Diagnosis of Schistosoma mansoni infections: what are the choices in Brazilian low-endemic areas?

The population of Brazil is currently characterised by many individuals harbouring low-intensity Schistosoma mansoni infections. The Kato-Katz technique is the diagnostic method recommended by the World Health Organization (WHO) to assess these infections, but this method is not sensitive enough in the context of low egg excretion. In this regard, potential alternatives are being employed to overcome the limits of the Kato-Katz technique. In the present review, we evaluated the performance of parasitological and immunological approaches adopted in Brazilian areas. Currently, the diagnostic choices involve a combination of strategies, including the utilisation of antibody methods to screen individuals and then subsequent confirmation of positive cases by intensive parasitological investigations.

Serodiagnosis of Trypanosoma cruzi infection using the new particle gel immunoassay - ID-PaGIA Chagas

The ID-Chagas test is a particle gel immunoassay (PaGIA). Red coloured particles are sensitised with three different synthtic peptides representing antigen sequences of Trypanosoma cruzi: Ag2, TcD and TcE. When these particles are mixed with serum containing specific antibodies, they agglutinate. The reaction mixture is centrifuged through a gel filtration matrix allowing free agglutinated particles to remain trapped on the top or distributed within the gel. The result can be read visually. In order to investigate the ability of the ID-PaGIA to discriminate negative and positive sera, 111 negative and 119 positive, collected in four different Brazilian institutions, were tested by each of the participants. All sera were previously classified as positive or negative according to results obtained with three conventional tests (indirect immunofluorescence, indirect hemaglutination, and enzyme linked immunosorbent assay). Sensitivity rates of ID-PaGIA varied from 95.7 per cent to 97.4 per cent with mean sensitivity of 96.8 per cent and specificity rates varied from 93.8 to 98.8 per cent with mean specificity of 94.6 per cent. The overall Kappa test was 0.94. The assay presents as advantages the simplicity of operation and the reaction time of 20 min. In this study, ID-PaGIA showed to be highly sensitive and specific.

Circulating antigens levels in different clinical forms of Schistosoma mansoni infection

With the aim to evaluate the circulating cathodic antigen (CCA) levels in relation to the different clinical phases of Schistosoma sp. infection a sandwich ELISA using monoclonal antibody 5H11 was performed. The sera of three groups of 25 Brazilian patients with acute, instestinal and hepatosplenic forms of S. mansoni infections were tested and compared to a non-infected control group. Patients and control groups were matched for age and sex and the number of eggs per gram of faeces was equally distributed among the three patient groups. Sensitivity of 100 per cent, 72 per cent, 52 per cent of the essays was observed for the intestinal, hepatosplenic and acute toxemic groups respectively. The specificity was 100 per cent. Intestinal and hepatosplenic groups presented CCA levels significantly higher in comparison to those observed for acute patients (F-ratio = 2,524; p = 0.000 and F-ratio = 6.314; p = 0.015 respectively). There was no significant difference of CCA serum levels between hepatosplenic and intestinal groups (F-ratio = 1,026; p = 0.316).

Novas abordagens para o diagnóstico da esquistossomose mansoni humana aguda e crônica / New techniques for the diagnosis of human acute and chronic schistosomiasis mansoni

Säo apresentados quatro artigos publicados e um aceito para publicaçäo em revistas científicas internacionais, que têm como linha de pesquisa comum o diagnóstico da esquistossomose mansoni humana crônica e aguda. Introduz-se o assunto, discutindo-se a importância do diagnóstico da esquistossomose no contexto do controle da endemia e seu estado atual de desenvolvimento e revendo-se a literatura da fase aguda da esquistossomose mansoni. O conteúdo dos trabalhos apresentados inclui a descriçäo de duas novas técnicas eficientes de diagnóstico imunológico, o dot-dye immunoassay e o dye-immunoassay, baseadas na substituiçäo dos sistemas enzima-substrato dos ensaios enzimáticos por um conjugado anti-imunoglobulina humana ligado a corantes têxteis. A técnica dot-dye-immunoassay é aplicada ao diagnóstico da esquistossomose aguda, utilizando o antígeno keyhole limpet haemocyanin (KLH), cuja resposta humoral é específica desta fase, obtendo-se elevadas sensibilidades e especificidade. Estabeleceu-se o valor da ultra-sonografia abdominal no diagnóstico da fase aguda da doença, por comparaçäo com grupos de pacientes crônicos e de pessoas näo infectadas. Por este método, a visualizaçäo de aumento de linfonodos abdominais é característica da fase aguda da doença. Estudando-se um grupo familiar com infecçäo esquistossomótica aguda, determinou-se que os anticorpos séricos IgA contra antígeno solúvel de ovos (SEA) e os anticorpos IgM e IgG contra KLH estäo especificamente elevados na fase aguda da esquistossomose. Estabeleceu-se um critério de morbidade de forma aguda, baseado em intensidade de manifestaçöes clínicas e achados ultra-sonográficos. Através deste critério, os anticorpos IgM e IgA contra SEA e IgM e IgG contra KLH relacionam-se com a morbidade da esquistossomose. A intensidade de manifestaçöes clínicas da forma aguda mostrou-se mais grave em crianças do que em adultos, independentemente da intensidade de contato com água e do número de ovos nas fezes. Os anticorpos IgA contra SEA säo os primeiros a retornarem a valores normais, seguidos pelos anticorpos IgM e IgG contra KLH.

