signal peptide that directs its secretion through the classical pathway and explains why this enzyme is found freely soluble in the secretome, Trx1 lacks a leader peptide and is secreted via an alternative pathway that packages the majority of this enzyme into extracellular vesicles (EVs). Here we propose that F. hepatica Prx1 and Trx1 do not function as part of the parasite’s stress-inducible thiol-dependant cascade, but play autonomous roles in defence against the general anti-pathogen oxidative burst by innate immune cells, in the modulation of host immune responses and regulation of inflammation.

Fasciola hepatica Infection Risk for Adult Household Members with Children with Fascioliasis in Cusco, Peru

Fasciola hepatica is highly prevalent in the highlands of Peru. School-age children have the greatest risk of infection. Mass treatment of at-risk populations has been proposed to control the infection and prevent complications. However, the decreasing effectiveness of triclabendazole raises concerns regarding this strategy. Previous studies reported aggregation of Fasciola infection among family members. This study aimed to determine the risk of fascioliasis among household members living with Fasciola-infected children identified through school-based testing. We conducted a cross-sectional study including adult members of households where children with and without fascioliasis were identified. Demographic, epidemiological, and socioeconomic information was collected. One blood sample was drawn to test for Fasciola antibodies, and three stool samples were collected for microscopy for Fasciola ova. We tested 326 adults from 213 households. Of these adult subjects, chronic fascioliasis (24 of 326, 7.4%) was the most common helminth infection. Thirty-nine subjects (12.7%) tested positive for Fasciola antibodies. Combining microscopy and serum antibody tests, 13.2% (43 of 326) had evidence of Fasciola infection. One third (104 of 326, 31.9%) of the participants lived with at least one child infected with Fasciola hepatica. Adults with fascioliasis were four times more likely to live with an infected child. Poverty and diet were associated with increased risk of Fasciola infection. Adults with fascioliasis were significantly more likely to live with Fasciola-infected children.

Meat-borne parasites in the Arab world: a review in a One Health perspective

Meat-borne parasitic zoonoses are generally not well-monitored, and so understanding extent and overall prevalence is problematic. Without sufficient attention, their prevalence can become unexpectedly and unacceptably high. This review sheds light on meat-borne parasites in the Arab world, which includes all the Arab countries situated in the continents of Asia and Africa, with more than 400 million inhabitants distributed in 22 countries. Meat-borne parasites can be divided into two main categories-helminths and protozoa. The main helminths included in this review are Taenia saginata, Taenia solium, Taenia asiatica, Echinococcus spp., Fasciola spp., and Trichinella spiralis, while the meat-borne protozoan parasites are Toxoplasma gondii, Cryptosporidium spp., and Sarcocystis spp. In addition, Linguatula serrata, which belongs to the class Pentastomida, was included. Among those, the genus Taenia is the most frequently reported in the Arab world, particularly T. saginata. Many parasitic infections that are mainly transmitted through pork, although widespread in many parts of the world, are rare in the Arab countries, primarily due to religious proscriptions. The majority of the publications concerning meat-borne parasites were from Egypt, which contains the largest population in the Arab world and the highest population density, in addition to various economic, social, and environmental reasons.

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

Purpose of the Review

This review aims to critically assess current knowledge about the epidemiology, diagnosis, and management of Fasciola infection in humans.

Recent Findings

Fascioliasis is an emerging neglected zoonotic infection affecting the health and wellbeing of human populations. The burden of infection is unclear, and studies have shown the geographic expansion of fascioliasis in human and livestock likely related to climate change. The infection can be asymptomatic or present in acute or chronic forms. Regardless of the presentation, fascioliasis can be associated with long-term complications such as anemia and malnutrition. Early in the infection, antibody testing is the only tool available for diagnosis confirmation. In the chronic forms serology and stool microscopy are helpful. Other tests such as antigen detection and PCR-based methods including isothermal tests have shown promising results. Triclabendazole is the only drug available to treat Fasciola infection. However, reports of resistant infections in livestock and human threaten the clinical care and control of the infection in endemic areas.

Summary

Fascioliasis is an emerging infection around the world with an uncertain burden. Lack of standardization of diagnostic testing and treatment alternatives hinder treatment and control of the infection.

