Serological diagnosis of echinococcosis: the diagnostic potential of native antigens

Cystic echinococcosis of the liver

BACKGROUND

Cystic echinococcosis (CE) is a widely endemic helminthic disease caused by infection with metacestodes (larval stage) of the Echinococcus granulosus tapeworm, which is transmitted by dogs and found on every continent, except Antarctica. This study aimed to review the life cycle, epidemiology, symptoms, diagnostic methods, and treatment of E granulosus infection of the liver.

METHODS

A comprehensive review was conducted using MEDLINE/PubMed, Google Scholar, Cochrane Library, and the Web of Science, which were accessed between 1990 and 2024. The main search focused on "CE of the liver." The following terms were used: cystic echinococcosis, hydatidosis, E granulosus, echinococcus life cycle, liver cyst, albendazole, liver resection, pericystectomy, cystobiliary fistula, and percutaneous aspiration injection and reaspiration (PAIR).

RESULTS

CE should be considered in the differential diagnosis of hepatic cysts, especially among individuals with risk factors, such as those who have traveled to or immigrated from areas with a high prevalence. Echinococcus species require 2 hosts to complete their life cycle, with humans acting as intermediate hosts that become infected by ingesting eggs from contaminated environments, leading to cyst formation, typically in the liver or lungs. Symptoms are based on cyst size and location, such as abdominal pain, jaundice, respiratory distress, or neurologic deficits, and can lead to severe complications, such as cyst rupture, allergic reactions, sepsis, or secondary hydatidosis. Imaging plays a key role in evaluating cyst stage, size, location, and potential complications and in determining the appropriateness of a minimally invasive PAIR procedure. Although serum antibody tests typically have a low sensitivity, antigen assays or recombinant proteins may provide useful diagnostic information. For uncomplicated active cysts, the treatment options include chemotherapy alone or in combination with the PAIR technique.

CONCLUSION

Hepatic echinococcal cysts, which are relatively rare in North America, should be considered in the differential diagnosis of hepatic cysts, especially in individuals with risk factors.

Serological Comparison of Native Antigen ELISAs with Rapid ICT Test Kits for the Diagnosis of Human Alveolar and Cystic Echinococcosis in China

BACKGROUND

The aim of this study was to compare the diagnostic performance of native antigen ELISAs and ADAMU-AE/CE commercial ICT test kits in subjects either exposed to Echinococcus infection or with clinically diagnosed alveolar (AE) or cystic (CE) echinococcosis.

METHODS

A total of 370 subjects with a previous clinical confirmation of CE or AE from northwestern China were recruited. Serum samples were also obtained from 3923 children/teenagers during a community survey. All sera were tested using native antigen ELISAs. The ADAMU-AE/CE test kits were subsequently used for the serology of the 370 clinically confirmed individuals and of 251 children/teenagers that were ELISA antibody-positive for both Echinococcus species but ultrasound-negative during baseline survey. An analysis of the association between the serological tests and ultrasound classification was carried out amongst 89 AE and 164 CE cases. A Kappa consistency analysis was undertaken to compare the diagnostic performance of the native antigen ELISAs and the ADAMU kits and the ultrasound imaging results. The χ² test was also used for a comparison of the different seropositivity rates between the groups.

FINDINGS

There was poor consistency (Kappa = 0.26 and 0.28 for AE and CE respectively) between the native antigen ELISAs and the ADAMU kits for the diagnosis of AE and CE among the cases and the surveyed children/teenagers, but a relatively good consistency (Kappa = 0.63) between the ADAMU-AE kit and ultrasound observations for the AE cases. Additionally, of the 251 teenagers co-positive for both AE and CE antibodies by the native antigen ELISAs, only one was found positive by the ADAMU-AE kit, verified as a new AE case on subsequent ultrasound follow-up. The remainder (N = 250) were negative by serology using the ADAMU-AE/CE kits and by ultrasound examination. The two native antigen ELISAs did not discriminate well between cases of clinically diagnosed AE and CE. In contrast, ADAMU-AE and ADAMU-CE commercial ICT test kits readily differentiated cases of AE from CE with specificities of 99% for AE and 100% for CE.

CONCLUSIONS

The ADAMU-AE/CE kits proved reliable, accurate, and amenable diagnostic tools in the clinical setting for confirmation of suspected AE/CE cases. The native antigen ELISAs tests can provide useful information on the level of human exposure to Echinococcus infection.

Management of biliary obstruction in patients with newly diagnosed alveolar echinococcosis: a Swiss retrospective cohort study

BACKGROUND AND STUDY AIMS

Alveolar echinococcosis, an orphan zoonosis affecting the liver, is of increasing concern worldwide. Most symptomatic cases present at an advanced and inoperable stage, sometimes with biliary obstruction prompting biliary tract interventions. These are, however, associated with a high risk of infectious complications. The aim of this retrospective study was to compare the effectiveness and safety of conservative and interventional treatment approaches in patients with newly diagnosed alveolar echinococcosis and biliary obstruction.

PATIENTS AND METHODS

Alveolar echinococcosis patients treated at two referral centres in Switzerland, presenting with hyperbilirubinaemia (total bilirubin >1.5 Upper Limit of Normal) at diagnosis were included, unless another underlying aetiology, i.e. common bile duct stones or decompensated cirrhosis, was identified. Patients were divided into two groups, according to whether they initially received a biliary tract intervention. The primary endpoint was normalisation of bilirubin levels within a 6-month period. Secondary endpoints included, among others, the occurrence of early and late biliary complications, the need for biliary tract interventions during follow-up and overall duration of hospital stays for treatment initiation and for biliary complications.

RESULTS

28 patients were included in this study, of whom 17 received benzimidazole therapy alone and 11 additionally received a biliary tract intervention. Baseline characteristics did not differ between groups. All but one patient in each group achieved the primary endpoint (p=0.747). Biliary tract intervention was associated with faster laboratory improvement (t1/2 1.3 vs 3.0 weeks), but also with more frequent early biliary complications (7/11 vs 1/17, p=0.002) and longer initial hospital stay (18 days vs 7 days, p=0.007).

CONCLUSION

Biliary obstruction in patients with newly diagnosed alveolar echinococcosis can be treated effectively with benzimidazole therapy alone. Biliary tract intervention, on the other hand, is associated with a high complication rate and should probably be reserved for patients with insufficient response to benzimidazole therapy.