Novas abordagens para o diagnósticos da esquistossomose mansoni humana aguda e crônica / New approaches for the diagnosis of schistosomiasis mansoni human acute and chronic

São apresentados quatro artigos publicados e um aceito para publicação em revistas científicas internacionais, que têm como linha de pesquisa comum o diagnóstico da esquistossomose mansoni humana crônica e aguda. Introduz-se o assunto, discutindo-se a importância do diagnóstico da esquistossomose no contexto do controle da endemia e seu estado atual de desenvolvimento e revendo-se a literatura da fase aguda da esquistossomose mansoni. O conteúdo dos trabalhos apresentados inclui a descrição de duas novas técnicas eficientes de diagnóstico imunológico, o dot-dye immunoassay e o dye-immunoassay, baseadas na substituição dos sistemas enzima-substrato dos ensaios enzimáticos por um conjugado anti-imunoglobulina humana ligado a corantes têxteis. A técnica dot-dye-immunoassay é aplicada ao diagnóstico da esquistossomose aguda, utilizando o antígeno keyhole limpet haemocyanin (KLH), cuja resposta humoral é específica desta fase, obtendo-se elevadas sensibilidade e especificidade. Estabeleceu-se o valor da ultra-sonografia abdominal no diagnóstico da fase aguda da doença, por comparação com grupos de pacientes crônicos e de pessoas não-infectadas. Por este método, a vizibilização de aumento de linfonodos abdominais é característica da fase aguda da doença. Estudando-se um grupo familiar com infecção esquistossomótica aguda, determinou-se que os anticorpos séricos IgA contra antígeno solúvel de ovos (SEA) e os anticorpos IgM e IgG contra KLH estão específicamente elevados na fase aguda da esquistossomose. Estabeleceu-se um critério de morbidade de fase aguda, baseado em intensidade de manifestações clínicas e achados ultra-sonográficos. Através deste critério, os anticorpos IgM e IgA contra SEA e IgM e IgG contra KLH relacionam-se com a morbidade da esquistossomose. A intensidade de manifestações clínicas da forma aguda mostrou-se mais grave em crianças do que em adultos, independentemente da intensidade de contato com água e do número de ovos nas fezes. O~ anticorpos IgA contra SEA são os primeiros a retornarem a valores normais, seguidos pelos anticorpos IgM e IgG contra KLH.

Stool examination and rectal biopsy in the diagnosis and evaluation of therapy of schistosomiasis mansoni

From each of a group of 217 adult males selected through enzyme-immunoassay or skin-test (Group A), six stool samples were examined by both the Lutz/Hoffman, Pons & Janer (Lutz/HPJ) and Kato/Katz methods. In addition, one oogram of the rectal mucosa was performed. By these methods, schistosomiasis was detected in 44.7%, 47.5% and 40.1% of the individuals respectively. To evaluate the methods in the assessment of cure, the last 40 patients from group A, treated with a single oral dose of oxamniquine at 15 mg/kg were followed up for six months (Group B). The criteria for parasitological cure included three stool examinations by Kato/Katz and Lutz/HPJ methods, one, three and six months post-treatment and a rectal biopsy between the fourth and sixth months post-treatment. The examinations were negative in 87.5%, 90% and 95% of the patients, respectively. The efficacy of oxamniquine was 82.5% when the three methods were considered together and there was no statistically significant difference between the sensitivity of the individual methods

Dot-dye-immunoassay for the diagnosis of schistosomiasis mansoni

A new serological assay dot-dye-immunoassay (dot-DIA) was evaluated for the diagnosis of schistosomiasis mansoni. This method consist of four steps: (a) biding of antigens to a nitrocellulose membrane (NC); (b) blocking of free sites of the NC; (c) incubation in specific primary antibody; (d) detection of primary antibody reactivity by color development using second antibody coupled to textile dyes. Sera from 82 individuals, 61 with Schistosoma mansoni eggs in the stool and 21 stool negative were tested by ELISA, dot-ELISA, and dotDIA. A high level of agreement between the methods tested was observed for all sera tested: ELISA x dot-ELISA: 95.1%, ELISA x dot-DIA: 92.7% and dot-ELISA x dot-DIA: 97.6%. In this study, dot-DIA proved to be a feasible, sensitive, rapid and practical test for the diagnosis of shcistosomiasis

Parasitological diagnosis of schistosomiasis mansoni: fecal examination and rectal biopsy

Even with all progress in the search of sensitive and methods for the immunological diagnosis of schistosomiasis, the microscopic detection of eggs of the parasite in the stool still remains the most widely used tool for the actual diagnosis of active infection. Among the coproscopic methods, Kato's technic modified by Katz et al (Kato/Katz) has the advantages of higher sensitivity, the possibility of egg quantification, its low operational cost and its feasibility in areas with minimal infra-structure. The oorgram of the rectal mucosa is valuable in initial clinical trials of schistosomicides, when it is needed to observe egg morphology in tissue. It could be an alternative method for individual diagnosis, being more sensitive than a single stool exam in low intensity infection. However, the increased sensitivity of a higher number of fecal exams makes that invasiveprocedure unnecessary. In the assessment of cure of schistosomiasis, Kato/Katz method (three fecal samples in one, three and six months after treatment) and the rectal biopsy four months after treatment, are equally reliable

A lesäo renal na esquistossomose e na associaçäo Salmonella - S. mansoni / Renal lesion in schistosomiasis and in Salmonella - S. mansoni association

Procurou-se apresentar de forma didática, os conhecimentos acumulados nos últimos 20 anos sobre a lesäo renal encontrada em pacientes com esquistossomose hepatesplênica e com a associaçäo Salmonella-S.mansoni. As semelhanças e diferenças observadas na apresentaçäo clínica e na resposta terapêutica säo enfatizadas. Conclui-se pela existência de duas nefropatias, distintas, que deveräo ficar melhor caracterizadas à medida que outros estudos sejam realizados