With reduced prevalence of visceral leishmaniasis (VL) in the Indian subcontinent (ISC), direct and field deployable diagnostic tests are needed to implement an effective diagnostic and surveillance algorithm for post-elimination VL control. In this regard, here we investigated the diagnostic efficacies of a loop-mediated isothermal amplification (LAMP) assay (Loopamp™ Leishmania Detection Kit, Eiken Chemical CO., Ltd, