Serodiagnosis of human hydatidosis with an ELISA developed based on antigens derived from sheep hydatid cysts and comparison with a commercial human ELISA kit

Comparison of the Diagnostic Performance of Antigen B Purified from Sheep Hydatid Cyst Fluid (HCF) with Commercial ELISA Kit

INTRODUCTION

Cystic echinococcosis (CE) is a zoonotic parasitic disease caused by the metacestode of Echinococcus granulosus. CE is a health problem in Middle Eastern countries, such as Iran. The purpose of this study was to purify subunit 8 KDa antigen B from crude sheep hydatid cyst fluid (HCF) and compare its sensitivity and specificity with a commercial human ELISA kit (PT-Hydatid-96).

METHODS

28 sera samples were collected from hydatid cyst patients who had surgery for a hydatid cyst and had their disease confirmed by pathology after the surgery. Furthermore, 35 samples of healthy individuals with no history of hydatid cysts were collected, as were nine serum samples from parasite-infected non-CE patients. HCF was obtained from sheep fertile cysts at a Sari slaughterhouse and used as an antigen. In an indirect ELISA test, the B antigen was employed, and the results were compared to those from a commercial ELISA kit.

RESULTS

The results of this study were analyzed using the Kappa test. The commercial ELISA kit showed 17 cases (23.6%) positive, 44 cases (61.1%) negative, and 11 cases (15.3%) borderline. B antigen showed that 18 (25%), 43 (59.7 %), and 11 (15.3%) were positive, negative, and borderline, respectively. One sample (1.4% of 72 total samples) of 35 serum samples from healthy individuals was positive using B antigen-based ELISA. In addition, all nine serum samples from parasite-infected non-CE patients were negative for both tests. The sensitivity and specificity of the commercial ELISA kit have been evaluated at 60.7% and 100%, respectively. For B antigenbased ELISA, these values are 64.3 and 97.7%, respectively.

CONCLUSION

Antigen B produced from hydatid cyst fluid is a promising option for serological identification of hydatid cysts in both infected and healthy individuals. In an indirect ELISA test, hydatid fluid antigen could be used as a precise source of detection.

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.

Animal hydatid cyst genotypes as a potential substitute for human hydatid cyst as a source of antigen for diagnosis of zoonotichydatidosis

The Diagnosis of hydatidosis is still an unsolved issue due to difficulties in obtaining of patient's hydatid cyst appropriate for antigen extraction. This study evaluated the suitability of HC protoscolices somatic antigens (HCPsS-Ag) fractions from animal origin to substitute that extracted from HC of patients in diagnosis of hydatidosis using enzyme-linked immunoelectro-transfer blot and Enzyme-linked immunosorbent assay (ELISA). Eight fractions in HC-G6 from patients react specifically versus HC-G6 infected patient's sera. Five of them (28, 32, 38, 59 and 89 Kilo Dalton (KDa) and two of them (28 KDa and 45 KDa) reacted versus HC-G1 and HC-G4 infected sheep and equine sera, respectively. Six fractions in HCPsS-Ag-G1 of sheep react versus HC-G1 sheep infected sera, four (28, 32, 52 and 58 KDa) and two of them reacted versus HC-G6 and HC-G4 infected patient and equine sera, respectively. Two fractions only in HCPsS-Ag-G4 of equine reacted versus infected human and sheep sera. This fraction displayed the same degree of ELISA value versus different infected sera with a significantly perfect classification for kappa agreement and non-statistically significant difference (p ≥ 0.05) for ELISA Optical density values of the positive samples without cross-reaction versus other parasites antibodies in sera. HCPsS-Ag from HC genotypes that developed in humans and animals as HC-G6 and HC-G1 can substitute each other for diagnosis of infection than antigens extracted from non-zoonotic HC-G4. The fraction at 28 KDa is the only fraction that can be extracted from any animals HC and used in diagnosis of zoonotic hydatidosis.

Epidemiology of echinococcosis in Iran: a systematic review and meta-analysis

BACKGROUND

Echinococcosis is a zoonotic disease caused by the larval stages of taeniid cestodes of the genus Echinococcus. The two major types of infection in humans are cystic echinococcosis (CE) or hydatidosis and alveolar echinococcosis (AE). It is endemic in some parts of the world, such as the Middle East, with Iran being a part of it. This systematic review and meta-analysis were conducted to determine the prevalence of CE and AE echinococcosis and their epidemiological and clinical aspects in Iran.

METHODS

Electronic databases, including MEDLINE (via PubMed), SCOPUS, Web of Science, SID and Mag Iran (two Persian scientific search engines) were searched from 1 January 1990 to 8 August 2017. The prevalence of CE and AE echinococcosis was estimated using the random effects meta-analysis. Heterogeneity was evaluated by subgroup analysis. Data were analyzed by STATA version 12.

