Threat of alveolar echinococcosis to public health – a challenge for Europe

Cestodes in Eurasian wolves (Canis lupus lupus) and domestic dogs (Canis lupus familiaris) in Switzerland

Eurasian wolves (Canis lupus lupus) and domestic dogs (Canis lupus familiaris) are definitive hosts of numerous cestode species. While infections with adult stages in canids are usually subclinical, some species pose a zoonotic risk or cause infections in wildlife and livestock, resulting in disease and/or economic losses. This study aimed to determine the prevalence, species composition, and geographical distribution of cestode infections in dogs and free-ranging wolves in Switzerland. Faecal samples from 2065 dogs and intestinal content from 121 necropsied wolves were macroscopically examined and tested using zinc chloride flotation method. When cestode eggs or adult cestodes were detected, a molecular identification based on multiplex-PCR and sequencing was performed. In the sampled wolves, the prevalence by flotation (42/121; 34.7%) was lower than the overall prevalence including macroscopic examination (76/121; 62.8%). The flotation method thus failed to detect cestode infections in 44.7% (34/76) of infected wolves. The most frequently detected species was Taenia hydatigena (46/121; 38.0%), followed by Taenia serialis (23/121; 19.0%), Mesocestoides spp. (3/121; 2.5%), Taenia ovis (1/121; 0.8%), and Echinococcus multilocularis (1/121; 0.8%). In the analysed dogs, the prevalence was 0.9% (19/2065), but the real prevalence is very likely to be higher, as no necropsy data were available. Identified cestode species included Taenia crassiceps (6/2065; 0.3%), E. multilocularis (3/2065; 0.1%), Mesocestoides sp. (2/2065; 0.1%), Taenia polyacantha (1/2065; 0.05%), and Dibothriocephalus latus (1/2065; 0.05%). By identifying the cestode species infecting two closely related host species with markedly different lifestyles, this study sheds light on the local distribution of these parasites and their potential impacts on wildlife, livestock, and human health. Due to their close contact with humans, infected dogs represent an important source of infection with zoonotic cestodes such as Echinococcus spp. and certain Taenia species, responsible for serious human diseases.

EchiNam: multicenter retrospective study on the experience, challenges, and pitfalls in the diagnosis and treatment of alveolar echinococcosis in Belgium

OBJECTIVES

The aim of this retrospective study was to collect epidemiological, clinical, laboratory, imaging, management, and follow-up data on cases of alveolar echinococcosis (AE) diagnosed and/or followed up within the Namur Hospital Network (NHN) in order to gather information on the challenges, pitfalls, and overall experience in the diagnosis and treatment of AE.

METHODS

EchiNam was a multicenter retrospective study. Patients diagnosed and/or treated for probable or confirmed AE in the NHN between 2002 and 2023 were included in the study. Patient selection was based on diagnosis codes, laboratory results, and albendazole (ABZ) dispensing.

RESULTS

A total of 22 AE cases were retrieved, of which four were classified as probable and 18 as confirmed cases. Nine patients were either asymptomatic or had symptoms attributed to another disease. Clinical examination yielded pathologic findings in 10 patients. The median duration from the first AE-suggestive laboratory abnormalities to diagnosis was 176 days, and the median duration from the first AE-related imaging abnormalities to diagnosis was 133 days. Overall, 12 patients underwent surgical resection, with only four achieving complete lesion resection. Nine patients experienced ABZ-related adverse effects, with temporary ABZ discontinuation in five.

CONCLUSION

Due to various factors such as a long incubation period and a lack of awareness among Belgian physicians, AE is often diagnosed at advanced disease stages. Treatment then becomes more complex or even suboptimal, resulting in prolonged therapy, higher risk of adverse effects, significantly impaired quality of life, poor prognosis, and higher mortality rates. Measures should be taken to achieve early diagnosis in endemic areas.

Usefulness of a murine model of hepatic cystic echinococcosis for preclinical drug trials: Efficacy of albendazole vs albendazole nanocrystals

Cystic echinococcosis is a zoonotic infection caused by the larval stage of Echinococcus granulosus sensu lato. The disease is characterized by the long-term growth of cysts, most commonly in the liver and lungs. Although an ideal model of cystic echinococcosis should induce the development of cysts in the liver and imitate the natural infection route, the murine model of intraperitoneal is still widely used in the field of experimental theraphy. The aim of the present work was to evaluate the usefulness of the murine model of hepatic CE for preclinical drug trials. The effectiveness of albendazole could also be assessed by measuring the diameter of the hepatic cyst. The albendazole significantly reduced the size of the cysts. The ultrastructural alterations of the germinal layer of hepatic cysts provoked by albendazole coincided with those observed in the intraperitoneal model. Similar results were obtained with both albendazole doses. Therefore, the efficacy of albendazole nanocrystals in the murine model of hepatic cystic echinococcosis was carried out at albendazole doses of 25 mg/kg. The abdominal ultrasound allows us to assess the response of cysts to drugs only in a qualitative manner. Although the size of cysts in the albendazole nanocrystal group was not significantly lower than that observed with albendazole, at the ultrastructural level, a greater extent of damage was observed. The murine model of hepatic cystic echinococcosis can be effectively used for assessing the effect of novel formulations or compounds. The main advantage of this model is that cysts are located in the orthotopic organ, which resembles the location most commonly found in human cases. In future studies, the usefulness of the model for pharmacokinetics studies in hepatic cysts will be evaluated.

MUSKRATS (ONDATRA ZIBETHICUS) ARE COMPETENT INTERMEDIATE HOSTS OF ECHINOCOCCUS MULTILOCULARIS IN NORTH AMERICA

The tapeworm Echinococcus multilocularis is an emerging pathogen of significance to human and animal health in Canada, yet little is known about key rodent intermediate hosts in local urban ecosystems. In Europe, invasive muskrats (Ondatra zibethicus) are an important indicator intermediate host species; however, the role of this semiaquatic rodent in the ecology of E. multilocularis is undetermined in the North American context. We examined 93 muskrats that were livetrapped in the spring of 2017 within Calgary, Alberta, Canada, for the presence of E. multilocularis infection. The objectives of this study were to 1) diagnose alveolar echinococcosis using macroscopic assessment, histopathology, and molecular analyses; 2) quantify infection severity; and 3) assess host demographic risk factors for infection. Macroscopic cysts consistent with alveolar echinococcosis were present in 24% of muskrats (22/93). Most individuals had hepatic cysts; however, cysts were also occasionally detected in the mesentery, reproductive organs, omentum, peritoneum, spleen, diaphragm, lung, or kidney. The mean number of cysts per liver was 2.1 (range, 1-4). We examined hepatic cysts from 18 individuals using histology; all had lesions compatible with alveolar echinococcosis. Protoscoleces, indicative of patent infections, were present in 14/18 (78%). No demographic risk factors (sex, body condition, body mass) were significantly associated with infection. Muskrats in the North American context are competent intermediate hosts with high infection prevalence and may play an important role in the ecology of this emerging parasite.

Establishment and application of unbiased in vitro drug screening assays for the identification of compounds against Echinococcus granulosus sensu stricto

Echinococcus multilocularis and E. granulosus s.l. are the causative agents of alveolar and cystic echinococcosis, respectively. Drug treatment options for these severe and neglected diseases are limited to benzimidazoles, which are not always efficacious, and adverse side effects are reported. Thus, novel and improved treatments are needed. In this study, the previously established platform for E. multilocularis in vitro drug assessment was adapted to E. granulosus s.s. In a first step, in vitro culture protocols for E. granulosus s.s. were established. This resulted in the generation of large amounts of E. granulosus s.s. metacestode vesicles as well as germinal layer (GL) cells. In vitro culture of these cells formed metacestode vesicles displaying structural characteristics of metacestode cysts generated in vivo. Next, drug susceptibilities of E. multilocularis and E. granulosus s.s. protoscoleces, metacestode vesicles and GL cells were comparatively assessed employing established assays including (i) metacestode vesicle damage marker release assay, (ii) metacestode vesicle viability assay, (iii) GL cell viability assay, and (iv) protoscolex motility assay. The standard drugs albendazole, buparvaquone, mefloquine, MMV665807, monepantel, niclosamide and nitazoxanide were included. MMV665807, niclosamide and nitazoxanide were active against the parasite in all four assays against both species. MMV665807 and monepantel were significantly more active against E. multilocularis metacestode vesicles, while albendazole and nitazoxanide were significantly more active against E. multilocularis GL cells. Albendazole displayed activity against E. multilocularis GL cells, but no effects were seen in albendazole-treated E. granulosus s.s. GL cells within five days. Treatment of protoscoleces with albendazole and monepantel had no impact on motility. Similar results were observed for both species with praziquantel and its enantiomers against protoscoleces. In conclusion, in vitro culture techniques and drug screening methods previously established for E. multilocularis were successfully implemented for E. granulosus s.s., allowing comparisons of drug efficacy between the two species. This study provides in vitro culture techniques for the reliable generation of E. granulosus s.s. metacestode vesicles and GL cell cultures and describes the validation of standardized in vitro drug screening methods for E. granulosus s.s.

