Autor/a:
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Beltrame, Anna; Guerriero, Massimo; Angheben, Andrea; Gobbi, Federico; Requena-Méndez, Ana; Zammarchi, Lorenzo; Formenti, Fabio; Perandin, Francesca; Buonfrate, Dora; Bisoffi, Zeno
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Abstract:
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BACKGROUND: Schistosomiasis is a neglected infection affecting
millions of people, mostly living in sub-Saharan Africa.
Morbidity and mortality due to chronic infection are relevant,
although schistosomiasis is often clinically silent. Different
diagnostic tests have been implemented in order to improve
screening and diagnosis, that traditionally rely on
parasitological tests with low sensitivity. Aim of this study
was to evaluate the accuracy of different tests for the
screening of schistosomiasis in African migrants, in a non
endemic setting. METHODOLOGY/PRINCIPAL FINDINGS: A retrospective
study was conducted on 373 patients screened at the Centre for
Tropical Diseases (CTD) in Negrar, Verona, Italy. Biological
samples were tested with: stool/urine microscopy, Circulating
Cathodic Antigen (CCA) dipstick test, ELISA, Western blot,
immune-chromatographic test (ICT). Test accuracy and predictive
values of the immunological tests were assessed primarily on the
basis of the results of microscopy (primary reference standard):
ICT and WB resulted the test with highest sensitivity (94% and
92%, respectively), with a high NPV (98%). CCA showed the
highest specificity (93%), but low sensitivity (48%). The
analysis was conducted also using a composite reference
standard, CRS (patients classified as infected in case of
positive microscopy and/or at least 2 concordant positive
immunological tests) and Latent Class Analysis (LCA). The latter
two models demonstrated excellent agreement (Cohen's kappa:
0.92) for the classification of the results. In fact, they both
confirmed ICT as the test with the highest sensitivity (96%) and
NPV (97%), moreover PPV was reasonably good (78% and 72%
according to CRS and LCA, respectively). ELISA resulted the most
specific immunological test (over 99%). The ICT appears to be a
suitable screening test, even when used alone. CONCLUSIONS: The
rapid test ICT was the most sensitive test, with the potential
of being used as a single screening test for African migrants. |