Rapid detection of a Schistosoma mansoni circulating antigen excreted in urine of infected individuals by using a monoclonal antibody

The Road to Elimination: Current State of Schistosomiasis Research and Progress Towards the End Game

The new WHO Roadmap for Neglected Tropical Diseases targets the global elimination of schistosomiasis as a public health problem. To date, control strategies have focused on effective diagnostics, mass drug administration, complementary and integrative public health interventions. Non-mammalian intermediate hosts and other vertebrates promote transmission of schistosomiasis and have been utilized as experimental model systems. Experimental animal models that recapitulate schistosomiasis immunology, disease progression, and pathology observed in humans are important in testing and validation of control interventions. We discuss the pivotal value of these models in contributing to elimination of schistosomiasis. Treatment of schistosomiasis relies heavily on mass drug administration of praziquantel whose efficacy is comprised due to re-infections and experimental systems have revealed the inability to kill juvenile schistosomes. In terms of diagnosis, nonhuman primate models have demonstrated the low sensitivity of the gold standard Kato Katz smear technique. Antibody assays are valuable tools for evaluating efficacy of candidate vaccines, and sera from graded infection experiments are useful for evaluating diagnostic sensitivity of different targets. Lastly, the presence of Schistosomes can compromise the efficacy of vaccines to other infectious diseases and its elimination will benefit control programs of the other diseases. As the focus moves towards schistosomiasis elimination, it will be critical to integrate treatment, diagnostics, novel research tools such as sequencing, improved understanding of disease pathogenesis and utilization of experimental models to assist with evaluating performance of new approaches.

Synergistic action of Viteselen with anti-Fasciola drug as a tool for improving fertility and hemato-biochemical biomarkers in Fasciola infected sheep

Fasciolosis causes public health problems and economic losses all over the world. The present study aimed to evaluate the synergistic action between Viteselen (anti-oxidant) and specific anti-Fasciola drug [Triclalbendazole (TCBZ)] for improving the body condition of F. gigantica naturally infected sheep with reference to some hematological and biochemical biomarkers in their sera. Animals were divided into five groups include G-1 as control non-infected animals, G-2 to G-5 are Fasciola naturally infected animals. G-2 are non-treated animals, G-3 treated with TCBZ, animals in G-4 were injected by Viteselen and those in G-5 were treated by both TCBZ and Viteselen. The results revealed a significant decrease in mean eggs in feces and F. gigantica circulating antigens (FCAg) in sera of TCBZ treated sheep after the 1st week post treatment. Complete disappearance of eggs from feces of drug treated groups was recorded at 21st d.p.t. While the value of FCAg decreased to negative at 14th d.p.t. The highest significant improvement (p < 0.05) in the estimated hematological parameters (RBCs, Hb and TLC), liver enzymes (AST and ALT), oxidative stress and anti-oxidant markers (TAC, MDA, SOD and GSH) and reproductive hormones (Progesterone and Estradiol) was recorded in animals in G-5 followed by G-3. While non-significant improvement was recorded in animals in G-4 in comparison with those in the control group. This improvement increased with increasing the time post treatment. In conclusion; using of Viteselen in association with specific anti-parasitic drug improved the general health parameters and reproductive performance of the investigated sheep.

Diagnosis of schistosomiasis mansoni: an evaluation of existing methods and research towards single worm pair detection

The inadequacy of current diagnostics for the detection of low worm burdens in humans means that schistosomiasis mansoni is more widespread than previously acknowledged. With the inception of mass drug treatment programmes aimed at disease elimination and the advent of human vaccine trials, the need for more sensitive diagnostics is evident. In this review, we evaluate the merits and limitations of the principal diagnostic methods, namely detection of eggs in faeces; anti-schistosome antibodies in serum; parasite-derived proteins and glycans in serum or urine; parasite DNA in blood, faeces or urine. Only in the baboon model, where actual worm burden is determined by portal perfusion, have faecal smear and circulating antigen methods been calibrated, and shown to have thresholds of detection of 10-19 worm pairs. There is scope for improvement in all the four methods of detection, e.g. the identification of single targets for host antibodies to improve the specificity of enzyme linked immunosorbent assay. Despite recent advances in the definition of the schistosome secretome, there have been no comprehensive biomarker investigations of parasite products in the urine of infected patients. Certainly, the admirable goal of eliminating schistosomiasis will not be achieved unless individuals with low worm burdens can be diagnosed.

