Evaluation of eleven immunochromatographic assays for SARS-CoV-2 detection: investigating the dengue cross-reaction

ABSTRACT COVID-19 disease is spread worldwide and diagnostic techniques have been studied in order to contain the pandemic. Immunochromatographic (IC) assays are feasible and a low-cost alternative especially in low and middle-income countries, which lack structure to perform certain diagnostic techniques. Here we evaluate the sensitivity and specificity of eleven different IC tests in 145 serum samples from confirmed cases of COVID-19 using RT-PCR and 100 negative serum samples from blood donors collected in February 2019. We also evaluated the cross-reactivity with dengue using 20 serum samples from patients with confirmed diagnosis for dengue collected in early 2019 through four different tests. We found high sensitivity (92%), specificity (100%) and an almost perfect agreement (Kappa 0.92) of IC assay, especially when we evaluated IgG and IgM combined after 10 days from the onset of symptoms with RT-PCR. However, we detected cross-reactivity between dengue and COVID-19 mainly with IgM antibodies (5 to 20% of cross-reaction) and demonstrated the need for better studies about diagnostic techniques for these diseases.

Reactivation of cutaneous and mucocutaneous tegumentary leishmaniasis in rheumatoid arthritis patients: an emerging problem?

ABSTRACT Rheumatoid arthritis (RA) is a chronic condition that is frequent in patients living in tropical areas exposed to leishmaniasis. RA therapy involves immunosuppressant drugs such as methotrexate (MTX), monoclonal antibodies (mAbs) and prednisone. We report an unusual presentation of cutaneous (CL) or mucocutaneous leishmaniasis (ML) in RA patients from an endemic area of leishmaniasis. A 51-year-old woman noted a cutaneous ulcer on her left ankle during MTX and prednisone RA therapy. Initially diagnosed as a venous stasis ulcer, the aspirate of the injury revealed the presence of Leishmania DNA. A 73-year-old woman presenting non-ulcerated, infiltrated and painful erythematous nodules inside her nostrils while receiving MTX, anti-TNF mAb, and prednisone for RA, had also the aspirate of injuries showing the presence of Leishmania DNA. Both patients healed after the therapy with liposomal amphotericin. The RA therapy has changed to low-dose prednisone, without further reactivation episodes. Both cases suggest that CL or ML can reactivate after administration of an immunosuppressant for RA treatment. Therefore, immunosuppressive treatments for RA should be carefully prescribed in patients from endemic areas or with a history of CL and ML.

USEFULNESS OF kDNA PCR IN THE DIAGNOSIS OF VISCERAL LEISHMANIASIS REACTIVATION IN CO-INFECTED PATIENTS / Utilidade da kDNA PCR no diagnostico de reativacao de leishmaniose visceral em pacientes co-infectados sintomaticos

SUMMARY It is important to develop new methods for diagnosing relapses in the co-infection of visceral leishmaniasis (VL) and HIV to enable earlier detection using less invasive methods. We report a case of a co-infected patient who had relapses after VL treatment, where the qualitative kDNA PCR showed a good performance. The kDNA PCR seems to be a useful tool for diagnosing VL and may be a good marker for predicting VL relapses after treatment of co-infected patients with clinical symptoms of the disease. .

RESUMO É importante a pesquisa de novos métodos laboratoriais para o diagnóstico de recidivas em casos de co-infecção leishmaniose visceral (LV) e vírus da imunodeficiência humana (HIV), que permitam o diagnóstico precoce das recidivas, utilizando métodos menos invasivos. Descrevemos aqui, o caso de paciente co-infectada que apresentou recidivas após o tratamento da LV e onde a PCR qualitativa demonstrou bom desempenho. A kDNA PCR parece ser ferramenta útil para o diagnóstico de recidivas de LV após o tratamento em pacientes co-infectados com sintomas clínicos da doença. .

Discrepancies and consequences of indirect hemagglutination, indirect immunofluorescence and Elisa tests for the diagnosis of Chagas disease / Discordâncias e consequências de resultados de provas de hemaglutinação indireta, imunofluorescência indireta e Elisa para o diagnóstico da doença de Chagas

Using the indirect hemagglutination (IH), indirect immunofluorescence (IIF) and enzyme linked immunosorbent assay (ELISA) tests for the diagnosis of Chagas disease, 4000 serum samples were examined. This study was conducted with different purposes: clinical interest, research support and parasitological monitoring of those patients with Chagas disease who were treated with heart transplantations. The tests occurred without patient selection and in accordance with the medical requests. The results showed discrepancies and brought about several questions, considering the different results that all three methods showed when considered together. What was found brought about concerns and we suggest the adoption of different measures, aiming to avoid these mismatches in the context of this disease.

Com as provas de hemaglutinação indireta (HI), imunofluorescência indireta (IFI) e Enzyme Linked Immunosorbent Assay (ELISA), para diagnóstico da doença de Chagas, foram examinadas concomitantemente 4000 amostras de soro, com diferentes finalidades, tais como interesse clínico, apoio a pesquisas e acompanhamento parasitológico de pacientes com tal moléstia tratados por meio de transplante de coração. Os testes ocorreram, sem seleção e conforme as solicitações, em Laboratório que essencialmente prestou colaboração. Os resultados mostraram discordâncias, inclusive motivadoras de dúvidas, considerando especificamente o revelado pelos três métodos em conjunto. O que ficou verificado suscita preocupações e sugere a adoção de medidas aptas a evitar essas inadequações no contexto da parasitose.