Background The World Health Organization recommends the use of Schisto point-of-care circulating cathodic anti-gens(Schisto POC-CCA)for screening of Schistosoma mansoni as it offers better sensitivity than microscopy....Background The World Health Organization recommends the use of Schisto point-of-care circulating cathodic anti-gens(Schisto POC-CCA)for screening of Schistosoma mansoni as it offers better sensitivity than microscopy.However,there are limitation facing the use of this method including timely availability of the test cassettes.The aim of this study was to determine the reliability of dried urine spot(DUS)method for collection of urine and detection of S.mansoni using Schisto POC-CCA cassettes in a resource-limited settings.Methods A cross-sectional study was conducted between October and November 2022 among 250 primary school children in Sengerema District,northwestern Tanzania.S.mansoni CCA was detected in filter paper-based DUSs,liquid urine using DUS Schisto POC-CCA(index),and direct urine Schisto POC-CCA(comparator)methods respectively.S.mansoni eggs in stool were detected using duplicate Kato-Katz(KK)method.The measures of accuracy were com-puted and compared between the index and comparator methods.The strength of agreement between inter-raters precisions was tested using Cohen's kappa(k).Results This study revealed S.mansoni prevalence rates of 28.8%,54.0%and 50.8%by duplicate KK,direct urine Schisto POC-CCA and DUS Schisto POC-CCA methods respectively.The mean intensity of infection among infected participants Was 86.3 eggs per gram of stool(EPG)ranging from 12.0 EPG to 824.0 EPG.The sensitivity of DUS Schisto POC-CCA and direct urine Schisto POC-CCA Was 94.44%(95%CI:89.15-99.74%)and 97.22%(95%CI:93.43-100.00%)respectively.The DUS Schisto POC-CCA method had slightly higher specificity(66.85%)than direct urine Schisto POC-CCA method(63.48%).The accuracy of the DUS Schisto POC-CCA Was found to be slightly high(74.80%,95%CI:68.94-79.06%)compared to that of direct urine Schisto POC-CCA(73.20%,95%CI:67.25-78.59%).There was good agreement between two laboratory technologists who performed the DUS Schisto POC-CCA method on similar samples(k=0.80,95%CI:0.59-0.95).Conclusions The DUS Schisto POC-CCA method had comparable S.mansoni detection accuracy to direct urine Schisto POC-CCA.This suggests that the method could be a potential alternative to direct urine Schisto POC-CCA for screening S.mansoni in resource-limited situations.展开更多
Objectives To investigate the nature of the common epitopes of Schistosoma japonicum (S. japonicum) circulating anodic (CAA) and circulating cathodic antigen (CCA) and to try to obtain sufficient purified material to...Objectives To investigate the nature of the common epitopes of Schistosoma japonicum (S. japonicum) circulating anodic (CAA) and circulating cathodic antigen (CCA) and to try to obtain sufficient purified material to set up a standard series for quantitative determinations.Methods Isolation of the two worm fractions from a trichloroacetic acid (TCA) soluble preparation of S. japonicum adult worm antigen (AWAj-TCA) via Mono-Q anion exchange chromatography was performed and analysis of specific reactivity of the eluted fractions was done by antigen-capture Enzyme Linked Immuno Sorbent Assay (ELISA) specific for CAA or CCA with reference to affinity purified preparations of S. mansoni CAA and CCA. Results When an ionic strength gradient was used, CCA was eluted in two major peaks, an unbound fraction CCA-1, and a major bound fraction, CCA-2. Two additional minor peaks, CCA-3 and CCA-4, were eluted at higher ionic strengths. CAA was only detected in the bound fraction, partly overlapping with CCA-3. In the CCA-1 and CCA-2 fractions, reactivity was only found in the antigen-capture ELISA using anti-CCA McAbs both for capture and detection. The CAA fraction was predominantly found to be positive in the antigen-capture ELISA using anti-CAA McAbs both for capture and detection. However, in ELISA using combined anti-CCA and anti-CAA McAbs for capture and detection, this fraction showed some reactivity.Conclusion The two CCA fractions contain molecules which bear at least two CCA-epitopes; the CAA fraction contains molecules which contain at least two CAA-epitopes, and one CCA-epitope.展开更多
