A multiplex PCR for differential detection of Echinococcus granulosus sensu stricto, Echinococcus multilocularis and Echinococcus canadensis in China

Plasma Circulating Cell-Free DNA Facilitated the Detection of an Alveolar Echinococcosis Patient Initially Misdiagnosed as Cystic Echinococcosis: A Case Report

Echinococcosis, especially alveolar echinococcosis (AE), is becoming an emerging/re-emerging disease with a growing number of cases reported globally. The diagnosis of echinococcosis is based mainly on imaging, which may be challenging when the image presentation is atypical. We reported one patient with suspected cystic echinococcosis (CE) by imaging. The cell-free DNA (cfDNA) obtained from sequencing the patient's plasma before the operation showed that this patient probably had AE with 45 reads mapped to the Echinococcus multilocularis reference genome (Read-Pairs Per Million = 0.24). The patients underwent surgery, and the pathological result showed that the patient had AE. The conventional polymerase chain reaction (PCR) of her lesion sample extraction also indicated that the infection was caused by Echinococcus multilocularis. The follow-up ultrasound after three months indicated no recurrence. We demonstrated that the differentiation of CE and AE by imaging may not be that easy, with further elaboration on the differentiation between AE and CE in different aspects. We demonstrated that it is possible to use patients' plasma cfDNA mapped to Echinococcus references before the operation to obtain the objective clue of the lesion to facilitate diagnosis.

Past and Present of Diagnosis of Echinococcosis: A Review (1999-2021)

The larval forms of taeniid cestodes belonging to the genus Echinococcus are the source of the zoonotic infection known as echinococcosis. Alveolar and cystic echinococcosis are caused by Echinococcus multilocularis and Echinococcus granulosus (s. s) respectively. It is endemic in several regions of the world. In this systematic review, we describe diagnosis, and the species (human, canids, livestock, and small rodents) affected by cystic (CE) and alveolar echinococcosis (AE). From 1999 to 2021, we searched the online directory through PubMed, SCOPUS, Web of Science, and google scholar. Among the 37,700 records found in the online databases, 187 publications met our eligibility requirements. The majority of investigations employed a range of diagnostic methods, such as ELISA, imaging, copro-PCR, necropsy or arecoline hydrobromide purgation, morphological cestode confirmation, and fecal sieving/flotation to detect and confirm Echinococcus infection. ELISA was the most commonly used method followed by PCR, and imaging. The research team retrieved data describing the incidence or assessment of the diagnostic test for E. multilocularis in humans (N = 99), canids (N = 63), small ruminants (N = 13), large ruminants (N= 3), camel (N= 2), pigs (N=2) and small mammals (N= 5). This study was conducted to explore the diagnostic tools applied to detect echinococcosis in humans as well as animals in prevalent countries, and to report the characteristic of new diagnostic tests for disease surveillance. This systematic review revealed that ELISA (alone or in combination) was the most common method used for disease diagnosis and diagnostic efficacy and prevalence rate increased when recombinant antigens were used. It is highly recommended to use combination protcols such as serological with molecular and imaging technique to diagnose disease. Our study identified scarcity of data of reporting echinococcosis in humans/ animals in low-income or developing countries particularly central Asian countries. Study reports in small rodents indicate their role in disease dissemination but real situation in these host is not refected due to limited number of studies. Even though echinococcosis affects both public health and the domestic animal sector, therefore, it is important to devise new and strengthe implementation of the existing monitoring, judging, and control measures in this estimate.

Optimization of single-tube nested PCR for the detection of Echinococcus spp

Echinococcosis is a serious zoonotic life-threatening parasitic disease caused by metacestodes of Echinococcus spp., and appropriate sensitive diagnosis and genotyping techniques are required to detect infections and study the genetic characterization of Echinococcus spp. isolates. In this study, a single-tube nested PCR (STNPCR) method was developed and evaluated for the detection of Echinococcus spp. DNA based on the COI gene. STNPCR was 100 times more sensitive than conventional PCR and showed the same sensitivity to common nested PCR (NPCR); but with a lower risk of cross-contamination. The limit of detection of the developed STNPCR method was estimated to be 10 copies/μL of the recombinant standard plasmids of Echinococcus spp. COI gene. In clinical application, 8 cyst tissue samples and 12 calcification tissue samples were analysed by conventional PCR with outer and inner primers and resulted in 100.00% (8/8) and 8.33% (1/12), 100.00% (8/8) and 16.67% (2/12) positive reactions, respectively, while STNPCR and NPCR were all able to identify the presence of genomic DNA in 100.00% (8/8) and 83.33% (10/12) of the same samples. Due to its high sensitivity combined with the potential for the elimination of cross-contamination, the STNPCR method was suitable for epidemiological investigations and characteristic genetic studies of Echinococcus spp. tissue samples. The STNPCR method can effectively amplify low concentrations of genomic DNA from calcification samples and cyst residues infected with Echinococcus spp. Subsequently, the sequences of positive PCR products were obtained, which were useful for haplotype analysis, genetic diversity, and evolution studies of Echinococcus spp., and understanding of Echinococcus spp. dissemination and transmission among the hosts.

