Lateral flow test using Echinococcus granulosus native antigen B and comparison of IgG and IgG4 dipsticks for detection of human cystic echinococcosis

Comparison of Native Hydatid Cyst Fluid (HCF), Lyophilized HCF, Antigen B (AgB) and Lyophilized AgB (LAgB) Originated from Echinococcus granulosus Sensu Stricto for Sero-Diagnosis of Active, Transitional and Inactive Human Liver Cystic Echinococcosis

Background

Cystic echinococcosis (CE) is an important zoonotic parasitic disease caused by the larval stage or metacestode of the tapeworm Echinococcus granulosus sensu lato. Due to treatment protocols for different liver cysts, diagnosis of cyst stages is very important. Different antigens have been used for CE diagnosis. However, each one is more sensitive and effective for the diagnosis of specific CE stages is not known well. We aimed to compare Native Hydatid Cyst Fluid (HCF), Lyophilized Hydatid Cyst Fluid (LHCF), antigen B (AgB) and Lyophilized antigen B (LAgB) originated from E. granulosus sensu stricto (G1-G3) genotype, for sero- diagnosis of active, transitional and inactive human liver CE using ELISA technique.

Methods

The HCF was collected aseptically from liver CE cysts of sheep slaughtered from 2018 to 2019 in Shiraz slaughterhouse, Southern, Iran. The cysts were characterized by PCR and sequencing for genotype specification. Four types of antigens were used: HCF, LHCF, AgB and LAgB originated from E. granulosus sensu stricto (G1-G3) genotype. Thirty-three serum samples from active, transitional, and inactive human cysts were collected. Overall, 48 samples from other parasitic diseases and 60 samples from healthy subjects as negative controls were checked using four antigens by ELISA method.

Results

The best diagnostic sensitivity with 96.97% was observed by anti-LHCF IgG ELISA test. The best specificity with 95.37% was observed in ELISA test using LAgB.

Conclusion

Simultaneous test of sera with anti-LHCF IgG ELISA and anti-LAgB IgG ELISA would be the best in the diagnosis of human liver cystic echinococcosis.

Comparison of Isoenzyme Pattern of Echinococcus granulosus sensu stricto (G1-G3) and E. canadensis (G6/G7) Protoscoleces

Background

Different genotypes of Echinococcus granulosus sensu lato (s.l.) infect humans and ungulate animals, causing cystic echinococcosis. Simultaneous isoenzyme, as well as molecular characterizations of this parasite, has not yet been investigated in Iran. The present study aimed to evaluate the isoenzyme pattern of the E. granulosus sensu stricto (s.s.) and E. canadensis genotypes in Iran.

Methods

A total of 32 (8 humans and 24 animals) cystic echinococcosis cysts were isolated from Shiraz, Tehran, Ilam, and Birjand from May 2018 to December 2020. The DNAs were extracted and their genotypes were determined by molecular methods. Enzymes were extracted from the cysts and subjected to polyacrylamide gel electrophoresis. The activities of glucose-6-phosphate sehydrogenase (G6PD), malate dehydrogenase (MDH), malic enzyme (ME), nucleoside hydrolyse 1 (NH1), and isocitrate dehydrogenase (ICD) were examined in the cyst samples using isoenzyme method and compared it with the genotyping findings.

Results

DNA sequence analysis of the samples showed that the specimens contained 75% E. granulosus s.s. (G1) and 25% E. canadensis (G6) genotypes. The isoenzyme pattern of ICD in both genotypes produced a six-band pattern with different relative factors. The G6PD also produced two bands with different relative migrations in both genotypes. The MDH and NH1 systems revealed a two-band pattern, while only one band was generated in the ME enzyme in the E. granulosus s.s. genotype. In the E. canadensis, the MDH and NH1 enzymes showed one band, and the ME enzyme represented a two-band pattern.

Conclusion

Our findings suggest that E. granulosus s.s. and E. canadensis genotypes have entirely different isoenzyme patterns for NH1, G6PD, MDH, and ME.

