Dot immunogold filtration assay (DIGFA) with multiple native antigens for rapid serodiagnosis of human cystic and alveolar echinococcosis

Crucial role of biosensors in the detection of helminth biomarkers in public health programmes

Helminthiases are highly prevalent but neglected infections that affect more than 1·5 billion people worldwide. Considering the worldwide prevalence of helminthiases, WHO has declared them a public health concern since 2001, necessitating rigorous control and elimination efforts. However, only a few reliable point-of-care diagnostic tests are available for assessing the effectiveness of public health interventions targeting helminthiases, thus increasing the risk of suboptimal outcomes, misallocation of resources, and emergence of drug-resistant helminths. This Review provides an introduction on helminthiases and strategies to achieve control, elimination, interruption in transmission, and eradication of these infections. The Review then comprehensively details the existent biosensors that can be used to detect these infections in human samples, focusing on their target biomarkers, the bioreceptors used, and the sensing readouts. The Review concludes with an in-depth discussion on the persistent challenges related to helminthiases, aiming to encourage the development of much-needed diagnostics specific to these neglected infections.

Determination of echinococcosis IgG antibodies using magnetic bead-based chemiluminescence immunoassay

Echinococcosis is a kind of parasitic disease shared by humans and animals. The aim of this study was to establish a new detection method for echinococcosis screening using magnetic bead-based chemiluminescence immunoassay (CLIA). A magnetic bead-based CLIA to determine anti-echinococcosis IgG antibodies was optimized and established. The sensitivity, accuracy, precision and recovery rate were evaluated using the national reference serum, and the reference interval, specificity and comparison assays were performed using the clinical negative/positive echinococcosis serum samples. This study established a new CLIA to determine anti-echinococcosis IgG antibodies. The sensitivity of this CLIA method was higher than that of the registered ELISA kit and the national standard, the conformance rate of the negative/positive references was 100% (8/8), the CVs of the sensitivity reference were all below 5%, and the CVs of the precision reference were 5.7%. There was no obvious cross-reactivity with the common parasitic disease-positive serum and serum interferents. Clinical sample testing found that the cutoff value of this CLIA was 5537.15 (RLU), and there was no significant difference between the CLIA method and the registered ELISA kit. This study established a fully automated CLIA method with high sensitivity, specificity, accuracy, precision, recovery rate, and satisfactory clinical testing performance, which may provide a new choice for echinococcosis screening.

Rapid vertical flow technique for the highly sensitive detection of Brucella antibodies with Prussian blue nanoparticle labeling and nanozyme-catalyzed signal amplification

Brucellosis is a chronic infectious disease caused by Brucella, which is characterized by inflammation of reproductive organs and fetal membranes, abortion, infertility, and local inflammatory lesions of various tissues. Due to the widespread prevalence and spread of brucellosis, it has not only caused huge losses to animal husbandry, but also brought serious impacts on human health and safety. Therefore, rapid and accurate diagnosis is of great significance for the effective control of brucellosis. Therefore, we have developed a rapid vertical flow technique (RVFT) using Prussian blue nanoparticles (PBNPs) as a marker material for the detection of brucellosis antibodies. Lipopolysaccharide (LPS) was purified and used to detect brucellosis antibodies to improve the sensitivity of this technique. To enhance the sensitivity of serum antibody detection, a single multifunctional compound buffer was created using whole blood as a biological sample while retaining the advantages of typical lateral flow immunoassays. After signal amplification, standard Brucella-positive serum (containing Brucella antibody at 4000 IU mL^-1) could be detected in this system even at a dilution factor of 1 × 10^-2. The detection limit was 40 IU mL^-1, which is ten times that before signal amplification. This RVFT displayed good specificity and no cross-reactivity. This RVFT effectively avoided the false negative phenomenon of lateral flow immunoassays, was easy to operate, had a short reaction time, has good repeatability, and could elicit results that were visible to the naked eye for 2 ~ 3 min without any equipment. Since this method is very important for controlling the prevalence of brucellosis, it holds great promise for application in primary medical units and veterinary brucellosis detection.

Flower-like gold nanoparticles labeled and silver deposition rapid vertical flow technology for highly sensitive detection of Brucella antibodies

To prevent the transmission of brucellosis, rapid vertical flow technology (RVFT) was developed to detect brucellosis antibodies. To improve the sensitivity of the technique, lipopolysaccharides (LPS) were purified and used to detect brucellosis antibodies. To improve the sensitivity of serum antibody detection, a single multifunctional buffer was established in whole blood and other biological samples, and the advantages of the lateral flow immunoassay were retained. Flower-like gold nanoparticles were applied to RVFT for the first time. In this study, silver ions were catalyzed by flower-like gold nanoparticles into metal silver deposited on the surface of gold nanoparticles for the first time, which not only increased the particle size of gold nanoparticles, but also showed a more distinguishable black color on the test zone, further improving the sensitivity of RVFT. Standard Brucella-positive serum (containing Brucella antibody at 4000 IU mL^-1) could be detected in this system even for a dilution factor of 2 × 10^-3. The detection limit was 2 IU mL^-1. RVFT can effectively avoid the false negative phenomenon in lateral flow immunoassay. RVFT is simple to operate, with a short reaction time, 2-3 minutes visible to the naked eye, without any equipment. Because it is very important to control the brucellosis epidemic, this approach has great application prospects in basic medical units and for veterinarians.

Echinococcoses in Iran, Turkey, and Pakistan: Old Diseases in the New Millennium

Echinococcosis is considered a cosmopolitan zoonosis caused by different species of small taeniid tapeworms of the genus Echinococcus and is regarded as a neglected zoonosis. Cystic and alveolar echinococcoses are endemic diseases of Tibetan, Pamir, and Iranian plateaus. All of the countries within the Iranian plateau are affected by echinococcosis. Pakistan, Turkey, and Iran are the three most populous countries of the region, in which echinococcosis is highly endemic. The three neighboring countries share strong cultural and socioeconomic ties. The present study aimed to provide a broad review of the status of cystic and alveolar echinococcosis, summarizing the current knowledge about geographical distribution, molecular epidemiology, and transmission dynamics of Echinococcus granulosus sensu lato and Echinococcus multilocularis in this region. Additionally, we aimed to understand disease burden and risk factors as basic requirements for establishing a surveillance system and planning prevention and control programs. A considerable body of information is available on different aspects of echinococcosis in this region; however, several information and research gaps need to be filled before planning control programs. None of the countries in the region have an elaborate echinococcosis control program. Effective control programs require multi/intersectoral coordination within a One Health approach with a long-term political and administrative commitment and enhanced international collaboration among the three countries.