Hydatid Disease of the Liver

Background

Echinococcosis also known as hydatid disease is a zoonotic parasitic disease caused by a tapeworm. It has a worldwide distribution. For long, it was thought to be a problem of the poorly sanitized "third world" and not given the importance it deserved. However, its occurrence in countries like Australia and New Zealand and recently in countries in Central Europe has meant that it is included in a WHO list of neglected diseases, has recently been the subject of extensive epidemiological studies, and has been the recipient of increased research funding.

Summary

The diagnosis is still based on clinical presentation in an endemic area corroborated with typical findings on imaging which routinely include ultrasound and CT scan. Serological tests have been used in some centers to support the diagnosis. Treatment depends on the site of involvement and can vary from wait and watch to extensive radical surgical procedures. The common element of all treatments is the addition of albendazole which forms an essential cornerstone of all treatment protocols. Inspite having been used for a fairly long time, there is still no consensus on the dose, duration, and timing of therapy with albendazole.

Key Message

Hydatid disease continues to be a significant global health problem inspite of a good understanding of its life cycle and rising standards of public sanitation. Though diagnosis is straightforward and not expensive, treatment can sometimes be complicated. The addition of albendazole to all treatment protocols is an important advance, but firm guidelines on duration of its use are still awaited.

Application and evaluation of native antigen B from Echinococcus granulosus sensu stricto and E. canadensis alone or mixture for serodiagnosis of human G1-G3 and G6/G7 genotypes cystic echinococcosis sera, using ELISA and Western blotting

Cystic echinococcosis (CE) is one of the most important helminthic diseases in the world with different genotypes distribution. The application of specific genotype antigens together with sera from patients with specific cyst genotypes have not been reported, so far. The present study aimed to apply and evaluate native AgB from Echinococcus granulosus sensu stricto (Eg) and Echinococcus canadensis (Ec) alone or mixture for serodiagnosis of human G1-G3 and G6/G7 genotypes cystic echinococcosis sera, using ELISA and Western blotting. A total of 47 human sera along with 47 human CE cysts were collected. CE genotypes were determined. Native AgB were prepared from E. granulosus s.s and E. canadensis genotypes. ELISA and Western blot were performed on human specific G1-G3 and G6/G7 genotypes sera. Species specific native AgB were used alone or mixed. The sensitivity of ELISA using alone and mixed 1Eg-1Ec, 1Eg-2Ec, and 2Eg-1Ec of native AgB from E. granulosus s.s and E. canadensis genotypes for human G1-G3 sera were 92.10, 89.47, 97.37, 100, and 100%, respectively; while using AgBs, alone and mixed for human G6/G7 sera were 100%. The sensitivity of Western blotting using native AgB of E. granulosus s.s and E. canadensis genotypes alone and mixed 2Eg-1Ec were 78.95% and 100% for human G1-G3 and G6/G7 genotypes sera, respectively. The mixture of AgB from Echinoccus granulosus sensu stricto and Echinococcus canadensis genotypes increased ELISA sensitivity for the diagnosis of human CE. Preparation and application of native AgB from specific and prevalent genotypes of CE in endemic regions is recommended.

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.

Monoclonal antibody-based localization of major diagnostic antigens in metacestode tissue, excretory/secretory products, and extracellular vesicles of Echinococcus species

Alveolar (AE) and cystic echinococcosis (CE) are severe parasitic zoonoses caused by the larval stages of Echinococcus multilocularis and E. granulosus sensu lato, respectively. A panel of 7 monoclonal antibodies (mAbs) was selected against major diagnostic epitopes of both species. The binding capacity of the mAbs to Echinococcus spp. excretory/secretory products (ESP) was analyzed by sandwich-ELISA, where mAb Em2G11 and mAb EmG3 detected in vitro extravesicular ESP of both E. multilocularis and E. granulosus s.s. These findings were subsequently confirmed by the detection of circulating ESP in a subset of serum samples from infected hosts including humans. Extracellular vesicles (EVs) were purified, and the binding to mAbs was analyzed by sandwich-ELISA. Transmission electron microscopy (TEM) was used to confirm the binding of mAb EmG3 to EVs from intravesicular fluid of Echinococcus spp. vesicles. The specificity of the mAbs in ELISA corresponded to the immunohistochemical staining (IHC-S) patterns performed on human AE and CE liver sections. Antigenic small particles designated as ''spems'' for E. multilocularis and ''spegs'' for E. granulosus s.l. were stained by the mAb EmG3IgM, mAb EmG3IgG1, mAb AgB, and mAb 2B2, while mAb Em2G11 reacted with spems and mAb Eg2 with spegs only. The laminated layer (LL) of both species was strongly visualized by using mAb EmG3IgM, mAb EmG3IgG1, mAb AgB, and mAb 2B2. The LL was specifically stained by mAb Em2G11 in E. multilocularis and by mAb Eg2 in E. granulosus s.l. In the germinal layer (GL), including the protoscoleces, a wide staining pattern with all structures of both species was observed with mAb EmG3IgG1, mAb EmG3IgM, mAb AgB, mAb 2B2, and mAb Em18. In the GL and protoscoleces, the mAb Eg2 displayed a strong E. granulosus s.l. specific binding, while mAb Em2G11 exhibited a weak granular E. multilocularis specific reaction. The most notable staining pattern in IHC-S was found with mAb Em18, which solely bound to the GL and protoscoleces of Echinococcus species and potentially to primary cells. To conclude, mAbs represent valuable tools for the visualization of major antigens in the most important Echinococcus species, as well as providing insights into parasite-host interactions and pathogenesis.

Analysis of gene expression profile of peripheral blood in alveolar and cystic echinococcosis

RNA-sequencing (RNA-seq) is a versatile, high-throughput technology that is being widely employed for screening differentially expressed genes (DEGs) in various diseases. Echinococcosis, a globally distributed zoonosis, has been reported to impose a heavy disease burden in pastoral areas of China. Herein we aimed to explore the molecular mechanisms underlying echinococcosis. In this study, peripheral blood samples were collected from six patients with alveolar echinococcosis (AE), six patients with cystic echinococcosis (CE), and six healthy controls. RNA-Seq (mRNA) was performed to detect gene transcript and expression levels, and DEGs were subjected to bioinformatic analyses. In comparison with healthy controls, 492 DEGs (270 upregulated, 222 downregulated) were found in the AE group and 424 DEGs (170 upregulated, 254 downregulated) were found in the CE group (|log₂ (fold change)| > 1 and P < 0.05). Further, 60 genes were upregulated and 39 were downregulated in both the AE and CE groups. Gene ontology enrichment analysis indicated that DEGs were mainly involved in molecular functions, including extracellular space, extracellular region, organ and system development, and anatomical structure development. Protein–protein interaction (PPI) networks were constructed to depict the complex relationship between DEGs and interacting proteins.