RESULTS

Of the 2051 records identified in the mentioned electronic databases, Seventy-eight articles met our eligibility criteria, with a total of 214124individuals. The meta-analysis was performed on only 37 out of 78 included studies. The pooled prevalence of CE and AE in Iran was 5% [95% confidence interval )CI(: 3-6%] and 2% [95% CI: 0-5%], respectively. Subgroup meta-analysis revealed that the prevalence of CE was significantly higher in North [9%, 95% CI: 4-18%] and West of Iran [6%, 95% CI: 3-11%], patients younger than 40 years of age [7%, 95% CI: 4-12%], villagers and nomads [6%, 95% CI: 2-12%], and studies that used the combination of serological, clinical, and imaging diagnostic methods [7%, 95% CI: 5-9%]. There were no significant differences between the prevalence of CE among low and high-quality studies. Housewives were the most affected group by hydatidosis (n=24/77, 31%), followed by illiterate people (n=11/77, 14%) and farmers (n= 9/77, 12%). Liver [55%, 95% CI: 46-65%] and lung [28%, 95% CI, 22-35%] were the most common sites of cyst formation.

CONCLUSIONS

Given to the importance of echinococcosis on human health and domestic animals industry, it is necessary to implement monitoring and control measures in this regard.

Cystic echinococcosis in Jordan: A review of causative species, previous studies, serological and radiological diagnosis

Cystic echinococcosis (CE)/hydatidosis is a zoonotic disease which occur in human and herbivore animals as a result of infection with the larval stage of the taeniid cestode Echinococcus granulosus sensu lato (s. l.). In human, CE is a serious public health concern in many parts of the world including Jordan. The present review will cover CE causative agent: E. granulosus species/genotypes; life cycle of E. granulosus parasite, all published previous studies on CE in Jordan (humans, intermediate hosts, definitive host) as well as its diagnostic methods in human.

The seroprevalence rate and population genetic structure of human cystic echinococcosis in the Middle East: A systematic review and meta-analysis

Cystic echinococcosis (CE) represents an increasing public health concern in many parts of the world, including the Middle East. The present study is the first systematic review and meta-analysis to assess the seroprevalence rate and population genetic structure of human CE in the eastern Mediterranean region. To estimate the population genetic structure, Echinococcus sequences of the cytochrome oxidase subunit 1 (cox1) gene isolated from countries from this geographical area were retrieved from the GenBank database. An electronic search for articles from 1990 until 2015 was performed using databases PubMed, ScienceDirect, and Scopus. A total of 53 articles reporting on CE seroprevalence and genotyping data met our eligibility criteria and were included in a meta-analysis. The overall CE seroprevalence rates in the general population and in individuals at high risk of infection were estimated using the random-effect model at 7.4% (95% CI = 4.8-10.6) and 10.7% (95% CI = 7.6-14.3), respectively. Risk factors including age group (P < 0.001), dog ownership (P = 0.03), residence area (P < 0.001), and educational level (P = 0.04) showed a statistically significant association with CE seroprevalence. A pairwise fixation index (Fst), used as an estimation of gene flow, suggested a moderate level of genetic differentiation between members of the E. granulosus sensu stricto (G1-G3) complex from Iranian and Turkish metapopulations (Fst = 0.171). The finding of common haplotypes may represent an ancestral transfer of alleles among populations probably during the early stages of animal domestication. The high CE seroprevalence rates found highlight the necessity of implementing appropriate public education for preventive and control strategies, particularly in individuals at high risk of infection; furthermore, our genetic findings reveal novel molecular data concerning microevolutionary events of Echinococcus isolates among Middle East countries.

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.

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.

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.

Human Cystic Echinococcosis in the Nalut District of Western Libya: A Clinico-epidemiological Study

Human cystic echinococcosis (CE) is an endemic disease in the Mediterranean area that has not yet been fully documented in western Libya. The present study describes the clinico-epidemiologic profile of CE in western Libya’s Nalut district. From April 2008 to July 2011, 36 cases of CE were confirmed following surgical removal of cysts. The cysts were most frequently found in the liver (61.1%), followed by the lungs (19.4%), kidneys (11.1%), peritoneal cavity (11.1%), and spleen (5.6%). Among the 36 patients, 6 possessed plural cysts and 3 had cysts in 2 organs. Blood samples from this group were examined for the presence of serum anti-hydatid IgG antibodies, which revealed positivity in 25 patients (69.4%). An additional 300 blood samples were collected randomly from the inpatient and outpatient clinics at Nalut Hospital. Twenty-seven samples (9%) were found to be positive for the anti-hydatid IgG antibody among which the prevalence of infection tended to be higher in men (12%) than in women (6%). This study demonstrates that CE is a major parasitic infectious disease of public health significance in Libya, notably in the western part of the country, and that disease awareness needs to be raised nationwide.