Screening of Strongyloides infection using an ELISA test in transplant candidates

OBJECTIVES: Hyperinfection or disseminated strongyloidiasis has been frequently reported after transplants and is related to high mortality. This study aimed to screen for strongyloidiasis using serological diagnoses in transplant candidates. METHODS: An ELISA test was performed with filariform larvae of Strongyloides venezuelensis as a source of antigen. RESULTS: In the serum from transplant candidates, anti-Strongyloides IgG antibodies were detected in 35/150 (23.3%) samples by soluble fractions in phosphate buffered saline (PBS), 31/150 (20.7%) samples by soluble fractions in Tris-HCl, 27/150 (18.0%) samples by membrane fractions in PBS and 22/150 (14.7%) samples by membrane fractions in Tris-HCl. CONCLUSIONS: The present results suggest the ELISA test, ideally using soluble fractions of filariform larvae S. venezuelensis in PBS, as an additional strategy for the diagnosis of strongyloidiasis in transplant candidates.

Seroepidemiological aspects of human infection by Strongyloides stercoralis in Alfenas, southern Minas Gerais, Brazil

Abstract INTRODUCTION: In most Strongyloides stercoralis infected individuals, nematoidosis occurs asymptomatically, but in immunocompromised patients, it can cause hyperinfection. Serological techniques seem to be a good alternative for detecting this parasite. METHODS The frequency of seropositivity for strongyloidiasis in Alfenas, MG, was estimated using the enzyme linked immunosorbent assay on blood samples, between May and August of 2015. RESULTS: Out of 258 samples tested, 53.9% were positive, and the frequency of seropositive individuals was higher in the peripheral districts of the municipality. CONCLUSIONS: The results indicate high seropositivity rates for strongyloidiasis among the residents of Alfenas city.

Immunoparasitological diagnosis of Strongyloides stercoralis in garbage collectors in Uberlândia, MQ Brazil

The objective of this study was to determine the presence of Strongyloides stercoralis in urban garbage collectors through the use of immunological and parasitological methods. A total of 92 individuals were evaluated from August, 1997, to June, 1998. For the parasitological diagnosis Baermann and Lutz' methods were applied. The immunological diagnosis involved the indirect fluorescence antibody test (IFAT) and the enzyme-linked immunosorbent assay (ELISA) to detect specific IgG antibodies. Of the 92 workers examined, six (6.5 percent) were infected with larvae of S. stercoralis. The IFAT detected 19 (16.3 percent) and the ELISA 17 (18.5 percent) positive serum samples. The differences between the results of parasitological and immunological methods were statistically significant (p<0.05). These results demonstrate that there is a need to improve the health conditions of this category of city employees.

Seroepidemiological aspects of human Strongyloides stercoralis infections in Chile

To determine the frequency of Strongyloides stercoralis antibodies by means of the enzyme linked immunosorbent assay (ELISA) in Chile, in 2001-2003, 675 blood samples of patients of two psychiatric hospitals and 172 of healthy individuals (doctors, nurses and paramedicals) of these institutions, and 1,200 serum samples of blood donors of Northern region (Arica and Antofagasta), Central region (Valparaiso and Santiago) and Southern region (La Union) were collected. ELISA showed positivity of 12.1 percent in psychiatric hospitalized patients, none (0 percent) in the health personnel and 0.25 percent in blood donors (p < 0.05). Only in blood donors of Arica (1 percent) and La Union (0.5 percent) the ELISA test was positive suggesting that strongyloidiasis is focalized in determinate zones of the country. In Chile, human infections by S. stercoralis are endemic with very low frequency in apparently healthy individuals and high prevalence in risk groups such as the mentally ill hospitalized patients.