Impact of old Schistosomiasis infection on the use of transient elastography (Fibroscan) for staging of fibrosis in chronic HCV patients

BACKGROUND AND AIM

In tropical regions, Hepatitis C virus (HCV) - Schistosomiasis coinfection remains one of the health problems. With the new era of HCV treatment and the variety of methods of assessment of liver fibrosis so we aimed to evaluate the effectiveness of FibroScan for staging hepatic fibrosis in HCV-Schistosomiasis coinfected patients.

METHODOLOGY

Three groups of patients were enrolled. Group 1: chronic HCV with out antischistosomal antibody (122 patients), Group 2: chronic HCV with positive antischistosomal antibodies and without periportal tract thickening (122 patients), Group 3: chronic HCV with positive antischistosomal antibodies and ultrasonographic picture of periportal tract thickening (108 patients). Routine laboratory workup, serum Antischistosomal antibody, and Schistosomal antigen in serum were performed. Ultrasound guided liver biopsy with histopathological examination; abdominal ultrasound and fibroscan examination were done for all patients.

RESULTS

The agreement between results of liver biopsy and results of fibroscan in the staging of fibrosis was the best in group 1 (55.7%), Although the agreement was higher among those with no periportal tract thickening (70.7%) and the disagreement was higher among those with positive schistosomal serology (66.5%), yet this relation was not statistically significant. Multivariate logistic regression analysis showed that disagreement is significantly associated with older age, higher BMI (≥30), and increase in anti Schistosomal antibody titer.

CONCLUSION

Fibroscan is a reliable, non-invasive tool for staging hepatic fibrosis among HCV-schistosomiasis co-infected patients with no effect of the induced periportal tract thickening on the readings. Only higher antischistosomal antibody titres may cause disagreement between liver biopsy and fibroscan.

Levels of Schistosoma mansoni Circulating Antigen in Chronic Hepatitis C Patients with Different Stages of Liver Fibrosis

The goal of this study was to determine the levels of S. mansoni antigen in different liver fibrosis stages with chronic hepatitis C (CHC) Egyptian patients. A total of 174 CHC patients showing HCV-NS4 antigen and HCV- RNA in their sera were included. S. mansoni antigen was detected in serum using Western blot and ELISA. The levels of interferon-γ (IFN- γ) were determined using ELISA. The 50 kDa S. mansoni antigen discriminated patients infected with S. mansoni from healthy individuals with 0.93 area under curve (AUC), 92% sensitivity, and 97% specificity. The level of S. mansoni antigen (μg/ml) was significantly (P < 0.0001) increased with the progression of liver fibrosis stages (26.9 ± 17.5 in F1, 42.1 ± 25.2 in F2, 49.8 ± 30.3 in F3 and 62.2 ± 26.3 μg/mL in F4 liver cirrhosis), 26.9 ± 17.59 in significant fibrosis (F2-F4); 51.2 ± 27.9 in advanced fibrosis (F3-F4). A significant correlation (r = 0.506; P < 0.0001) was shown between the levels of the S. mansoni antigen and the HCV-NS4 antigen. In conclusion, the presence of S. mansoni antigen in different liver fibrosis stages of CHC patients confirming that concomitant schistosome infection aggravates liver disease.

Factors impacting on progress towards elimination of transmission of schistosomiasis japonica in China

Over the past decades China has made a great stride in controlling schistosomiasis, eliminating transmission of Schistosoma japonicum in 5 provinces and remarkably reducing transmission intensities in the rest of the seven endemic provinces. Recently, an integrated control strategy, which focuses on interventions on humans and bovines, has been implemented throughout endemic areas in China. This strategy assumes that a reduction in transmission of S. japonicum from humans and bovines to the intermediate Oncomelania snail host would eventually block the transmission of this parasite, and has yielded effective results in some endemic areas. Yet the transmission of S. japonicum is relatively complicated--in addition to humans and bovines, more than 40 species of mammalians can serve as potential zoonotic reservoirs. Here, we caution that some factors--potential roles of other mammalian reservoirs and human movement in sustaining the transmission, low sensitivity/specificity of current diagnostic tools for infections, praziquantel treatment failures, changes in environmental and socio-economic factors such as flooding in key endemic areas--may pose great obstacles towards transmission interruption of the parasite. Assessing potential roles of these factors in the transmission and implications for current control strategies aiming at transmission interruption is needed.

