Immunodiagnostic Methods: What Is Their Role in Areas of Low Endemicity?

Grenfell, Rafaella Fortini Queiroz; Silva-Moraes, Vanessa; Taboada, Diana; Mattos, Ana Carolina Alves de; Castro, Ana Karine Sarvel de; Coelho, Paulo Marcos Zech

doi:10.1100/2012/593947

Cited by 24 publications

(10 citation statements)

References 39 publications

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“…However, there is increasing evidence demonstrating that light infections are epidemiologically important since they contribute significantly to maintain the transmission cycle [ 34 ].…”

Section: Discussionmentioning

confidence: 99%

Schistosoma mansoni reinfection: Analysis of risk factors by classification and regression tree (CART) modeling

et al. 2017

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Praziquantel (PZQ) is an effective chemotherapy for schistosomiasis mansoni and a mainstay for its control and potential elimination. However, it does not prevent against reinfection, which can occur rapidly in areas with active transmission. A guide to ranking the risk factors for Schistosoma mansoni reinfection would greatly contribute to prioritizing resources and focusing prevention and control measures to prevent rapid reinfection. The objective of the current study was to explore the relationship among the socioeconomic, demographic, and epidemiological factors that can influence reinfection by S. mansoni one year after successful treatment with PZQ in school-aged children in Northeastern Minas Gerais state Brazil. Parasitological, socioeconomic, demographic, and water contact information were surveyed in 506 S. mansoni-infected individuals, aged 6 to 15 years, resident in these endemic areas. Eligible individuals were treated with PZQ until they were determined to be negative by the absence of S. mansoni eggs in the feces on two consecutive days of Kato-Katz fecal thick smear. These individuals were surveyed again 12 months from the date of successful treatment with PZQ. A classification and regression tree modeling (CART) was then used to explore the relationship between socioeconomic, demographic, and epidemiological variables and their reinfection status. The most important risk factor identified for S. mansoni reinfection was their “heavy” infection at baseline. Additional analyses, excluding heavy infection status, showed that lower socioeconomic status and a lower level of education of the household head were also most important risk factors for S. mansoni reinfection. Our results provide an important contribution toward the control and possible elimination of schistosomiasis by identifying three major risk factors that can be used for targeted treatment and monitoring of reinfection. We suggest that control measures that target heavily infected children in the most economically disadvantaged households would be most beneficial to maintain the success of mass chemotherapy campaigns.

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“…However, there is increasing evidence demonstrating that light infections are epidemiologically important since they contribute significantly to maintain the transmission cycle [ 34 ].…”

Section: Discussionmentioning

confidence: 99%

Schistosoma mansoni reinfection: Analysis of risk factors by classification and regression tree (CART) modeling

et al. 2017

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“…g ., a range of 81.4 to 91% for sensitivity, 84.0 to 95.5% for NPV, 47 to 81.0% for specificity and 36 to 84.0% for PPV [ 58 – 59 , 61 , 70 ] ( S1 Table ). Similar data for sensitivity and specificity were also recorded when comparing data from multiple-CCA-ICT and stool samples or a combination of several diagnostic methods were used in order to determine the “real” status of infection [ 39 , 62 – 63 , 65 , 74 , 80 ] ( S1 Table ).The efficacy of the CCA-ICT was also compared with the performance of the SEA-ELISA and SWAP-ELISA which measure antibody and are considered the most sensitive techniques to diagnose exposure to schistosomiasis [ 43 , 78 – 79 ]. However, the major drawback of antibody-based assays is their inability to differentiate between past and current infections which make these tests inadequate to assess disease prevalence in populations that have received treatment [ 38 ].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the CCA Immuno-Chromatographic Test to Diagnose Schistosoma mansoni in Minas Gerais State, Brazil

et al. 2016

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BackgroundThe Kato-Katz (KK) stool smear is the standard test for the diagnosis of Schistosoma mansoni infection, but suffers from low sensitivity when infections intensities are moderate to low. Thus, misdiagnosed individuals remain untreated and contribute to the disease transmission, thereby forestalling public health efforts to move from a modality of disease control to one of elimination. As an alternative, the urine-based diagnosis of schistosomiasis mansoni via the circulating cathodic antigen immuno-chromatographic test (CCA-ICT) has been extensively evaluated in Africa with the conclusion that it may replace the KK test in areas where prevalences are moderate or high.Methods and FindingsThe objective was to measure the performance of the CCA-ICT in a sample study population composed of residents from non-endemic and endemic areas for schistosomiasis mansoni in two municipalities of Minas Gerais state, Brazil. Volunteers (130) were classified into three infection status groups based on duplicate Kato-Katz thick smears from one stool sample (2KK test): 41 negative individuals from non-endemic areas, 41 negative individuals from endemic areas and 48 infected individuals from endemic areas. Infection status was also determined by the CCA-ICT and infection exposure by antibody ELISA (enzyme-linked immunosorbent assay) to S. mansoni soluble egg antigen (SEA) and soluble (adult) worm antigen preparation (SWAP). Sensitivity and specificity were influenced by whether the trace score visually adjudicated in the CCA-ICT was characterized as positive or negative for S. mansoni infection. An analysis of a two-graph receiver operating characteristic was performed to change the cutoff point. When the trace score was interpreted as a positive rather than as a negative result, the specificity decreased from 97.6% to 78.0% whereas sensitivity increased from 68.7% to 85.4%. A significantly positive correlation between the CCA-ICT scores and egg counts was identified (r = 0.6252, p = 0.0001). However, the CCA-ICT misdiagnosed as negative 14.6% of 2KK positive individuals, predominantly those with light infections (fewer than 100 eggs/g feces). Considering 2KK as reference test, the discriminating power of the CCA-ICT (the area under the curve [AUC] = 0.817) was greater than the SEA-ELISA (AUC = 0.744) and SWAP-ELISA (AUC = 0.704).ConclusionOur data for the performance of the CCA-ICT in the Brazilian communities endemic for schistosomiasis mansoni support those from Africa, i.e., in areas with greater infection prevalence and intensities, the CCA-ICT may be useful as a tool to indicate community-based preventative chemotherapy without individual diagnosis. However, because of the Brazilian Ministry of Health’s recommendation for individual diagnosis in areas where prevalence is less than 15%, i.e., those areas in which infection intensities are likely to be lowest, the CCA-ICT lacks the sensitivity to be used as standalone diagnostic tool.