Non-resectable pulmonary alveolar echinococcosis with multi-stage vertebral location

Alveolar echinococcosis (also known as Hydatid cyst or Hydatydosis) is a zoonosis with a high degree of disability and morbidity. Bone echinococcosis is a rare presentation. Authors are always defending a personalized approach taking account of the particularities of the cyst location. Recognition of this syndrome is crucial because advances in medical and surgical management strategies have controlled and relieved symptoms in numerous cases. We report, hereby, a case of a patient with a thoracic spine alveolar echinococcosis of an unusual extension. We discussed the outcome of the treatment after fifteen years of follow-up.

Oral Delivery of Anti-Parasitic Agent-Loaded PLGA Nanoparticles: Enhanced Liver Targeting and Improved Therapeutic Effect on Hepatic Alveolar Echinococcosis

Background

Alveolar echinococcosis (AE) is a lethal parasitic disease caused by infection with the metacestode of the dog/fox tapeworm Echinococcus multilocularis, which primarily affects the liver. Although continued efforts have been made to find new drugs against this orphan and neglected disease, the current treatment options remain limited, with drug delivery considered a likely barrier for successful treatment.

Methods

Nanoparticles (NPs) have gained much attention in the field of drug delivery due to their potential to improve delivery efficiency and targetability. In this study, biocompatible PLGA nanoparticles encapsulating a novel carbazole aminoalcohol anti-AE agent (H1402) were prepared to promote the delivery of the parent drug to liver tissue for treating hepatic AE.

Results

H1402-loaded nanoparticles (H1402-NPs) had a uniform spherical shape and a mean particle size of 55 nm. Compound H1402 was efficiently encapsulated into PLGA NPs with a maximal encapsulation efficiency of 82.1% and drug loading content of 8.2%. An in vitro uptake assay demonstrated that H1402-NPs rapidly penetrated the in vitro cultured pre-cyst wall and extensively accumulated in the pre-cysts of E. multilocularis within only 1 h. The biodistribution profile of H1402-NPs determined through ex vivo fluorescence imaging revealed significantly enhanced liver distribution compared to unencapsulated H1402, which translated to improved therapeutic efficacy and reduced systemic toxicity (especially hepatotoxicity and cytotoxicity) in a hepatic AE murine model. Following a 30-day oral regimen (100 mg/kg/day), H1402-NPs significantly reduced the parasitic burden in both the parasite mass (liver and metacestode total weight, 8.8%) and average metacestode size (89.9%) compared to unmedicated infected mice (both p-values < 0.05); the treatment outcome was more effective than those of albendazole- and free H1402-treated individuals.

Conclusion

Our findings demonstrate the advantages of encapsulating H1402 into PLGA nanoparticles and highlight the potential of H1402-NPs as a promising liver-targeting therapeutic strategy for hepatic AE.

[Spread and Development of Alveolar Echinococcosis in Germany, 1992-2018]

GOAL OF THE STUDY

Alveolar echinococcosis (AE) is a rare parasitosis caused by the pathogen Echinococcus multilocularis. There is an increase in the number of cases in many countries. The aim of the study was to investigate the current prevalence and the change in the geographical distribution pattern.

METHODOLOGY

Data were collected retrospectively for the period 1992-2018 using the registered cases in the national disease register for AE in Germany. Statistical analysis was performed using the SAS statistical analysis system version 9.4 (SAS Institute, Cary, N.C., USA).

RESULTS

The study population of n=569 patients included n=322 (56,59%) women and n=247 (43,40%) men. The mean average age of patients with alveolar echinococcosis at first presentation was 53,90±17,54 years (median: 56,00 years). The Moran's I test statistic showed a positive spatial autocorrelation for the period 1992-2018 corresponding to a heterogeneous distribution of disease cases in Germany (I=0,4165; Z=10,9591, p=0,001). An increase in age- and sex-specific prevalence could be determined for the entire study period (1992-2018). The overall prevalence in the period 1992-2018 was 0,71 cases per 100,000 population. The determination of the prevalence for the period 1992-2018 resulted in 0,31 cases for men and 0,40 cases for women per 100,000 population. In the period 1992-1996, no AE cases had been registered in 11/16 (68,8%) federal states (Berlin, Brandenburg, Bremen, Hamburg, Mecklenburg-Vorpommern, Rheinland-Pfalz, Saarland, Sachsen, Sachsen-Anhalt, Schleswig-Holstein und Thüringen). The evaluation recently shows an increased occurrence of cases in the federal states of Hessen, Rheinland-Pfalz and Nordrhein-Westfalen.

CONCLUSIONS

The analysis shows a rise in prevalence and an increasing number of cases outside the classic endemic areas of Baden-Württemberg and Bavaria.

It's a small world for parasites: evidence supporting the North American invasion of European Echinococcus multilocularis

Echinococcus multilocularis (Em), the causative agent of human alveolar echinococcosis (AE), is present in the Holarctic region, and several genetic variants deem to have differential infectivity and pathogenicity. An unprecedented outbreak of human AE cases in Western Canada infected with a European-like strain circulating in wild hosts warranted assessment of whether this strain was derived from a recent invasion or was endemic but undetected. Using nuclear and mitochondrial markers, we investigated the genetic diversity of Em in wild coyotes and red foxes from Western Canada, compared the genetic variants identified to global isolates and assessed their spatial distribution to infer possible invasion dynamics. Genetic variants from Western Canada were closely related to the original European clade, with lesser genetic diversity than that expected for a long-established strain and spatial genetic discontinuities within the study area, supporting the hypothesis of a relatively recent invasion with various founder events.

NIR-II fluorescence microscopic bioimaging for intrahepatic angiography and the early detection of Echinococcus multilocularis microlesions

Hepatic alveolar echinococcosis (HAE) is caused by the metacestode of Echinococcus multilocularis, which shows characteristics of malignant tumors with high mortality. However, traditional diagnostic imaging methods are still not sufficient for the recognition of HAE microlesions in the early stages. Near-infrared-II (900-1700 nm, NIR-II) fluorescence microscopic imaging (NIR-II-FMI) has shown great potential for biomedical detection. A novel type of negative target imaging method based on NIR-II-FMI with the assistance of indocyanine green (ICG) was explored. Then, NIR-II-FMI was applied to the early detection of HAE for the first time. The negative targeting NIR-II fluorescence imaging of HAE-infected mice at different stages with the assistance of ICG under 808 nm of laser irradiation was obtained. Especially, HAE microlesions at the early stage were detected clearly. Moreover, clear intrahepatic angiography was achieved under the same NIR-II-FMI system.

Assessing Red Fox (Vulpes vulpes) Demographics to Monitor Wildlife Diseases: A Spotlight on Echinococcus multilocularis

The assessment of red fox population density is considered relevant to the surveillance of zoonotic agents vectored by this species. However, density is difficult to estimate reliably, since the ecological plasticity and elusive behavior of this carnivore hinder classic methods of inference. In this study, red fox population density was estimated using a non-invasive molecular spatial capture-recapture (SCR) approach in two study areas: one in a known hotspot of the zoonotic cestode Echinococcus multilocularis, and another naïve to the parasite. Parasitological investigations on collected samples confirmed the presence of the parasite exclusively in the former area; the SCR results indicated a higher fox population density in the control area than in the hotspot, suggesting either that the relationship between fox density and parasite prevalence is not linear and/or the existence of other latent factors supporting the parasitic cycle in the known focus. In addition, fox spotlight count data for the two study areas were used to estimate the index of kilometric abundance (IKA). Although this method is cheaper and less time-consuming than SCR, IKA values were the highest in the areas with the lower molecular SCR density estimates, confirming that IKA should be regarded as a relative index only.

Laparoscopic resection of hepatic alveolar echinococcosis: A single-center experience

Introduction

Alveolar echinococcosis (AE) remains a very rare disease requiring complete radical resection for curative treatment. While open approaches are common, safety and efficacy of laparoscopic resections remain unknown.

Methods

This is a single-center, retrospective cohort study with patients undergoing liver resection for hepatic AE at the Department of Visceral Surgery and Medicine, Bern University Hospital from December 2002 to December 2020. Postoperative outcomes of patients following laparoscopic hepatectomy (LH) for hepatic AE were compared with those of patients undergoing open hepatectomy (OH).