Evaluation of a novel Echinococcus granulosus recombinant fusion B-EpC1 antigen for the diagnosis of human cystic echinococcosis using indirect ELISA in comparison with a commercial diagnostic ELISA kit

Cystic echinococcosis (CE) is a zoonotic parasitic disease caused by the metacestode of Echinococcus granulosus sensu lato (s.l.). A large proportion of the patients are asymptomatic at the early and late stages of the disease. CE diagnosis is mainly based on imaging techniques. Laboratory diagnosis including antibody-antigen (recombinant or fusion recombinant) can be used for the diagnosis and follow up of CE and alveolar echinococcosis (AE), but need optimization and standardization. This study aimed to evaluate the efficacy of a recombinant B-EpC1 (rB-EpC1) fusion antigen comprising B1, B2, B4, and EpC1 antigens of E. granulosus using indirect ELISA in comparison with a commercial ELISA kit for the serodiagnosis of CE. The recombinant protein was expressed in the expression host, E. coli BL21, and purified. This recombinant antigen was then evaluated by indirect ELISA and compared to the commercial CE diagnostic kit (Vircell, Spain). The study samples included 124 human sera consisting of 62 sera of patients with CE, and 62 sera of individuals without clinical evidences of CE and specific anti-CE antibodies in routine indirect ELISA. The diagnostic sensitivity and specificity of the indirect rB-EpC1-ELISA test for detection of specific anti-hydatid cyst antibodies in human CE were 95.2% and 96.8%, respectively. Also, the diagnostic sensitivity and specificity of the commercial ELISA test were 96.8% in this study. Initial evaluation of the recombinant fusion antigen (B-EpC1) was promising for the detection of CE by ELISA in clinical settings. Standardization and evaluation of recombinant fusion protein require further studies.

Follow-up PET/CT of alveolar echinococcosis: Comparison of metabolic activity and immunodiagnostic testing

Purpose

To investigate the potential role of follow-up ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in therapy control of inoperable patients with alveolar echinococcosis.

Materials and methods

In this single-center retrospective cohort study, 48 PET/CT of 16 patients with confirmed alveolar echinococcosis were analysed. FDG-uptake of the most active echinococcosis manifestation was measured (i.e., maximum standardized uptake value (SUVmax) and in relation to background activity in normal liver tissue (SUVratio)) and compared to immunodiagnostic testing. For clinical patient follow-up, patient demographics, laboratory data, including E. granulosus hydatid fluid (EgHF) antibody units (AU) as well as clinical and treatment information were assessed for all patients at the time of PET/CT, and at the last recorded clinical visit.

Results

Metabolic activity of PET/CT measured in the echinococcosis manifestation was significantly correlated with EgHF AU (p < 0.001). The differences in metabolic activity of echinococcosis manifestations between two consecutive PET/CT examinations of the same patient and differences in EgHF AU in the respective time intervals displayed a significant positive correlation (p = 0.01). A trend for a more rapid decline in SUVratio liver over time was found in patients who stopped benzimidazole therapy versus patients who did not stop therapy (p = 0.059).

Conclusion

In inoperable patients with alveolar echinococcosis, the course of metabolic activity in follow-up PET/CT is associated to the course EgHF antibody levels. Both parameters may potentially be used to evaluate the course of the disease and potentially predict the duration of benzimidazole therapy.

Serological Assays for Alveolar and Cystic Echinococcosis—A Comparative Multi-Test Study in Switzerland and Kyrgyzstan

Both alveolar (AE) and cystic echinococcosis (CE) are lacking pathognomonic clinical signs; consequently imaging technologies and serology remain the main pillars for diagnosis. The present study included 100 confirmed treatment-naïve AE and 64 CE patients that were diagnosed in Switzerland or Kyrgyzstan. Overall, 10 native Echinococcus spp. antigens, 3 recombinant antigens, and 4 commercial assays were comparatively evaluated. All native E. multilocularis antigens were produced in duplicates with a European and a Kyrgyz isolate and showed identical test values for the diagnosis of AE and CE. Native antigens and three commercial tests showed high diagnostic sensitivities (Se: 86–96%) and specificities (Sp: 96–99%) for the diagnosis of AE and CE in Swiss patients. In Kyrgyz patients, values of sensitivities and specificities were 10–20% lower as compared to the Swiss patients’ findings. For the sero-diagnosis of AE in Kyrgyzstan, a test-combination of an E. multilocularis protoscolex antigen and the recombinant antigen Em95 appears to be the most suitable test strategy (Se: 98%, Sp: 87%). For the diagnosis of CE in both countries, test performances were hampered by major cross-reactions with AE patients and other parasitic diseases as well as by limited diagnostic sensitivities (93% in Switzerland and 76% in Kyrgyzstan, respectively).

Characteristics and Clinical Course of Alveolar Echinococcosis in Patients with Immunosuppression-Associated Conditions: A Retrospective Cohort Study

Objectives: Since the change in the millennium, an increase in cases of alveolar echinococcosis (AE) has been observed in endemic European countries. Previous studies indicate that a significant proportion of the new AE cases have an immunosuppression-associated condition (IAC). The aim of the current study was to determine how IACs impact the number of new AE diagnoses per year and the characteristics of AE at diagnosis and its clinical course at our center. Methods: Retrospective analysis of 189 patients with AE diagnosed between 2000 and 2021 and participating in the Zurich Echinococcosis Cohort Study (ZECS) included clinical characteristics of AE at diagnosis and report of an IAC, as well as the clinical course during follow-up. Results: Of 189 patients participating in this study, 38 had an IAC reported at, or shortly after, AE diagnosis. Over time, there was a steeper increase in the number of newly diagnosed AE patients without an IAC than the number of patients with IAC. Patients with an IAC were older at diagnosis, more frequently had an incidental finding of AE, smaller mean lesion size, and negative Em18 serology. All but two showed favorable outcomes on the last follow-up. Conclusion: IACs have little impact on the increase in new AE cases, as well as on the extent of the disease at diagnosis and clinical course.