Comparison of Isoenzyme Pattern of Echinococcus granulosus sensu stricto (G1-G3) and E. canadensis (G6/G7) Protoscoleces

Background

Different genotypes of Echinococcus granulosus sensu lato (s.l.) infect humans and ungulate animals, causing cystic echinococcosis. Simultaneous isoenzyme, as well as molecular characterizations of this parasite, has not yet been investigated in Iran. The present study aimed to evaluate the isoenzyme pattern of the E. granulosus sensu stricto (s.s.) and E. canadensis genotypes in Iran.

Methods

A total of 32 (8 humans and 24 animals) cystic echinococcosis cysts were isolated from Shiraz, Tehran, Ilam, and Birjand from May 2018 to December 2020. The DNAs were extracted and their genotypes were determined by molecular methods. Enzymes were extracted from the cysts and subjected to polyacrylamide gel electrophoresis. The activities of glucose-6-phosphate sehydrogenase (G6PD), malate dehydrogenase (MDH), malic enzyme (ME), nucleoside hydrolyse 1 (NH1), and isocitrate dehydrogenase (ICD) were examined in the cyst samples using isoenzyme method and compared it with the genotyping findings.

Results

DNA sequence analysis of the samples showed that the specimens contained 75% E. granulosus s.s. (G1) and 25% E. canadensis (G6) genotypes. The isoenzyme pattern of ICD in both genotypes produced a six-band pattern with different relative factors. The G6PD also produced two bands with different relative migrations in both genotypes. The MDH and NH1 systems revealed a two-band pattern, while only one band was generated in the ME enzyme in the E. granulosus s.s. genotype. In the E. canadensis, the MDH and NH1 enzymes showed one band, and the ME enzyme represented a two-band pattern.

Conclusion

Our findings suggest that E. granulosus s.s. and E. canadensis genotypes have entirely different isoenzyme patterns for NH1, G6PD, MDH, and ME.

One-tube nested MGB Probe Real-time PCR assay for detection of Echinococcus multilocularis infection in plasma cell free DNA

INTRODUCTION

The main objective of this study was to develop a One-tube nested MGB probe real-time PCR Assay for detecting Echinococcus multilocularis infection in human plasma cell free DNA (cfDNA).

METHODS

cfDNA was extracted from 10 E.m.-infected patients using a NucleoSnap DNA Plasma Kit and characterized by genomic sequencing. We designed nested PCR primers and MGB probe for Echinococcus multilocularis detection. The specificity, sensitivity and reproducibility of this assay were analyzed, and its validity was confirmed in 13 early stage clinical samples.

RESULTS

Several Echinococcus multilocularis-specific sequences were detected in the cfDNA of E.m.-infected patients, and CBLO020001206.1 was selected as the candidate sequence. We designed the primers and probe for the one tube nested real-time PCR. No cross-reactions with E.g. were observed. The detection limit was as low as 1 copy for Echinococcus multilocularis. The coefficients of variation were lower than 5% in intra- and inter-assays. 11 out of 13 patients were positive with nested MGB Probe PCR Assay and 3 patients were positive without outer primer in early stage Alveolar Echinococcosis pateints.

CONCLUSION

The one-tube nested MGB probe real-time PCR assay is a simple, rapid, and cost-effective method for detection of Echinococcus multilocularis infection in patients' Plasma DNA.

Evaluation of the Ability of Antigen B Originated from Echinococcus granulosus Sensu Stricto and E. canadensis for the Diagnosis of Confirmed Human Cystic Echinococcosis Using ELISA

BACKGROUND

Cystic echinococcosis (CE) is an important zoonotic parasitic disease worldwide. Application of species-specific antigen for serodiagnosis of human CE has not been utilized, so far. In this regard, AgB originated from Echinococcus granulosus sensu stricto (G1-G3) and E. canadensis (G6/G7) CE cysts, confirmed by molecular biology and sequencing was used for evaluation of their ability in the diagnosis of confirmed human CE.

