Detection of hydatid-specific antibodies in the serum and urine for the diagnosis of cystic echinococcosis in patients from the Kashmir Valley, India. J Helminthol. 2015;89:232-237. [PMID: 24429044 DOI: 10.1017/s0022149x13000837]

Metabolomic profiling of early inactive hepatic alveolar and cystic echinococcosis

Hepatic alveolar echinococcosis (AE) and cystic echinococcosis (CE) are severe helminthic zoonoses and leading causes of parasitic liver damage. They pose a high mortality risk due to invisible clinical signs, especially at the early inactive stage. However, the specific metabolic profiles induced by inactive AE and CE lesions remain largely unclear. Therefore, we used gas chromatography-mass spectrometry-based metabolomic profiling to identify the global metabolic variations in AE and CE patient sera to differentiate between the two diseases and reveal the mechanisms underlying their pathogenesis. In addition, specific serum biomarkers of inactive hepatic AE and CE were screened using receiver operating curves, which can contribute to the clinical diagnosis of both diseases, especially in the earlier phase. These differential metabolites are involved in glycine, serine, tyrosine, and phenylalanine metabolism. Further analysis of key metabolic pathways showed that inactive AE lesions strongly alter amino acid metabolism in the host. CE lesions have an altered metabolism of oxidative stress response. These changes suggest these metabolite-associated pathways can serve as biomarkers to distinguish individuals with inactive AE and CE from healthy populations. This study also investigated the differences in serum metabolic profiles in patients with CE and AE. The biomarkers identified belonged to different metabolic pathways, including lipid, carnitine, androgen, and bile acid metabolism. Taken together, by investigating the different phenotypes of CE and AE with metabolomic profiling, serum biomarkers facilitating early diagnosis were identified.

Seroprevalence of human cystic echinococcosis: A study from a tertiary care center of North India

Present study retrospectively analysed the serological data of patients suspected of cystic echinococcosis (CE) attending the outpatient clinics or admitted in our hospital. An enzyme-linked immunoassay was used to analyse anti-CE antibodies in serum samples of 3680 patients. Microscopy of aspirated cystic fluid was performed on 170 cases only. CE seropositive cases were 595 (16.2%), of which 293 (49.2%) were males and 302 (50.8%) were females. A higher percentage of seropositivity was found in adults within age range of 21-40 years of age. There has been a decrease in seropositivity in the study years (2016-2021) in comparison to previous years (1999-2015).

Diagnostic performance of a urine-based ELISA assay for the screening of human schistosomiasis japonica: A comparative study

The current study developed and evaluated the performance of a urine-based enzyme-linked immunosorbent assay (ELISA) for the screening of Schistosoma japonicum infection in a human cohort (n = 412) recruited from endemic areas, Northern Samar, the Philippines. The diagnostic performance of the urine ELISA assay was further compared with the Kato-Katz (KK) technique, serum-based ELISA assays, point-of-care circulating cathodic antigen (POC-CCA) urine cassette test, and droplet digital (dd)PCR assays performed on feces, serum, urine, and saliva samples, which were designated as F_ddPCR, SR_ddPCR, U_ddPCR, and SL_ddPCR, respectively. When urine samples concentrated 16× were assessed, the SjSAP4 + Sj23-LHD-ELISA (U) showed sensitivity/specificity values of 47.2/93.8% for the detection of S. japonicum infection in KK-positive individuals (n = 108). The prevalence of S. japonicum infection in the total cohort determined by the urine ELISA assay was 48.8%, which was lower than that obtained with the F_ddPCR (74.5%, p < 0.001), SR_ddPCR (67.2%, p < 0.001), and SjSAP4 + Sj23-LHD-ELISA (S) (66.0%, p < 0.001), but higher than that determined by the Sj23-LHD-ELISA (S) (24.5%, p < 0.001), POC-CCA assay (12.4%, p < 0.001), and SL_ddPCR (25.5%, p < 0.001). Using the other diagnostic tests as a reference, the urine ELISA assay showed a sensitivity between 47.2 and 56.9%, a specificity between 50.7 and 55.2%, and an accuracy between 49.3 and 53.4%. The concentrated urine SjSAP4 + Sj23-LHD-ELISA developed in the current study was more sensitive than both the KK test and POC-CCA assay, and showed a comparable level of diagnostic accuracy to that of the U_ddPCR. However, its diagnostic performance was less robust than that of the F_ddPCR, SR_ddPCR, and SjSAP4 + Sj23-LHD-ELISA (S) assays. Although they are convenient and involve a highly acceptable non-invasive procedure for clinical sample collection, the insufficient sensitivity of the three urine-based assays (the urine ELISA assay, the U_ddPCR test, and the POC-CCA assay) will limit their value for the routine screening of schistosomiasis japonica in the post mass drug administration (MDA) era, where low-intensity infections are predominant in many endemic areas.