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.

Intrahepatic manifestation and distant extrahepatic disease in alveolar echinococcosis: a multicenter cohort study

BACKGROUND

The main endemic areas of alveolar echinococcosis (AE) are in central Europe and western China. The infiltration of intrahepatic vascular and bile ducts as well as extrahepatic disease can lead to complications and may increase morbidity in AE.

PURPOSE

To evaluate the vascular/biliary involvement of hepatic alveolar echinococcosis (HAE) and distant extrahepatic disease at each of four locations in Germany, France, and China.

MATERIAL AND METHODS

Contrast-enhanced abdominal magnetic resonance imaging (MRI) scans of patients with HAE, 200 in total, were evaluated by five examiners. AE liver lesions were classified according to Kodama's classification. Furthermore, distant extrahepatic manifestations were documented with additionally performed imaging modalities. Vascular/biliary involvement of hepatic manifestations as well as the presence of extrahepatic manifestations were correlated with the respective Kodama type of the liver lesion.

RESULTS

Distant extrahepatic AE manifestations were significantly more frequent in China than in Europe (12/100 vs. 3/100; Fisher's exact test: P=0.0286). A significant relationship exists between presence of distant extrahepatic disease manifestation and size of the AE liver lesion (132.53 ± 48.65 vs. 92.49 ± 50.06; P = 0.0030). Vascular/biliary involvement is significantly more frequent in China than in Europe (86/100 vs. 65/100; χ² = 11.92; P = 0.0006). Vascular/biliary involvement depends on lesion size (111.10 ± 47.44 vs. 47.36 ± 24.36; P<0.0001). Different types of AE liver lesions are associated with differences in vascular/biliary involvement and extrahepatic manifestations.

CONCLUSION

Vascular/biliary involvement and presence of distant extrahepatic manifestations depend on size of the HAE lesions and are more frequently detected in China. Different MRI morphological patterns influence vascular/biliary involvement and the occurrence of distant extrahepatic manifestations.

Field Performance of a Rapid Diagnostic Test for the Serodiagnosis of Abdominal Cystic Echinococcosis in the Peruvian Highlands

We evaluated the performance of a commercial rapid diagnostic test (RDT) in a field setting for the diagnosis of abdominal cystic echinococcosis (CE) using sera collected during an ultrasound population screening in a highly endemic region of the Peruvian Andes. Abdominal CE was investigated by ultrasonography. Sera collected from individuals with abdominal CE (cases) and age- and gender-matched volunteers with no abdominal CE (controls) were tested independently in two laboratories (Peru and Italy) using the VIRapid® HYDATIDOSIS RDT and RIDASCREEN® Echinococcus IgG enzyme-linked immunosorbent assay. Performance indexes of single and serially combined tests were calculated and applied to hypothetical screening and clinical scenarios. Test concordance was also evaluated. Prevalence of abdominal CE was 6.00% (33 of 546) by ultrasound. Serum was obtained from 33 cases and 81 controls. The VIRapid test showed similar sensitivity (76% versus 74%) and lower specificity (79% versus 96%) than results obtained in a hospital setting. RDTs showed better performance when excluding subjects reporting surgery for CE and if weak bands were considered negative. Concordance between tests was moderate to very good. In hypothetical screening scenarios, ultrasound alone or confirmed by RDTs provided more reliable prevalence figures than serology alone, which overestimated it by 5 to 20 times. In a simulation of case diagnosis with pre-test probability of CE of 50%, positive and negative post-test probabilities of the VIRapid test were 78% and 22%, respectively. The application of the VIRapid test alone would not be reliable for the assessment of population prevalence of CE, but could help clinical decision making in resource-limited settings.

Serology for the diagnosis of human hepatic cystic echinococcosis and its relation with cyst staging: A systematic review of the literature with meta-analysis

Background

The diagnosis of cystic echinococcosis (CE) is primarily based on imaging, while serology should be applied when imaging is inconclusive. CE cyst stage has been reported among the most important factors influencing the outcome of serodiagnosis. We performed a systematic review and meta-analysis of the relation between cyst stage of hepatic CE and diagnostic sensitivity of serological tests, to evaluate whether their relation is a consistent finding and provide guidance for the interpretation of results of serological tests.

Methodology/Principal findings

MEDLINE, EMBASE, CENTRAL, and Lilacs databases were searched on December 1^st 2019. Original studies published after 2003 (year of publication of the CE cyst classification), reporting sensitivity of serological tests applied to the diagnosis of human hepatic CE, as diagnosed and staged by imaging, were included. The quality of studies was assessed using the Newcastle-Ottawa Scale. Data from 14 studies were included in the meta-analysis. Summary estimates of sensitivities and 95% confidence intervals were obtained using random effects meta-analysis. Overall, test sensitivity was highest in the presence of CE2 and CE3 (CE3a and/or CE3b), and lowest in the presence of CE5 and CE4 cysts. ELISA, ICT and WB showed the highest sensitivities, while IHA performed worst.

Conclusions/Significance

The results of our study confirm the presence of a clear and consistent relation between cyst stage and serological tests results. Limitations of evidence included the heterogeneity of the antigenic preparations used, which prevented to determine whether the relation between cyst stage and sensitivity was influenced by the type of antigenic preparation, the paucity of studies testing the same panel of sera with different assays, and the lack of studies assessing the performance of the same assay in both field and hospital-based settings. Our results indicate the absolute need to consider cyst staging when evaluating serological results of patients with hepatic CE.

Cystic echinococcosis is a neglected zoonosis induced by the development of parasitic cysts in intermediate hosts, including humans, mostly in the liver. The diagnosis of CE is based on imaging. As CE cysts may assume different aspects (stages), the range of differential diagnoses is broad, from harmless simple cysts to neoplasms. Serological assays for the detection of serum antibodies are applied when imaging is inconclusive, but their performance depend on a number of factors, among which cyst stage has been reported as important. If this was a robust finding, it would be absolutely required to interpret serological findings in the light of CE cyst staging. The results of our systematic review and meta-analysis of the relation between cyst stage of hepatic CE and diagnostic sensitivity of serological tests confirmed that such relation is clear and consistent, and indicate the absolute need to consider cyst staging when evaluating serology results of patients with hepatic CE.