Entre os anos de 2001-2003 foram coletadas amostras de sangue de 675 pacientes de dois hospitais psiquiátricos da região central do Chile, 172 de indivíduos sadios (médicos, enfermeiros e paramédicos) destas instituições e 1200 de doadores de sangue de cidades das regiões norte (Arica e Antofagasta), central (Valparaiso e Santiago) e sul (La Union) para determinar a frequência de anticorpos anti Strongyloides stercoralis mediante a reação de enzyme linked immunosorbent assay (ELISA). Foram observadas soropositividade de 12.1 por cento em pacientes de hospitais psiquiátricos e de 0,25 por cento em doadores de sangue (p < 0.05). Todas as amostras dos indivíduos sadios foram não reagentes. Entre os doadores de sangue a soropositividade ocorreu somente nos indivíduos de Arica (1,0 por cento) e La Union (0,5 por cento) sugerindo que a estrongiloidíase poderia estar localizada em determinadas áreas geográficas do país. Conclui-se que no Chile as infecções por S. stercoralis seriam endêmicas, de baixa freqüência e afetando especialmente grupos de risco como os pacientes psiquiátricos.

Epidemiologic study of the association between human T-cell lymphotropic virus type 1 and Strongyloides stercoralis infection in female blood donors (Guadeloupe, French West Indies)

This case control study was conducted among female blood donors in Guadeloupe. A total of 85 HTLV-1 positive subjects were matched by age (+/- 5 years) in a 1:3 ratio to 255 HTLV-1 negative controls. The mean age was 48.5 and 48.9 years respectively. Ethnic, environmental and socio-economic risk factors were studied. Four risk factors were found independently associated with HTLV-1 seropositivity: Strongyloides stercoralis antibodies (OR = 3.6, CI 1.8, 7.3), low socio-economic status (OR = 2.0 CI 1.0, 4.0), low educational level (OR = 2.0 CI 1.0, 4.0) and agricultural activity (OR = 2.8 CI 1.4, 5.6). This logistic regression analysis demonstrates the reality of the association between HTLV-1 carriers and Strongyloides stercoralis, and its association with socio-economic and environmental risk factors

Evaluation of enzyme-linked immunosorbent assay for the serodiagnosis of strongyloidosis

To evaluate an enzyme- linked immunosorbaent assay using filariform larvae of Strongyloides stercoralis to detect specific antibodies in patients with strongytoidosis. Design: Serum samples obtained from individuals infected with strongytoidosis and other parasitic diseases as well as normal people were analyzed by IgG-ELISA using crude antigen of filariform larvae. Setting: School of Public Health Serum Blood Bank, Tehran University of Medical Sciences, volunteers people and selected patients. Subjects: Serum samples were obtained from 46 individuals infected with strongytoidosis, 37 from normal individuals and 379 cases from others with different parasitic infections. Main outcome measures: The sensitivity, specificity, positive and negative predictive values of the test. Result: The cut-off point was 0.537. The sensitivity of the test was 93.47%, whereas the specificity was 96.15%. The positive and negative predictive values were 72.88% and 99.25% respectively. Three individuals with hydatidosis, one with ascariasis and 12 with toxocariasis had antibodies that were reactive against larval antigen. ELISA method using filariform larval antigen provides a sensitive and specific diagnostic assay

Specific monoclonal antibodies to Strongyloides stercoralis: a potential diagnostic reagent for strongyloidiasis.

In this study, specific hybridomas secreting monoclonal antibodies (MAb) to antigen of Strongyloides stercoralis filariform larvae were produced. Specific epitopes targeted by the MAb were protein in nature and located in situ in the internal content of the filariform larvae of the parasite but not in the esophagus. The MAb reacted to the homologous antigen in an indirect ELISA but did not reveal any reaction to the SDS-PAGE separated-homologous antigen in a Western blot analysis (WB) suggesting a conformational epitope specificity. The MAb were of IgG1 isotype which is the isotype known to have high affinity to this epitope so they were used in a dot-ELISA to detect the antigen of the parasite. The assay could detect the epitopes in 78 ng or more of the crude filariform larval extract but did not reveal any positive result when applied to detect antigen in stool samples of parasitologically confirmed strongyloidiasis patients. The negative antigen test results can be explained as follows. Either the MAb were filariform stage-specific and thus did not recognize the rhabditiform larval antigen mainly contained in the patient's stool or the amounts of antigen in the stool samples were too small and/or unevenly dispersed. In the latter instance, the MAb developed in this study would have a diagnostic potential if used in an immunological test design where more volume of fresh stool sample could be accommodated in the test, e.g. a sandwich plate ELISA.