Objective To establish a highly sensitive serologic method for detecting the circulating antigen of Schistosoma japonicum for the diagnosis of this disease and the evaluation of drug therapy effect.Methods A set of ...Objective To establish a highly sensitive serologic method for detecting the circulating antigen of Schistosoma japonicum for the diagnosis of this disease and the evaluation of drug therapy effect.Methods A set of complex support made of poly vinyl chloride (PVC) film slide, adsorbed with specific antibody, was used to test serum samples collected from cases with schistosomiasis japonica, by adding specific enzyme conjugate and substrate tetra methyl benzidine (TMB) with 3% H 2O 2 in 10∶0.1, developed or prepared in our laboratory. Tests were carried out with the set on cases with malaria, paragonimiasis, clonorchiasis, visceral leishmaniasis and cysticercosis as well as normal individuals as control. Serum sample of 50 μl was used in each test and reacted with reagents at room temperature for 30 minutes. The color of positive reaction was blue while negative reaction was colorless.Results Positive rate among cases with schistosomiasis japonica was 100% (45/45) in acute stage, 94.8% (530/559) in early chronic stage and 52.4% (66/126) in late stage. False positive reaction was found neither among all normal individuals (0/513), nor among cases of 155 with malaria, 120 with clonorchiasis, 24 with visceral leishmaniasis and 110 with cysticercosis, except one among 29 cases with parasgonimiasis (1/29).Conclusions The rapid one step enzyme Immunoassay (EIA) to detect circulating schistosome antigen (CSA) has been well established in our laboratory with high sensitivity and good specificity as well as reproducibility. The reaction result can be read easily even in field conditions without power supply. Moreover, the assay is time saving, simple to handle and suitable for the diagnosis of shistosomiasis japonica and evaluation of drug therapeutic effect in practice in the control program of the disease.展开更多
文摘Background The World Health Organization recommends the use of Schisto point-of-care circulating cathodic anti-gens(Schisto POC-CCA)for screening of Schistosoma mansoni as it offers better sensitivity than microscopy.However,there are limitation facing the use of this method including timely availability of the test cassettes.The aim of this study was to determine the reliability of dried urine spot(DUS)method for collection of urine and detection of S.mansoni using Schisto POC-CCA cassettes in a resource-limited settings.Methods A cross-sectional study was conducted between October and November 2022 among 250 primary school children in Sengerema District,northwestern Tanzania.S.mansoni CCA was detected in filter paper-based DUSs,liquid urine using DUS Schisto POC-CCA(index),and direct urine Schisto POC-CCA(comparator)methods respectively.S.mansoni eggs in stool were detected using duplicate Kato-Katz(KK)method.The measures of accuracy were com-puted and compared between the index and comparator methods.The strength of agreement between inter-raters precisions was tested using Cohen's kappa(k).Results This study revealed S.mansoni prevalence rates of 28.8%,54.0%and 50.8%by duplicate KK,direct urine Schisto POC-CCA and DUS Schisto POC-CCA methods respectively.The mean intensity of infection among infected participants Was 86.3 eggs per gram of stool(EPG)ranging from 12.0 EPG to 824.0 EPG.The sensitivity of DUS Schisto POC-CCA and direct urine Schisto POC-CCA Was 94.44%(95%CI:89.15-99.74%)and 97.22%(95%CI:93.43-100.00%)respectively.The DUS Schisto POC-CCA method had slightly higher specificity(66.85%)than direct urine Schisto POC-CCA method(63.48%).The accuracy of the DUS Schisto POC-CCA Was found to be slightly high(74.80%,95%CI:68.94-79.06%)compared to that of direct urine Schisto POC-CCA(73.20%,95%CI:67.25-78.59%).There was good agreement between two laboratory technologists who performed the DUS Schisto POC-CCA method on similar samples(k=0.80,95%CI:0.59-0.95).Conclusions The DUS Schisto POC-CCA method had comparable S.mansoni detection accuracy to direct urine Schisto POC-CCA.This suggests that the method could be a potential alternative to direct urine Schisto POC-CCA for screening S.mansoni in resource-limited situations.