Targeted Sequencing of Genomic Repeat Regions Detects Circulating Cell-free Echinococcus DNA

Background

Echinococcosis is a chronic zoonosis caused by tapeworms of the genus Echinococcus. Treatment of the disease is often expensive and complicated, sometimes requiring extensive surgery. Ultrasonographic imaging is currently the main technique for diagnosis, while immunological analysis provides additional information. Confirmation still needs pathological analysis. However, these diagnostic techniques generally detect infection in late stages of the disease. An accurate, early and non-invasive molecular diagnostic method is still unavailable.

Methodology/Principal findings

We sequenced the cell-free DNA (cfDNA) from plasma of echinococcosis patients and confirmed the presence of Echinococcus DNA. To improve detection sensitivity, we developed a method based on targeted next-generation sequencing of repeat regions. Simulation experiments demonstrate that the targeted sequencing is sensitive enough to detect as little as 0.1% of an Echinococcus genome in 1 mL of plasma. Results obtained using patient plasma shows that the Area Under the Curve (AUC) of the method is 0.862, with a detection sensitivity of 62.50% and specificity of 100%, corresponding to a Youden-index of 0.625.

Conclusions/Significance

This study provides evidence that hydatid cysts release cfDNA fragments into patient plasma. Using the repeat region targeted sequencing method, highly specific detection of Echinococcus infection was achieved. This study paves a new avenue for potential non-invasive screening and diagnosis of echinococcosis.

Echinococcosis is a severe chronic parasitic disease caused by tapeworms of the genus Echinococcus. According to the World Health Organization, there are more than 1 million people living with echinococcosis worldwide. For decades, little progress has been made to develop a molecular diagnosis and specific treatment for the disease. Although imaging and immunological detection are used for diagnosis, these technologies are either only effective for late stages of the disease or hardly conclusive. The detection of cell-free DNA has been a powerful tool for precise diagnosis. In this study, we showed the presence of Echinococcus-derived cell-free DNA in plasma of echinococcosis patients. We further established an assay to detect parasite DNA in blood samples based on amplification of Echinococcus specific repeat regions followed by targeted next-generation sequencing. This technique provides a new method for potential extensive screening and precision diagnosis of echinococcosis with high specificity.

Co-existence of hepatocellular carcinoma and cystic echinococcosis

PURPOSE

Co-existence of hepatocellular carcinoma (HCC) and cystic echinococcus (CE) is extremely rare. Echinococcus granulosus may exhibit a protective effect against cancer. Herein, this study aimed to evaluate the possible effects of echinococcal infection on HCC patients.

METHODS

Three thousand three hundred hepatic CE patients and 815 HCC patients were retrospectively reviewed between January 2010 and December 2018 in Xinjiang, China, and these patients were 1:5 matched according to their sex, age and tumor TMN stage, and only 13 patients coexisted both CE and HCC. Preoperative ultrasonography (US), computed tomography (CT), liver magnetic resonance imaging (MRI) and dot immune-gold filtration assay (DIGFA) were used for preoperative identification and intraoperative specimens from liver resections were pathologically examined for further confirmation. Survival time was analyzed through Cox proportional hazard model analysis.

RESULTS

The co-existing incidence rate of two diseases was 0.39%. For these concurrent cases, HCC was all at the advanced stage and CE lesions were inactive. Median survival time for HCC patients was 6 month (1-17). However, it was 8 month (3-90) for the co-existing cases and was much longer than the median survival time of HCC patients (P<0.05), which was closely associated with tumor size, location, TMN stage and hydatid size, location, classification. Four of the patients underwent surgical intervention and their median survival time was 17 month (3-68).

CONCLUSIONS

Echinococcus granulosus may elicit a protective effect against the development and progression of HCC, while more basic and clinical researches are needed.

Development of a nano-gold immunodiagnostic assay for rapid on-site detection of invasive aspergillosis

Introduction. Timely detection of invasive aspergillosis (IA) caused by fungal pathogens, i.e. Aspergillus fumigatus and Aspergillus flavus, in immunocompromised patients is crucial in preventing high mortality.Aim. To develop a simple immunoassay for the detection of galactomannan (GM), an IA biomarker.Methodology. GM from A. fumigatus and A. flavus clinical strains was purified and characterized by X-ray diffraction, IR spectroscopy and ¹³C/¹H nuclear magnetic resonance (NMR) for polyclonal antibody (pAb) production in rabbits. An enzyme-linked immunosorbent assay (ELISA) was standardized using concanavalin A to capture Aspergillus GM and pAbs to detect it. Gold nanoparticles (AuNPs) were synthesized and conjugated to pAbs for the development of a dot-blot immunoassay. The developed dot-blot was evaluated with 109 clinical serum and bronchoalveolar lavage samples.Results. Spectroscopy studies characterized the d-galactofuranosyl groups of GM responsible for the immune response and generation of pAbs. The ELISA employing pAbs showed a sensitivity of 1 ng ml^-1 for Aspergillus GM. Furthermore, a sensitive, visual, rapid dot-blot assay developed by the conjugation of pAbs to AuNPs (~24±5 nm size, -36±2 mV zeta potential) had a detection limit of 1 pg ml^-1 in serum. The pAbs interacted with Aspergillus spp. but did not cross-react with other fungal pathogen genera such as Penicillium and Candida. Evaluation of the dot-blot with 109 clinical samples showed high sensitivity (80 %) and specificity (93.2 %), with an overall assay accuracy of 89%.Conclusion. The developed nano-gold immunodiagnostic assay has immense potential for practical use in rapid, specific and sensitive on-site diagnosis of IA, even under resource-limited settings.