Detection of Urinary Antibodies and Its Application in Epidemiological Studies for Parasitic Diseases

For epidemiological studies of infectious diseases, pathogen-specific antibody levels in an area give us essential and appropriate information. The antibodies against pathogens are usually detected in blood, the drawing of which inconveniences people. Collection of blood increases the risk of accidental infections through blood, and it is difficult to obtain the participation of the target populations, especially the younger generation. On the other hand, urine samples, which contain a high enough level of antibodies for ELISA, can be harmlessly and easily collected and therefore have been used for epidemiological studies for diseases. The antibody examination of urine has been used for the epidemiology of parasitic diseases with a high sensitivity and specificity of serum samples. In this paper, we reviewed antibody assays with urine for seven parasitic diseases that urine diagnostic methods have reported in the past, and these are important infections included in NTDs, caused, for example, by Leishmania donovani, Wuchereria bancrofti, Schistosoma japonicum, Paragonimus westermani, Echinococcus granulosus, Echinococcus multilocularis, Strongyloides stercoralis, and Opisthorchis viverrini. The easy and safe urine surveillance system might be an admirable tool for future epidemiological studies for infectious diseases.

Seroprevalence of human cystic echinococcosis in South Kashmir, India

Cystic echinococcosis is a zoonotic disease that causes economic losses and public health problems throughout the globe. Present study was undertaken to estimate the seroprevalence of cystic echinococcosis in humans of South Kashmir and to determine the risk factors associated with this disease. The present study was carried out from April 2017 to March 2018, during which 458 blood samples (from 222 males and 236 females) were collected from selected subjects from 12 villages of four districts along with demographic characteristics. Samples were analyzed by an Enzyme-linked Immunosorbent Assay (ELISA) (commercially prepared kit) for detection of immunoglobulin IgG against cystic echinococcosis. Out of 458 samples, 20(4.36%) samples were found positive. Results implied that the seroprevalence of cystic echinococcosis in South Kashmir had significant relationship with age, gender and occupation (P < .05). Seroprevalence for cystic echinococcosis was significantly higher among males, children, and illiterate persons.

Detection of Echinococcus granulosus sensu lato infection by using extracts derived from a protoscoleces G1 cell line

Cystic echinococcosis (CE) can be diagnosed by means of several serological approaches, but their results vary among laboratories due to the molecular characteristics of the reference antigens used. Thus, this study aimed to address both the relevance of an EGPE cell line previously obtained from Echinococcus granulosus protoscoleces G1 and the complexity of the immune response by using two different in vitro growth stages as separate sources of parasite antigens. The serum reactivity was investigated by western blotting (WB) in 21 CE patients from an endemic area in a matched case-control design and also in seven experimentally infected sheep and five healthy control sheep. EGPE-antigen-human serum sensitivity by WB was higher than that of hydatid fluid (HF) WB, ELISA and DD5 (P < .05, Chi-square test). EGPE protein extract was immunogenic in mice and hyperimmune plasma reacted with HF proteins, and AgB2 expression was detected by molecular analysis. Proteins of 37 to 60 kDa were recognized by 95.24% of the CE patients' sera but, with poor specificity. Statistically significant differences were found between serum protein extract recognition at 7 and 20 days of cell growth. The EGPE cell line is a laboratory source of antigens for improvement of CE serological diagnosis.

