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Efficacy of parasitological methods for the diagnosis of Strongyloides stercoralis and hookworm in faecal specimens.

Abstract

To compare the efficacy of stool examination for the detection of Strongyloides stercoralis and hookworm, a total of 634 stool samples from the routine laboratory service of the Pharmacia Faculty, Federal University of Bahia, Brazil, were examined by agar plate culture (APC), Baermann-Moraes and spontaneous sedimentation. The sensitivity of agar plate culture, calculated by combining results of all 3 methods, was 95% for S. stercoralis and 77.6% for hookwoorm. Moreover, APC had superior accuracy than Baermann-Moraes and spontaneous sedimentation for S. stercoralis and hookworm diagnosis, respectively. The S. stercoralis and hookworm positive samples from the laboratory routine, obtained after the previous analysis, along with those initially selected, were used to evaluate the concordance between microscopic examination and both the type of furrows left by larvae and the time for culture positivity using the APC method. Of 115 stool samples positive for S. stercoralis and 92 positive for hookworm, 110 (95.7%) and 89 (96.7%), respectively, had concordant results for furrows and morphological characteristics. The cumulative percentage of positivity increased to 94% by the third day of observation; at this time, only 19.6% of hookworm-positive samples had positive culture plates. Analyses of 74 S. stercoralis-positive stool samples stored at 4°C for 24, 48 and 72h showed the presence of larvae in 48.6%, 28.4% and 23% of samples, respectively when re-examined by the APC. As a definitive diagnosis of strongyloidiasis depends on the microscopic demonstration of parasites, increasing the sensitivity of the detection requires the use of different parasitological methods, including APC.

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  • Publisher Full Text
  • Authors

    Inês Ede J, Souza JN, Santos RC, Souza ES, Santos FL, Silva ML, Silva MP, Teixeira MC, Soares NM

    Institution

    Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal da Bahia, Salvador, Brazil.

    Source

    Acta tropica 120:3 2011 Dec pg 206-10

    MeSH

    Ancylostomatoidea
    Animals
    Brazil
    Clinical Laboratory Techniques
    Culture Media
    Feces
    Hookworm Infections
    Humans
    Microscopy
    Parasitology
    Sensitivity and Specificity
    Strongyloides stercoralis
    Strongyloidiasis

    Pub Type(s)

    Evaluation Studies
    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    21896267