Genetic Differentiation of Opisthorchis-Like Eggs in Northern Thailand Using Stool Specimens Under National Strategic Plan to Control Liver Fluke Infection and Cholangiocarcinoma

Liver fluke infection caused by Opisthorchis viverrini is recognized as a potential risk factor for cholangiocarcinoma (CCA). The National Strategic Plan to Control Liver Fluke Infection and Cholangiocarcinoma has implemented microscopic-based stool examination screening. However, eggs of O. viverrini and minute intestinal flukes (MIFs) are nearly morphologically similar and could result in inaccurate O. viverrini diagnosis. Stool specimens were collected from eight districts of Chiang Mai Province in northern Thailand. Opisthorchis-like eggs were identified with the Kato-Katz technique and differentiated for O. viverrini and MIFs using molecular study by PCR and PCR-restriction fragment length polymorphism targeting the internal transcribed spacer 2 (ITS2) gene. Prevalence of Opisthorchis-like eggs was 5.9% from a total of 9,570 specimens. From PCR assays, all liver flukes were O. viverrini and all MIFs were Haplorchis taichui. The distribution of species was H. taichui (38.2%), O. viverrini (10.5%), coinfection of H. taichui and O. viverrini (37.2%), and 14.1% were negative from PCR. Totally, H. taichui was found in 75.4% of infections from Opisthorchis-like specimens. ITS2 nucleotide sequencing analysis showed a single variant of O. viverrini with no variation and two variants of H. taichui. This study first revealed the genetic background of Opisthorchis-like eggs in northern Thailand. Minute intestinal flukes are occasionally misdiagnosed as O. viverrini leading to misinterpretation and overestimation of the burden of O. viverrini infection. Molecular diagnosis such as PCR could effectively discriminate species of Opisthorchis-like eggs and help shape the robustness of epidemiological data to control liver fluke infection and raise awareness of other risk factors for CCA.

Proteomics and bioinformatics analysis of Fasciola hepatica somatic proteome in different growth phases

Fasciola hepatica (F. hepatica) is a well-known zoonotic parasite that is crucial for economic and public health worldwide. Quantitative proteomics studies have been performed on proteins expressed by F. hepatica to investigate the differential expression of proteomes in different growth phases. And the screening of several marker proteins for use as early diagnostic antigens is essential. In this study, high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was conducted to analyze the differences in the expression of F. hepatica somatic proteins in different growth phases. Furthermore, gene ontology (GO) functional annotation, KEGG metabolic pathway, and clustering analyses were also performed. LC-MS/MS identified 629, 2286, 2254, and 2192 proteins in metacercariae, juvenile flukes 28dpi, immature flukes 59dpi, and adult phases, respectively. GO analysis revealed that differentially expressed proteins (DEPs) were mainly involved in transport, localization, metabolism, enzyme regulation, protein folding and binding, and nucleoside and nucleotide binding. The DEPs were enriched in cells, intracellular components, organelles, cytoplasm, vesicles, and membranes. KEGG pathway annotation results showed that the DEPs were involved in metabolism, genetic information processing, environmental information processing, cellular processes, organismal systems, and other processes. These findings provide a theoretical basis for vaccine development and establishing early diagnostic methods in the future.

Liver fluke infections by Amphimerus sp. (Digenea: Opisthorchiidae) in definitive and fish intermediate hosts in Manabí province, Ecuador

Amphimerus sp. is a fluke that dwells in the biliary tracts of vertebrate definitive hosts including humans, domestic, and wild mammals in Latin America. Opisthorchiid liver infections are rarely studied in the Americas confirming its status as a neglected tropical disease. In Ecuador, small trematode eggs were reported in human cases from the province of Manabí in 1949, and recently, Amphimerus sp. adults were recovered from human and reservoir hosts in the province of Esmeraldas. Due to the lack of research on the infectious sources of Amphimerus sp. in the continent, we have developed a series of epidemiological studies with parasitological and molecular techniques to elucidate the endemicity of opisthorchiid fluke infections. We developed a cross-sectional study in three communities at Pedro Pablo Gómez parish in the province of Manabí, Ecuador. We examined a total of 176 fecal samples to detect opisthorchiid eggs, and four fish species to find opisthorchiid metacercariae. To study adult worms, we treated and purged seven patients in a family and dissected the livers of a dog and a cat infected. We observed morphological features of adults and metacercariae and used polymerase chain reaction with restricted fragment length polymorphism (PCR-RFLP) and DNA sequencing of a section of the ITS2 gene for identification. Small trematode eggs were detected in 63 (35.8%) out of 176 fecal samples of residents in the three study sites. Adult opisthorchiid flukes were recovered from human patients, a dog and a cat, and they were morphologically and molecularly identified as Amphimerus sp. Opisthorchiid metacercariae were also identified molecularly as Amphimerus sp. in four fish species, i.e., Rhoadsia altipinna, Bryconamericus bucay, Andinoacara rivulatus, and Piabucina aureoguttata. Metacercariae of the heterophyid Haplorchis pumilio were also found in the four fish species examined. This is the first study to confirm the current endemicity of Amphimerus sp. in Pedro Pablo Gómez, Manabí, Ecuador. The adult worms isolated here shared morphological characteristics with previous Amphimerus sp. descriptions and were molecularly similar to Amphimerus sp. described in the province of Esmeraldas. Moreover, this study is the first to document four fish species as infection sources of Amphimerus sp. detected via a molecular protocol targeting the metacercariae of the parasite. Fish species identified here should be targeted for public health campaigns to avoid further human liver-fluke infections by Amphimerus sp. or potential intestinal-fluke infections by H. pumilio or others.

Among neglected tropical diseases, foodborne trematodiases rank among the least studied, especially in the Americas. In Ecuador, a parasite of the genus Amphimerus, family Opisthorchiidae, has been found in the biliary ducts of humans, cats, and dogs, in the northern province of Esmeraldas. Reports as old as 1949 document opisthorchiid infections in the coastal province of Manabí. Given a lack of studies elucidating the infective larval stage of these flukes in Ecuador, we decided to conduct parasitological and molecular experiments to characterize the presence of these human liver infections in the area. We found adult Amphimerus sp. flukes in humans and other domestic animals, and its metacercariae in four edible freshwater fish species: Rhoadsia altipinna, Bryconamericus bucay, Andinoacara rivulatus, and Piabucina aureoguttata. Moreover, we found a prevalence of 35.8% of small trematode eggs in humans. Finally, we also found the metacercariae of the intestinal fluke Haplorchis pumilio in all fish species examined. Our findings confirm the area of Pedro Pablo Gómez as an endemic region for opisthorchiid liver infections due to Amphimerus sp., and expand the human differential diagnosis of small trematode eggs to liver and intestinal flukes. Consumption of undercooked freshwater fish of the species identified here could lead to Amphimerus sp. infections. Surveillance in other areas known for raw fish consumption would likely unveil new cases of foodborne trematodiases in Ecuador and other regions.

A Case of Fasciolosis in a 11-Year-Old Syrian Immigrant Boy

Fasciolosis is a chronic parasitic disease caused by two species of liver trematodes, Fasciola hepatica and Fasciola gigantica, which infest ruminants and rarely humans. The disease is spread all over the world, but more common in Asia in areas with extensive livestock farming and can be imported cases in Europe and America. In this case, we describe imported infection with F. hepatica in Bulgaria from 11-year-old Syrian immigrant boy.

Case Report: Hepatic Fascioliasis in a Young Afghani Woman with Severe Wheezing, High-Grade Peripheral Eosinophilia, and Liver Lesions: A Brief Literature Review

A 23-year-old recent emigrant from Afghanistan presented in August 2017 with severe wheezing and dyspnea that required hospital admission. Her illness was associated with marked peripheral blood eosinophilia (9,900-15,600/µL; 45.2-68%), as well as mild nausea, epigastric pain, and decreased appetite. She had lived until 3 months earlier in close proximity to cattle in her home in Kabul and did not recall eating watercress or other leafy plants associated with Fasciola hepatica transmission. Computerized tomography scanning showed bilateral ground-glass lung consolidations and multiple distinctive hypo-attenuating linear, tubuliform, and nodular liver lesions, including a large subcapsular hematoma. Numerous tests for rheumatological and malignant disorders were negative. Fasciola hepatica infestation was suspected on epidemiological, clinical, and radiographic grounds, and was confirmed by immunoblotting at the Centers for Disease Control (CDC). Multiple stool ova and parasite examinations were negative and endoscopic retrograde cholangiopancreatography did not identify trematodes. Her acute respiratory illness resolved with asthma-targeted therapies and her eosinophilia resolved with triclabendazole, which was obtained from CDC via an FDA Investigational New Drug application. Fascioliasis is uncommon in the United States, but the prolonged warfare and civil strife in Afghanistan and adjacent areas may lead to increased incidence outside the endemic region. Her case also demonstrates how hepatic imaging features of fascioliasis can be pathognomonic in clinical scenarios with eosinophilia and appropriate epidemiology and clinical features. We also highlight her relatively unusual presentation with symptoms of Loeffler-like syndrome alone.

Highlights of human ectopic fascioliasis: a systematic review

Fascioliasis is a tropical zoonotic disease caused by the Fasciola parasite. The adult parasite usually resides in the liver and biliary ducts; however, several cases of ectopic fascioliasis (EF) have been reported. This study is a highlight on EF according to the confirmed case reports. In a setting of systematic review, we found 25 eligible articles containing 26 confirmed cases of EF (any date until 30 November 2018), including abdominal and intestinal EF in six cases, skin and subcutaneous tissues in five cases, eye in four cases, brain and pancreas in three cases, neck and lymph node in two cases, and lung, dorsal spine, and peritoneal cavity in one case, respectively. The result indicates that fascioliasis can have diverse ectopic forms and should be more attended in the endemic regions of fascioliasis in order to distinguish from other endemic diseases.

Recent developments in the epidemiology, diagnosis, and treatment of Fasciola infection

PURPOSE OF REVIEW

This review aims at describing the latest research in Fasciola epidemiology, diagnosis, treatment, and control in endemic countries.