High-performance triplex PCR detection of three tapeworm species belonging to the genus Raillietina in infected poultry

Chickens and ducks are important sources of essential proteins and nutrition for global consumption, especially their eggs and meat. Tapeworm infections in chickens and ducks are the cause of serious poultry health and economic problems in the processing of livestock and food production systems. Raillietina are cosmopolitan in distribution and are possibly the most common tapeworm parasites. There are three important species regarding avian infection, with different pathogenicity, including Raillietina echinobothrida, R. tetragona, and R. cesticillus. Co-infection diagnosis of these tapeworms using morphological analysis can be performed, but this is time-consuming and complicated. Therefore, this study aimed to develop a triplex PCR for the detection and discrimination of three Raillietina species. The triplex PCR assay specifically amplified target DNAs with no inter-specific interference and produced a specific band for each species. According to the specificity test, there was no cross-amplification with the DNA template of related parasites and their hosts. The lowest detectable DNA concentrations were evaluated and provided sensitivities of 0.5 pg/μL for R. echinobothrida, 5 pg/μL for R. tetragona, 50 fg/μL for R. cesticillus, and 5 pg/μL for the combination of DNA from all three species. Simultaneous detection limits of egg capsules and gravid proglottids was also performed, with and without feces. The interference of feces in the reaction was related to a decrease in sensitivity, but simultaneous detection of three Raillietina species in amounts lower than one gravid proglottid and ten egg capsules was still successful. Thus, this study is the first triplex PCR assay for Raillietina detection and can be utilized as an alternative diagnostic tool for the detection and discrimination of R. echinobothrida, R. tetragona, and R. cesticillus infection in poultry through the verification of fecal specimens. In addition, it could improve the performance of specific treatments and promote veterinary healthcare.

First Report of Alveolar Hydatid Disease (Echinococcus multilocularis) in a Golden Jackal (Canis aureus)

BACKGROUND

Alveolar hydatid disease caused by the tapeworm Echinococcus multilocularis is a parasitic disease present in the northern hemisphere. Echinococcus multilocularis is a parasite of canid and felid carnivores as definitive hosts, and small mammals, particularly rodents as intermediate hosts. Other animal species and humans can be aberrant intermediate hosts for this parasite. It is known that besides acting as definitive hosts, domestic dogs can rarely become infected with the larval form of E. multilocularis and develop alveolar echinococcosis; however, a role of wild canids as aberrant intermediate hosts has not been documented until now. To the best of our knowledge the present paper provides the first description of alveolar hydatid disease in a golden jackal (Canis aureus).

CASE PRESENTATION

Necropsy of the yearling female animal found a large, round, tumor-like mass, 20 cm in diameter, with a rough, multilobulated surface in the abdominal cavity, connected to the liver and omentum. On the cut surface this tumor-like lesion was multicystic, with a number of locular cavities filled with a clear yellowish to orange watery fluid and a large area of necrosis in the central part of the mass. Histopathology revealed multiple cystic spaces separated by fibrous sheaths and inflammatory cells-lymphocytes, plasma cells, neutrophil and eosinophil granulocytes. The cysts contained either pale, hyaline, eosinophilic laminar and occasionally amorphous, acellular, PAS-positive structures, or metacestodes with invaginated protoscolices. In several cysts round calcified bodies (calcareous corpuscles) were noted. Microscopic examination showed everted and inverted protoscolices which were attached to fragments of the brood capsule or free in hydatid fluid. By comparing consensus nucleotide sequence of 457 bp obtained by PCR reaction with sequences deposited in NCBI GenBank it is determined that it was 100% identical with E. multilocularis sequences under accession numbers MH259778.1, MH259776.1, AB668376.1, EU704124.1 and AB018440.2.

CONCLUSIONS

The present paper provides a proof that the golden jackal, besides being a definitive host, can also serve as the aberrant intermediate host for E. multilocularis.

Development of Loop-Mediated Isothermal Amplification Combined with Lateral Flow Dipstick Assay for a Rapid and Sensitive Detection of Cystic Echinococcosis in Livestock in Kenya

Background

Cystic echinococcosis is a zoonotic disease caused by the metacestode stage of Echinococcus granulosus and occurs worldwide, causing considerable economic losses and public health problems. The currently available methods for the diagnosis of animal hydatidosis are time-consuming and require well-equipped laboratories which make them incompatible with testing in resource-poor settings. This study developed and evaluated a rapid, more sensitive, and specific loop-mediated isothermal amplification combined with a lateral flow dipstick assay for the rapid and sensitive detection of cystic echinococcosis.