High endemicity of alveolar echinococcosis in Yili Prefecture, Xinjiang Autonomous Region, the People's Republic of China: Infection status in different ethnic communities and in small mammals

Alveolar echinococcosis (AE) is a life-threatening disease in humans caused by the larval stage of Echinococcus multilocularis. The tapeworm is transmitted between small mammals and dogs/foxes in the Northern Hemisphere. In this study 286 AE cases were reported from eight counties and one city in Yili Prefecture, Xinjiang Autonomous Region, the People's Republic of China from 1989 to 2015 with an annual incidence (AI) of 0.41/100,000. Among the patients, 73.08% were diagnosed in the last 11 years. Four counties in the high mountainous areas showed higher AI (0.51-1.22 cases/100,000 residents) than the four counties in low level areas (0.19-0.29/100,000 residents). The AI of AE in Mongolian (2.06/100,000 residents) and Kazak (0.93/100,000 residents) ethnic groups was higher than the incidence in other ethnic groups indicating sheep-farming is a risk for infection given this activity is mainly practiced by these two groups in the prefecture. A total of 1411 small mammals were captured with 9.14% infected with E. multilocularis metacestodes. Microtus obscurus was the dominant species in the mountain pasture areas with 15.01% of the voles infected, whereas Mus musculus and Apodemus sylvaticus were the dominant small mammals in the low altitude areas. Only 0.40% of A. sylvaticus were infected with E. multilocularis. PCR amplification and sequencing analysis of the mitochondrial cox1 gene showed that E. multilocularis DNA sequences from the small mammals were identical to isolates of local human AE cases. The overall results show that Yili Prefecture is a highly endemic area for AE and that the high-altitude pasture areas favorable for M. obscurus may play an important role in its transmission in this region.

Human Alveolar Echinococcosis, Croatia

Alveolar echinococcosis is a parasitic disease caused by the tapeworm larval stage of Echinococcus multilocularis. This zoonotic disease has not been known to occur in Croatia. We report a confirmed case of human alveolar echinococcosis in a patient in Croatia who had never visited a known E. multilocularis–endemic area.

Evaluation of the Diagnostic Performance of Recombinant Antigen B1 for Detection of Cystic Echinococcosis Using Lateral Flow Dipstick Test

Background

Human echinococcosis is a neglected zoonotic disease distributed worldwide. It comprises cystic and alveolar forms, the former being the more prevalent disease. Imaging techniques are the first choice for diagnosis of cystic echinococcosis and serology is used as an additional diagnostic technique in doubtful cases or as the sole test in low-resource settings. Rapid diagnostic tests are useful and convenient for immunodiagnosis of cystic echinococcosis in endemic areas, where medical facilities often struggle with limited resources.

Methods

Recently, we have developed Hyd Rapid™, an IgG4 lateral flow dipstick test using recombinant antigen B1 for detection of cystic echinococcosis. This study was performed between 2016 until 2018 at the Institute for Research in Molecular Medicine, Universiti Sains Malaysia. The diagnostic performance of Hyd Rapid™ was tested in-house and at two international laboratories in Switzerland and Iran.

Results

The overall diagnostic sensitivity for detection of cystic and alveolar echinococcosis was 95% (56/59). Meanwhile, the diagnostic specificity, with and without exclusion of cysticercosis and fascioliasis, was 100% (n=48) and 88% (63/72), respectively.

Conclusion

Hyd Rapid™ detected cystic echinococcosis as well as probable cases of alveolar echinococcosis. Therefore, Hyd Rapid™ showed good potential as a serological tool for echinococcosis, and merits further evaluation.

Evaluation of intrahepatic manifestation and distant extrahepatic disease in alveolar echinococcosis

BACKGROUND

The main endemic areas of alveolar echinococcosis (AE) are in Central Europe and Western China. Both the infiltration of intrahepatic vascular and bile duct structures as well as extrahepatic disease can lead to further complications and may increase morbidity in patients with AE.

AIM

To evaluate vascular/biliary involvement in hepatic AE and its distant extrahepatic disease manifestations in an international collective was the aim.

METHODS

Consecutively, five experienced examiners evaluated contrast-enhanced abdominal computed tomography (CT) scans for 200 patients with hepatic AE of each of four locations (n = 50) in Germany, France and China. Therefore, we retrospectively included the 50 most recent abdominal contrast-enhanced CT examinations at each center, performed because of hepatic AE from September 21, 2007 to March 21, 2018. AE liver lesions were classified according to the echinococcosis multilocularis Ulm classification for CT (EMUC-CT). Distant extrahepatic manifestations were documented either by whole body positron emission tomography–CT or with the addition of thoracic CT and cranial magnetic resonance imaging. Vascular/biliary involvement of the hepatic disease as well as the presence of distant extrahepatic manifestations were correlated with the EMUC-CT types of liver lesion. Statistical analysis was performed using SAS Version 9.4 (SAS Institute Inc., Cary, NC, United States).

RESULTS

Distant extrahepatic AE manifestations were significantly more frequent in China than in Europe (P = 0.0091). A significant relationship was found between the presence of distant extrahepatic disease and AE liver lesion size (P = 0.0075). Vascular/biliary structures were involved by the liver lesions significantly more frequently in China than in Europe (P < 0.0001), and vascular/biliary involvement depended on lesion size. Different morphological types of AE liver lesions led to varying frequencies of vascular/biliary involvement and were associated with different frequencies of distant extrahepatic manifestations: Vascular/biliary involvement as a function of lesions primary morphology ranged from 5.88% of type IV liver lesions to 100% among type III lesions. Type IV differed significantly in these associations from types I, II, and III (P < 0.0001). With respect to extrahepatic disease, the primary morphology types IV and V of liver lesions were not associated with any case of distant extrahepatic disease. In contrast, distant extrahepatic manifestations in types I–III were found to varying degrees, with a maximum of 22% for type III.

CONCLUSION

Different CT morphological patterns of hepatic AE lesions influence vascular/biliary involvement and the occurrence of distant extrahepatic manifestations. There are intercontinental differences regarding the characteristics of AE manifestation.