RECENT FINDINGS

The geographic distribution and range of reservoirs for Fasciola hepatica continues to expand. The impact of fascioliasis goes beyond human disease to affect food security and income in developed and developing countries. Promising serologic and molecular methods to diagnose fascioliasis have been described, but are not widely available. Triclabendazole remains the only highly active medication to treat human and livestock infected with juvenile and adult forms of Fasciola spp. Efforts to control fascioliasis may be hindered by the emergence of resistance to triclabendazole among livestock and subsequently in humans.

SUMMARY

Increased awareness and surveillance are likely to uncover the real distribution and burden of fascioliasis in human. Research into new drugs or adjuvants to tackle the emerging resistance to triclabendazole is imperative to treat and control Fasciola infection.

Is Opisthorchis viverrini Emerging in Cambodia?

Opisthorchis viverrini infection is widely prevalent in Southeast Asia. In Cambodia information on this helminth infection is scare. Recent reports suggest that O. viverrini is an emerging public health problem. We aimed to synthesize all information in relation to the infection, epidemiology, and morbidity of O. viverrini in Cambodia; from published as well as thus far unpublished sources. First reports on O. viverrini date back to 1995. In 2006 an O. viverrini initiative was launched by the national helminth control program. Since then O. viverrini has been reported in all - except two - provinces. Villages with high prevalences (>20%) were found in provinces from Preah Vihear to Takeo. The infection has a highly focal distribution. In many villages no infections were detected. O. viverrini infection was also reported in cats, dogs and intermediate hosts. No report on morbidity associated with O. viverrini was found. The current evidence suggests that O. viverrini infection remains underreported in Cambodia. It is likely that the transmission will further increase in the future with potentially serious consequences for human health.

The cathepsin-like cysteine peptidases of trematodes of the genus Fasciola

Fasciolosis caused by trematode parasites of the genus Fasciola is a global disease of livestock, particularly cattle, sheep, water buffalo and goats. It is also a major human zoonosis with reports suggesting that 2.4-17 million people are infected worldwide, and 91.1 million people currently living at risk of infection. A unique feature of these worms is their reliance on a family of developmentally-regulated papain-like cysteine peptidases, termed cathepsins. These proteolytic enzymes play central roles in virulence, infection, tissue migration and modulation of host innate and adaptive immune responses. The availability of a Fasciola hepatica genome, and the exploitation of transcriptomic and proteomic technologies to probe parasite growth and development, has enlightened our understanding of the cathepsin-like cysteine peptidases. Here, we clarify the structure of the cathepsin-like cysteine peptidase families and, in this context, review the phylogenetics, structure, biochemistry and function of these enzymes in the host-parasite relationship.

Uncooked fish consumption among those at risk of Opisthorchis viverrini infection in central Thailand

In contrast to northern and northeastern Thailand, central Thailand was believed not to be endemic for Opisthorchis viverrini (OV). Fieldwork conducted in a rural area of central Thailand revealed that the prevalence and incidence were relatively high compared with regional average data. We hypothesized that the behavioural-psycho-social background of the study population might play an important role in the high burden of the infection. As a result, a qualitative study was conducted to highlight potential social determinants of the infection dynamics to gain greater understanding of the risk behaviours and their contexts. A qualitative study using focus group discussion and in-depth interviews was conducted in Na-ngam Village, Chachoengsao Province from 2012-14. Framework analysis was used to explore associations between infection and thematic content. Social influence showed a strong impact on infection dynamics of OV infection. Our results revealed that Koi pla (chopped raw fish salad) remains a popular dish in the community, as the dish itself represents northeastern culture. The cultural norm had been transferred from ancestors to their descendants. Some elders complained that discontinuing the consumption of Koi pla went against old traditions with respect to cultural norms and socialization. In contrast, modern education teaches about hygiene including OV infection risks, and accordingly teenagers and young adults were reported to modify their lifestyles including their eating habits. Children are a potential key to pass knowledge to their parents and school-based education programs can serve as a practical hub for knowledge dissemination. However, health education alone might not lead to behavioural change in other age groups. Therefore, more efforts are needed to support the transformation.

Paragonimiasis

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species (Table 5.1). Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex (Table 5.1). Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 5.1).

Estimation of disability weight for paragonimiasis: a systematic analysis

Background

Paragonimiasis, caused by helminths of the genus Paragonimus spp., is a neglected tropical disease. Human suffering from paragonimiasis is often misunderstood and its quantification by the disability weight of the disability-adjusted life years largely varies in different global burden of disease (GBD) estimates. This paper is to systematically review clinical paragonimiasis cases and requantify the disability weight of human paragonimiasis.