Results

A total of 93 patients underwent liver resection for hepatic AE. Laparoscopic hepatectomy was performed in 23 patients and open hepatectomy in 70 patients. While there were no significant differences in terms of gender, age and diagnostic tools, the majority of patients of the LH cohort were PNM stage 1 (78%) in contrast to only 39% in the OH cohort (p = 0.002). Patients undergoing laparoscopic hepatectomy were treated by minor liver resections in 91% and in 9% by major liver resections in comparison to the open hepatectomy cohort with 61% major liver resections and 39% minor resections. Laparoscopic hepatectomy was associated with shorter mean operation time (127 minutes vs. 242 minutes, p <0.001), lower major complication rate (0% vs. 11%, p = 0.322) and shorter mean length of hospital stay (4 days vs. 13 days, p <0.001). Patients with LH had a distinct, but not significant lower recurrence rate (0% vs. 4%, p = 0.210) during a mean follow-up of 55 months compared with a follow-up of 76 months in the OH cohort. After subgroup analysis of PNM stage 1 patients, similar results are seen with persistent shorter mean operation time (120 minutes vs. 223 minutes, p <0.001), lower major complication rate (0% vs. 8%, p = 0.759) and shorter length of hospital stay (4 days vs. 12 days, p <0.001).

Conclusion

Laparoscopy appears as a feasible and safe approach for patients with PNM stage 1 alveolar echinococcosis without impact on early disease recurrence.

In this retrospective cohort study laparoscopic hepatectomy for hepatic alveolar echinococcosis had no negative impact on perioperative outcomes, disease recurrence or survival compared with open hepatectomy. The importance of this finding is that the laparoscopic approach is feasible and safe for selected patients with hepatic alveolar echinococcosis, especially those with PNM stage 1.

Knowledge, attitudes, and practices of municipal veterinary practitioners towards echinococcosis

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are among the most relevant zoonoses in Europe. According to the European Food Safety Authority (EFSA), Echinococcus granulosus sensu lato causing CE is the most significant foodborne parasite in South-Western Europe, followed by Echinococcus multilocularis, the etiological agent of AE. Among the challenges and opportunities highlighted in the literature to combat these diseases are the need to evaluate and increase awareness of stakeholders. In Portugal, Municipal Veterinary Practitioners (MVP) are the animal health authority at the municipality level, playing a crucial role in diagnosis, prevention and control of infectious diseases in animals, helping to mitigate transmission to humans. However, their knowledge, attitudes, and practices (KAP) towards CE, as well as awareness of AE expansion across Europe, remain overlooked. In this work, a cross-sectional study was conducted for the first time in Portugal to bridge knowledge gaps concerning CE and AE, using an online self-administered questionnaire collecting information on the municipal kennel, KAP towards CE, and understanding of AE epidemiology. Eighty-three MVP from mainland and islands completed the questionnaire, with highest representability from the central-northern region. MVP had, on average, a medium to high level of knowledge of CE but acquaintance with AE was insufficient, although echinococcosis was frequently mentioned as target of health education sessions (77.0%). A high rate (60%) of reported entries into municipal kennels of stray dogs originating from countries with AE endemic areas was registered, suggesting that the presence of these potentially AE-infected stray dogs pose public health risks. Most kennels did not perform routine coprological analysis or faecal matter disinfection after dog internal deworming. The lack of proper training and well-conceived written plans of infection control and prevention were evidenced in several kennels. Altogether, our findings highlight the need to update knowledge and practice of MVP under the One Health approach, through reinforced education, training and communication involving all stakeholders.

Alveolar echinococcosis in nutria (Myocastor coypus), invasive species in Slovenia

The present report describes a case of Echinococcus multilocularis infection in nutria (Myocastor coypus) culled in the central area of Slovenia. Post-mortem exam showed multiple cystic lesions in the liver. Gross examination, as well as parasitological and histopathological examinations, revealed numerous cysts of various sizes, filled with yellow clear fluid and displacing most of the liver parenchyma. The cyst lumina contained numerous protoscolices approximately 100 μm in diameter and calcareous corpuscles. The protoscolices had two visible suckers and a rostellum with birefringent hooks. The lesions were consistent with an E. multilocularis cyst. Molecular analysis confirmed that the nutria was infected with E. multilocularis. To our knowledge, this is the first report of echinococcosis in nutria in Slovenia that presents gross, parasitological, and histological lesions and the result of molecular analysis. Nutrias in Slovenia are dangerous invaders but can also be a relevant bioindicator of the presence of the parasite in the environment.

HIV protease inhibitor nelfinavir is a potent drug candidate against echinococcosis by targeting Ddi1-like protein

Background

Alveolar echinococcosis (AE), which is caused by larval Echinococcus multilocularis, is one of the world's most dangerous neglected diseases. Currently, no fully effective treatments are available to cure this disease.

Methods

In vitro protoscolicidal assay along with in vivo murine models was applied in repurposing drugs against AE. Genome-wide identification and homology-based modeling were used for predicting drug targets. RNAi, enzyme assay, and RNA-Seq analyses were utilized for investigating the roles in parasite survival and validations for the drug target.

Findings

We identified nelfinavir as the most effective HIV protease inhibitor against larval E. multilocularis. Once-daily oral administration of nelfinavir for 28 days resulted in a remarkable reduction in parasite infection in either immune-competent or immunocompromised mice. E. multilocularis DNA damage-inducible 1 protein (EmuDdi1) is predicted as a target candidate for nelfinavir. We proved that EmuDdi1 is essential for parasite survival and protein excretion and acts as a functionally active protease for this helminth. We found nelfinavir is able to inhibit the proteolytic activity of recombinant EmuDdi1 and block the EmuDdi1-related pathways for protein export. With other evidence of drug efficacy comparison, our results suggest that inhibition of EmuDdi1 is a mechanism by which this HIV proteinase inhibitor mediates its antiparasitic action on echinococcosis.

Interpretation

This study demonstrates that nelfinavir is a promising candidate for treating echinococcosis. This drug repurposing study proves that the widely prescribed drug for AIDS treatment is potent in combating E. multilocularis infection and thus provides valuable insights into the development of single-drug therapy for highly prevalent co-infection between HIV and helminth diseases.

Funding

This work was supported by the National Natural Science Foundation of China (31802179), the Natural Science Foundation of Gansu Province, China (No. 21JR7RA027), and the State Key Laboratory of Veterinary Etiological Biology (No. SKLVEB2021YQRC01).

Efficient delivery of Echinococcus multilocularis miRNAs using chitosan nanoparticles

Alveolar echinococcosis caused by Echinococcus multilocularis is an important zoonotic disease, a great threat to human health due to limited interventions. microRNAs are a type of small non-coding RNA that plays a key role in many diseases and is considered as a potential therapeutic target for control of parasitic diseases. However, naked miRNAs are difficult to enter into cells and are easily degraded in both external and internal environments. Chitosan (CS) has recently been used as a promising vehicle for delivery of nucleic acids. Therefore, we prepared miRNA-bearing CS nanoparticles and investigated the physicochemical properties as well as the delivery efficiency. We found that CS nanoparticles was relatively stable, offered miRNA strong protection from degradation and had low cytotoxicity with no significant effects on cell proliferation and apoptosis. CS nanoparticles were shown to be easily absorbed by cells and have remarkable liver tropism. Furthermore, CS nanoparticles were used to efficiently deliver E. multilocularis miR-4989 in vitro and in vivo and caused a significant reduction in the expression of UBE2N in the liver, a potential target of emu-miR-4989, at both mRNA and protein levels. Our data demonstrate that CS nanoparticles can act as a vehicle for efficient liver-targeted delivery of miRNAs and for development of miRNA-based therapeutics against E. multilocularis infection.

Molecular characterization of the serotonergic transporter from the cestode Echinococcus granulosus: pharmacology and potential role in the nervous system

Echinococcus granulosus, the etiological agent of human cystic echinococcosis (formerly known as hydatid disease), represents a serious worldwide public health problem with limited treatment options. The essential role played by the neuromuscular system in parasite survival and the relevance of serotonin (5-HT) in parasite movement and development make the serotonergic system an attractive source of drug targets. In this study, we cloned and sequenced a cDNA coding for the serotonin transporter from E. granulosus (EgSERT). Bioinformatic analyses suggest that EgSERT has twelve transmembrane domains with highly conserved ligand and ionic binding sites but a less conserved allosteric site compared with the human orthologue (HsSERT). Modeling studies also suggest a good degree of conservation of the overall structure compared with HsSERT. Functional and pharmacological studies performed on the cloned EgSERT confirm that this protein is indeed a serotonin transporter. EgSERT is specific for 5-HT and does not transport other neurotransmitters. Typical monoamine transport inhibitors also displayed inhibitory activities towards EgSERT, but with lower affinity than for the human SERT (HsSERT), suggesting a high divergence of the cestode transporter compared with HsSERT. In situ hybridization studies performed in the larval protoscolex stage suggest that EgSERT is located in discrete regions that are compatible with the major ganglia of the serotonergic nervous system. The pharmacological properties, the amino acidic substitutions at important functional regions compared with the HsSERT, and the putative role of EgSERT in the nervous system suggest that it could be an important target for pharmacological intervention.