Pathology of Echinococcosis: A Morphologic and Immunohistochemical Study on 138 Specimens With Focus on the Differential Diagnosis Between Cystic and Alveolar Echinococcosis

Infection of humans by the larval stage of the tapeworms Echinococcus granulosus sensu lato or Echinococcus multilocularis causes the life-threatening zoonoses cystic echinococcosis (CE) and alveolar echinococcosis (AE). Although cystic liver lesions are a hallmark of both diseases, course, prognosis, and patients' management decisively differ between the two. The wide and overlapping spectrum of morphologies and the limited availability of ancillary tools are challenges for pathologists to reliably diagnose and subtype echinococcosis. Here, we systematically and quantitatively recorded the pathologic spectrum in a clinically and molecularly defined echinococcosis cohort (138 specimens from 112 patients). Immunohistochemistry using a novel monoclonal antibody (mAbEmG3) was implemented, including its combined application with the mAbEm2G11. Six morphologic criteria sufficiently discriminated between CE and AE: size of smallest (CE/AE: >2/≤2 mm) and largest cyst (CE/AE: >25/≤25 mm), thickness of laminated layer (CE/AE: >0.15/≤0.15 mm) and pericystic fibrosis (CE/AE: >0.6/≤0.6 mm), striation of laminated layer (CE/AE: moderate-strong/weak), and number of cysts (CE/AE: ≤9/>9). Combined immunohistochemistry with mAbEm2G11 (E. multilocularis specific) and mAbEmG3 (reactive in AE and CE) was equally specific as and occasionally more sensitive than polymerase chain reaction. On the basis of these findings, we developed a diagnostic algorithm for the differential diagnosis of echinococcosis. In summary, we have not only identified the means to diagnose echinococcosis with greater certainty, but also defined morphologic criteria, which robustly discriminate between CE and AE. We expect our findings to improve echinococcosis diagnostics, especially of challenging cases, beneficially impacting the management of echinococcosis patients.

Species specificity preliminary evaluation of an IL-4-based test for the differential diagnosis of human echinococcosis

The diagnosis of cystic echinococcosis (CE) is based on imaging, while serology is a complementary test of particular use when imaging is inconclusive. Serology has several limitations. Among them, false‐positive results are often obtained in subjects with alveolar echinococcosis (AE), rendering difficult the differential diagnosis. We set up an immune assay based on IL‐4‐specific production after stimulating whole blood with an antigen B (AgB)‐enriched fraction from E granulosus that associates with CE and CE cysts in active stage. We aimed to evaluate potential cross‐reactivity of this test using samples from patients with AE. Twelve patients with AE were recruited; IL‐4 levels ranged from 0 to 0.07 pg/mL. Based on the previously identified cut‐off of 0.39 pg/mL using samples from patients with CE, none of samples from AE patients scored positive. In contrast, almost 80% of samples from AE patients scored positive in serology tests based on different E granulosus‐derived antigenic preparations. Our preliminary data show that this experimental whole‐blood assay has no cross‐reactivity in our cohort of patients with AE, in turn indicating a high specificity of the assay for CE diagnosis. This result supports further work towards the development of improved diagnostic tests for CE.

Cystic Echinococcosis of the Bone: A European Multicenter Study

Cystic echinococcosis (CE) is a zoonosis caused by the larval stage of the tapeworm Echinococcus granulosus. In humans, the infection induces the formation of parasitic cysts mostly in the liver and lungs, but virtually any organ can be affected. CE of the bone is one of the rarest forms of the disease, yet it is also extremely debilitating for patients and hard to manage for clinicians. Unlike abdominal CE, there is currently no expert consensus on the management of bone CE. In this study, we conducted a survey of the clinical records of seven European referral centers for the management of patients with CE and retrieved data on the clinical management of 32 patients with a diagnosis of bone CE. Our survey confirmed that the patients endured chronic debilitating disease with a high rate of complications (84%). We also found that diagnostic approaches were highly heterogeneous. Surgery was extensively used to treat these patients, as well as albendazole, occasionally combined with praziquantel or nitaxozanide. Treatment was curative only for two patients, with one requiring amputation of the involved bone. Our survey highlights the need to conduct systematic studies on bone CE, both retrospectively and prospectively.

A multiplex PCR for the identification of Echinococcus multilocularis, E. granulosus sensu stricto and E. canadensis that infect human

Echinococcus granulosus sensu stricto (s.s.), Echinococcus multilocularis and Echinococcus canadensis are the common causes of human echinococcosis in China. An accurate species identification tool for human echinococcosis is needed as the treatments and prognosis are different among species. The present work demonstrates a method for the simultaneous detection of these three Echinococcus species based on multiplex polymerase chain reaction (mPCR). Specific primers of this mPCR were designed based on the mitochondrial genes and determined by extensive tests. The method can successfully detect either separated or mixed target species, and generate expected amplicons of distinct size for each species. Sensitivity of the method was tested by serially diluted DNA, showing a detection threshold as less as 0.32 pg for both E. granulosus s.s. and E. canadensis, and 1.6 pg for E. multilocularis. Specificity assessed against 18 other parasites was found to be 100% except weakly cross-react with E. shiquicus. The assay was additionally applied to 69 echinococcosis patients and 38 healthy persons, confirming the high reliability of the method. Thus, the mPCR described here has high application potential for clinical identification purposes, and can further provide a useful tool for evaluation of serology and imaging method.

Intense Focus of Alveolar Echinococcosis, South Kyrgyzstan

Human alveolar echinococcosis (AE) is a highly pathogenic zoonotic parasitic disease caused by Echinococcus multilocularis. An ultrasound study in southern Kyrgyzstan during 2012 revealed a prevalence of 4.2% probable or confirmed AE and an additional 2.2% possible AE, representing an emerging situation. The risk for probable or confirmed AE was significantly higher in dog owners.

Optimized dexamethasone immunosuppression enables Echinococcus multilocularis liver establishment after oral egg inoculation in a rat model

Comparable with immunocompetent humans, rats are considered highly resistant to Echinococcus multilocularis oncosphere invasion, both in nature and after experimental oral inoculation with eggs. Pharmacological immunosuppression with dexamethasone (DMX) was shown to abrogate the resistance of RccHan™:WIST rats, but due to weight losses >20%, many animals had to be excluded from previous experiments. The optimized DXM (Dexafort, MSD Animal Health, Germany) dosage regime presented in this study (each animal: 750 μg DXM at day -13 and 600 μg DXM at day -9 before inoculation) applied subcutaneously to RccHan™:WIST rats, resulted in weight losses ≤20%, but led to liver alveolar echinococcosis (AE) in all eight inoculated animals. Untreated control groups (each n = 8) including RccHan™:WIST (Wistar) and F344/DuCrl (Fischer-344) rats showed no parasite establishment. Antibodies against E. multilocularis metacestode vesicle fluid were present in 7/8 of the infected RccHan™:WIST rats 70 days after inoculation but in none of the control animals. Serology can therefore be used to diagnose AE. This optimized animal model enables a high infection rate in rats and may be applied in future immunological and experimental studies.