Mouse monoclonal antibodies against human urinary protein Sm-UP(2)IP of Schistosoma mansoni

There are innumerable clinical and pathological problems associated with schistosomiasis that have necessitated various control programs. Successful control would naturally depend on effective rapid diagnosis in the field. However, the overlapping distribution of urinary and intestinal schistosomiasis in hyperendemic areas calls for differential diagnosis. This study was aimed at producing anti-Schistosoma mansoni monoclonal antibodies (MAbs) for possible utilization in assays to detect antigens in the urine of infected persons. In order to raise antibodies to less immunogenic urinary parasite antigens, BALB/c mice were immunized with Schistosoma mansoni soluble worm antigens (Sm-SWA) while urinary proteins (Sm-UP(2)IP), isolated from infected human urine samples, was used as a final booster before cell fusion. Hybridoma cells were obtained by the fusion of mouse myeloma and spleen cells from the immunized mice, which were screened by microplate ELISA and then studied further to obtain anti-S. mansoni specific MAbs. The MAbs analyzed presented IgM isotypes. The reactivity of anti-S. mansoni MAbs with Sm-UP(2)IP, 13/43 (30.2%), MAbs showed stronger reactivity. It was observed that one of the MAbs cross-reacted with antigen associated with S. haematobium urinary antigen (Sh-UP(2)IP). Nine (9/13, 69.2%) MAbs recognized glycoprotein antigenic epitopes of Sm-UP(2)IP and Sm-SWA. On the other hand, 4/13 (30.8%) MAbs recognized carbohydrate antigenic epitopes. Band size of 8.9 kDa associated with Sm-UP(2)IP was detected by the 13 MAbs. With Sm-SWA, all the MAbs detected band sizes of 177.8 and 158.5 kDa. In addition, three MAbs recognized a 38.9 kDa band. The generation of anti-S. mansoni species-specific MAbs offers opportunities to develop a specific MAb-based diagnostic tool for use in the field to detect Schistosoma mansoni infection in Ghana.

A diagnostic challenge for Schistosomiasis japonica in China: consequences on praziquantel-based morbidity control

Worldwide schistosomiasis continues to be a serious public health problem. Over the past five decades, China has made remarkable progress in reducing Schistosoma japonicum infections in humans to a relatively low level. Endemic regions are currently circumscribed in certain core areas where re-infection and repeated chemotherapy are frequent. At present, selective chemotherapy with praziquantel is one of the main strategies in China's National Schistosomiasis Control Program, and thus diagnosis of infected individuals is a key step for such control. In this paper we review the current status of our knowledge about diagnostic tools for schistosomiasis japonica. A simple, affordable, sensitive, and specific assay for field diagnosis of schistosomiasis japonica is not yet available, and this poses great barriers towards full control of schistosomiasis. Hence, a search for a diagnostic approach, which delivers these characteristics, is essential and should be given high priority.

Sensitivities and specificities of diagnostic tests and infection prevalence of Schistosoma haematobium estimated from data on adults in villages northwest of Accra, Ghana

Substantial uncertainties surround the sensitivities and specificities of diagnostic techniques for urinary schistosomiasis. We used latent class (LC) modeling to address this problem. In this study, 220 adults in three villages northwest of Accra, Ghana were examined using five Schistosoma haematobium diagnostic measures: microscopic examination of urine for detection of S. haematobium eggs, dipsticks for detection of hematuria, tests for circulating antigens, antibody tests, and ultrasound scans of the urinary system. Testing of the LC model indicated non-invariance of the performance of the diagnostic tests across different age groups, and measurement invariance held for males and females and for the three villages. We therefore recommend the use of LC models for comparison between and the identification of the most accurate schistosomiasis diagnostic tests. Furthermore, microscopy and hematuria dipsticks were indicated through these models as the most appropriate techniques for detection of S. haematobium infection.

Sensitivities and specificities of diagnostic tests and infection prevalence of Schistosoma haematobium estimated from data on adults in villages northwest of Accra, Ghana

Substantial uncertainties surround the sensitivities and specificities of diagnostic techniques for urinary schistosomiasis. We used latent class (LC) modeling to address this problem. In this study, 220 adults in three villages northwest of Accra, Ghana were examined using five Schistosoma haematobium diagnostic measures: microscopic examination of urine for detection of S. haematobium eggs, dipsticks for detection of hematuria, tests for circulating antigens, antibody tests, and ultrasound scans of the urinary system. Testing of the LC model indicated non-invariance of the performance of the diagnostic tests across different age groups, and measurement invariance held for males and females and for the three villages. We therefore recommend the use of LC models for comparison between and the identification of the most accurate schistosomiasis diagnostic tests. Furthermore, microscopy and hematuria dipsticks were indicated through these models as the most appropriate techniques for detection of S. haematobium infection.