METHODS

The hydatid cyst fluid (HCF) of E. granulosus sensu stricto and E. canadensis species were separately, used for preparation of AgB during 2017-2018 in Shiraz and Tehran, Iran. A total of 45 sera samples from confirmed CE patients, 102 sera from healthy people as negative control and 44 sera from other parasitic diseases, were used for measurement of the diagnostic ability of antigen B originated from E. granulosus sensu stricto and E. canadensis species of CE, alone or in 50%:50% mixture using ELISA method.

RESULTS

Overall, 38 (84.4%) out of 45 confirmed human CE were positive by ELISA using AgB originated from E. granulosus sensu stricto. This items for AgB originated from E. canadensis was 39 (86.6) out of 45 serum samples. A total of 39 out of 45 samples (86.6%) showed positivity by a mixture of antigen B originating from both species. The specificity of the above tests was calculated as 93.15%, 96.58%, and 93.84%, respectively.

CONCLUSION

Due to the diversity of the cyst species in human population, application of AgB from prevalent species alone or in combination with other species is suggested.

Sero-Epidemiological Study of Human Hydatidosis in Semnan and Sorkheh, Semnan Province, Iran

BACKGROUND

To determine the seroprevalence of human cystic echinococcosis/hydatidosis which is one of the most important zoonotic diseases by ELISA using native antigen B in Semnan and Sorkheh, Semnan province, Iran, where no significant information about human infection exists.

METHODS

Overall, 957 human serum samples were randomly prepared from Semnan, Sorkheh, and its 13 surrounding villages in different seasons from 2017 to 2018. Antigen B was prepared from native hydatid cyst fluid of domestic sheep. All serum samples were evaluated by ELISA while the suspected cases were rechecked. The cut-off was calculated as the X ¯ ±2SD.

RESULTS

Overall, 48(5%) out of 957 (422 males and 535 females) were positive for hydatidosis. The seropositivity based on sex showed 20(2.1%) out of 422 in males and 28(2.9%) out of 535 in females. The distribution of seropositive samples based on residence area showed 41 (4.3) out of 882 in urban and 7 (0.7) out of 75 in rural areas. The highest seroprevalence cases was among housewives (2.1%) followed by employers (1.5%). Based on education, source of drinking water, and age groups the highest seropositivity was observed in high school and less, in the plumping water consumers, and 50 to 59 yr old age group, respectively. There was a significant difference between seropositivity with occupation, literacy, and age group (P<0.05). Semnan with 4% seropositivity had the highest prevalence followed by Sorkheh, county.

CONCLUSION

High prevalence of the disease in this area emphasizes the importance of increasing people's awareness about hydatidosis.

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.

Genetic Diversity of Hepatic/Non-Hepatic Cystic Echinococcosis in Baqiyatallah Hospital, Tehran, Iran

BACKGROUND

Cystic echinococcosis (CE) is a worldwide zoonotic helminthic disease caused by the larval stage of Echinococcus granulosus. The infection is particularly important in terms of economic and medico-veterinary aspects in endemic areas including Iran. Considering the possibility of organ-tropism in E. granulosus strains, the present study was aimed to identify the genotypes of E. granulosus in different organs involved in patients, undergone surgery in Baqiyatallah Hospital, Tehran, Iran from 2005-2015.

METHODS

Overall, 29 formalin-fixed paraffin-embedded tissues (FFPT) from patients with histologically confirmed CE including liver (N: 14) lungs (N: 6) abdomen (N: 2), pancreas (N: 2) and each of spleen, gallbladder and, muscles (N: 1) plus unknown organs (N: 2) were used and genetically characterized using polymerase chain reaction, followed by partial sequencing of mitochondrial cytochrome c oxidase gene subunit 1(cox1) and analyzed.

