Early detection of circulating anodic antigen (CAA) in a case of acute schistosomiasis mansoni with Katayama fever

UCP-LF and other assay methods for schistosome circulating anodic antigen between 1978 and 2022

Detection of circulating anodic antigen (CAA) is known for its high sensitivity in diagnosing schistosomiasis infection, even in low-prevalence settings. The Up-Converting Phosphor-Lateral Flow (UCP-LF) assay developed in 2008 presented greater sensitivity than other assay methods in use for CAA detection. Our study aims to comprehensively review all studies conducted in this area and thus generate informed conclusions on the potential for adopting the UCP-LF assay for diagnosing this important yet neglected tropical disease. Using the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, we generated search criteria to capture all studies in English journals available in the Scopus and PubMed databases on 20 December 2022. A total of 219 articles were identified, and 84 that met the inclusion criteria were retrieved and eventually included in the study. Twelve different assay methods were identified with a noteworthy transition from enzyme-linked immunosorbent assay (ELISA) to the UCP-LF assay, a laboratory-based assay that may be applicable as a point-of-care (POC) diagnostic test for schistosomiasis. Reducing the time, cost, and dependence on specialized laboratory skills and equipment, especially relating to the trichloroacetic acid extraction step and centrifugation in the UCP-LF CAA assay may go a long way to aid its potential as a POC tool. We also propose the development of a CAA-specific aptamer (short protein/antigen-binding oligonucleotide) as a possible alternative to monoclonal antibodies in the assay. UCP-LF has great potential for POC application.

Colonic schistosomiasis: A case report

BACKGROUND

Schistosomiasis is a chronic parasitic infection endemic in many countries. Colonic schistosomiasis is a rare entity with no specific clinical manifestations or endoscopic aspects, which delays the diagnosis. Diagnosis is primarily dependent on histopathological analysis, and treatment with antihelminthics typically resolves the infection.

CASE SUMMARY

We present the case of a 21-year-old male who suffered from chronic diarrhea and abdominal pain. Physical examination found no abnormalities, blood tests were normal, and stool examination was negative. A colonoscopy revealed a nodular terminal ileal mucosa, two cecal polypoid lesions with no particular surface pattern, and millimetric erosions in the rectum. The presence of Schistosoma eggs with thick peripheral capsules and viable embryos inside and numerous eosinophils surrounding the egg capsule were observed on histopathological examination. The patient received praziquantel, and his symptoms were resolved.

CONCLUSION

Colonic schistosomiasis should be considered as a differential diagnosis, especially in endemic countries. Endoscopy and histopathological examination can confirm the diagnosis, and antihelminthics are an effective treatment.

The Advances in Molecular and New Point-of-Care (POC) Diagnosis of Schistosomiasis Pre- and Post-praziquantel Use: In the Pursuit of More Reliable Approaches for Low Endemic and Non-endemic Areas

Like soil-transmitted helminth infections, schistosomiasis is an important neglected tropical disease (NTD) related to poverty with a major impact on public health in developing countries. Diagnosis of active infection is crucial for surveillance of controlled or post-elimination schistosomiasis areas. In addition, the use of conventional diagnostic tools in non-exposed populations (such as travelers) results in misdiagnoses in the prepatent period of infection. Also, the accuracy of standard tests applied in low-endemicity areas (LEAs) decreases after several rounds of treatment. We aimed to determine whether it would be necessary to replace schistosomiasis conventional diagnostic tests such as parasitological methods in LEAs. Also, we evaluate the use of new tools in non-endemic areas. Reliable, cheap and easy-to-use diagnostic tools are needed to respond to the demands of a new era of elimination and eradication of schistosomiasis. To this end, molecular diagnosis-including nucleic acid-based assays (loop-mediated isothermal amplification, polymerase chain reaction) and circulating cathodic and anodic antigen detection tests have become promising strategies. In this review, we attempt to address the use of alternative diagnostic tests for active infection detection and drug-monitoring after specific schistosomiasis treatment.

Schistosomiasis manifesting as a colon polyp: a case report

INTRODUCTION

Schistosomiasis is a rare disease with a common intestinal involvement. However, colon polyps associated with Schistosoma in the absence of inflammation have rarely been reported, especially in young people; this is the first case with the following presentation.

CASE PRESENTATION

We describe the case of a 20-year-old Ethiopian woman living in Lebanon who presented with nonspecific abdominal symptoms. Her biochemical profile was normal in addition to the results of her stool and urine tests. A colonoscopy showed normal colonic mucosa but surprisingly a large pedunculated polyp was found in her ascending colon. Pathology revealed a hamartomatous polyp but it was full of partially calcified parasitic eggs of Schistosoma mansoni compatible with chronic schistosomiasis.