Simultaneous occurrence of hepatic alveolar and cystic echinococcosis

The co-occurrence of hepatic cystic echinococcosis (CE) and alveolar echinococcosis (AE) is extremely rare. Here, we present the clinical manifestations and treatment outcomes of three cases with co-occurring CE and AE in the liver. Computed tomography (CT), magnetic resonance imaging and 18FFluorodeoxyglucose Positron Emission Tomography-CT were used for preoperative diagnosis. Specimens were taken intraoperatively and sent for pathological studies to confirm the coexistence of CE and AE by laminated membrane, daughter cysts or germinal layer and infiltration structure. Albendazole was prescribed after operation for 12 months. All patients were completely recovered and showed no recurrence at last follow-up. Therefore, surgical intervention and postoperative application of albendazole are recommended for patients with concurrence of hepatic AE and CE.

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.

A One Health systematic review of diagnostic tools for Echinococcus multilocularis surveillance: Towards equity in global detection

Echinococcus multilocularis is a zoonotic cestode of canid definitive hosts that is emerging as a parasite of medical and veterinary concern in regions of North America, Europe and Asia. Infection with the metacestode stage (alveolar echinococcosis - AE) is life-threatening, especially for patients who reside in low resource countries and lack access to modern diagnostic tests and treatments. The overall objectives of this One Health review were to systematically describe the diagnostic tests currently employed in endemic countries to detect E. multilocularis in people, canids and the environment, and to report the test characteristics of new diagnostic techniques for population surveillance. In this systematic review of English and Chinese language databases, we identified 92 primary records of E. multilocularis surveillance in canids (N = 75), humans (N = 20) and/or the environment (food, soil; N = 3) and 12 grey literature records that reported E. multilocularis surveillance or health systems protocols between 2008 and 2018. Surveillance for E. multilocularis was conducted using a broad range of combined morphological, molecular, immunological and imaging techniques. Nine studies reporting diagnostic evaluations for cestode or metacestode detection were identified, including studies on copro-antigen ELISA, copro-PCR, intestinal examination, Western Blot, magnetic capture RT-PCR and immunochromatography. Our dataset includes prevalence estimates for E. multilocularis in canids, people, or environment in 27 of the 43 endemic countries and reports data gaps in surveillance, laboratory methods, and diagnostic sensitivity. International consensus on gold standard diagnostic techniques and harmonization of human, canid and environmental surveillance data across political boundaries are needed to comprehensively assess the global burden and distribution of this parasite.

Multi-Epitope Fusion Protein Eg mefAg-1 as a Serodiagnostic Candidate for Cystic Echinococcosis in Sheep

Cystic echinococcosis (CE) in sheep is a hazardous zoonotic parasitic disease that is caused by Echinococcus granulosus (Eg). At present, serological test is an important diagnostic method for Eg infection in domestic animals. Here, a fusion protein Eg mefAg-1 harboring 8 dominant B-cell epitopes of Eg such as antigen B, tetraspanin 1, tetraspanin 6, reticulon and Eg95 was produced in E. coli and evaluated for CE in sheep by indirect ELISA. Eg mefAg-1 showed in ELISA a high sensitivity (93.41%) and specificity (99.31%), with a coincidence rate of 97.02%. Overall, it is suggested that the Eg mefAg-1 could be a potential antigen candidate for CE serodiagnosis in sheep.

Paragonimiasis

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

Evaluation of the recombinant antigens B2t and 2B2t, compared with hydatid fluid, in IgG-ELISA and immunostrips for the diagnosis and follow up of CE patients

Cystic echinococcosis (CE) is one of the most widespread helminthic zoonoses and is caused by the tapeworm Echinococcus granulosus complex. CE diagnosis and monitoring primarily rely on imaging techniques, complemented by serology. This is usually approached by the detection of IgG antibodies against hydatid fluid (HF), but the use of this heterogeneous antigenic mixture results in a variable percentage of false positive and negative results, and has shown to be useless for follow-up due to the long persistence of anti-HF antibodies in cured patients. To improve test performances and standardization, a number of recombinant antigens mainly derived from HF have been described, among them the B2t and 2B2t antigens. The performance of these antigens in the diagnosis and follow up of patients with CE has been so far evaluated on a limited number of samples. Here, we evaluated the performances of tests based on B2t and 2B2t recombinant antigens compared to HF in IgG-ELISA and immunochromatography (IC) for the diagnosis and follow-up of patients with CE in a retrospective cohort study. A total of 721 serum samples were collected: 587 from 253 patients with CE diagnosed by ultrasonography (US), 42 from patients with alveolar echinococcosis and 92 from healthy donors from Salamanca (Spain). The highest overall sensitivity was obtained with HF in ELISA (85.5%), followed by IC containing HF and 2B2t-HF (83.0% and 78.2%, respectively). The lowest sensitivity was obtained with B2t and 2B2t in ELISA (51.8%). The highest specificity was obtained with IC containing 2B2t-HF (100%), and the lowest with HF-ELISA (78.0%). The lowest cross-reactivity with sera from patients with alveolar echinococcosis was detected with the recombinant antigens in ELISA (9.5% - 16.7%) and the highest with the HF-IC (64.3%). The results of B2t and 2B2t-ELISA were influenced by cyst stage, as classified by US according to the WHO-Informal Working Group on Echinococcosis (WHO-IWGE), with low sensitivity for inactive (CE4 and CE5) cysts, and by the drug treatment, with higher sensitivity in patients after drug treatment compared with patients not subjected to drug treatment. The two recombinant antigens in ELISA provided promising results for monitoring patients in follow-up, although their use is limited to patients with positive serology against them at the beginning of the follow-up. Potential biological reasons behind the low sensitivity of the recombinant antigens and possible strategies to enhance the performance of CE serology are discussed.

Cystic echinococcosis (CE) is a helminthic zoonosis caused by Echinococcus granulosus sensu lato. CE diagnosis and monitoring is of paramount importance for the clinical management of patients and primarily rely on imaging techniques, complemented by serology. CE serology is usually based on the detection of antibodies against hydatid fluid (HF), but the use of this heterogeneous antigenic mixture shows several drawbacks, including false positive and negative results, unsatisfied predictive values, and long persistence of detectable antibody levels in cured patients. As an alternative, to improve test performances and standardization, several recombinant antigens have been described, but these have been so far evaluated only on a limited number of samples. Here, two recombinant antigens derived from one of the immunodominant HF antigens (antigen B2) have been tested in enzyme-linked immunosorbent assay (ELISA) and in immunochromatographic strips (IC) against 721 serum samples. Although more specific than the HF, the recombinant antigens in ELISA showed low sensitivity for patients with inactive (CE4 and CE5) cysts and for patients not subjected to drug treatment. This limited their use for follow-up, although promising, to those patients with positive serology at the beginning of the follow-up period. These results will aid in the future development of a serological test with enhanced performance in the diagnosis and follow-up of patients with CE.

