Introduction: Few data on the diagnostic performance of serological tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are currently available. We evaluated sensitivity and specificity of five different widely used commercial serological assays for the detection of SARS-CoV-2–specific IgG, IgM, and IgA antibodies using reverse transcriptase-PCR assay in nasopharyngeal swab as reference standard test.Methods: A total of 337 plasma samples collected in the period April–June 2020 from SARS-CoV-2 RT-PCR positive (n = 207) and negative (n = 130) subjects were investigated by one point-of-care lateral flow immunochromatographic assay (LFIA IgG and IgM, Technogenetics) and four fully automated assays: two chemiluminescence immunoassays (CLIA-iFlash IgG and IgM, Shenzhen YHLO Biotech and CLIA-LIAISON® XL IgG, DiaSorin), one electrochemiluminescence immunoassay (ECLIA-Elecsys® total predominant IgG, Roche), and one enzyme-linked immunosorbent assay (ELISA IgA, Euroimmune).Results: The overall sensitivity of all IgG serological assays was >80% and the specificity was >97%. The sensitivity of IgG assays was lower within 2 weeks from the onset of symptoms ranging from 70.8 to 80%. The LFIA and CLIA-iFlash IgM showed an overall low sensitivity of 47.6 and 54.6%, while the specificity was 98.5 and 96.2%, respectively. The ELISA IgA yielded a sensitivity of 84.3% and specificity of 81.7%. However, the ELISA IgA result was indeterminate in 11.7% of cases.Conclusions: IgG serological assays seem to be a reliable tool for the retrospective diagnosis of SARS-CoV-2 infection. IgM assays seem to have a low sensitivity and IgA assay is limited by a substantial rate of indeterminate results.
Purpose
Visceral leishmaniasis (VL) has become a rising concern to transplantation teams, being associated with graft dysfunction and reduced survival of renal transplant recipients. Here, we describe a case of VL occurring in a kidney transplant (KT) recipient in Italy, a country in which Leishmania infantum is endemic and we reviewed the literature on the clinical course and diagnosis of VL in KT recipients residing or travelling to southern Europe.
Results
The VL case was diagnosed 18 months after transplant and 28 days after the onset of symptoms by quantitative PCR (qPCR) on peripheral blood. A graft biopsy showed renal involvement, and PCR performed on graft tissue displayed the presence of Leishmania DNA. The retrospective confirmation of Leishmania-positive serology in a serum sample collected before transplantation, as well as the absence of anti-Leishmania IgG in the graft donor strongly suggest that reactivation of a latent parasitic infection caused VL in the current case.
Conclusion
VL is often underdiagnosed in transplant recipients, despite the presence of latent Leishmania infection being reported in endemic countries. This case report, as well as the literature review on leishmaniasis in KT recipients, underline the importance of rapid VL diagnosis to promptly undergo treatment. Serology is scarcely sensitive in immunocompromised patients, thus molecular tests in peripheral blood should be implemented and standardized for both VL identification and follow-up.
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