Early detection of Schistosoma mansoni infection by touchdown PCR in a mouse model

A detection assay for Schistosoma mansoni DNA in mouse serum samples based on touchdown PCR was developed and evaluated. The serum samples could be assayed directly without the need to extract DNA. No cross reactions between S. mansoni and related species inducing human schistosomiasis were observed. After the infection, mouse sera and feces were collected for 8 weeks. Anti-worm antigen IgG and anti-soluble egg antigen IgG were detected in the sera at 6 weeks post-infection by ELISA. The parasite's eggs were detected in the feces at 8 weeks. In contrast, S. mansoni DNA was detected in the sera at 2 weeks post-infection. These data suggest that touchdown PCR is a potential tool for the early diagnosis of S. mansoni infection.

Schistosomiasis--an unusual cause of ureteral obstruction: a case history and perspective

A male, 32 years of age, presented with dysuria and abdominal pain, but no gross hematuria. He emigrated three years earlier from Somalia, East Africa, and was currently employed as a poultry processor in a rural Wisconsin community. The patient denied any trauma, sexual activity, or family history of significant illness. Abdominal and genitourinary exams were normal with negative tests for gonococcus and chlamydia. Urinalysis demonstrated microhematuria. A urogram and retrograde pyelogram revealed a mildly dilated right ureter down to the ureterovesical junction. Cystoscopy showed punctate white lesions on the bladder urothelium. Ureteroscopy was used to biopsy abnormal tissue in the distal ureter and bladder. Biopsy tissue demonstrated deposits of Schistosoma haematobium eggs. No ova were seen in collected urine specimens. The patient was successfully treated with praziquantel and will be monitored for sequelae of the disease. Schistosomiasis (Bilharziasis) can be expected to be seen with increasing frequency in the United States with the continuing influx of immigrants and refugees, as well as the return of travelers and soldiers from endemic areas. While no intermediate snail host exists for the transmission of Schistosoma sp. in the United States, the continued importation of exotic animals including snails from Africa, as well as the ability of schistosomes to shift host species warrants concern. Additionally, increasing disease associated with non-human bird schistosomes of the same genus seen in the midwestern United States is occurring throughout Europe. One should be aware that praziquantel may not always be available or effective in the treatment of schistosomiasis. It behooves the practicing clinician to remain updated on the status of this widespread zoonosis.

Human infection with Wuchereria bancrofti in Matara, Sri Lanka: the use, in parallel, of an ELISA to detect filaria-specific IgG4 in urine and of ICT card tests to detect filarial antigen in whole blood

The ICT card test to detect circulating filarial antigen and an ELISA that detects filaria-specific urinary IgG(4) were each used to screen 473 subjects from a community in Sri Lanka where Wuchereria bancrofti is endemic. When the ICT test was used as the gold standard, the ELISA was found to have a sensitivity of 91.2%. However, far more of the subjects were found ELISA-positive than ICT-positive (76.5% v. 31.1%). The youngest children studied (aged 1-10 years) were similar to the adult subjects in terms of the prevalence of antigenaemia (33.8%) and the prevalence (72.1%) and concentration of filaria-specific IgG(4) in their urine. Therefore, especially as urine samples are easier, less painful and safer to collect than blood samples, the ELISA may be particularly useful to screen very young and school-age children, to estimate current levels of transmission in a particular area.

Identification and characterization of a 26- to 28-kDa circulating antigen of Fasciola gigantica

As a disease of domestic ruminants, fascioliasis is of considerable economic importance. Although serological tests are available for the diagnosis of the disease, they are of generally low specificity because of cross-reactivity with antigens from other parasites. There is a need to identify other Fasciola antigens on which more specific tests could be based. In the present study, a specific rabbit anti-serum and western-blot analyses were used to demonstrate the presence of a highly reactive antigen of 26-28 kDa not only in an extract of adult F. gigantica but also in the excretory/secretory products of the worms and in the bile secretions and sera of cattle that were naturally infected with this parasite. The 26- to 28-kDa antigen was isolated from preparative polyacrylamide gels, by electro-elution. The purified antigen showed a single peak at 5.8 min when analysed by capillary zone electrophoresis. It was characterized as protein containing 47.5% hydrophilic and 29.3% hydrophobic amino acids. Immunostaining demonstrated that the target epitope was located in the gut and tegument of adult F. gigantica and within the bile ducts, the portal tracts of the livers and the mucosa and muscularis of the gallbladders of infected cattle. A simple and rapid dot-ELISA technique based on the specific rabbit anti-serum was 100% specific when tested on the sera from nine cattle infected with F. gigantea and 27 uninfected cattle. In conclusion, the 26- to 28-kDa Fasciola antigen may be a promising candidate for the immunodiagnosis of fascioliasis.