Evaluation of the diagnostic value of the immunoblotting and ELISA tests using recombinant Em18 antigen in human alveolar echinococcosis from Xingjiang China

Alveolar echinococcosis (AE) is a prevalent epidemic in the northern hemisphere, especially in central Europe and western China. Serum diagnosis is important for patients with AE, especially during the first screening. The present study purified the recombinant Em18-GST (rEm18-GST), and detected its diagnostic performance in human alveolar echinococcosis patients of Xinjiang, China with immunoblotting (IB) and enzyme-linked immunosorbent assay (ELISA). Serum samples were collected from 50 patients with AE, 222 patients with cystic echinococcosis (CE), 158 patients with other unrelated infections and 106 healthy individuals. The IB results showed that serum samples of 47 patients with AE and 12 patients with CE were rEm18-positive. However, only one sample from patients with cancer showed a cross-reaction with rEm18 in IB. The overall sensitivity was 94%, and the total specificity was 96.58%. For the rEm18 results using ELISA, the sera of 46 patients with AE were positive, and the overall sensitivity was 92%. In conclusion, compared with imaging tools, including computed tomography, magnetic resonance imaging and positron emission tomography, rEm18 has considerable advantages for AE serodiagnosis.

Field evaluation of an immunochromatographic test for diagnosis of cystic and alveolar echinococcosis

Background

The larval stages of the tapeworms Echinocoocus granulosus and Echinococcus multilocularis are the causative agents of human cystic echinococcosis (CE) and human alveolar echinococcosis (AE), respectively. Both CE and AE are chronic diseases characterised by long asymptomatic periods of many years. However, early diagnosis of the disease is important if treatment and management of echinococcosis patients are to be successful.

Methods

A previously developed rapid diagnostic test (RDT) for the differential detection of CE and AE was evaluated under field conditions with finger prick blood samples taken from 1502 people living in the Ganzi Tibetan Autonomous Prefecture, China, a region with a high prevalence for both forms of human echinococcosis. The results were compared with simultaneously obtained abdominal ultrasonographic scans of the individuals.

Results

Using the ultrasonography as the gold standard, sensitivity and specificity, and the diagnostic accuracy of the RDT were determined to be greater than 94% for both CE and AE. For CE cases, high detection rates (95.6–98.8%) were found with patients having active cysts while lower detection rates (40.0–68.8%) were obtained with patients having transient or inactive cysts. In contrast, detection rates in AE patients were independent of the lesion type. The positive likelihood ratio of the RDT for CE and AE was greater than 20 and thus fairly high, indicating that a patient with a positive test result has a high probability of having echinococcosis.

Conclusions

The results suggest that our previously developed RDT is suitable as a screening tool for the early detection of human echinococcosis in endemic areas.

Plasma IL-23 and IL-5 as surrogate markers of lesion metabolic activity in patients with hepatic alveolar echinococcosis

Fluorodeoxyglucose (FDG) uptake by alveolar echinococcosis (AE) liver lesions is a signal of their metabolic activity and of disease progression. In order to find a surrogate marker for this status, we investigated whether parameters of the peripheral and/or periparasitic immune responses were associated with metabolic activity in a prospective case-control study of 30 AE patients and 22 healthy controls. Levels of 18 cytokines and chemokines, representative of innate and adaptive immune responses, were assessed in plasma and peripheral cells of two groups of patients with (MAAE) and without (MIAE) metabolically active lesions, and in the liver of MAAE patients. Mixed cytokine profile was observed in the peripheral blood of AE patients, with a predominance of Th2, Th17 and Treg responses. Among the detected markers only plasma IL-5 and IL-23, more elevated in MAAE patients, were found discriminant. Discrimination between MAAE and MIAE patients obtained by using IL-23 was improved when IL-5 was used in combination. The combination of elevated levels of IL-5 and IL-23 is significantly associated with FDG uptake at PET scan. It offers a new tool for the follow-up of AE patients which could substitute to FDG-PET whenever non-available to assess disease progression.

[Rapid diagnostic tests for the serodiagnosis of human cystic echinococcosis]

Cystic echinococcosis (CE) is a parasitic zoonosis especially affecting resource-poor populations in livestock raising areas. Imaging, in particular ultrasound (US), is crucial for the diagnosis, staging, and clinical management of abdominal CE in humans. Serology is a valuable complement to imaging, especially when ultrasound features of CE are absent or unclear. In rural endemic areas, where expertise in US is scant, and conventional serology techniques are unavailable due to lack of laboratory equipment, rapid diagnostic tests (RDTs) may be very useful. Several reports have described the performance of commercial and experimental RDTs in the diagnosis of CE, including a recent study by our group that compared the diagnostic performances of three commercial RDTs for the diagnosis of hepatic CE. To put RDTs for CE in context, we reviewed the available literature in English on this topic. Overall, RDTs appear to be useful in resourcepoor settings where they may replace conventional serodiagnostic tests. However, like other serodiagnostic tests, RDTs lack standardization and show unsatisfactory sensitivity and specificity. An important issue that needs to be addressed is that studies on the diagnostic performance of RDTs fail to take into account the variables known to influence results such as anatomical location and cyst stage.

Factors Associated with Echinococcosis-Induced Perioperative Anaphylactic Shock

This retrospective case-control study explored the factors associated with anaphylactic shock during surgery for cystic echinococcosis (CE) at the First Affiliated Hospital of Xinjiang Medical University between October 2008 and September 2013. Patients who suffered from anaphylactic shock (n=16) were age-matched 3:1 to patients who did not (n=43). Multivariate analysis suggested that IL-4 levels (odds ratio=1.096; 95% confidence interval=1.015–1.185; P=0.02) and cyst size (odds ratio=3.028, 95% confidence interval=1.259–7.283, P=0.013) were independently associated with CE-induced perioperative anaphylactic shock. Using the receiver operating characteristic (ROC) curves and a cut-off value of 415.7 ng/ml, IL-4 showed an area under the ROC (AUC) of 0.926, sensitivity of 75.0%, and specificity of 97.7%. Using a cut-off value of 7.8 cm, cyst size showed an AUC of 0.828, sensitivity of 81.3%, and specificity of 76.7%. In conclusion, results suggest that levels of IL-4 and cyst size were independently associated with echinococcosis-induced perioperative anaphylactic shock. These results could help identifying patients with echinococcosis at risk of anaphylactic shock in whom appropriate prophylaxis could be undertaken.