RESULTS

Nineteen out of 29 isolates including liver (N: 6) lungs (N: 4) abdomen (N: 2), pancreas (N: 2) and each of spleen, gallbladder, and muscle (N: 1), unknown organs (N: 2) obtained from paraffin-embedded blocks of human CE created an acceptable sequence in two directions. All 19 isolates regardless of the organ involved were recognized as E. granulosus sensu stricto (G1).

CONCLUSION

The sequence alignments of the isolates displayed two profiles. All sequenced samples showed E. granulosus sensu stricto (G1) with no organ-related genotype.

Progress on the development of rapid diagnostic tests for foodborne neglected zoonotic helminthiases: A systematic review

BACKGROUND

Foodborne Neglected Zoonotic Helminths (FNZH) are parasites of both economic and public health importance. They include Taenia solium, Echinococcus granulosus sensu lato, Echinococcus multilocularis and Foodborne trematodes (FBT). FNZH are earmarked for major interventions for control, elimination and eradication. This systematic review highlights the progress towards development of rapid tests for the diagnosis of FNZH since 2010 when they were listed as neglected tropical diseases.

METHODOLOGY

A systematic search was conducted in three databases, World of Science, Embase and PubMed using the same search phrase. The search produced 480 hits. Three studies from back referencing were included. Only 22 of these met the inclusion criteria. Data was extracted from these and presented qualitatively.

RESULTS

Twenty-five rapid diagnostic tests were found to have been developed since 2010, eight for diagnosis of T. solium infections, eight for echinococcosis and nine for FBT infections. The rapid tests for diagnosing T. solium infections included six antibody detecting and two antigen detecting tests. They constitute a combination among them, with some tests providing qualitative, others quantitative results. Similarly, seven out of the eight rapid tests developed for Echinococcus infections were antibody detecting tests save for one loop mediated isothermal amplification test. All of them were qualitative tests. For FBT infections, nine rapid tests were described; two antibody and one nucleic acid detecting test for diagnosis of Fascioliasis; three nucleic acid detecting tests for Opisthorchiasis; one antibody detecting test for Paragonimiasis; and for Clonorchiasis, one antibody and one nucleic acid detecting test. The FBT infection rapid tests were all qualitative in nature. Most of these tests have not undergone field evaluation in endemic areas where they will be used most.

CONCLUSION

This review describes the development and evaluation of rapid diagnostic tests, while highlighting the need for in depth validations of the tools to determine how well they can perform in endemic areas.

Lateral flow dipstick antigen assay for human cystic echinococcosis

Cystic echinococcosis (CE) is a neglected zoonotic disease with a worldwide distribution and is a major public health problem in some areas. Diagnosis of CE is mainly based on clinical symptoms, imaging and serological testing, however, improvement in serodiagnosis is still needed. This study was aimed at detecting circulating Echinococcus antigen in CE patients using a lateral flow dipstick (LFD) assay. Three types of hydatid antigens i.e. hydatid cyst fluid (HCF), native antigen B (nAgB) and recombinant antigen B (rAgB) were prepared and polyclonal rabbit antiserum was raised against each antigen. Purified IgG fractions were prepared and a portion was conjugated to gold nanoparticles. After a series of optimizations, a final antigen detection LFD assay was developed using a combination of anti-nAgB-IgG and gold-conjugated anti-HCF-IgG. Evaluation of the assay showed that 27 out of 35 (77%) serum samples from CE patients gave positive results. Meanwhile, the test showed a diagnostic specificity of 82% when tested with sera from 38 healthy individuals and 13 patients with other parasitic diseases. In conclusion, the antigen detection LFD assay seemed to be useful for diagnosis of CE and possibly for post-treatment follow-up, and merit further evaluation studies. We foresee that it may improve serodiagnosis of CE when used in tandem with an antibody detection test.