Identification of B‐cell dominant epitopes in the recombinant protein P29 from Echinococcus granulosus

Introduction

Echinococcus granulosus (E. granulosus) causes a hazardous zoonotic parasitic disease. This parasite can occupy the liver and several areas of the body, causing incurable damage. Our previous studies have provided evidence that the recombinant protein P29 (rEg.P29) exhibit immune protection in sheep and mice against pathological damage induced by E. granulosus, showing its potential as candidate for vaccine development. However, information on the B‐cell epitopes of rEg.P29 has not yet been reported.

Methods

Immunological model was established in mice with rEg.P29. SDS‐PAGE and Western blot were used to identify protein. Screening for B‐cell dominant epitope peptides of rEg.P29 by enzyme‐linked immunosorbent assay (ELISA) and immune serum. Dominant epitopes were validated using ELISA and flow cytometry. Multiple sequence alignment analysis was performed using BLAST and UniProt.

Results

Immunization with rEg.P29 induced intense and persistent antibody responses, and the epitope of the dominant antigen of B cells are identified as rEg.P29_166–185 (LKNAKTAEQKAKWEAEVRKD). Anti‐rEg.P29_166–185‐specific antibodies lack epitopes against IgA, IgE, and IgG3, compared to anti‐rEg.P29‐specific antibodies. However, anti‐rEg.P29_166–185 IgG showed comparatively higher titers, as determined among those peptides by endpoint titration. In addition, rEg.P29 and rEg.P29_166–185 promote B‐cell activation and proliferation in vitro. The dominant epitopes are relatively conserved in different subtypes of the rEg.P29 sequence.

Conclusion

rEg.P29_166–185 can act as a dominant B‐cell epitope for rEg.P29 and promote cell activation and proliferation in the same way as rEg.P29.

Identification of a dominant murine T-cell epitope in recombinant protein P29 from Echinococcus granulosus

Echinococcus granulosus causes echinococcosis, an important zoonotic disease worldwide and a major public health issue. Vaccination is an economical and practical approach for controlling E. granulosus. We have previously revealed that a recombinant protein P29 (rEg.P29) is a good vaccine candidate against E. granulosus. However, T cell immunogenic epitopes have not been identified. In the present study, we use rEg.P29-immunized mice as models to screen immunogenic epitopes for the construction of a novel multi-epitope vaccine. We search for immunodominant epitopes from an overlapping peptide library to screen the peptides of rEg.P29. Our results confirm that rEg.P29 immunization in mice elicits the activation of T cells and induces cellular immune responses. Further analyses show that a T cell epitope within amino acids 86–100 of rEg.P29 elicits significant antigen-specific IFN-γ production in CD4+ and CD8+ T cells and promotes specific T-cell activation and proliferation. Collectively, these results provide a reference for the construction of a novel vaccine against broad E. granulosus genotypes based on epitopes of rEg.P29.

Integrative Analysis of RNA Expression and Regulatory Networks in Mice Liver Infected by Echinococcus multilocularis

The larvae of Echinococcus multilocularis causes alveolar echinococcosis, which poses a great threat to the public health. However, the molecular mechanisms underlying the host and parasite interactions are still unclear. Exploring the transcriptomic maps of mRNA, miRNA and lncRNA expressed in the liver in response to E. multilocularis infection will help us to understand its pathogenesis. Using liver perfusion, different cell populations including the hepatic cells, hepatic stellate cells and Kupffer cells were isolated from mice interperitoneally inoculated with protoscoleces. Their transcriptional profiles including lncRNAs, miRNAs and mRNAs were done by RNA-seq. Among these cell populations, the most differentially-expressed (DE) mRNA, lncRNAs and miRNAs were annotated and may involve in the pathological processes, mainly including metabolic disorders, immune responses and liver fibrosis. Following the integrative analysis of 38 differentially-expressed DEmiRNAs and 8 DElncRNAs, the lncRNA-mRNA-miRNA networks were constructed, including F63-miR-223-3p-Fbxw7/ZFP36/map1b, F63-miR-27-5p-Tdrd6/Dip2c/Wdfy4 and IFNgAS1-IFN-γ. These results unveil the presence of several potential lncRNA-mRNA-miRNA axes during E. multilocularis infection, and further exploring of these axes may contribute to better understanding of the pathogenic mechanisms.

Identification and characterization of sirtuin enzymes in cestodes and evaluation of sirtuin inhibitors as new cestocidal molecules

Anti-parasitic treatment of neglected tropical diseases (NTDs) caused by cestodes such as echinococcosis and cysticercosis relies on a small number of approved anthelmintic drugs. Furthermore, the treatment is usually prolonged and often partially effective and not well tolerated by some patients. Therefore, the identification of novel drug targets and their associated compounds is critical. In this study, we identified and characterized sirtuin (SIRT) enzymes in cestodes and evaluated the cestocidal potential of SIRT inhibitors. SIRTs are a highly conserved family of nicotinamide-adenine dinucleotide (NAD⁺)-lysine deacylases involved in multiple cellular functions. Here, we described the full repertoire of SIRT-encoding genes in several cestode species. We identified six SIRT-encoding genes that were classified into SIRTs Class I (SIRT1, SIRT2, and SIRT3), Class III (SIRT5), and Class IV (SIRT6 and SIRT7). In Echinococcus spp., SIRT genes showed transcriptional expression throughout several developmental stages, SIRT2 being the most expressed. To evaluate the potential of SIRT inhibitors as new cestocidal molecules, we determined the in vitro effect of several Class I SIRT inhibitors by motility assay. Of those, the selective SIRT2 inhibitor Mz25 showed a strong cestocidal activity in Mesocestoides vogae (syn. Mesocestoides corti) tetrathyridia at various concentrations. The Mz25 cestocidal activity was time- and dose-dependent with a half-maximal inhibitory concentration (IC₅₀) value significantly lower than that of albendazole. Additionally, Mz25 induced extensive damage in the general morphology with marked alterations in the tegument and ultrastructural features. By homology modeling, we found that cestode SIRT2s showed a high conservation of the canonical SIRT structure as well as in the residues related to Mz25 binding. Interestingly, some non-conservative mutations were found on the selectivity pocket (an Mz25-induced structural rearrangement on the active site), which represent a promising lead for developing selective cestode SIRT2 inhibitors derived from Mz25. Nevertheless, the Mz25 molecular target in M. vogae is unknown and remains to be determined. This report provides the basis for further studies of SIRTs to understand their roles in cestode biology and to develop selective SIRT inhibitors to treat these parasitic NTDs.

Status and prospect of novel treatment options toward alveolar and cystic echinococcosis

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are the two most important global parasitic infectious diseases caused by species of Echinococcus granulosus and E. multilocularis, respectively. Although numerous trials have been performed in search of novel therapeutic options to curb the neglected zoonosis, no other nonsurgical options are currently available to replace the licensed anti echinococcal drugs albendazole (ABZ) and mebendazole (MBZ). A safer and more effective treatment plan for echinococcosis is therefore urgently needed to compensate for this therapeutic shortfall. Here, we present a review of the literature for state-of-the-art valuable anti-parasitic compounds and novel strategies that have proved effective against CE and AE, which includes details about the pharmaceutical type, practical approach, experimental plan, model application and protoscolecidal effects in vivo and in vitro. The content includes the current application of traditional clinical chemicals, the preparation of new compounds with various drug loadings, repurposing findings, combined programs, the prospects for Chinese herbal medicines, non-drug administrations and the exploration of target inhibitors based on open-source information for parasitic genes. Next the conventional experimental projects and pharmacodynamic evaluation methods are systematically summarized and evaluated. The demands to optimize the construction of the echinococcosis model and improve the dynamic monitoring method in vivo are also discussed given the shortcomings of in vivo models and monitoring methods.

Evaluation of a structured treatment discontinuation in patients with inoperable alveolar echinococcosis on long-term benzimidazole therapy: A retrospective cohort study

Objectives

Alveolar echinococcosis (AE) is an orphan zoonosis of increasing concern in endemic areas, including Europe. It frequently presents in an advanced, inoperable stage, that requires life-long parasitostatic benzimidazole therapy. In some patients, long-term therapy leads to negative anti-Em18 antibody ELISA and PET. It is disputed, whether these patients are truly cured and treatment can be safely discontinued. Our aim was to retrospectively assess long-term outcome of 34 patients with inoperable AE who participated in a previous study to determine feasibility of benzimidazole treatment cessation.

Methods

Retrospective analysis of medical charts was undertaken in all 34 AE patients who participated in our previous study. Of particular interest were AE recurrence or other reasons for re-treatment in patients who stopped benzimidazole therapy and whether baseline clinical and laboratory parameters help identify of patients that might qualifiy for treatment cessation. Additionally, volumetric measurement of AE lesions on contrast-enhanced cross-sectional imaging was performed at baseline and last follow-up in order to quantify treatment response.

Results

12 of 34 patients stopped benzimidazole therapy for a median of 131 months. 11 of these patients showed stable or regressive AE lesions as determined by volumetric measurement. One patient developed progressive lesions with persistently negative anti-Em18 antibody ELISA but slight FDG-uptake in repeated PET imaging. At baseline, patients who met criteria for treatment cessation demonstrated higher lymphocyte count and lower total IgE.

Conclusion

Treatment cessation is feasible in inoperable AE patients, who demonstrate negative anti-Em18 antibody ELISA and PET on follow-up. Close monitoring including sectional imaging is strongly advised.

Canine and Feline Parasitology: Analogies, Differences, and Relevance for Human Health

Cats and dogs are treated as family members by most pet owners. Therefore, a high quality of veterinary care and preventive medicine is imperative for animal health and welfare and for the protection of humans from zoonotic pathogens. There is a general perception of cats being treated as "small dogs," especially in the field of clinical parasitology. As a result, several important differences between the two animal species are not taken into proper consideration and are often overlooked. Dogs and cats are profoundly different under evolutionary, biological, ethological, behavioral, and immunological standpoints. These differences impact clinical features, diagnosis, and control of canine and feline parasites and transmission risk for humans. This review outlines the most common parasitoses and vector-borne diseases of dogs and cats, with a focus on major convergences and divergences, and discusses parasites that have (i) evolved based on different preys for dogs and cats, (ii) adapted due to different immunological or behavioral animal profiles, and (iii) developed more similarities than differences in canine and feline infections and associated diseases. Differences, similarities, and peculiarities of canine and feline parasitology are herein reviewed in three macrosections: (i) carnivorism, vegetarianism, anatomy, genetics, and parasites, (ii) evolutionary adaptation of nematodes, including veterinary reconsideration and zoonotic importance, and (iii) behavior and immune system driving ectoparasites and transmitted diseases. Emphasis is given to provide further steps toward a more accurate evaluation of canine and feline parasitology in a changing world in terms of public health relevance and One Health approach.

Accelerated Course of Alveolar Echinococcosis After Treatment With Steroids in a Patient With Autoimmune Encephalitis

Human alveolar echinococcosis (AE) is a zoonotic infection caused by the fox tapeworm Echinococcus ​​​​​​multilocularis. We report the case of a patient who developed an accelerated course of AE with diffuse liver involvement after high-dose steroid treatment for autoimmune encephalitis. Immunosuppressive therapies present us with new challenges regarding the management of AE. With this article, we would like to draw attention to the importance of a screening program for AE before planned immunosuppressive therapy.

Alveolar echinococcosis: what triggers emergence in North America, Central Europe and Asia?

PURPOSE OF REVIEW

Infection with the larval (metacestode) stage of Echinococcus multilocularis causes alveolar echinococcosis (AE), a serious hepatic disorder. The parasite has increased its infection extensity in wildlife and domestic dogs, mainly due to urbanization and spatial extension of wildlife hosts in Europe, Asia as well as North America, resulting in emerging infection risk for humans.

RECENT FINDINGS

In hyperendemic areas such as Kyrgyzstan and China, ecological and socioeconomic changes have been associated with the unpredictable increase of AE cases. In North America, the appearance of the European-like genotype is of concern. In Europe, the annual increase of human case numbers reached a plateau even in hyperendemic situations. Therefore, we conclude that most of the exposed individuals are resistant to parasite invasion and/or to disease development. Thus, AE develops in a few healthy individuals, but preferentially in immunosuppressed patients.

SUMMARY

In the future, improved diagnostic strategies will allow more precise estimations of transmission routes including the role of food, water and direct dog contact, which should yield improved public health recommendations. Finally, understanding protective innate and acquired immune mechanisms as well as parasite-driven immune-evasion processes will be essential to develop curative therapies in nonoperable patients and, futuristically, appropriate vaccines.

Clinical tolerance and efficacy of anti-parasitic treatment with albendazole in patients with alveolar echinococcosis: long-term follow-up observation in 117 patients

Alveolar echinococcosis is the most severe worm disease primarily detected in the liver. This study aimed to determine the clinical tolerance and efficacy of albendazole in patients with alveolar echinococcosis, depending on the volume of previous surgical treatment or its absence and the duration of anti-parasitic therapy. We retrospectively (over the last 15 years) analyzed the data of 117 patients, who were divided into 4 groups according to curability: R₀ (radical resection), R₁₊₂ (incomplete resection), N_r (unresectable), and R_r (recurrence). All of them received albendazole from 3 months to 11 years, depending on the volume of resection. We evaluated patients' tolerability of albendazole according to the level of hepatic transaminases and blood cell count. The effectiveness of anti-parasitic treatment was evaluated by imaging studies and the absence of serum antibodies. There was no direct relationship between the frequency of adverse reactions and the duration of taking albendazole (r - 0.20229). Adverse reactions were significantly more often observed in unresectable patients (p < 0.01), which is most likely associated with the general serious condition of the patients and with individual drug intolerance. The effectiveness of the anti-parasitic treatment was manifested in the inhibition of tumor development in 88% of patients in group R₁₊₂ and 60% in group N_r. Follow-up of group R₀ patients from 3 to 14 years did not reveal new lesions of the liver and other organs. The chance of a complete cure depends on the early detection of a parasitic tumor and can reach 50%.

Hepatic Alveolar Echinococcosis

Hepatic alveolar echinococcosis (HAE) is a rare but severe zoonosis caused by the pseudotumoral intrahepatic development of the larval stage of the tapeworm Echinococcus multilocularis. HAE is present only in the Northern Hemisphere, predominantly in China. Currently, there is a significant resurgence of cases in historically endemic areas associated with emergence of HAE in countries not previously concerned. Today, in European countries, HAE is often discovered by chance; however, clinicians should be made aware of opportunistic infections that progressively emerged recently as a result of therapeutic or pathological immunosuppression. Ultrasonography is the key first-line diagnostic procedure, with specific serology providing confirmation in 95% of the cases. Albendazole, only parasitostatic, is the mainstay for treatment. Surgical resection, if feasible, is the gold standard for treatment, and more patients are currently eligible for this option because of an earlier diagnosis. The prognosis has considerably improved but remains poor in countries where access to care is less favorable.

Molecular cloning and functional characterization of a thioredoxin peroxidase gene in Echinococcus multilocularis

Thioredoxin peroxidase (TPx) plays an important role in protecting parasites against oxidative damage. However, studies on the role of TPxs in Echinococcus multilocularis are limited. In this study, one tpx gene of E. multilocularis, named as emtpx-1, was identified. EmTPx-1 shares two positionally conserved cysteine residues (Cys48 and Cys169) with orthologs from other platyhelminths. EmTPx-1 is highly expressed in the germinal layer and present in exosome-like vesicles secreted by E. multilocularis metacestodes. EmTPx-1 displays peroxidase activity, which removes hydrogen peroxide in the presence of dithiothreitol. Furthermore, EmTPx-1 could protect DNA from oxidative damages, and EmTPx-1-expressing E. coli cells had an enhanced resistance to oxidative stress. In addition, EmTPx-1 enhanced the expression of arg1, ym1, and il-10, but suppressed inos, tnf-α, and il-1β expression in LPS-stimulated macrophages. Our data suggest a critical role for EmTPx-1 in oxidative stresses and M2 macrophage polarization.

Echinococcus multilocularis genetic diversity in Swiss domestic pigs assessed by EmsB microsatellite analyzes

Assessing the genetic diversity of the parasite Echinococcus multilocularis provides key information about the temporal and spatial strain flow in a given area. Previous studies indicated that a historical endemic area conventionally presents a relatively high genetic diversity, whereas peripheral or newly endemic areas exhibit a more restricted variability of the parasite. The Swiss plateau region is part of the European historically endemic area, and the genetic diversity has already been investigated by assessing either human metacestode isolates or adult worms from foxes. To date, there have been no studies covering the whole geographical area affected by the parasite. The aim of the present study was to make use of the domestic pig to investigate the genetic diversity of E. multilocularis in relation to spatial distribution. A total of 55 E. multilocularis-induced hepatic lesions from slaughtered pigs from Switzerland were studied using EmsB microsatellite analyzes, and findings were compared to already published data (originating from human, primate, foxes, and rodent samples). A total of 12 EmsB profiles were described among the domestic pigs, some of them presenting a clear spatial organization in the Swiss plateau, with three of the main profiles geographically separated. One of the 12 EmsB profiles has been newly identified for Switzerland in this study, while the other 11 profiles had been previously described in other Swiss E. multilocularis isolates from other hosts. Overall, a total of 18 EmsB profiles have so far been described within the Swiss endemic area. Six profiles appeared only among human, primate, rodent, and fox samples. Based on a richness and diversity accumulation analysis, the sampling efficiency for the whole studied area has now been improved considerably by compilation of 178 E. multilocularis specimens obtained from four different intermediate and one definitive host species in Switzerland.