Methods

A systematic analysis was conducted using articles from the following databases: PubMed, Institute for Scientific Information Web of Science, China National Knowledge Infrastructure, the Chinese scientific journal databases Wanfang Data and CQVIP, Africa Journal Online, and the System for Information on Grey Literature in Europe. Search terms were the combination of “paragonim*” with “clinical” or “infection”. Only articles fulfilling the following conditions were recruited for this study: the occurrence of clinical signs and symptoms of paragonimiasis in human beings were reported; diagnosis was confirmed; no comorbidities were reported; the reviewed clinical cases or epidemiological findings were not already included in any other articles. The information and frequencies of paragonimiasis outcomes from included articles using predefined data fields were extracted two times by two separate individuals. Outcome disability weights were selected mainly from the GBD 2004 and GBD 2013 datasets. Frequencies and disability weights of paragonimiasis outcomes were modelled into a decision tree using the additive approach and multiplicative approach, respectively. Monte Carlo simulations were run 5000 times for an uncertainty analysis.

Results

The disability weight estimates of paragonimiasis were simulated with 5302 clinical cases from 80 general articles. The overall disability weight was estimated at 0.1927 (median 0.1956) with a 95% uncertainty interval (UI) of 0.1632–0.2378 using the additive approach, and 0.1791 (median 0.1816) with a 95% UI of 0.1530–0.2182 using the multiplicative approach. The simulated disability weights of Paragonimus westermani cases were higher than that of P. skrjabini cases. Lung outcomes and headache were the top two contributors to disability weight for both species.

Conclusions

The use of paragonimiasis disability weight needs to be reconsidered with regard to availability of morbidity data and species variation. Calculating the disease burden of paragonimiasis requires further modification and thus has considerable implications for public health prioritization in research, monitoring, and control.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0485-5) contains supplementary material, which is available to authorized users.

Paragonimus and paragonimiasis in West and Central Africa: unresolved questions

Paragonimiasis, human lung fluke disease, is a foodborne anthropozoonosis caused by the trematodes assigned to Paragonimus and is regarded by the World Health Organization as a Neglected Tropical Disease (NTD). The life cycle of this medically important parasite centres on a complex freshwater biological community that includes two intermediate hosts: a mollusc and a decapod, usually a brachyuran. Although there is a perception that the biology, symptoms, diagnosis and treatment of Paragonimus is well understood, in reality, this is not the case, especially in Africa. Much remains unknown concerning the life-cycle of the parasite, its transmission, the current epidemiology of the disease, diagnosis and the effectiveness of treatment. Furthermore, cases of paragonimiasis may be misdiagnosed as resistant tuberculosis (TB) because of the similar pulmonary symptoms and no remission after anti TB therapy. The endemic foci of human paragonimiasis in Africa have been reported mainly in the forest zones of Upper Guinea (Liberia, Guinea and Ivory Coast) and Lower Guinea (Nigeria, Cameroon, Equatorial Guinea and Gabon). Despite the perceived medical importance of paragonimiasis, relatively little attention has been paid to this NTD since its discovery in Africa in the 1960s. This review focuses on the current understanding of the life cycle and transmission of Paragonimus in Africa, discusses its diagnosis and public health importance and highlights many outstanding gaps in the knowledge that still exist for this NTD.

Impact of Human Activities on Fasciolosis Transmission

Fasciolosis is a worldwide disease caused by the liver fluke Fasciola spp. This food- and water-borne disease is a major public health and veterinary issue. It is currently (re)emerging in several regions mainly due to the rapid evolution of human activities. This article reviews the current knowledge of the impact of irrigation-system management, livestock management, and human diet and hygiene habits on the emergence of fasciolosis. We also identify the gaps in this knowledge and the possible solutions for limiting these impacts. Integrated control seems to be the most effective solution for controlling fasciolosis, because it enables monitoring, prevention, and rapid action in case of the (re)emergence of the disease.

A Case of Fascioliasis in A Wild Nutria, Myocastor coypus, in Republic of Korea

A total of 44 adult or juvenile nutrias were necropsied for disease survey. A large nodule was found in the liver of a nutria. The histopathological specimen of the hepatic nodule was microscopically examined, and sectional worms were found in the bile duct. The worms showed a tegument with spines, highly branches of vitelline glands and intestine. Finally, we histopathologically confirmed fascioliasis in a wild nutria. In the present study, a case of fascioliasis in a wild nutria is first confirmed in Korea.

Rapid diagnosis of parasitic diseases: current scenario and future needs

BACKGROUND

Parasitic diseases are one of the world's most devastating and prevalent infections, causing millions of morbidities and mortalities annually. In the past, many of these infections have been linked predominantly to tropical or subtropical areas. Nowadays, however, climatic and vector ecology changes, a significant increase in international travel, armed conflicts, and migration of humans and animals have influenced the transmission of some parasitic diseases from 'book pages' to reality in developed countries. It has also been noted that many patients who have never travelled to endemic areas suffer from blood-borne infections caused by protozoa. In the light of existing knowledge, this new trend can be explained by the fact that in the process of migration a large number of asymptomatic carriers become a part of the blood bank donor and transplant donor populations. Accurate and rapid diagnosis represents the crucial weapon in the fight against parasitic infections.