In Vitro Study on Protoscolicidal Effect of Methanolic Extract of Allium hirtifolium on Protoscoleces of Cystic Echinococcosis

BACKGROUND

Cystic echinococcosis/ hydatidosis is one of the most important parasitic zoonoses worldwide. Usually, surgery is used for the treatment of active cysts. Due to the risk of cyst rupture during surgery, a protoscolicidal agent is usually injected into the cyst before surgery to prevent secondary cyst formation in case of cyst rupture. Due to the side effects of chemical protoscolicidal agents attempts have been focused on herbal medicine. In this regard, Allium sativum has already been used; however, the protoscolicidal effect of Allium hirtifolium from Allium family has not been investigated, so far.

OBJECTIVE

The present study was conducted in order to assess the protoscolicidal effect of methanolic extract of Allium hirtifolium in different concentrations, temperature and exposure times. Cetrimide as a positive control and DMSO as a negative control were also used in this study.

METHODS

The viability of protoscoleces was determined by 0.1% eosin staining method.

RESULTS

The protoscolicidal effect of Allium hirtifolium on protoscoleces was as follows: The mean percent and standard deviation (SD) of protoscolicidal activity of 50 mg/ml concentration of Allium hirtifolium extract in room temperature at 10, 20, 30, 40 and 50 minutes of exposure was 5.88±2.39, 8.59±4.54, 11.82±5.81, 12.31±6.16and 16.96±8.42 respectively; while at 37°C it was 9.10±5.01, 11.52±7.36, 18.64±4.36, 27.07±6.57 and 38.15±12.80, respectively.

CONCLUSION

In conclusion, although Allium hirtifolium from Allium family is similar to Allium sativum; the protoscolicidal effect of its methanolic extract is not similar and less than A. sativum extract.

Protoscolicidal Effects of the Garlic Chloroformic Extract on the Protoscolices of Hydatid Cyst at a Short Exposure Time, up to Five Minutes

BACKGROUND

The treatment of choice for hydatidosis as an important zoonotic disease is surgery. Different agents are injected into the cyst to prevent secondary hydatidosis. To avoid the side effects of such protoscolicidal agents, considering the high protoscolicidal effects of the garlic extract, we conducted the present study on protoscolices in limited applicable times and compared the extract with some chemical agents.

METHODS

Sheep's liver and lung cysts were collected. Ninety tubes were selected and divided into 3 sets (for different exposure times), each one comprising 5 groups of 6 tubes. Each tube contained 3000-4000 protoscolices. The groups were 0.5% cetrimide (as positive control), 20% hypertonic sodium chloride, 0.5% silver nitrate, 0.9% normal saline (as negative control), and the garlic chloroformic extract (200 mg/mL). The viability of the protoscolices was assessed using 0.1% eosin. The ANOVA and LSD were used to compare the mean viability of the protoscolices after exposure to the different agents at different times and concentrations. The data were analyzed using SPSS software, version 17. A P<0.05 was considered significant.

RESULTS

Our findings showed that the protoscolicidal effects of the garlic extract at 1 (P<0.001) and 2 (P<0.001 and P=0.003) minutes of exposure were higher than those of sodium chloride and silver nitrate. At 5 minutes of exposure, there was no difference between the garlic extract and sodium chloride (P=0.36); however, the difference between these agents and silver nitrate was significant.

CONCLUSION

The garlic chloroformic extract in a short exposure time had high protoscolicidal effects and could substitute other agents.

Evaluation of Echinococcus granulosus recombinant EgAgB8/1, EgAgB8/2 and EPC1 antigens in the diagnosis of cystic echinococcosis in buffaloes

Three recombinant proteins of Echinococcus granulosus including two antigen B sub-units EgAgB8/1 and EgAgB8/2 and Echinococcus protoscolex calcium binding protein 1 (EPC1) were expressed in prokaryotic expression vectors. The diagnostic potential of these three recombinant proteins was evaluated in the detection of cystic echinococcosis in buffaloes in IgG-ELISA. The EgAgB8/1 and EgAgB8/2 recombinant proteins reacted fairly with the hydatid infected buffaloes with sensitivity of 75.0% and 78.6%, respectively and specificity of 75.8% while EPC1 recombinant protein showed higher sensitivity (89.3%) but lower specificity (51.5%). Cross-reactivity of these three antigens was assayed with buffalo sera naturally infected with Explanatum explanatum, Paramphistomum epiclitum, Gastrothylax spp., Fasciola gigantica and Sarcocystis spp. EgAgB8/1 and EPC1 antigens cross-reacted with all these sera while EgAgB8/2 showed no cross-reaction with Sarcocystis spp. and reacted with some of the E. explanatum infected buffalo sera. This study explores the potential of three hydatid antigens viz. EgAgB8/1, EgAgB8/2 and EPC1 for their diagnostic potential in buffaloes positive for cystic echinococcosis.