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.

Echinococcosis: Control and Prevention

Human cystic echinococcosis (CE) has been eliminated or significantly reduced as a public health problem in several previously highly endemic regions. This has been achieved by the long-term application of prevention and control measures primarily targeted to deworming dogs, health education, meat inspection, and effective surveillance in livestock and human populations. Human CE, however, remains a serious neglected zoonotic disease in many resource-poor pastoral regions. The incidence of human alveolar echinococcosis (AE) has increased in continental Europe and is a major public health problem in parts of Eurasia. Better understanding of wildlife ecology for fox and small mammal hosts has enabled targeted anthelmintic baiting of fox populations and development of spatially explicit models to predict population dynamics for key intermediate host species and human AE risk in endemic landscapes. Challenges that remain for echinococcosis control include effective intervention in resource-poor communities, better availability of surveillance tools, optimal application of livestock vaccination, and management and ecology of dog and wildlife host populations.

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.

Comparison of the Diagnostic Accuracy of Three Rapid Tests for the Serodiagnosis of Hepatic Cystic Echinococcosis in Humans

BACKGROUND

The diagnosis of cystic echinococcosis (CE) is based primarily on imaging, in particular with ultrasound for abdominal CE, complemented by serology when imaging results are unclear. In rural endemic areas, where expertise in ultrasound may be scant and conventional serology techniques are unavailable due to lack of laboratory equipment, Rapid Diagnostic Tests (RDTs) are appealing.

METHODOLOGY/PRINCIPAL FINDINGS

We evaluated the diagnostic accuracy of 3 commercial RDTs for the diagnosis of hepatic CE. Sera from 59 patients with single hepatic CE cysts in well-defined ultrasound stages (gold standard) and 25 patients with non-parasitic cysts were analyzed by RDTs VIRapid HYDATIDOSIS (Vircell, Spain), Echinococcus DIGFA (Unibiotest, China), ADAMU-CE (ICST, Japan), and by RIDASCREEN Echinococcus IgG ELISA (R-Biopharm, Germany). Sensitivity, specificity and ROC curves were compared with McNemar and t-test. For VIRapid and DIGFA, correlation between semiquantitative results and ELISA OD values were evaluated by Spearman's coefficient. Reproducibility was assessed on 16 randomly selected sera with Cohen's Kappa coefficient. Sensitivity and Specificity of VIRapid (74%, 96%) and ADAMU-CE (57%, 100%) did not differ from ELISA (69%, 96%) while DIGFA (72%, 72%) did (p = 0.045). ADAMU-CE was significantly less sensitive in the diagnosis of active cysts (p = 0.019) while DIGFA was significantly less specific (p = 0.014) compared to ELISA. All tests were poorly sensitive in diagnosing inactive cysts (33.3% ELISA and ADAMU-CE, 42.8% DIGFA, 47.6% VIRapid). The reproducibility of all RDTs was good-very good. Band intensity of VIRapid and DIGFA correlated with ELISA OD values (r = 0.76 and r = 0.79 respectively, p<0.001).

CONCLUSIONS/SIGNIFICANCE

RDTs may be useful in resource-poor settings to complement ultrasound diagnosis of CE in uncertain cases. VIRapid test appears to perform best among the examined kits, but all tests are poorly sensitive in the presence of inactive cysts, which may pose problems with accurate diagnosis.

Rapid detection of ochratoxin A on membrane by dot immunogold filtration assay

BACKGROUND

Ochratoxin A (OTA), a widely distributed mycotoxin produced by certain species of Aspergillus and Penicillium, has been identified as a carcinogenic, hepatotoxic, teratogenic, nephrotoxic and immunotoxic toxin. To reduce the risk of OTA contamination, a rapid, inexpensive, suitable and on-site assay for its detection is required.

RESULTS

In this study a dot immunogold filtration assay (DIGFA) of OTA on high-flow nitrocellulose membrane was developed. Firstly colloidal gold was synthesized and colloidal gold-polyclonal antibody (PcAb) conjugates against OTA were prepared at the optimal colloidal gold-labeled pH value and package amount. Then the colloidal gold-PcAb conjugates were used to develop the OTA DIGFA. The results demonstrated a visual detection limit of approximately 10 ng mL(-1) OTA. In addition, this method had no cross-reaction with zearalenone, aflatoxin B1 or citrinin.

CONCLUSION

These results indicated that the developed DIGFA could be applied for the actual detection of samples without complicated steps.

Human cystic and alveolar echinococcosis in the Tibet Autonomous Region (TAR), China

Human cystic echinococcosis (CE) is known to be endemic in the Tibet Autonomous Region (TAR), China; however, there is relatively little data from hospital records or community prevalence studies, and the situation regarding occurrence of human alveolar echinococcosis (AE) is unclear. Here we review the available reports about human echinococcosis in the seven prefectures of TAR. In addition, two pilot studies by mass screening using ultrasound (with serology) were undertaken (2006/7) in Dangxiong County of Lhasa Prefecture (north central TAR) and Dingqing County of Changdu Prefecture (eastern TAR). In Dangxiong County a prevalence of 9.9% (55/557) for human CE was obtained but no human AE cases were detected. By contrast, in Dingqing County (N= 232 persons screened), 11 CE cases (4.7%) and 12 AE cases (5.2%) (including one mixed CE and AE case) were diagnosed by ultrasound. Hospital records and published reports indicated that CE cases were recorded in all of seven prefectures in Tibet Autonomous Region, and AE cases in four prefectures. Incidence rates of human CE were estimated to range from 1.9 to 155 per 100,000 across the seven prefectures of TAR, with a regional incidence of 45.1 per 100,000. Incidence of AE was estimated to be between 0.6 and 2.8 cases per 100,000. Overall for TAR, human AE prevalence appeared relatively low; however, the pilot mass screening in Dingqing in eastern TAR indicated that human AE disease is a potential public health problem, possibly similar to that already well described in Tibetan communities bordering TAR in north-west Sichuan and south-west Qinghai provinces.