Implicações clínicas e imunológicas da associação entre o HTLV-1 e a estrongiloidíase / Clinical and immunological consequences of the association between HTLV-1 and strongyloidiasis

A estrongiloidíase é uma das mais importantes helmintíases em países tropicais e estudos epidemiológicos têm demonstrado associaçäo desta parasitose com o vírus HTLV-1. Em regiöes onde estes dois agentes säo endêmicos a coinfecçäo pode resultar no desenvolvimento de formas disseminadas da estrongiloidíase assim como em estrongiloidíase recorrente. Enquanto que o vírus HTLV-1 está relacionado com uma alta produçäo de IFN-gama e desvio da resposta imune para o tipo Th1, a proteçäo contra helmintos está associada a uma resposta Th2. Devido a este viés da resposta imune, indivíduos infectados pelo HTLV-1 apresentam reduçäo na produçäo de IL-4, IL-5, IL-13 e IgE, componentes participantes dos mecanismos de defesa contra S. stercoralis. Estas anormalidades constituem a base para a ocorrência de maior freqüência e de formas mais graves da estrongiloidíase em pacientes infectados pelo HTLV-1

Inmunodiagnóstico de las infecciones por Strongloides stercoralis en Chile utilizando la prueba de ELISA / Immunodiagnosis of Strongyloides stercoralis infections in Chile using ELISA test

BACKGROUND: Strongyloides stercoralis is a world wide distributed small intestinal nematode parasite. In immunocompetent individuals S stercoralis can produce asymptomatic infections or a moderate clinical picture of diarrhea, some cases become chronic. In immunocompromised patients, a disseminated disease may appear, sometimes fatal. In Chile, there is little epidemiological information about S stercoralis infections and appropriate diagnostic techniques are usually not used. AIM: To evaluate the yield of an ELISA test for the diagnosis of strongyloidiasis in Chilean patients. MATERIAL AND METHODS: Ten serum samples from patients with S stercoralis infections confirmed by a positive stool examination, 66 samples from individuals with other infections by tissue helminthes (24 toxocariasis, 15 trichinellosis, 11 hydatidosis, 12 fascioliasis and 4 cysticercosis), 13 samples from subjects with autoimmune diseases and 49 samples from apparently healthy individuals with a normal eosinophil count, were studied. ELISA antigen was prepared using a filariform larval extract obtained from a murine species of Strongyloides, maintained in laboratory animals. RESULTS: Using 0.33 optical density units as a cut off value, 9 of 10 sera of S stercoralis infected individuals, had a positive ELISA test. No cross reactions were observed with sera of patients with other helminthic infections, autoimmune diseases or in healthy individuals. Thus, specificity, positive and negative predictive values were 100 per cent. CONCLUSIONS: The results obtained are similar with those found by other investigators. ELISA test for strongyloidiasis is a useful tool for the diagnosis of clinical cases and for seroepidemiological studies of this nematode infection in Chile.

Improved antigens for IgG-ELISA diagnosis of strongyloidiasis.

Two preparations of antigens for the diagnosis of strongyloidiasis were prepared from an extract of the infective larvae of Strongyloides stercoralis: a crude antigen (CA) and a molecular weight cut-off antigen (MWCOA). Both antigens were analysed by indirect ELISA against the sera of strongyloidiasis (26 cases), other helminthiases (167) and normal controls (30). The larvae were obtained from fecal culture by a modified polyethylene tube technique after screening tests by triple simple smears per case. The larvae were extracted with distilled water and further sonicated to obtain a supernatant, the CA. A part of the CA was separated for an antigen containing molecules of lower than 30 kDa by an ultrafree-MC centrifugal filter tube (PLTK): this was designed as the MWCOA. The CA gave 96.15% sensitivity and 40.12% (67/167) specificity at a cut-off value of 0.980 (5SD); false positives were produced by 19 of 20 different helminthiases. The MWCOA produced 96.15% sensitivity at cut-off value of 0.71 (4SD); the specificity of the test was 78.44% (131/167), higher than that of CA. False positives also appeared with 15 other helminthic infections. This study suggests that MWCOA is more specific than CA. A purified MWCOA will be necessary in order to reduce cross-reactivity and provide the suitable diagnosis of strongyloidiasis.