Rodent control programmes can integrate Echinococcus multilocularis surveillance by facilitating parasite genotyping: the case of Arvicola terrestris voles screening in France

The tapeworm Echinococcus multilocularis is the causative agent of alveolar echinococcosis, the most serious parasitic disease for humans in Europe. In Europe, the E. multilocularis lifecycle is based on a prey-predator relationship between the red fox and small rodents. Over the last three decades, the surveillance of E. multilocularis infection in red foxes has led to the description of a wider distribution pattern across Europe. France constitutes the current European western border, but only the north-eastern half of the country is considered endemic. The red fox is the host mainly targeted in E. multilocularis surveillance programmes, but surveys targeting small rodents may be useful for obtaining molecular data, especially when the time-consuming trapping is already carried out in dedicated pest-control programmes. Here, we screened for parasitic lesions in the livers of 1238 Arvicola terrestris voles originating from the historical, but neglected focal area located in central France (Auvergne region) and from Hautes-Alpes, a recently identified endemic department in south-eastern France. This screening identified six voles infected with E. multilocularis in Hautes-Alpes and none in Puy-de-Dôme (Auvergne region) after molecular confirmation. The absence of infected rodents from Puy-de-Dôme can be mainly explained by the generally low prevalence reported in intermediate hosts. The infected Hautes-Alpes samples come all from the same trapping site situated at around 5 km from one of the three fox faecal samples with E. multilocularis DNA collected 15 years prior, thereby confirming the existence and persistence of the E. multilocularis lifecycle in the area. All the rodent E. multilocularis samples from Hautes-Alpes showed the same EmsB microsatellite marker profile. This profile has previously been described in Europe only in the Jura department (central eastern France), located at least 180 km further north. Successive migrations of infected foxes from the historical focal area, including from Jura, to Hautes-Alpes may explain the detection of the parasite in A. terrestris in Hautes-Alpes. Existing trapping efforts in areas where farmers trap A. terrestris for surveillance and pest control can be an effective complement to sampling foxes or fox faeces to obtain E. multilocularis molecular profiles.

Copro-polymerase chain reaction has higher sensitivity compared to centrifugal fecal flotation in the diagnosis of taeniid cestodes, especially Echinococcus spp, in canids

Prompt and reliable diagnostic tests for taeniid infection in canids are important due to the risk of zoonoses like Echinococcus spp. Current diagnostic methods relying on fecal flotation lack sensitivity and specificity, but this has rarely been quantified due to the challenges in performing adult cestode recovery (the gold standard) in domestic dogs (Canis familiaris). Therefore, we recovered adult Taenia and Echinococcus spp. from intestines, as well as fecal/intestinal material from 484 wild canids trapped for fur in two Canadian provinces (276 foxes - primarily Vulpes vulpes, coyotes - Canis latrans, and wolves - Canis lupus in Québec and 208 coyotes in Saskatchewan). The performances of a newly developed coproPCR for tapeworm DNA detection in dogs, and centrifugal fecal flotation using Sheather's solution, were evaluated against adult cestode recovery. Overall, adult taeniid cestode prevalence (Taenia and/or Echinococcus) was 28 % (95 % CI: 23-33 %) in Québec (62 % (CI: 51-73%) of 74 coyotes, 65 % (CI: 44-82) of 23 wolves, and 11 % (CI: 7-16%) of 179 foxes) and 79 % (CI: 73-84%) of 208 coyotes in Saskatchewan. In Québec, E. canadensis and Taenia spp. were detected in coyotes and wolves, and foxes were only infected with Taenia spp., whereas Saskatchewan coyotes were predominantly infected with E. multilocularis (at significantly higher prevalence, but not intensity, than coyotes in Québec). Compared with centrifugal fecal flotation, the new coproPCR had at least double the sensitivity (58 % vs 23 % in QC coyotes, 57 % vs 23 % in QC wolves, 24 % vs 0% in QC foxes, and 80 % vs 25 % in SK coyotes). Notably, no taeniid eggs were detected on flotations from foxes infected with Taenia spp., and the new coproPCR had highest sensitivity in Saskatchewan coyotes, which were predominantly infected with E. multilocularis. CoproPCR has promising prospects for use in Veterinary clinics and diagnostic laboratories to detect taeniid cestode infections because of its higher sensitivity than faecal flotation methods. This is particularly important for zoonotic Echinococcus spp. where, from a public health perspective, false negatives are a much greater concern than false positives.

The potential for histone deacetylase (HDAC) inhibitors as cestocidal drugs

Background

Echinococcosis and cysticercosis are neglected tropical diseases caused by cestode parasites (family Taeniidae). Not only there is a small number of approved anthelmintics for the treatment of these cestodiases, but also some of them are not highly effective against larval stages, such that identifying novel drug targets and their associated compounds is critical. Histone deacetylase (HDAC) enzymes are validated drug targets in cancers and other diseases, and have been gaining relevance for developing new potential anti-parasitic treatments in the last years. Here, we present the anthelmintic profile for a panel of recently developed HDAC inhibitors against the model cestode Mesocestoides vogae (syn. M. corti).

Methodology/Principal findings

Phenotypic screening was performed on M. vogae by motility measurements and optical microscopic observations. Some HDAC inhibitors showed potent anthelmintic activities; three of them -entinostat, TH65, and TH92- had pronounced anthelmintic effects, reducing parasite viability by ~100% at concentrations of ≤ 20 μM. These compounds were selected for further characterization and showed anthelmintic effects in the micromolar range and in a time- and dose-dependent manner. Moreover, these compounds induced major alterations on the morphology and ultrastructural features of M. vogae. The potencies of these compounds were higher than albendazole and the anthelmintic effects were irreversible. Additionally, we evaluated pairwise drug combinations of these HDAC inhibitors and albendazole. The results suggested a positive interaction in the anthelmintic effect for individual pairs of compounds. Due to the maximum dose approved for entinostat, adjustments in the dose regime and/or combinations with currently-used anthelmintic drugs are needed, and the selectivity of TH65 and TH92 towards parasite targets should be assessed.

Conclusion, significance

The results presented here suggest that HDAC inhibitors represent novel and potent drug candidates against cestodes and pave the way to understanding the roles of HDACs in these parasites.

Neglected tropical diseases, such as echinococcosis and cysticercosis, which are caused by taeniid cestodes (tapeworms), represent serious public health problems in many countries around the world. Given that there is only a small number of approved anthelmintics for the treatment of cestodiases, and that most of them are not highly effective against larval stages, identifying novel drug targets and their associated compounds is critical. Histone deacetylases (HDACs) are enzymes that produce epigenetic modifications of chromatin, thus modifying cellular gene expression. In this study, we evaluate and characterize a number of HDAC inhibitors on the model cestode Mesocestoides vogae and report the anthelmintic profile of these compounds. Some of the HDAC inhibitors tested showed potent anthelmintic effects, particularly entinostat, TH65 and TH92. These compounds were selected as the most promising candidates due to their high potencies, which were superior to the commercially-available anthelmintic drug albendazole. We also evaluated pairwise drug combinations of HDAC inhibitors and albendazole. The findings of this study provide a starting point for the development of new HDAC-based cestocidal compounds.

Alveolar Echinococcosis of the Liver with a Rare Infiltration of the Adrenal Gland

Human alveolar echinococcosis (AE) is a silently-progressing disorder that has become a threat in many countries. Since 2000, when the first case was recorded, the number of human AE patients in Slovakia is on continuous raise. The article presents a rare case of alveolar echinococcosis with infiltration in the adrenal gland and discusses the problems associated with differential diagnosis of the disease. In 2016, abdominal ultrasound performed due abdominal pain complaint showed the presence of cystic lesions in the right liver lobe of 54-year old female patient. During surgery, another lesion in the right adrenal gland was found, and neoplastic processes or echinococcosis were considered in the differential diagnosis. Due to unclear correlation between radiology, serology and histopathology results and endemic situation in Slovakia, molecular examination was recommended. Subsequently E. multilocularis was confirmed as etiological agent of infection. Alveolar echinococcosis is considered as a rare disease, with very few patients referred to clinicians or hospitals that sometimes have almost none existing experience with the diagnosis and treatment of the disease. Therefore, the establishment of networks or reference centres specialized on management of the disease would be suitable way to provide the patients with the best care and improve the disease diagnosis, treatment and prognosis.