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.

A paper-based detection method of cancer cells using the photo-thermal effect of nanocomposite

A novel paper-based dot immune-graphene-gold filtration assay (DIGGFA) for the detection of breast cancer cells was developed based on the photo-thermal effect of graphene oxide (GO)-Au nanocomposite. Anti-EpCAM antibody which specific to the MCF-7 cell surface antigen, was immobilized on the nitrocellulose paper. The GO-Au-anti-EpCAM composite would interact with the MCF-7 cells captured on the nitrocellulose paper. After the test zone was irradiated by a laser, GO-Au nanocomposite could generate heat, temperature contrast was recorded and positive correlated with the cell number. Standard curve was prepared according to the temperature contrast and the cell number. Under optimal conditions, this method could detect a minimum of 600 MCF-7 cells with a near infrared laser and an infrared temperature gun within 15 min. This simple and rapid method could be applied to the clinical diagnosis in hospitals.

Evaluation of immunochromatographic test for the detection of antibodies against Echinococcosis granulosus

BACKGROUND

Echinococcosis in humans is a disease caused by the larvae of Echinococcus granulosus (E. granulosus) and Echinococcus multilocularis (E. multilocularis). Serological tests are valuable, especially in the clarification of unexplained clinical findings and imaging methods. For this reason, indirect hemagglutination (IHA), latex agglutination, immunoelectrophoresis, immunoblotting, immuno-enzymatic tests, indirect fluorescence antibody test (IFAT), and enzyme-linked immunosorbent assay (ELISA) are used. The purpose of this study was to investigate the value of an immunochromatographic test (ICT) specific for E. granulosus antibodies in the diagnosis of echinococcosis.

MATERIAL/METHODS

ICT evaluated 102 cases of cystic echinococcosis, 38 cases of other parasitic diseases, and 50 healthy individuals. ELISA (DRG, Germany) that detects IgG antibodies specific for E. granulosus was used as the reference method.

RESULTS

The sensitivity, specificity, and positive and negative predictive values of ICT were 96.8%, 87.5%, 98.9%, and 70%, respectively. Diagnostic value was 96.1%. No significant differences and high degrees of agreement were found between ELISA and immunochromatographic test for cystic echinococcosis. Serum samples included 4 taeniasis, 2 leishmaniasis, and 2 healthy individuals were diagnosed to be positive with immunochromatographic test.

CONCLUSIONS

The ability of test to give fast results without need for equipment, devices, and specific storage conditions is an advantage. This test may be used due to its advantages in endemic regions for screening and diagnostic purposes.

Surgical treatment of hepatic cystic echinococcosis in patients co-infected with HIV/AIDS

Co-infections of cystic echinococcosis (CE) and HIV/AIDS is rare. We report four CE cases that were HIV positive. Three out of the four patients underwent a surgical operation to remove the hydatid cysts in their livers. The operation confirmed that in two of the cases their cysts had ruptured. These patients were given 3 months of albendazole after the operation. Follow-up showed they were remarkably improved in term of their health, although they were still HIV antibody positive 6 months after surgical treatment. Interestingly, the treatment remarkably increased their CD4+ cell population. We showed that surgery is suitable for treating hepatic cystic echinococcosis with HIV/AIDS co-infection.

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.

Laparoscopic approach for total cystectomy in treating hepatic cystic echinococcosis

Background: The laparoscopic approach has been proposed for treating hepatic cystic echinococcosis (HCE) and has already been used in clinical practice, mostly for non-radical operations. In this study, we aimed to evaluate the feasibility of total cystectomy of HCE under laparoscopy (LS).

Results: A retrospective review of the medical records obtained from 22 patients diagnosed with HCE between June 2009 and June 2013 and treated with an LS approach was conducted in the First Affiliated Hospital of Xinjiang Medical University. A total of 15 patients underwent total cystectomy of HCE using LS. The average time of surgery was 174 min (160–210 min). Intraoperative bleeding was 103 mL (80–200 mL). The mean duration of hospitalization was 7 days (6–15 days). Seven patients were transferred to open surgery (OS). For these patients, the average duration of surgery was 177 min (150–230 min). Intraoperative bleeding was 237 mL (160–350 mL), and the mean duration of hospitalization was 10 days (8–15 days). The most frequent postoperative complications were hydrops in the surgical area (two cases in LS and three cases in OS), and temporary bile leakage (one patient in the LS group). Recurrence was not seen in any cases in either group with a follow-up of 6–12 months.

Conclusions: Total cystectomy of HCE appears to be safe and effective in selected patients with unique, small-sized, superficially located cysts. To establish precise recommendations about the technique and its indications, prospective studies are necessary.

Spleen-preserving surgery is effective for the treatment of spleen cystic echinococcosis

OBJECTIVE

This study evaluated two surgical procedures, total splenectomy and spleen-preserving surgery, for the treatment of spleen cystic echinococcosis (CE).

METHODS

A total of 21 patients who underwent surgery for removal of spleen CE were evaluated retrospectively. Patients were divided into two groups, those who received a total splenectomy (n=7) and those who underwent spleen-preserving surgery (n=14).

RESULTS

Total splenectomy surgery took 127.1±11.1min and spleen-preserving surgery took 104.3±25.3min (p<0.05). The length of hospital stay was the same for both patient groups (10.6 days on average). No patient suffered from recurrence during follow-up and all of the patients made a good recovery. No patient developed post-splenectomy sepsis or serious infectious complications. No patient suffered recurrence.

CONCLUSIONS

The spleen-saving approach is likely an effective method for the removal of CE spleen cysts given that it is a quick procedure and preserves the function of the spleen. Total splenectomy procedures may be performed particularly for larger, centrally located cysts.

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

Cystic echinococcosis (CE) caused by infection with Echinococcus granulosus is of major concern for humans in many parts of the world. Antigen B was prepared from E. granulosus hydatid fluid, and Western blots confirmed eight batches showing a band corresponding to the 8-/12-kDa subunit with positive serum and no low-molecular mass band (< 15 kDa) with negative serum. The batches were pooled and used to prepare lateral flow immunoglobulin G4 (IgG4) and IgG dipsticks. Diagnostic sensitivity was determined using serum samples from 21 hydatidosis patients, and diagnostic specificity was established using sera from 17 individuals infected with other parasites and 15 healthy people. IgG4 dipstick had a diagnostic sensitivity of 95% (20 of 21) and a specificity of 100% (32 of 32). The IgG dipstick had a sensitivity of 100% (21 of 21) and a specificity of 87.5% (28 of 32). Thus, both IgG and IgG4 dipsticks had high sensitivities, but IgG4 had greater specificity for the diagnosis of human CE.