CONCLUSIONS

She was treated with two doses of praziquantel and showed immediate marked clinical improvement. This unusual case will give us the opportunity to discuss schistosomiasis, its occurrence in colon polyps, clinical significance and the various means of management.

Prospective European-wide multicentre study on a blood based real-time PCR for the diagnosis of acute schistosomiasis

Background

Acute schistosomiasis constitutes a rare but serious condition in individuals experiencing their first prepatent Schistosoma infection. To circumvent costly and time-consuming diagnostics, an early and rapid diagnosis is required. So far, classic diagnostic tools such as parasite microscopy or serology lack considerable sensitivity at this early stage of Schistosoma infection. To validate the use of a blood based real-time polymerase chain reaction (PCR) test for the detection of Schistosoma DNA in patients with acute schistosomiasis who acquired their infection in various endemic regions we conducted a European-wide prospective study in 11 centres specialized in travel medicine and tropical medicine.

Methods

Patients with a history of recent travelling to schistosomiasis endemic regions and freshwater contacts, an episode of fever (body temperature ≥38.5°C) and an absolute or relative eosinophil count of ≥700/μl or 10%, were eligible for participation. PCR testing with DNA extracted from serum was compared with results from serology and microscopy.

Results

Of the 38 patients with acute schistosomiasis included into the study, PCR detected Schistosoma DNA in 35 patients at initial presentation (sensitivity 92%). In contrast, sensitivity of serology (enzyme immunoassay and/or immunofluorescence assay) or parasite microscopy was only 70% and 24%, respectively.

Conclusion

For the early diagnosis of acute schistosomiasis, real-time PCR for the detection of schistosoma DNA in serum is more sensitive than classic diagnostic tools such as serology or microscopy, irrespective of the region of infection. Generalization of the results to all Schistosoma species may be difficult as in the study presented here only eggs of S. mansoni were detected by microscopy. A minimum amount of two millilitre of serum is required for sufficient diagnostic accuracy.

Infectious diseases and the liver

The liver plays an important role in host defense against invasive microorganisms. The effect of microbial pathogens on the liver can vary greatly, presenting with a wide variety of manifestations from asymptomatic increases in aminotransaminases, acute liver failure, hepatic fibrosis, and cirrhosis. In evaluating the liver manifestations of a potential infectious pathogen, diagnosis of some of the less common infectious pathogens is dependent on a high level of suspicion and recognition of some of the key diagnostic clues. Successful diagnosis can only be accomplished through a careful history, including travel and exposures, physical examination, and appropriate microbiologic studies. This article reviews the involvement of the liver during systemic infections with organisms that are not considered to be primarily hepatotropic.

Immunodiagnosis of schistosomiasis by determination of the circulating antigens CAA and CCA, in particular in individuals with recent or light infections

In the present paper, we evaluate determination of circulating anodic (CAA) and cathodic (CCA) antigen for the diagnosis of an active Schistosoma infection in humans, in comparison to the diagnostic performance of parasitological examination and the demonstration of specific antibodies. Illustrated by three different studies, which all deal with the diagnosis of either recent or low intensity infections, we further discuss our experiences with these diagnostic methods. For the diagnosis of recent infections, specific antibody determination showed to be very sensitive, particularly in individuals originating from non-endemic areas. For the assessment of cure and for the diagnosis of active infections in endemic areas, the methods of choice are parasitological examination and CAA or CCA determination. Depending on infection levels of the target population and on logistic conditions, CAA and CCA determination may either replace parasitological examination or, in the case of light infections, may be used as a complementary diagnostic tool.

Enhanced detection of Schistosoma circulating antigens by testing 1 ml urine samples using immunomagnetic beads

The potential advantage of increasing the sample volume for enhanced detection of two Schistosoma circulating antigens in urine has been evaluated. Two different, monoclonal antibody based, immunomagnetic beads assays detecting circulating anodic antigen (CAA) and circulating soluble egg antigen (CSEA), respectively, were investigated. By increasing the sample volume to 1.0 ml, the lower detection limit of antigen dilution series was improved six eight-fold in both immunomagnetic beads assays. Indeed, an improvement could be shown when testing the urine of Schistosoma-infected individuals with these magnetic beads assays. To compare the sensitivity of the immunomagnetic beads method with the standard ELISA, urine was experimentally adjusted to mirror low natural infection intensities. CSEA-positive urine samples were adjusted to levels below the detection limit of the corresponding ELISA and indeed were still found positive by the CSEA immunomagnetic beads assay. These results demonstrate that by using immunomagnetic beads, an assay method which can utilise larger sample volumes than an ELISA, enhanced detection can be achieved. This might be particularly valuable in areas with low prevalence of schistosomiasis or for the assessment of cure after chemotherapy.