Laboratory Diagnosis of Echinococcus spp. in Human Patients and Infected Animals

Among the species composing the genus Echinococcus, four species are of human clinical interest. The most prevalent species are Echinococcus granulosus and Echinococcus multilocularis, followed by Echinococcus vogeli and Echinococcus oligarthrus. The first two species cause cystic echinococcosis (CE) and alveolar echinococcosis (AE) respectively. Both diseases have a complex clinical management, in which laboratory diagnosis could be an adjunctive to the imaging techniques. To date, several approaches have been described for the laboratory diagnosis and followup of CE and AE, including antibody, antigen and cytokine detection. All of these approaches are far from being optimal as adjunctive diagnosis particularly for CE, since they do not reach enough sensitivity and/or specificity. A combination of several methods (e.g., antibody and antigen detection) or of several (recombinant) antigens could improve the performance of the adjunctive laboratory methods, although the complexity of echinococcosis and heterogeneity of clinical cases make necessary a deep understanding of the host-parasite relationships and the parasite phenotype at different developmental stages to reach the best diagnostic tool and to make it accepted in clinical practice. Standardization approaches and a deep understanding of the performance of each of the available antigens in the diagnosis of echinococcosis for the different clinical pictures are also needed. The detection of the parasite in definitive hosts is also reviewed in this chapter. Finally, the different methods for the detection of parasite DNA in different analytes and matrices are also reviewed.

A Serological Survey About Zoonoses in the Verkhoyansk Area, Northeastern Siberia (Sakha Republic, Russian Federation)

In 2012, a seroprevalence survey concerning 10 zoonoses, which were bacterial (Lyme borreliosis and Q fever), parasitic (alveolar echinococcosis [AE] and cystic echinococcosis [CE], cysticercosis, toxoplasmosis, toxocariasis, and trichinellosis), or arboviral (tick-borne encephalitis and West Nile virus infection), was conducted among 77 adult volunteers inhabiting Suordakh and Tomtor Arctic villages in the Verkhoyansk area (Yakutia). Following serological testing by enzyme-linked immunosorbent assay and/or western blot, no positive result was found for cysticercosis, CE, toxocariasis, trichinellosis, and both arboviral zoonoses. Four subjects (5.2%) had anti-Toxoplasma IgG, without the presence of specific IgM. More importantly, eight subjects (10.4%) tested positive for Lyme borreliosis, two (2.6%) for recently acquired Q fever, and one (1.3%) for AE. Lyme infection and Q fever, whose presence had not been reported so far in Arctic Yakutia, appeared therefore to be a major health threat for people dwelling, sporting, or working in the Arctic area of the Sakha Republic.

Immunodiagnosis of human hydatid disease: Where do we stand?

Cystic echinococcosis (CE) is a zoonotic parasitic infection caused by the larval stage of Echinococcus granulosus. Diagnosis of CE mainly relies on a combination of serological testing along with imaging approaches. A variety of serological methods, mainly based on hydatid cyst fluid, antigen B (AgB) and antigen 5, have been developed and used for immunodiagnosis of CE, yet their performances are not satisfactory. Although utilizing of recombinant or synthetic antigens, improved the performance of serological tests, it has not applicably overcome the problem of low sensitivity and cross reactivity, seen in the diagnosis of CE. Performances of immunodiagnostic tests based on AgB subunits are promising. The 8 kDa subunit of AgB is the most studied antigen in native, synthetic or recombinant form for diagnosis of CE. From the 5 subunits of AgB, antigen B8/1 and B8/2 provided the highest diagnostic sensitivity and specificity. Moreover, detecting of specific antibodies of IgG subclasses has improved the efficacy of immunodiagnostic tests. Among the IgG subclasses, both IgG2 and IgG4 are considered as good markers for diagnosis and IgG4 as a suitable marker for follow up of the patients. In this review an overview of immunodiagnostic methods, related antigens and their performances in the diagnosis of CE are given. The paper highlights pitfall and challenges in the serological diagnosis of CE. Moreover, limitation of currently available immunodiagnostic tests and the most recent development in the designing and application of serological assays for diagnosis of CE in human are addressed.

Serological Diagnosis and Follow-Up of Human Cystic Echinococcosis: A New Hope for the Future?

Cystic echinococcosis (CE) is an important helminthic zoonotic disease caused by the Echinococcus granulosus complex. In humans, CE is a chronic disease driven by the growth of echinococcal cysts in different organs. Prognosis of this disease depends on multiple factors, including location, number, size, and stage of the cysts, making CE a disease of complex management. CE is usually asymptomatic for years and attracts limited attention from funding organizations and health authorities. For this reason, only experts' recommendations are available but no evidence-based conclusions have been drawn for CE clinical management. One of those pitfalls refers to the lack of evidence to support the use of serological tools for the diagnosis and follow-up of CE patients. In this respect, crude antigens are used to detect specific antibodies in patients, giving rise to false positive results. The advent of molecular techniques allowing the production of recombinant proteins has provided a number of candidate antigens that could overcome the problems associated with the use of crude parasite extracts in the serological assays. In this review, we present the last advances in this field, proposing the use of serology to support cyst stage-specific diagnosis and follow-up.

Outcome after Discontinuing Long-Term Benzimidazole Treatment in 11 Patients with Non-resectable Alveolar Echinococcosis with Negative FDG-PET/CT and Anti-EmII/3-10 Serology

Background/Aims

Benzimidazoles are efficacious for treating non-resectable alveolar echinococcosis (AE), but their long-term parasitocidal (curative) effect is disputed. In this study, we prospectively analyzed the potential parasitocidal effect of benzimidazoles and whether normalization of FDG-PET/CT scans and anti-Emll/3-10-antibody levels could act as reliable "in vivo" parameters of AE-inactivation permitting to abrogate chemotherapy with a low risk for AE-recurrence.