Paragonimiasis

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

Treatment experiences of pelvic bone hydatidosis

BACKGROUND

Hydatid diseases of the pelvic bone are rare, generally incurable, and have high rates of recurrence.

METHODS

We report nine cases of osseous hydatidosis involving the pelvis. Patients were treated through different surgical options, including simple debridement, bone cement filling with or without internal fixation, reconstruction using a pedicle screw-rod system, and hemipelvic replantation after liquid nitrogen devitalization combined with femoral prosthesis replacement. The therapy was completed by medical treatment or radiotherapy.

RESULTS

The average follow-up was 7.3 years (range 2-19 years). Whilst five patients were symptom-free at the last follow-up, the remaining patients suffered from hip pain or productive sinuses.

CONCLUSIONS

Patients must be treated at the early stages of the disease. Total exeresis and individual reconstruction is necessary when osseous and soft tissue involvement is not extensive. Internal fixation should not be used when surgical eradication is uncertain.

Differential diagnosis of cystic and alveolar echinococcosis using an immunochromatographic test based on the detection of specific antibodies

Human cystic and alveolar echinococcoses are zoonotic diseases caused by the larval stages of Echinococcus granulosus and Echinococcus multilocularis, respectively. As the diseases are co-endemic in many areas of the world, a simple and rapid test for the differential diagnosis of cystic echinococcosis (CE) and alveolar echinocoocosis (AE) is needed. Here, we describe the development of an immunochromatographic test (ICT) using crude hydatid cyst fluid and a recombinant 18-kDa protein (rEm18) as antigens for the detection of E. granulosus and E. multilocularis antibodies in serum samples. The ICT was evaluated with serum samples from 195 echinococcosis patients from different endemic areas in northwestern China. These included 144 from CE patients, 51 from AE patients, 67 from patients with other parasitic diseases, 13 from patients with serous hepatic cysts, and 60 from healthy individuals. The sensitivity and specificity of the ICT for CE were 91.0 and 96.9% and for AE were 98.0 and 99.3% with diagnostic efficiencies of 94.1 and 99.1%, respectively. No significant differences and high degrees of agreement were found between the ICT and an enzyme-linked immunosorbent assay for both CE and AE. Five serum samples from cysticercosis patients and one serum sample from a healthy control were found positive for CE with the ICT. These findings indicate that this test allows for discrimination between both forms of human echinococcosis. In conclusion, the ICT developed in this study is a promising tool for the simultaneous detection and discrimination of CE and AE. This test will be useful for serodiagnosis of CE and AE in clinical settings and screening programs.

Dot immunogold filtration assay (DIGFA) for the rapid detection of specific antibodies against the rat lungworm Angiostrongylus cantonensis (Nematoda: Metastrongyloidea) using purified 31-kDa antigen

A rapid dot immunogold filtration assay (DIGFA) was adopted for specific immunodiagnosis of human cerebral angiostrongyliasis, using purified 31-kDa glycoprotein specific to Angiostrongylus cantonensis as diagnostic antigen and protein A colloidal gold conjugate as antigen-antibody detector. A total of 59 serum samples were assayed - 11 samples from clinically diagnosed patients with detectable A. cantonensis-specific antibody in immunoblotting; 23 samples from patients with other related parasitic diseases, i.e. gnathostomiasis (n= 8), cysticercosis (n= 5), toxocariasis (n= 2), filariasis (n= 4), paragonimiasis (n= 2) and malaria (n= 2); and 25 samples from normal healthy subjects. The sensitivity and specificity of DIGFA to detect anti-A. cantonensis specific antibodies in serologically confirmed angiostrongyliasis cases, were both 100%. No positive DIGFA was observed in cases with other parasitic diseases, and the healthy control subjects. The 3-min DIGFA is as sensitive and specific as the 3-h immunoblot test in angiostrongyliasis confirmed cases that revealed a 31-kDa reactive band. The gold-based DIGFA is more rapid and easier to perform than the traditional enzyme-linked immunosorbent assay (ELISA). The test utilizing purified A. cantonensis antigen is reliable and reproducible for specific immunodiagnosis of human infection with A. cantonensis - thus can be applied as an additional routine test for clinical diagnostic support. Large-scale sero-epidemiological studies in endemic communities in north-east Thailand are under way to evaluate its usefulness under field conditions.

Development of a dot-immunoenzyme filtration assay for the detection of enterovirus 71 antigen in human serum via immunoglobulin M

OBJECTIVES

This study evaluated the sensitivity and specificity of a rapid, sensitive dot-immunoenzyme filtration assay to detect enterovirus 71 (EV71) antigen in serum samples from paediatric patients with hand, foot and mouth disease (HFMD), through detection of anti-EV71 immunoglobulin (Ig)M.

METHODS

Serum samples from HFMD patients and healthy adult controls were evaluated for the presence of anti-EV71 IgM using a dot-immunoenzyme filtration assay (DIEFA). The results were compared with those obtained using a dot-immunogold filtration assay (DIGFA). The EV71 structural protein VP1 was used as the antigen for both assays.

RESULTS

Serum samples from 72 HFMD patients and 54 healthy controls were evaluated. The DIGFA procedure showed a sensitivity of 98.5% and a specificity of 100%, whereas the DIEFA procedure showed a sensitivity of 98.6% and a specificity of 98.0%. There were no significant differences between the assays in either specificity or sensitivity.

CONCLUSION

The DIEFA procedure developed in this study has potential as a rapid, simple, sensitive and cost-effective screening technique for detecting EV71 antigen in serum samples from patients with HFMD.