基金theINCO DC (persistentfrom STD 3)ProjectoftheEuropeanCommunityandtheChinesePremier FoundationforVaccineDevelopmentAgainstSchis
文摘Objectives To investigate the nature of the common epitopes of Schistosoma japonicum (S. japonicum) circulating anodic (CAA) and circulating cathodic antigen (CCA) and to try to obtain sufficient purified material to set up a standard series for quantitative determinations.Methods Isolation of the two worm fractions from a trichloroacetic acid (TCA) soluble preparation of S. japonicum adult worm antigen (AWAj-TCA) via Mono-Q anion exchange chromatography was performed and analysis of specific reactivity of the eluted fractions was done by antigen-capture Enzyme Linked Immuno Sorbent Assay (ELISA) specific for CAA or CCA with reference to affinity purified preparations of S. mansoni CAA and CCA. Results When an ionic strength gradient was used, CCA was eluted in two major peaks, an unbound fraction CCA-1, and a major bound fraction, CCA-2. Two additional minor peaks, CCA-3 and CCA-4, were eluted at higher ionic strengths. CAA was only detected in the bound fraction, partly overlapping with CCA-3. In the CCA-1 and CCA-2 fractions, reactivity was only found in the antigen-capture ELISA using anti-CCA McAbs both for capture and detection. The CAA fraction was predominantly found to be positive in the antigen-capture ELISA using anti-CAA McAbs both for capture and detection. However, in ELISA using combined anti-CCA and anti-CAA McAbs for capture and detection, this fraction showed some reactivity.Conclusion The two CCA fractions contain molecules which bear at least two CCA-epitopes; the CAA fraction contains molecules which contain at least two CAA-epitopes, and one CCA-epitope.
文摘Objective To establish a highly sensitive serologic method for detecting the circulating antigen of Schistosoma japonicum for the diagnosis of this disease and the evaluation of drug therapy effect.Methods A set of complex support made of poly vinyl chloride (PVC) film slide, adsorbed with specific antibody, was used to test serum samples collected from cases with schistosomiasis japonica, by adding specific enzyme conjugate and substrate tetra methyl benzidine (TMB) with 3% H 2O 2 in 10∶0.1, developed or prepared in our laboratory. Tests were carried out with the set on cases with malaria, paragonimiasis, clonorchiasis, visceral leishmaniasis and cysticercosis as well as normal individuals as control. Serum sample of 50 μl was used in each test and reacted with reagents at room temperature for 30 minutes. The color of positive reaction was blue while negative reaction was colorless.Results Positive rate among cases with schistosomiasis japonica was 100% (45/45) in acute stage, 94.8% (530/559) in early chronic stage and 52.4% (66/126) in late stage. False positive reaction was found neither among all normal individuals (0/513), nor among cases of 155 with malaria, 120 with clonorchiasis, 24 with visceral leishmaniasis and 110 with cysticercosis, except one among 29 cases with parasgonimiasis (1/29).Conclusions The rapid one step enzyme Immunoassay (EIA) to detect circulating schistosome antigen (CSA) has been well established in our laboratory with high sensitivity and good specificity as well as reproducibility. The reaction result can be read easily even in field conditions without power supply. Moreover, the assay is time saving, simple to handle and suitable for the diagnosis of shistosomiasis japonica and evaluation of drug therapeutic effect in practice in the control program of the disease.