Results

In this study, a specific primer set and FITC-labeled probe targeting the conserved region of the NADH-1 gene were designed. The LAMP reaction was performed at 60°C for 40 minutes, and the amplification products were successfully visualized by LFD strips. The analytical sensitivity of LAMP-LFD was determined using 10-fold serial dilutions of E. granulosus DNA. The minimal concentration detected was 10 fg/μl, and no cross-reactivity was observed with DNA extracted from Taenia solium, Taenia saginata, and Fasciola hepatica. The ability of the developed LAMP-LFD assay to detect cystic echinococcosis was further evaluated with 62 cyst samples from slaughtered cattle in Juja Abattoir, Kiambu County, Kenya. The LAMP-LFD was able to detect 59/62 (95.2%, 95% CI 0.87–0.98) as positive samples of E. granulosus compared to 53/62 (85.5%, 95% CI 0.75–0.92) by nested PCR assay.

Conclusion

Our results indicated that the developed LAMP-LFD technique was more sensitive than the nested PCR assay, rapid, and easy to perform with a simple visual detection of products. Therefore, it could be an important point-of-care diagnostic tool for cystic echinococcosis.

A Sarcopenia-Based Prediction Model for Postoperative Complications of ex vivo Liver Resection and Autotransplantation to Treat End-Stage Hepatic Alveolar Echinococcosis

Background

Sarcopenia and visceral adiposity have been shown to be associated with postoperative complications in numerous diseases. However, their effects on the postoperative complications of end-stage hepatic alveolar echinococcosis (HAE) patients undergoing ex vivo liver resection and autotransplantation (ELRA) remain unclear.

Methods

This retrospective study included 101 end-stage HAE patients who underwent ELRA from January 2014 to August 2020. We measured the skeletal muscle and adipose tissue of all patients at the level of the third lumbar vertebra on plain abdominal computed tomography (CT) images and subsequently derived an equation via least absolute shrinkage and selection operator (LASSO) regression analysis to calculate the sarcopenia score. Univariate and multivariate regression were performed to reveal the relationship between major postoperative complications and perioperative clinical data, and the obtained nomogram was validated with the bootstrapping method.

Results

The sarcopenia score was constructed as a personalized indicator to evaluate sarcopenia and visceral adiposity in each patient. Logistic regression analysis finally selected duration from primary diagnosis to obvious symptoms (OR=1.024, 95% CI, 1.007-1.042), surgical time (OR=1.003, 95% CI, 0.999-1.007) and sarcopenia score (OR=4.283, 95% CI, 1.739-10.551) as independent risk factors for predicting major postoperative complications following ELRA for end-stage HAE patients. The area under the receiver operating characteristic curve (AUROC) of 0.807 (95% CI, 0.720-0.895) and the calibration curve for this prediction model were satisfactory.

Conclusion

The sarcopenia score, which systematically evaluates the skeletal muscle and adipose tissue of end-stage HAE patients, was a significant predictive factor for major postoperative complications of ELRA. Relevant interventions should be conducted for those who have a high risk of postoperative complications according to the nomogram.

Epidemiological analysis of cystic echinococcosis and alveolar echinococcosis in an extremely high prevalence region: Population-based survey and host animal monitoring in Shiqu County, China

Echinococcosis is the most common parasitic disease in the Tibetan Plateau, placing a large disease burden on the local population. Shiqu County, located in western Sichuan Tibetan region, had a particularly high prevalence rate of cystic echinococcosis (CE) and alveolar echinococcosis (AE) in previous surveys. From 2015 to 2018, a population-based field survey was conducted to explore the epidemic situation. Epidemiological features were examined through demographic analysis and mapping. In addition, the infection prevalence of Echinococcus in dogs was also investigated and mapped by spatial autoregression. A total of 84,768 people were screened by abdominal ultrasound inspection, and 2,341 CE and 3,930 AE cases were detected, with a corresponding prevalence of 2.76% and 4.64%, respectively. This made Shiqu County one of the most severe echinococcosis endemic regions in the world, especially with regard to AE. The cases were not evenly distributed among towns: particularly, the AE rates in the northwest towns were very high and closely related to the infection rate of neighboring host animals. Simultaneously, a comprehensive prevention project including patient treatment and host management was conducted and achieved preliminary success in source control. According to feces monitoring findings, the infection rate of dogs declined from 26.38% in early 2016 to 3.71% in 2018. Combined with host animal distribution data at the town level, the predicted risk ranks were categorized by risk index and mapped to guide further control operations.