Improved serodiagnosis of cystic echinococcosis using the new recombinant 2B2t antigen

A standardized test for the serodiagnosis of human cystic echinococcosis (CE) is still needed, because of the low specificity and sensitivity of the currently available commercial tools and the lack of proper evaluation of the existing recombinant antigens. In a previous work, we defined the new ELISA-B2t diagnostic tool for the detection of specific IgGs in CE patients, which showed high sensitivity and specificity, and was useful in monitoring the clinical evolution of surgically treated CE patients. Nevertheless, this recombinant antigen gave rise to false-negative results in a percentage of CE patients. Therefore, in an attempt to improve its sensitivity, we constructed B2t-derived recombinant antigens with two, four and eight tandem repeat of B2t units, and tested them by ELISA on serum samples of CE patients and patients with related parasites. The best diagnostic values were obtained with the two tandem repeat 2B2t antigen. The influence of several clinical variables on the performance of the tests was also evaluated. Finally, the diagnostic performance of the 2B2t-ELISA was compared with that of an indirect haemagglutination commercial test. The 2B2t recombinant antigen performed better than the HF and B2t antigens, and the IHA commercial kit. Therefore, this new 2B2t-ELISA is a promising candidate test for the serodiagnosis of CE in clinical settings.

Cystic echinococcosis (CE) is a widespread zoonotic disease. Its complex clinical presentation precludes a “one-size-fits-all” approach to clinical management, particularly with regard to serodiagnosis. While CE is often detected incidentally by imaging, imaging findings may be inconclusive. Therefore, there is a need for standardised and approachable diagnostic tools that may complement imaging data. In this regard, serological tests based in the use of native antigens like hydatid fluid present a low specificity and sensitivity. Although recombinant antigens with potential to replace native antigens have been proposed in the literature, none has been systematically tested for diagnostic performance. Here, we describe the new recombinant antigen 2B2t, derived from the previously described recombinant B2t, and determine its usefulness for the serodiagnosis of CE by ELISA in patients with a complete set of clinical data. The influence of clinical variables on the performance of 2B2t was evaluated and compared with the hydatid fluid (the most commonly used antigen for CE serology) and a commercial diagnostic kit based on the haemagglutination reaction. Our results show that the 2B2t antigen has potential to be routinely used for the standardised diagnosis of CE in clinical settings.

Immunology and immunodiagnosis of cystic echinococcosis: an update

Cystic echinococcosis (CE) is a cosmopolitan zoonosis caused by the larval cystic stage of the dog tapeworm Echinococcus granulosus. This complex multicellular pathogen produces various antigens which modulate the host immune response and promote parasite survival and development. The recent application of modern molecular and immunological approaches has revealed novel insights on the nature of the immune responses generated during the course of a hydatid infection, although many aspects of the Echinococcus-host interplay remain unexplored. This paper summarizes recent developments in our understanding of the immunology and diagnosis of echinococcosis, indicates areas where information is lacking, and suggests possible new strategies to improve serodiagnosis for practical application.

Serological diagnosis of echinococcosis: the diagnostic potential of native antigens

PURPOSE

Human alveolar (AE) and cystic echinococcosis (CE) caused by the metacestode stages of Echinococcus multilocularis and E. granulosus, respectively, lack pathognomonic clinical signs. Diagnosis therefore relies on the results of imaging and serological studies. The primary goal of this study was to evaluate the efficacy of several easy-to-produce crude or partially purified E. granulosus and E. multilocularis metacestode-derived antigens as tools for the serological diagnosis and differential diagnosis of patients suspicious for AE or CE.

METHODS

The sera of 51 treatment-naïve AE and 32 CE patients, 98 Swiss blood donors and 38 patients who were initially suspicious for echinococcosis but suffering from various other liver diseases (e.g., liver neoplasia, etc.) were analysed.

RESULTS

According to the results of enzyme-linked immunosorbent assays (ELISA), metacestode-derived antigens of E. granulosus had sensitivities varying from 81 to 97% and >99.9% for the diagnosis of CE and AE, respectively. Antigens derived from E. multilocularis metacestodes had sensitivities ranging from 84 to 91% and >99.9% for the diagnosis of CE and AE, respectively. Specificities ranged from 92 to >99.9%. Post-test probabilities for the differential diagnosis of AE from liver neoplasias, CE from cystic liver lesions, and screening for AE in Switzerland were around 95, 86 and 2.2%, respectively. Cross-reactions with antibodies in sera of patients with other parasitic affections (fasciolosis, schistosomosis, amebosis, cysticercosis, and filarioses) did occur at variable frequencies, but could be eliminated through the use of confirmatory testing.

CONCLUSIONS

Different metacestode-derived antigens of E. granulosus and E. multilocularis are valuable, widely accessible, and cost-efficient tools for the serological diagnosis of echinococcosis. However, confirmatory testing is necessary, due to the lack of species specificity and the occurrence of cross-reactions to other helminthic diseases.

Demographic and clinical characteristics of patients with anaphylactic shock after surgery for cystic echinococcosis

We reviewed the records of 446 patients who were treated surgically for cystic echinococcosis (CE) to identify risk factors for anaphylactic shock. Of 446 patients, 10 had final diagnoses of anaphylactic shock induced by CE; none died. The incidence of anaphylactic shock was significantly higher in younger age groups (P < 0.001) and in patients with pulmonary cysts. Anaphylactic shock induced by CE appears to differ from type I immediate hypersensitivity shock, which suggests that in CE, shock may be caused by a combination of immediate hypersensitivity and endotoxic shock. This possibility suggests that additional precautions should be taken during surgery. These precautions include reducing intracystic pressure, which would prevent possible leaked liquid from reaching other organs by surrounding the cyst with sterile gauze and decrease the chance of spreading the echinococcus; preventing antigen from contacting other tissues where it might trigger anaphylaxis; and resecting the cyst completely when feasible.

Immunochromatographic test with recombinant Em18 antigen for the follow-up study of alveolar echinococcosis

The performance of a rapid and simple immunochromatographic test (ICT) with recombinant Em18 (rEm18) antigen for serological follow-up of Echinococcus multilocularis infection was evaluated by comparison with that of an enzyme-linked immunosorbent assay (ELISA) with rEm18, using serum samples from patients who underwent surgery and/or received antiparasitic chemotherapy. The degree of Em18-band intensity on the ICT correlated highly with the absorbance value obtained by the ELISA. The kinetics of antibody levels obtained by the ICT paralleled those of the ELISA. These data suggest that the ICT has high potential as an easy-to-handle, fast, and reliable follow-up tool to monitor the status of alveolar echinococcosis in different stages.