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“…Assessing diagnostic performance of adult S.guineensis extract as well as other whole or purified extracts from Schistosoma species found in Cameroon will enable production of local and cheaper highly specific immunodiagnostic reagent which are urgently needed as Cameroon as well as other African schistosomiasis endemic countries are looking forward to move from schistosomiasis control to elimination. In this respect, the importance of immunodiagnosis has been reaffirmed since decades but the most limitation relies on the low specificity of commercially available antibody or antigen detection tests which need improvement (Mott and Dixon,1982;Mott et al, 1987;Grenfell et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

IgM and IgG Antibody Enzyme Linked Immunosorbent Assay Profile Detected Using Adult Schistosoma guineensis Extract In Sera from Cameroonian Infected by Schistosoma mansoni, Schistosoma haematobium and Schistosoma guineensis

Kueté¹,

Landó²,

Asonganyi³

et al. 2019

ijSciences

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Schistosomiasis is endemic in Cameroon with three Schistosoma species infecting human in many areas. Data from many countries endemic for S.mansoni, S.haematobium and S.japonicum reported an age-dependent antibody response profile using homologous adult schistosome antigen extract. Less is known about the antibody profile in schistosomiasis endemic areas in Cameroon. This study aimed to assess the IgM and IgG antibody profiles using adult S.guineensis extract in immune sera from Schistosoma egg positive Cameroonians from intestinal or urinary schistosomiasis endemic areas. Whole adult S.guineensis antigen was extracted from a Cameroonian S.guineensis strain maintained in laboratory. The antigen extract was a supernatant obtained after centrifugation of grinded freeze-thawed 45 days old worms in enzyme inhibitor solution. Sera were obtained from residents of schistosomiasis endemic areas with microscopically confirmed monospecific infection by S.guineensis, S.mansoni or S.haematobium and Schistosoma free control sera from non endemic area. IgM and IgG antibody titers detection was proceeded by indirect ELISA using HRP-conjugated secondary IgM or IgG antibody. Optical densities (OD) were recorded with a spectrophotometer plate reader at 495 nm and mean OD were statistically analyzed according to age using Student t-test and egg load using ANOVA test. A total of 189 sera were tested. Sera from S.haematobium, S.mansoni and S.guineensis infections represented 68, 73 and 46 respectively. Of S.mansoni infection sera, 31 were collected at Lagdo and 42 in S.mansoni monospecific focus. Age had no significant influence on mean IgM and IgG antibodies OD although mean IgM and IgG changed with age. Mean IgG antibody increased with age in the three schistosomiasis sera. According to age, mean IgM decreased in S.guineensis infections sera, decreased from young to participants aged 15 to 24 years then increased in older in schistosomiasis mansoni sera. In schistosomiasis haematobium sera, mean IgM increased from young to participants aged 15 to 24 years then decreased in older. Egg load influenced significantly mean IgM and IgG titers. Mean IgM OD decreased with egg load in each of the schistosomiasis whereas mean IgG decreased in intestinal schistosomiasis sera. Mean IgM and IgG antibody titers detected with adult S.guineensis extract using ELISA technique in either intestinal or urinary schistosomiasis endemic areas in Cameroon were not age dependent but egg load depended on egg load in urine and stool samples. Diagnostic performance of the adult S.guineensis extract in antibody detection has been tested.

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Immunodiagnostic Methods: What Is Their Role in Areas of Low Endemicity?

Cited by 24 publications

References 39 publications

Schistosoma mansoni reinfection: Analysis of risk factors by classification and regression tree (CART) modeling

Schistosoma mansoni reinfection: Analysis of risk factors by classification and regression tree (CART) modeling

Evaluation of the CCA Immuno-Chromatographic Test to Diagnose Schistosoma mansoni in Minas Gerais State, Brazil

IgM and IgG Antibody Enzyme Linked Immunosorbent Assay Profile Detected Using Adult Schistosoma guineensis Extract In Sera from Cameroonian Infected by Schistosoma mansoni, Schistosoma haematobium and Schistosoma guineensis

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