Predators in northern Germany are reservoirs for parasites of One Health concern

Urbanisation and invasion of wildlife into urban areas as well as human leisure activities create diverse wildlife-domestic animal-human interfaces, increasing the risk of (zoonotic) parasite spillover from sylvatic to domestic and synanthropic cycles. This study investigated the endo- and ectoparasite fauna, emphasising on parasites of One Health Concern, of the most common predators in northern Germany between November 2013 and January 2016. Eighty red foxes (Vulpes vulpes), 18 stone martens (Martes foina) and nine raccoon dogs (Nyctereutes procyonoides) were available for the study. Overall, 79 (73.8%) of the examined predators (n=107) harboured at least one endoparasite. The most frequently detected endoparasites in red foxes were Toxocara canis (43.8% positive individuals), Capillaria spp. (36.3%), Alaria alata (25.0%), Echinococcus multilocularis (26.3%) and Uncinaria stenocephala (25.0%). Furthermore, Toxascaris leonina, Trichuris vulpis, Taenia ssp., Mesocestoides spp. and coccidian oocysts were observed. The endoparasite species richness in raccoon dogs was comparable to red foxes, while in stone martens, only Capillaria spp. were found. Muscle digestion for detection of Trichinella spp. and antigen testing for Giardia spp. did not show positive results. Ectoparasite analyses revealed infestations with ticks species of the genus Ixodes as well as Dermacentor reticulatus. Scabies mites were not present in digested skin samples, while Demodex spp. mites were observed by faecal flotation in one red fox. Furthermore, fleas (Archaeopsylla erinacei and Chaetopsylla globiceps) were observed in the fur of red foxes, while lice were not present in any predator species. However, infestation frequency with ectoparasites was with 19.2% generally low in available predator skins (n=99). Overall, the present study showed that predators in northern Germany serve as reservoirs for parasites of One Health concern, with four of the five most frequent endoparasites being zoonotic, highlighting the need of parasite surveillance in wildlife predators in order to implement measures avoiding spillovers to domestic animals and humans.

Application of target repositioning and in silico screening to exploit fatty acid binding proteins (FABPs) from Echinococcus multilocularis as possible drug targets

Fatty acid binding proteins (FABPs) are small intracellular proteins that reversibly bind fatty acids and other hydrophobic ligands. In cestodes, due to their inability to synthesise fatty acids and cholesterol de novo, FABPs, together with other lipid binding proteins, have been proposed as essential, involved in the trafficking and delivery of such lipophilic metabolites. Pharmacological agents that modify specific parasite FABP function may provide control of lipid signalling pathways, inflammatory responses and metabolic regulation that could be of crucial importance for the parasite development and survival. Echinococcus multilocularis and Echinococcus granulosus are, respectively, the causative agents of alveolar and cystic echinococcosis (or hydatidosis). These diseases are included in the World Health Organization's list of priority neglected tropical diseases. Here, we explore the potential of FABPs from cestodes as drug targets. To this end, we have applied a target repurposing approach to identify novel inhibitors of Echinococcus spp. FABPs. An ensemble of computational models was developed and applied in a virtual screening campaign of DrugBank library. 21 hits belonging to the applicability domain of the ensemble models were identified, and 3 of the hits were assayed against purified E. multilocularis FABP, experimentally confirming the model's predictions. Noteworthy, this is to our best knowledge the first report on isolation and purification of such four FABP, for which initial structural and functional characterization is reported here.

Short communication: Efficacy of albendazole in Echinococcus multilocularis-infected mice depends on the functional immunity of the host

Alveolar echinococcosis (AE) is a deadly parasitic disease that requires lifelong treatment with albendazole. Development of host immunity is pivotal with regard to the clinical outcome of AE, but its influence on conventional albendazole treatment is unknown. Using T-cell deficient athymic nude mice, we demonstrated that functional immunity is required for albendazole to be efficacious against murine AE. These results call for attention given the increasing number of immunocompromised patients with AE.

Combined cross-sectional and case-control study on Echinococcus multilocularis infection in pigs in Switzerland

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Minimal prevalence for Echinococcus multilocularis infection in Swiss domestic pigs was established.

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Minimal prevalence was 0.008% for fattening pigs and 0.11% for breeding pigs, respectively.

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All but one metacestode were degenerated; no protoscoleces were detected in histopathology.

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Main risk factors were foxes or other animals in the barns, no hygiene barrier, outdoor feeding and grass feeding.

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No geographical clusters of higher infection with E. multilocularis were evident.

The canid tapeworm Echinococcus multilocularis causes alveolar echinococcosis (AE) in humans and other intermediate hosts. Depending on the permissiveness of the intermediate host, the larval form of E. multilocularis (metacestode) may be either fertile, e.g. in rodents, and thus supporting the life cycle of the parasite, or infertile, e.g. in pigs, and thus interrupting the life cycle. Pigs have been shown to act as aberrant hosts for the metacestode and consequently develop liver lesions but represent a dead-end for the parasite. Routine liver inspection at slaughter provided the basis for a large-scale surveillance study on E. multilocularis infection in pigs. The aim of this combined cross-sectional and case-control study was to estimate the minimal prevalence of E. multilocularis in pigs in Switzerland, to find factors associated with infection, and to assess potential regional clusters of infection.

During the 12-month-study period, approximately 85% of all pigs slaughtered in Switzerland were assessed. In total, 450 pig livers with macroscopic lesions suggestive of E. multilocularis infection were analysed. Of those, 200 samples were positive by E. multilocularis-PCR. Thus, the overall minimal prevalence detected by molecular means was 0.009% in all slaughter pigs (200 of 2'143'996), 0.008% in finishing pigs (177 of 2'123'542), and 0.11% in breeding pigs (22 of 20'454). Histology revealed the unique presence of a laminated layer in 105 cases, and an additional germinal layer detected in a single case. Protoscoleces could not be observed in any of the lesions. Factors positively associated with infection were "foxes seen in the pig shed", "foxes on premises", "presence of other animals in the shed", "absence of a hygiene barrier", "outdoor feeding", "feeding grass", "lack of rodent control", "not having own dogs on the farm" and "infrequent deworming of sows". Infection was present in all regions sampled and was representative of the important pig rearing areas of Switzerland, without evidence of any obvious geographical cluster.

Conclusively, our study provided further evidence of widespread environmental contamination with E. multilocularis eggs in Switzerland. Furthermore, the absence of protoscoleces in any of the lesions supported the concept that pigs act only as a dead-end host and thus do not contribute to the life cycle of the parasite. Factors associated with E. multilocularis infection were in-line with parasite biology, and many can be addressed by increasing hygiene and management standards.

Spatial distribution and incidence trend of human alveolar echinococcosis in southwest Germany: increased incidence and urbanization of the disease?

Ecology and epidemiology of Echinococcus multilocularis and human alveolar echinococcosis (AE) are changing in Central Europe. Our data from a regional referral center for AE in southwest Germany suggest rising regional incidence for AE (annual incidence per 100,000 population 2004–2011: 0.12; 2012–2019: 0.20) and emerging urban AE (of 7 cases of AE in Freiburg city dwellers none was diagnosed before 2012) calling for an intensification of E. multilocularis and AE surveillance and of AE prevention measures.

Prevalence of human alveolar echinococcosis in China: a systematic review and meta-analysis

Background

Human alveolar echinococcosis (HAE), caused by the larvae of Echinococcus multilocularis, is a severe parasitic disease that is a major public health concern. New HAE cases in China account for 91% of the global HAE burden every year. Although there are a few studies and systematic reviews (SRs) on the prevalence of HAE in China, trends in the prevalence have not been estimated. This study aims to describe the overall variation in the trend of HAE prevalence in China, and provide evidence for preventive measures in the future.

Methods

Thirty-five eligible studies were retrieved from PubMed, Web of Science, EMBASE, CNKI, Wanfang Data, and VIP, and included in the SR and meta-analysis. An adjusted Agency for Healthcare Research and Quality checklist was used to evaluate study quality. The arcsine transformation was used to adjust the individual reported prevalence, and the pooled HAE prevalence was calculated. Heterogeneity was evaluated using the chi-square test and I² statistic. Forest plots were generated for the meta-analysis, and publication bias of the studies was assessed using the Egger’s test and funnel plots. We conducted subgroup analyses, sensitivity analyses, and meta-regression analyses to analyze the source of heterogeneity and factors potentially influencing the prevalence of HAE.

Results

The meta-analysis indicated that the pooled HAE prevalence in China was 0.96% (95% CI: 0.71 to 1.25%). Factors potentially influencing HAE prevalence were female sex (OR = 1.60, 95% CI: 1.35 to 1.91, P<0.01), being ≥30 years old (OR = 4.72, 95% CI: 2.29 to 9.75, P<0.01), and being farmers and/or herdsmen (OR = 2.54, 95% CI: 1.60 to 4.02, P<0.01). The results of the meta-regression analysis (R² = 38.11%, P < 0.01) indicated that HAE prevalence is on a downward trend.

Conclusions

HAE prevalence has decreased over time and maintained low levels after 2005 in China. This decline was influenced by the utilization of One Health strategies as intervention measures. Therefore, these One Health strategies should be used as references to formulate future programs for HAE control. More high-quality epidemiological investigations and surveillance programs should be conducted in order to improve HAE control in the future.