AIMS

To review old and new approaches for rapid diagnosis of parasitic infections.

SOURCES

Data for this review were obtained through searches of PubMed using combinations of the following terms: parasitological diagnostics, microscopy, lateral flow assays, immunochromatographic assays, multiplex-PCR, and transplantation.

CONTENT

In this review, we provide a brief account of the advantages and limitations of rapid methods for diagnosis of parasitic diseases and focus our attention on current and future research in this area. The approximate costs associated with the use of different techniques and their applicability in endemic and non-endemic areas are also discussed.

IMPLICATIONS

Microscopy remains the cornerstone of parasitological diagnostics, especially in the field and low-resource settings, and provides epidemiological assessment of parasite burden. However, increased use and availability of point-of-care tests and molecular assays in modern era allow more rapid and accurate diagnoses and increased sensitivity in the identification of parasitic infections.

Pleiotropic alterations in gene expression in Latin American Fasciola hepatica isolates with different susceptibility to drugs

Background

Fasciola hepatica is the main agent of fasciolosis, a zoonotic disease affecting livestock worldwide, and an emerging food-borne disease in humans. Even when effective treatments are available, drugs are costly and can result in tolerance, liver damage and normally they do not prevent reinfection. Drug-resistant strains in livestock have been reported in various countries and, more worryingly, drug resistance in human cases has emerged in South America. The present study aims to characterize the transcriptome of two South American resistant isolates, the Cajamarca isolate from Peru, resistant to both triclabendazole and albendazole (TCBZR/ABZR) and the Rubino isolate from Uruguay, resistant to ABZ (TCBZS/ABZR), and compare them to a sensitive strain (Cenapa, Mexico, TCBZS/ABZS) to reveal putative molecular mechanisms leading to drug resistance.

Results

We observed a major reduction in transcription in the Cajamarca TCBZR/ABZR isolate in comparison to the other isolates. While most of the differentially expressed genes are still unannotated, several trends could be detected. Specific reduction in the expression levels of cytoskeleton proteins was consistent with a role of tubulins as putative targets of triclabendazole (TCBZ). A marked reduction of adenylate cyclase might be underlying pleiotropic effects on diverse metabolic pathways of the parasite. Upregulation of GST mu isoforms suggests this detoxifying mechanism as one of the strategies associated with resistance.

Conclusions

Our results stress the value of transcriptomic approaches as a means of providing novel insights to advance the understanding of drug mode of action and drug resistance. The results provide evidence for pleiotropic variations in drug-resistant isolates consistent with early observations of TCBZ and ABZ effects and recent proteomic findings.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2553-2) contains supplementary material, which is available to authorized users.

Efficacy and safety of tribendimidine versus praziquantel against Opisthorchis viverrini in Laos: an open-label, randomised, non-inferiority, phase 2 trial

BACKGROUND

Praziquantel is the only option for treatment of the liver fluke infection Opisthorchis viverrini. Tribendimidine could be an alternative drug. We aimed to assess the efficacy and safety of a single, oral dose of tribendimidine, compared with praziquantel administered in two doses, in participants with O viverrini infection.

METHOD

We did an open-label, randomised, non-inferiority, phase 2 trial in children (8-14 years) and adolescents and adults (≥15 years) in Champasack province, southern Laos. Participants infected with O viverrini were randomly assigned (1:1), via a computer-generated block-randomisation procedure (block sizes of two, four, and six), to receive a single, oral dose of tribendimidine (200 mg for children, 400 mg for adolescents and adults) or two oral doses of praziquantel (50 mg/kg bodyweight and 25 mg/kg bodyweight, 6 h apart). Physicians assessing adverse events and laboratory personnel were masked to treatment allocation, but the investigators administering treatment and the participants could have recognised the treatment group based on differences in the number, appearance, and odour of the tablets. The primary outcomes were cure rate, defined as no parasite eggs in stool at 3 weeks' follow-up, and egg reduction rate. We did available-case analysis of all participants with primary endpoint data. The non-inferiority margin for the difference in cure rates between the groups was pre-specified as -3 percentage points. Adverse events were monitored at 3 h and 24 h after treatment. This trial is registered, number ISRCTN96948551.

