title: Detection of parasite-specific IgG and IgA in paired serum and saliva samples for diagnosis of human strongyloidiasis in northern Paraná state, Brazil.
abstract: Human strongyloidiasis is an infection caused by the helminth Strongyloides stercoralis that can be fatal, especially in immunosuppressed patients. The aim of this study is to evaluate parasite-specific IgG and IgA levels using S. venezuelensis third-stage (L3) infective larvae alkaline extract as a heterologous antigen by ELISA in paired serum and saliva samples with improved sensitivity and specificity. Individuals from northern Paraná state, Brazil were divided into three groups: 30 patients copropositive for S. stercoralis (Group I); 30 clinically healthy individuals (Group II); and 30 patients copropositive for other parasites (Group III). The area under ROC curve (AUC), an overall index of diagnostic accuracy, and Kappa index were calculated. Data were analyzed using analysis of variance (ANOVA) followed by a Kruskal-Wallis test. Probability (p) values of <0.05 were regarded as significant. In Group I, IgG was detected in 96.7% serum and in 6.7% saliva samples. IgG was not detected in Group II. In Group III, cross-reactivity was observed for serum IgG in 26.7% and in 6.7% for saliva samples. In Group I, IgA was detected in 76.7% serum and 56.7% saliva samples. In Group II, 3.3% were positive for IgA in serum, whereas IgA was not detected in any saliva samples. Group III showed 6.7% serum and 26.7% saliva-positive samples. The sensitivity values for detection of IgG and IgA in serum samples were 96.7% and 76.7%, respectively. In saliva samples, the sensitivity values for detection of IgG and IgA were 6.7% and 56.7%, respectively. The specificity value was 100% for the detection of IgG in serum and for detection of IgG and IgA in saliva, and 96.7% for detection of IgA in serum samples. The proper choice of immunological diagnosis to supplement parasitological methods is essential to estimate the true prevalence of the parasite, and will permit analysis of population immune response profiles, particularly in northern Paraná state, where there are no previous reports.
authors.affiliation: Departamento de Ciências Patológicas, Laboratório de Parasitologia, Universidade Estadual de Londrina, PR, Brazil.
authors.forename: Larissa R
authors.initials: LR
authors.lastname: Bosqui
authors.affiliation: Departamento de Imunologia, Microbiologia e Parasitologia, Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, MG, Brazil.
authors.forename: Ana Lúcia R
authors.initials: AL
authors.lastname: Gonçalves
authors.affiliation: Departamento de Imunologia, Microbiologia e Parasitologia, Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, MG, Brazil.
authors.forename: Maria do Rosário F
authors.initials: Mdo R
authors.lastname: Gonçalves-Pires
authors.affiliation: Ambulatório de Especialidades do Hospital Universitário de Londrina, PR, Brazil.
authors.forename: Luiz Antonio
authors.initials: LA
authors.lastname: Custodio
authors.affiliation: Departamento de Ciências Patológicas, Laboratório de Parasitologia, Universidade Estadual de Londrina, PR, Brazil.
authors.forename: Maria Cláudia N D
authors.initials: MC
authors.lastname: de Menezes
authors.affiliation: Ambulatório de Especialidades do Hospital Universitário de Londrina, PR, Brazil.
authors.forename: Valter A
authors.initials: VA
authors.lastname: Murad
authors.affiliation: Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, SP, Brazil.
authors.forename: Fabiana M
authors.initials: FM
authors.lastname: de Paula
authors.affiliation: Departamento de Ciências Patológicas, Laboratório de Parasitologia, Universidade Estadual de Londrina, PR, Brazil.
authors.forename: Wander R
authors.initials: WR
authors.lastname: Pavanelli
authors.affiliation: Departamento de Ciências Patológicas, Laboratório de Parasitologia, Universidade Estadual de Londrina, PR, Brazil.
authors.forename: Ivete
authors.initials: I
authors.lastname: Conchon-Costa
authors.affiliation: Departamento de Imunologia, Microbiologia e Parasitologia, Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, MG, Brazil.
authors.forename: Julia Maria
authors.initials: JM
authors.lastname: Costa-Cruz
authors.affiliation: Departamento de Ciências Patológicas, Laboratório de Parasitologia, Universidade Estadual de Londrina, PR, Brazil. Electronic address: idessania@hotmail.com.
authors.forename: Idessania N
authors.initials: IN
authors.lastname: Costa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000909:Antibodies, Helminth / Q000032:analysis* / Q000097:blood; D019540:Area Under Curve; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D007070:Immunoglobulin A / Q000032:analysis / Q000097:blood; D007074:Immunoglobulin G / Q000032:analysis / Q000097:blood; D007814:Larva / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012463:Saliva / Q000276:immunology; D012680:Sensitivity and Specificity; D044967:Serum / Q000276:immunology; D017171:Strongyloides stercoralis / Q000276:immunology*; D013322:Strongyloidiasis / Q000175:diagnosis* / Q000453:epidemiology / Q000469:parasitology; D055815:Young Adult
chemical_list: D000909:Antibodies, Helminth; D007070:Immunoglobulin A; D007074:Immunoglobulin G
keywords: Brazil; Immunodiagnostic; Paraná state; Saliva; Strongyloidiasis