Drug repurposing applied: Activity of the anti-malarial mefloquine against Echinococcus multilocularis

The current chemotherapeutical treatment against alveolar echinococcosis relies exclusively on benzimidazoles, which are not parasiticidal and can induce severe toxicity. There are no alternative treatment options. To identify novel drugs with activity against Echinococcus multilocularis metacestodes, researchers have studied potentially interesting drug targets (e.g. the parasite's energy metabolism), and/or adopted drug repurposing approaches by undertaking whole organism screenings. We here focus on drug screening approaches, which utilize an in vitro screening cascade that includes assessment of the drug-induced physical damage of metacestodes, the impact on metacestode viability and the viability of isolated parasite stem cells, structure-activity relationship (SAR) analysis of compound derivatives, and the mode of action. Finally, once in vitro data are indicative for a therapeutic window, the efficacy of selected compounds is assessed in experimentally infected mice. Using this screening cascade, we found that the anti-malarial mefloquine was active against E. multilocularis metacestodes in vitro and in vivo. To shed more light into the mode of action of mefloquine, SAR analysis on mefloquine analogues was performed. E. multilocularis ferritin was identified as a mefloquine-binding protein, but its precise role as a drug target remains to be elucidated. In mice that were infected either intraperitoneally with metacestodes or orally with eggs, oral treatment with mefloquine led to a significant reduction of parasite growth compared to the standard treatment with albendazole. However, mefloquine was not acting parasiticidally. Assessment of mefloquine plasma concentrations in treated mice showed that levels were reached which are close to serum concentrations that are achieved in humans during long-term malaria prophylaxis. Mefloquine might be applied in human AE patients as a salvage treatment. Future studies should focus on other repurposed anti-infective compounds (MMV665807, niclosamide, atovaquone), which showed stronger in vitro activity against E. multilocularis than mefloquine.

Epidemic cystic and alveolar echinococcosis in Kyrgyzstan: an analysis of national surveillance data

BACKGROUND

Human cystic and alveolar echinococcosis are among the priority neglected zoonotic diseases for which WHO advocates control. The incidence of both cystic echinococcosis and alveolar echinococcosis has increased substantially in the past 30 years in Kyrgyzstan. Given the scarcity of adequate data on the local geographical variation of these focal diseases, we aimed to investigate within-country incidence and geographical variation of cystic echinococcosis and alveolar echinococcosis at a high spatial resolution in Kyrgyzstan.

METHODS

We mapped all confirmed surgical cases of cystic echinococcosis and alveolar echinococcosis reported through the national echinococcosis surveillance system in Kyrgyzstan between Jan 1, 2014, and Dec 31, 2016, from nine regional databases. We then estimated crude surgical incidence, standardised incidence, and standardised incidence ratios (SIRs) of primary cases (ie, excluding relapses) based on age and sex at country, region, district, and local community levels. Finally, we tested the SIRs for global and local spatial autocorrelation to identify disease hotspots at the local community level. All incidence estimates were calculated per 100 000 population and averaged across the 3-year study period to obtain annual estimates.

FINDINGS

The surveillance system reported 2359 primary surgical cases of cystic echinococcosis and 546 primary surgical cases of alveolar echinococcosis. Country-level crude surgical incidence was 13·1 per 100 000 population per year for cystic echinococcosis and 3·02 per 100 000 population per year for alveolar echinococcosis. At the local community level, we found annual crude surgical incidences up to 176 per 100 000 population in Sary-Kamysh (Jalal-Abad region) for cystic echinococcosis and 246 per 100 000 population in Uch-Dobo (Alay district, Osh region) for alveolar echinococcosis. Significant hotspots of cystic echinococcosis were found in four regions: Osh (five local communities in Uzgen district and four in Alay district), Naryn (three local communities in Jumgal district and one in Naryn district), Talas (three local communities in Talas district), and Chuy (one local community in Jayyl district). Significant alveolar echinococcosis hotspots were detected in the Osh region (11 communities in Alay district, including the local community of Sary Mogol, and one in Chong-Alay district) and in the Naryn region (five communities in Jumgal district and three in At-Bashy district), in the southwest and centre of the country.

INTERPRETATION

Our analyses reveal remarkable within-country variation in the surgical incidence of cystic echinococcosis and alveolar echinococcosis in Kyrgyzstan. These high-resolution maps identify precise locations where interventions and epidemiological research should be targeted to reduce the burden of human cystic echinococcosis and alveolar echinococcosis.

FUNDING

Swiss National Science Foundation.

Assessment of Electronic Sensing Techniques for the Rapid Identification of Alveolar Echinococcosis through Exhaled Breath Analysis

Here we present a proof-of-concept study showing the potential of a chemical gas sensors system to identify the patients with alveolar echinococcosis disease through exhaled breath analysis. The sensors system employed comprised an array of three commercial gas sensors and a custom gas sensor based on WO₃ nanowires doped with gold nanoparticles, optimized for the measurement of common breath volatile organic compounds. The measurement setup was designed for the concomitant measurement of both sensors DC resistance and AC fluctuations during breath samples exposure. Discriminant Function Analysis classification models were built with features extracted from sensors responses, and the discrimination of alveolar echinococcosis was estimated through bootstrap validation. The commercial sensor that detects gases such as alkane derivatives and ethanol, associated with lipid peroxidation and intestinal gut flora, provided the best classification (63.4% success rate, 66.3% sensitivity and 54.6% specificity) when sensors’ responses were individually analyzed, while the model built with the AC features extracted from the responses of the cross-reactive sensors array yielded 90.2% classification success rate, 93.6% sensitivity and 79.4% specificity. This result paves the way for the development of a noninvasive, easy to use, fast and inexpensive diagnostic test for alveolar echinococcosis diagnosis at an early stage, when curative treatment can be applied to the patients.

In vitro metabolomic footprint of the Echinococcus multilocularis metacestode

Alveolar echinococcosis (AE) is a zoonotic disease that is deadly if left untreated. AE is caused by the larval metacestode stage of the cestode Echinococcus multilocularis. Better knowledge on the host-parasite interface could yield novel targets for improvement of the treatment against AE. We analyzed culture media incubated with in vitro grown E. multilocularis metacestodes by 1H nuclear magnetic resonance spectroscopy to identify the unknown metabolic footprint of the parasite. Moreover, we quantitatively analyzed all amino acids, acetate, glucose, lactate, and succinate in time-course experiments using liquid chromatography and enzymatic assays. The E. multilocularis metacestodes consumed glucose and, surprisingly, threonine and produced succinate, acetate, and alanine as major fermentation products. The metabolic composition of vesicle fluid (VF) from in vitro grown E. multilocularis metacestodes was different from parasite-incubated culture medium with respect to the abundance, but not the spectrum, of metabolites, and some metabolites, in particular amino acids, accumulated in the VF. Overall, this study presents the first characterization of the in vitro metabolic footprint of E. multilocularis metacestodes and VF composition, and it provides the basis for analyses of potentially targetable pathways for future drug development.

Editorial overview: From farms and forests to forks? A review of diagnosis and management of globally important zoonotic Echinococcus spp. cestodes

This FAWPAR Special Issue is dedicated to zoonotic Echinococcus species. It is a compilation of invited papers that spans important aspects from molecular markers of emergence, diagnostics in both definitive and intermediate hosts, treatment of human alveolar echinococcosis, to control strategies in definitive hosts.

Relevance of Pulmonary Alveolar Echinococcosis

BACKGROUND

Pulmonary alveolar echinococcosis (PAE) is a chronic disease caused by Echinococcus multilocularis with very low incidence in developed countries.

METHODS

This single-center, retrospective study included 34 patients who were diagnosed with PAE between January 2001 and February 2019 (15 males, 19 females, mean age: 52.4±15.8 years, age range: 28-78 years) in Ataturk University Medical School, Erzurum, Turkey.

RESULTS

The liver was the primary involved organ in all cases. Pulmonary involvement was detected in 13.0% (34/261) of all cases with hepatic alveolar echinococcosis (AE), and three patients (8.8%) had both pulmonary metastasis and brain metastasis. The route of spread to the lungs based on radiological data was hematogeneous in 25 patients (73.5%), transdiaphragmatic in three patients (8.8%) and both hematogeneous and transdiaphragmatic in six patients (17.7%). AE showed bilateral involvement in 19 patients (55.9%), whereas only the right lung was involved in 12 patients (35.3%) and the left lung in three patients (8.8%). Of the patients, five underwent surgery due to PAE and 29 patients received medical therapy with albendazole. A total of three patients died during the follow-up period (2, 5 and 10 years after the diagnosis of PAE), while 31 patients continued with follow-up and treatment for a mean duration of 5.4±3.8 years (1-14 years).

CONCLUSIONS

Patients with hepatic AE must, as a matter of course, be screened for possible lung involvement. Albendazole therapy may slow down disease progression in patients with widespread pulmonary involvement who are not eligible for surgery.