FINDINGS

Between Feb 1, and April 30, 2014, we assigned 607 participants with confirmed O viverrini infection to receive tribendimidine (n=300) or praziquantel (n=307). 11 participants (five in the tribendimidine group and six in the praziquantel group) did not provide stool samples at 3 weeks' follow-up and were excluded from the available-case analysis. 276 (93·6%) of 295 participants in the tribendimidine group were cured compared with 293 (97·3%) of 301 participants in the praziquantel group. The difference in cure rates between the two groups was -3·8 percentage points (95% CI -7·1 to -0·4), thus the lower limit of the confidence interval exceeded the non-inferiority margin. In both treatment groups, egg reduction rates were 99·9%. Adverse events were of mild and moderate intensity and were more frequent in the praziquantel group than in the tribendimidine group (odds ratio 4·5, 95% CI 3·2-6·3; p<0·0001). The most frequent adverse events were headache, vertigo, nausea, and fatigue.

INTERPRETATION

Tribendimidine has a slightly lower cure rate than praziquantel and non-inferiority was not shown. However, tribendimidine has a similar egg reduction rate to praziquantel and leads to fewer adverse events and thus might complement praziquantel in O viverrini control programmes, particularly in settings co-endemic for hookworm.

FUNDING

Joint Global Health Trials scheme from the Wellcome Trust, Department for International Development, and Medical Research Council.

Soluble expression and purification of a full-length asparaginyl tRNA synthetase from Fasciola gigantica

We report the molecular cloning, expression, and single-step homogeneous purification of a full-length asparaginyl tRNA synthetase (NRS) from Fasciola gigantica (FgNRS). Fasciola gigantica is a parasitic liver fluke of the class Trematoda. It causes fascioliasis that infects the liver of various mammals, including humans. Aminoacyl tRNA synthetases (AARS) catalyze the first step of protein synthesis. They attach an amino acid to its cognate tRNA, forming an amino acid-tRNA complex. The gene that codes for FgNRS was generated by amplification by polymerase chain reaction. It was then inserted in the expression vector pQE30 under the transcriptional control of the bacteriophage T5 promoter and lac operator. M15 Escherichia coli strain transformed with the FgNRS expression vector pQE30-NRS accumulates large amounts of a soluble protein of about 61 kDa. The protein was purified to homogeneity using immobilized metal affinity chromatography. The recombinant protein was further confirmed by immunoblotting with anti-His antibody. Following size exclusion chromatography, the FgNRS was stable and observed to be a dimeric protein. In this study, the expression and purification procedures have provided a simple and efficient method to obtain full-length FgNRS in large quantities. This will provide an opportunity to study the structure, dynamics and function of NRS.

Association of Fasciola hepatica Infection with Liver Fibrosis, Cirrhosis, and Cancer: A Systematic Review

Background

Fascioliasis has been sporadically associated with chronic liver disease on previous studies. In order to describe the current evidence, we carried out a systematic review to assess the association between fascioliasis with liver fibrosis, cirrhosis and cancer.

Methodology and Principal Findings

A systematic search of electronic databases (PubMed, LILACS, Scopus, Embase, Cochrane, and Scielo) was conducted from June to July 2015 and yielded 1,557 published studies. Among 21 studies that met inclusion and exclusion criteria, 12 studies explored the association of F. hepatica with liver fibrosis, 4 with liver cirrhosis, and 5 with cancer. Globally these studies suggested the ability of F. hepatica to promote liver fibrosis and cirrhosis. The role of F. hepatica in cancer is unknown. Given the heterogeneity of the studies, a meta-analysis could not be performed.

Conclusions

Future high-quality studies are needed to determine the role of F. hepatica on the development of liver fibrosis, liver cirrhosis, and cancer in humans.

Fascioliasis is a neglected infectious disease caused by the trematode Fasciola. This parasite (liver fluke) is endemic in many parts of the world including countries from Asia, Africa, Europe and the Americas. High prevalence rates of fascioliasis has been repeatedly reported in the Andean region of South America. Liver complications in infected humans by this fluke have been sporadically reported in the literature. For instance, the relationship between F. hepatica infection and liver fibrosis has been suggested but its association with cancer is unclear. In this study, we found some evidence of an association between Fasciola infection with liver fibrosis and cirrhosis, but little between Fasciola and cancer. As Fasciola is highly endemic in some regions of the developing world, our study shed light on the complications of this parasitic infection which are not that different from flukes such as Schistosoma or Opisthorchis. We believe that further investigations are needed in order to elucidate the pathways in how F. hepatica infection causes liver damage.