Management of osseous cystic echinococcosis

INTRODUCTION

Osseous cystic echinococcosis (CE) is one of the most complicated and devastating conditions caused by Echinococcus granulosus. Its management is difficult and there is scant literature about it. Areas covered: A literature review was performed to provide an update on its diagnosis, treatment and follow-up. Expert commentary: In most cases diagnosis of osseous CE can only be confirmed by surgery. Osseous CE should be managed by experienced physicians and addressed as a chronic disease with therapies must be aimed at controlling the disease and its sequels or complications, rather than with a curative intent.

Proteomic-based biomarker discovery for development of next generation diagnostics

In the post-genome age, proteomics is receiving significant attention because they provide an invaluable source of biological structures and functions at the protein level. The search for disease-specific biomarkers for diagnostic and/or therapeutic applications is one of the areas that proteomics is having a significant impact. Thus, the identification of a "good" biomarker enables a more accurate early diagnosis and prognosis of disease. Rapid advancements in mass spectrometry (MS) instrumentation, liquid chromatography MS (LCMS), protein microarray technology, and other protein profiling methodologies have a substantial expansion of our toolbox to identify disease-specific protein and peptide biomarkers. This review covers a selection of widely used proteomic technologies for biomarker discovery. In addition, we describe the most commonly used approaches for diagnosis based on proteomic biomarkers and further discuss trends and critical challenges during development of cost-effective rapid diagnostic tests and microfluidic diagnostic systems based on proteomic biomarkers.

Diagnostic Accuracy of Antigen 5-Based ELISAs for Human Cystic Echinococcosis

BACKGROUND

Clinical diagnosis and follow up of cystic echinococcosis (CE) are based on imaging complemented by serology. Several immunodiagnostic tests are commercially available, but the development of new tools is still needed to overcome the lack of standardization of the target antigen, generally consisting of a crude extract of Echinococcus granulosus hydatid cyst fluid. In a previous work, we described a chromatographic method for the preparation of a highly enriched Antigen 5 fraction from hydatid cyst fluid. The high reactivity of patient sera against this preparation prompted us to evaluate further this antigen for the serodiagnosis of CE on a larger cohort of samples.

METHODOLOGY/PRINCIPAL FINDINGS

A total of 327 sera from CE patients with heterogeneous conditions for cyst stage, cyst number, organ localization, drug therapy, and surgical intervention, together with 253 sera from healthy controls, were first analyzed by an ELISA based on the Ag5 preparation in two different experimental setups and, in parallel, by a commercial ELISA routinely used in clinical laboratories for CE serodiagnosis. The Ag5 ELISAs revealed different sensitivity (88.3% vs 95.3%) without significant differences in specificity (94.1% vs 92.5%), for the two setups, respectively. Moreover, possible relationships between the Ag5 ELISA absorbance results and clinical variables were investigated. Chi squared test, bivariate logistic regression and multiple regression analyses highlighted differences in the serology reactivity according to pharmacological treatment, cyst activity, and cyst number.

CONCLUSIONS/SIGNIFICANCE

The two Ag5 ELISAs revealed different performances depending on the setup. The good diagnostic sensitivity and the high reliability of the Ag5 preparation method make this antigen a promising candidate for the serodiagnosis of CE. Further studies will be needed to evaluate the ability of our test to provide useful information on specific CE clinical traits.

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.