Method

This prospective study included 34 patients with non-resectable AE subdivided into group A (n = 11), followed-up after diagnosis and begin of chemotherapy at months 6, 12 and 24, and group B (n = 23) with a medium duration of chemotherapy of 10 (range 2–25) years. All patients were assessed by FDG-PET/CT examinations and anti-EmII/3-10 serology. Chemotherapy was abrogated in patients with normalization of FDG-PET/CT and serum anti-EmII/3-10 levels. These patients were closely followed-up for AE recurrence. Endpoint (parasitocidal efficacy) was defined by the absence of AE-recurrence >24 months after stopping treatment.

Results

Normalization of FDG-PET/CT scan and anti-EmII/3-10 levels occurred in 11 of 34 patients (32%). After abrogation of chemotherapy in these 11 patients, there was no evidence of AE-recurrence within a median of 70.5 (range 16–82) months. However, the patients’ immunocompetence appears pivotal for the described long-term parasitocidal effect of benzimidazoles.

Conclusions

The combination of negative FDG-PET/CT-scans and anti-EmII/3-10 antibody levels seem to be reliable parameters for assessing in vivo AE-larval inactivity after long-term benzimidazole chemotherapy.

Trial Registration

clinicaltrials.gov: NCT00658294

Alveolar echinococcosis is one of the mostly deadly human parasitic diseases if left untreated. The treatment of choice is surgical resection, followed by two years of benzimidazole treatment. Unfortunately, only about 30–40% of patients have a resectable disease, while the others require medical treatment with benzimidazoles. As this therapy is only considered to be parasitostatic and as there are not yet reliable tools to assess parasite viability, the treatment usually is life-long. In this study, we evaluated FDG-PET/CT and antibody levels against the recombinant Emll/3-10 antigen as markers for parasite viability, allowing to select patients in whom chemotherapy could be stopped with low risk of AE-recurrence. Eleven 11 patients were identified with negative FDG-PET/CT-scans and anti-EmII/3-10 antibody levels in whom benzimidazole treatment was stopped with no evidence of AE-recurrence within a median follow-up of 70.5 (range 16–82) months. Therefore, this study provides evidence that benzimidazole treatment is parasitocidal in a subset of patients.

The production and comparative evaluation of native and recombinant antigens for the fast serodiagnosis of cystic echinococcosis with dot immunogold filtration assay

Clinical diagnosis and post-surgery assessment of cystic echinococcosis depend on laboratory serodiagnosis and ultrasound examinations. This study aims to produce the recombinant antigen (rAgB) and compare its diagnostic effect with natural antigens (crude fluid antigen, protoscolex antigen). After rAgB, crude fluid antigen, protoscolex antigen were produced, and the diagnostic accuracy was evaluated with dot immunogold filtration assay (DIGFA) by the sera from the following groups: surgically confirmed cystic echinococcosis patients (n = 113), alveolar echinococcosis patients (n = 46), other parasitic diseases (n = 49), nonparasitic hepatic diseases (n = 63) and healthy people (n = 121). In diagnosing cystic echinococcosis, the sensitivity of recombinant AgB was 77.9% and the specificity was 98.3%. The crude fluid antigen B showed a sensitivity of 92.9% and specificity of 81.0%. The protoscolex antigen had sensitivity of 87.6% and specificity of 90.9%. The recombinant AgB indicates the advantage of no cross-reaction with other parasite diseases or nonparasite hepatic diseases. Recombinant antigen B can improve the specificity but decrease the sensitivity. The combination of native and recombinant antigens will improve the overall performance of serodiagnosis of cystic echinococcosis.

Sensitive and specific immunohistochemical diagnosis of human alveolar echinococcosis with the monoclonal antibody Em2G11

Background

Alveolar echinococcosis (AE) is caused by the metacestode stage of Echinococcus multilocularis. Differential diagnosis with cystic echinococcosis (CE) caused by E. granulosus and AE is challenging. We aimed at improving diagnosis of AE on paraffin sections of infected human tissue by immunohistochemical testing of a specific antibody.

Methodology/Principal Findings

We have analysed 96 paraffin archived specimens, including 6 cutting needle biopsies and 3 fine needle aspirates, from patients with suspected AE or CE with the monoclonal antibody (mAb) Em2G11 specific for the Em2 antigen of E. multilocularis metacestodes. In human tissue, staining with mAb Em2G11 is highly specific for E. multilocularis metacestodes while no staining is detected in CE lesions. In addition, the antibody detects small particles of E. multilocularis (spems) of less than 1 µm outside the main lesion in necrotic tissue, liver sinusoids and lymphatic tissue most probably caused by shedding of parasitic material. The conventional histological diagnosis based on haematoxylin and eosin and PAS stainings were in accordance with the immunohistological diagnosis using mAb Em2G11 in 90 of 96 samples. In 6 samples conventional subtype diagnosis of echinococcosis had to be adjusted when revised by immunohistology with mAb Em2G11.

Conclusions/Significance

Immunohistochemistry with the mAb Em2G11 is a new, highly specific and sensitive diagnostic tool for AE. The staining of small particles of E. multilocularis (spems) outside the main lesion including immunocompetent tissue, such as lymph nodes, suggests a systemic effect on the host.

Echinococcosis is a life-threatening disease in humans that is caused by the larval stages of the tapeworms Echinococcus multilocularis and Echinococcus granulosus. The eggs of the parasites are released with faeces of canids, and humans are aberrantly infected. In humans, the larval stages of the parasites cause tumour-like lesions mainly in the liver and the lungs. Precise diagnosis of the parasite responsible for human disease is of utmost importance since therapy regimens largely differ between cystic and alveolar echinococcosis. Diagnosis is based on serology, imaging and histology, the latter being the gold standard. However, conventional histology cannot always clearly identify the causative parasite because both parasites can cause human tissue to present similar features. Therefore, we have developed the monoclonal antibody Em2G11 and an immunohistological technique that allows a cheap and fast clear-cut diagnosis of E. multilocularis even on aspirates and small archived bioptic tissue samples. Furthermore, this technique disclosed an unknown feature of human alveolar echinococosis we called "small particles of E. multilocularis" (spems). We argue that these small particles represent micro-fragments of E. multilocularis and thus point to a new form of host-parasite interaction.

Evaluation of liver lesions

The differential diagnosis of a liver mass is large and requires understanding of the clinical and imaging features of liver lesions. A detailed history, physical examination, hepatic biochemical tests, and imaging studies are all essential in making the diagnosis. Decisions regarding specific imaging modalities for diagnoses, the use of liver biopsy, therapeutic options, and appropriate follow-up are all determined by the presentation of the lesion and associated patient characteristics.