Infections Associated with Exotic Cuisine: The Dangers of Delicacies

"Exotic" food dishes are an expression of regional culture, religion, and ethnicity worldwide. With the increase in international travel to remote areas of the world, globalization of the food supply, and changes in food habits, more people are consuming dishes once considered exotic. Such behavioral changes require awareness by consumers and clinicians about the risks of food-borne infections. This chapter addresses pathogens associated with consumption of raw or undercooked seafood including anisakidosis, Diphyllobothrium latum infection, flukes, and other infectious and toxin-mediated diseases. We discuss the geographic distribution of the pathogens, symptomatology, and basic principles of treatment. Food products derived from turtles, snakes, and other reptiles are reviewed, and we address the risk of gnathostomiasis, sparganosis, trichinellosis, and other pathogens. In discussing infections associated with undercooked beef, pork, and bush meat, we address dysentery, amebiasis, toxoplasmosis, Taenia infections, and risks of novel viral infections, among others. We also review infectious risks from poultry, dairy, and other food items, focusing on those organisms encountered less frequently by clinicians in developed countries. The wide range of infectious organisms related to exotic cuisine underscores the importance of educating the adventurous traveler and warrants continued vigilance on the part of the clinician.

A prospective view of animal and human Fasciolosis

Fasciolosis, a food-borne trematodiasis, results following infection with the parasites, Fasciola hepatica and Fasciola gigantica. These trematodes greatly affect the global agricultural community, infecting millions of ruminants worldwide and causing annual economic losses in excess of US $3 billion. Fasciolosis, an important zoonosis, is classified by WHO as a neglected tropical disease with an estimated 17 million people infected and a further 180 million people at risk of infection. The significant impact on agriculture and human health together with the increasing demand for animal-derived food products to support global population growth demonstrate that fasciolosis is a major One Health problem. This review details the problematic issues surrounding fasciolosis control, including drug resistance, lack of diagnosis and the threat that hybridization of the Fasciola species poses to future animal and human health. We discuss how these parasites may mediate their long-term survival through regulation and modulation of the host immune system, by altering the host immune homeostasis and/or by influencing the intestinal microbiome particularly in respect to concurrent infections with other pathogens. Large genome, transcriptome and proteomic data sets are now available to support an integrated One Health approach to develop novel diagnostic and control strategies for both animal and human disease.

Molecular testing for clinical diagnosis and epidemiological investigations of intestinal parasitic infections

Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.

Mucocutaneous manifestations of helminth infections: Trematodes and cestodes

In the 21st century, despite increased international travel for vacation, work, and medical missions and immigration into the United States, there is little published in the dermatology literature regarding the cutaneous manifestations of helminth infections. It has been estimated that 20% to 70% of international travelers suffer from some travel-related health problem. Approximately 17% of travelers seek medical care because of cutaneous disorders, many related to infectious etiologies. This review will focus on cutaneous diseases caused by helminth infections. Part I of the review focused on nematode infections; part II will focus on trematode and cestode infections. Nematodes are roundworms that cause diseases with cutaneous manifestations, such as cutaneous larval migrans, onchocerciasis, filariasis, gnathostomiasis, loiasis, dracunculiasis, strongyloidiasis, ascariasis, streptocerciasis, dirofilariasis, and trichinosis. Tremadotes, also known as flukes, cause schistosomiasis, paragonimiasis, and fascioliasis. Cestodes (tapeworms) are flat, hermaphroditic parasites that cause diseases such as sparganosis, cysticercosis, and echinococcus.

Declining prevalence of pulmonary paragonimiasis following treatment & community education in a remote tribal population of Arunachal Pradesh, India

Background & objectives:

In India, human pulmonary paragonimiasis is an important public health problem in the northeastern (NE) region. In 2005 we reported a hyperendemic focus of paragonimiasis in a remote tribal village in the hills of Changlang district in Arunachal Pradesh. The community was made aware of the disease and all active cases were treated. This study was aimed to assess the decline in the prevelance of paragonimiasis in the same area after a re-survey done in 2011 after a gap of six years.

Methods:

Re-surveys were carried to determine the reduction in the prevalence of paragonimiasis. Community education was given to the villagers to raise their awareness about paragonimiasis. A total of 624 individuals including 301 children (age < 15 yr) were included in the study. Sputum and stool samples were examined for eggs of lung flukes. Serum samples were screened for IgG antibodies against lung fluke antigen by ELISA.

Results:

A significant (P<0.001) decline in the prevalence of paragonimiasis was found. There was decline in both ELISA positivity and egg positivity. Antibody positivity against excretory-secretary (ES) antigen in children (age ≤ 15 yr) fell down from earlier 51.7 to 15.9 per cent and in individuals 16 - 30 yr of age the serological prevalence fell down from 22.4 to 8.2 per cent and in individuals aged ≥ 31 yr, the decline in prevalence was from 15.3 to 3.7 per cent. Gender-wise analysis revealed that the decline in ELISA positivity was similar in both genders and fell down from 33.9 to 11.5 per cent in males and from 29.8 to 10.7 per cent in females. Similarly, there was a significant decline rate in egg positivity also.

Interpretation & conclusions:

The strategy of hotspot targeted active paragonimiasis case detection and treatment of infected cases together with community education appears to be feasible methods to achieve control of paragonimiasis in this region.