Establishing and evaluation of a polymerase chain reaction for the detection of Echinococcus multilocularis in human tissue

BACKGROUND

Alveolar echinococcosis (AE) is caused by metacestode larva of the tapeworm Echinococcus multilocularis. AE diagnostics currently rely on imaging techniques supported by serology, but unequivocal detection of AE is difficult. Although polymerase chain reaction (PCR)-based methods to detect tapeworm DNA in biopsies have been suggested for several species, no validated protocol adhering to accepted guidelines has so far been presented for AE diagnostics. We herein established a PCR protocol for metacestode biopsies and technically evaluated the method using isolated parasite DNA and cells, biopsies of clinically relevant material, and formalin fixed paraffin-embedded (FFPE) human tissue blocks. We compared the results with an immunochemical (IHC) approach using the monoclonal antibody Em2G11 specific for the antigen Em2 of E. mulitlocularis.

METHODOLOGY/PRINCIPAL FINDINGS

Based on tapeworm 12S rDNA sequences we established and validated a PCR protocol for robust detection of as little as 50 parasite cells per specimen and report 127 cases of positive identification of Echinococcus species in samples from humans and animals. For further validation, we analyzed 45 liver, heart, brain, and soft tissue samples as well as cytological probes of aspirates of FFPE-material from 18 patients with clinically confirmed AE. Of each patient we analyzed (i) fully viable lesions with laminated layer; (ii) tissue with mAbEm2G11-positive small particles of E. multilocularis (spems); (iii) mAbEm2G11-negative tissue adjacent to the main lesion; and (iv) lymph node tissue with mAbEm2G11-positive spems. To identify the areas for the PCR-based approach, we performed IHC-staining with the monoclonal antibody Em2G11. Micro-dissected tissue of these areas was then used for PCR-analysis. 9 of 15 analyzed samples with viable E. multilocularis lesions with laminated layer were positive by PCR. Of this group, all samples preserved for less than 6 years (6/6) were tested positive. 11 of 15 samples of spems and 7 of 9 samples of the control group mAbEm2G11-negative tissue were negative by PCR. We further show that all probes from lymph nodes with spems are PCR negative.

CONCLUSIONS/SIGNIFICANCE

We present a sensitive PCR method for the detection of E. multilocularis in human tissue, particularly in fresh biopsy material and tissue blocks stored for less than 5 years. While the diagnostic sensitivity of material containing only spems was higher using IHC, PCR detection was possible in IHC negative liver tissue and in patients with negative serology. Our results support the view that spems do not contain parasitic DNA or viable cells of the parasite. spems thus most probably do not directly contribute to metastasis formation during AE.

A validated method to identify Echinococcus granulosus sensu lato at species level

The zoonotic tapeworm Echinococcus granulosus sensu lato (s.l.) represents a species complex encompassing multiple causative agents of cystic echinococcosis, a neglected tropical disease affecting more than one million people in the world. At least eight genotypes, grouped in five species, are currently recognized within this species complex, and they differ in terms of relative public health impact. Here we present a molecular method that first identifies the common E. granulosus sensu stricto (s.s.) (genotypes G1 and G3) based on a PCR-RFLP assay, and can further identify the remaining species based on a multiplex PCR assay. We demonstrate the applicability of the method to DNA extracted from parasitic cyst material of human and animal origin, preserved in ethanol or frozen. The method has been developed and validated at the European Union Reference Laboratory for Parasites (EURLP), according to the ISO/IE 17025.

Diagnostic urinary cfDNA detected in human cystic echinococcosis

Cystic echinococcosis (CE) is a major neglected tropical zoonotic disease caused by the tissue-dwelling larval stage of the cestode parasite Echinococcus granulosus. For individuals suspected of CE, the diagnostic standard is imaging using ultrasonography, X rays, or computed tomography. These resource-demanding and expensive procedures are rarely available in endemic rural areas where CE is most prevalent. There is a critical need for a new approach to identify CE patients so that they can be managed early in the course of their infection. This study reports on the results of a diagnostic approach that identifies E. granulosus-derived cell-free DNA (cfDNA) in the urine of CE patients. Utilizing PCR to amplify a fragment of a major tandem repeat element found in E. granulosus nuclear DNA, urine samples from all seven imaging-confirmed CE patients who harbored active liver cysts were positive. In addition, the urine samples from 2/4 patients who presented with non-viable/calcified liver cysts were also PCR positive for the repeat fragment. To our knowledge, this is the first report of using parasite cfDNA from urine to diagnose CE. This approach provides an easy to implement and cost-effective method to survey for the prevalence of E. granulosus in humans populations.