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.

Bethony J. Diagnostic performance of urinary IgG antibody detection: A novel approach for population screening of strongyloidiasis

The diagnosis of strongyloidiasis by coprological methods has a low sensitivity, underestimating the prevalence of Strongyloides stercoralis in endemic areas. Serodiagnostic tests for strongyloidiasis have shown robust diagnostic properties. However, these methods require a blood draw, an invasive and labor-intensive sample collection method, especially in the resource-limited settings where S. stercoralis is endemic. Our study examines a urine-based assay for strongyloidiasis and compares its diagnostic accuracy with coprological and serological methods. Receiver operating characteristic (ROC) curve analyses determined the diagnostic sensitivity (D-Sn) and specificity (D-Sp) of the urine ELISA, as well as estimates its positive predictive value and diagnostic risk. The likelihood ratios of obtaining a positive test result (LR+) or a negative test result (LR-) were calculated for each diagnostic positivity threshold. The urine ELISA assay correlated significantly with the serological ELISA assay for strongyloidiasis, with a D-Sn of 92.7% and a D-Sp of 40.7%, when compared to coprological methods. Moreover, the urine ELISA IgG test had a detection rate of 69%, which far exceeds the coprological method (28%). The likelihood of a positive diagnosis of strongyloidiasis by the urine ELISA IgG test increased significantly with increasing units of IgG detected in urine. The urine ELISA IgG assay for strongyloidiasis assay has a diagnostic accuracy comparable to serological assay, both of which are more sensitive than coprological methods. Since the collection of urine is easy and non-invasive, the urine ELISA IgG assay for strongyloidiasis could be used to screen populations at risk for strongyloidiasis in S. stercoralis endemic areas.

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.

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.

Sero-epidemiological survey of human cystic echinococcosis in Kashmir, North India

BACKGROUND

Echinococcosis is a human and animal health problem in many endemic areas worldwide. There are numerous reports and hospital-based studies from Kashmir, North India, yet there has been no epidemiological study conducted in Kashmir, the apparently endemic area for human hydatidosis. This study was designed to determine the seroprevalence of hydatid infection in Kashmir Valley and to find out association of risk factors for acquisition of this infection.

METHODOLOGY

Fourteen hundred and twenty-nine samples were collected from different districts in the Kashmir region (North India) using systematic random sampling. The 130 control samples included were from apparently healthy blood donors (100), patients with other parasitic infections (20), surgically confirmed hydatidosis patients (5), and apparently healthy subjects excluded for hydatidosis and intestinal parasitic infections (5). Hydatid-specific IgG antibody was detected by enzyme-linked immunosorbent assay, and seropositive samples were analysed further by Western blotting.

RESULTS

Out of 1,429 samples, 72 (5.03%) were IgG positive by ELISA. The percentage occurrence of the highly immunoreactive antigenic fractions in IgG ELISA positive samples was 57 kDa (72.2%) followed by 70 kDa (66.7%) and 39 kDa (58.3%) by immunoblotting. Samples with other parasitic infections were reactive with the cluster of 54-59 kDa antigenic fractions. Age <15 years, male gender, contact with dog, and rural residence were the most significant factors associated with the seropositivity.

CONCLUSION

The study revealed that 72 (5.03%) out of 1,429 subjects asymptomatic for hydatidosis were seropositve to E.granulosus antigen by ELISA. Western blot analysis of 72 ELISA seropositive samples showed that 66.7% and 58.3% of samples were immunoreactive with 70 and 39 kDa specific antigenic fractions, respectively. The seropositivity was significantly higher (5.79%) in the younger age group (<15 years) as compared to the 16-55 years (4.07%) and > 55 years (3.05%) age groups, suggesting ongoing transmission of this infection in the younger age group. The number of seropositive males was significantly higher as compared to females. The risk factors identified were rural residence and contact with dogs. The study suggests the presence of asymptomatic infection in subjects in Kashmir, North India, and efforts need to be made for implementation of effective prevention measures to reduce the infection burden, which may otherwise lead to symptomatology and complications in the infected subjects.