Parasitological and immunological diagnoses of strongyloidiasis in immunocompromised and non-immunocompromised children at Uberlândia, state of Minas Gerais, Brazil

Parasitological and immunological diagnoses were part of a study conducted among 151 children, 83 immunocompromised (IC) and 68 non-immunocompromised (non-IC) aged from zero to 12, seen at the University Hospital, Universidade Federal de Uberlândia, State of Minas Gerais, Brazil, from February, 1996, to June, 1998. Three fecal samples from each child were analyzed for the parasitological diagnosis by Baermann-Moraes and Lutz methods. The immunological diagnosis to detect IgG and IgM antibodies was carried out by the indirect immunofluorescence antibody test (IFAT) with cryo-microtome sections of Strongyloides stercoralis and Strongyloides ratti larvae as antigens and by the ELISA test with an alkaline extract of S. ratti as the antigens. Of the 151 children 5 (3.31 percent) were infected with larvae of S. stercoralis (2 cases IC, 2.41 percent, and 3 cases non-IC, 4.41 percent). The IFAT-IgG detected 7 (8.43 percent) serum samples positive among IC, and 2 (2.94 percent) cases among non-IC. The ELISA-IgG test detected 10 (12.05 percent) serum samples positive among IC, and 1 (1.47 percent) case among non-IC. The IFAT-IgM detected 6 (7.22 percent) positive cases among IC, and 3 (4.41 percent) cases among non-IC. ELISA-IgM test detected 10 (12.05 percent) positive cases among IC, and 3 (4.41 percent) cases among non-IC. It was concluded that the immunological tests can help in the diagnosis of strongyloidiasis in immunocompromised children

Strongyloidiasis as an opportunistic infection in a HAM/TSP patient

Infection by human T-cell lymphotropic virus type I (HTLV-I) is associated with neurological diseases, malignancies, and other less commun pathologies. In addition, infection by HTLV-I has been implicated in some degree of immunological impairment. Some previous reports detected an association between HTLV-I infection and an increased rate of antibodies against S. stercoralis, as well as a higher frequency of S. stercoralis carrier state. Here, we report a case of a chronic, recurrent S. stercoralis parasitism in a patient infected by HTLV-I. The patient demonstrated evidence of immunosupression characterized by skin allergy to commun antigens, oral candidiasis and severe, recurrent diarrhea caused by S. stercoralis. The infection requires maintenance of supressive therapy to control diarrhea and its consequences. We postulate that S. stercoralis may act as an opportunistic agent in patients infected by HTLV-I.

Estudo das imunoglobinas intestinais na estrongiloidíase / Intestinal immunoglobulin study in clinical strongyloidiasis

Foram selecionados 32 pacientes infectados pelo Strongyloides stercoralis, sem imunodeficiência prévia ou outra doença associada. Foram divididos em três grupos: assintomáticos, sintomáticos leves e sintomáticos graves, com o objetivo de estudar a resposta imunológica do hospedeiro ao parasita. Os pacientes do grupo sintomático grave apresentavam esteatorréia, emagrecimento acentuado, albuminemia menor que 3 por cento e alteraçöes radiológicas. Doze voluntários sadios, sem verminose, formaram o grupo controle. A biópsia peroral do intestino delgado foi o método utilizado para obtençäo de fragmento da mucosa intestinal, ao nível do ângulo de Treitz. O estudo da concentraçäo das imunoglobulinas locais (IgA, IgC e IgM), pela técnica da imunofluorescência direta, demonstrou diminuiçäo significativa da concentraçäo de IgA nos pacientes sintomáticos graves e diminuiçäo da concentraçäo de IgM nos três grupos, quando comparados ao grupo controle. Näo houve alteraçöes da concentraçäo da concentraçäo de IgC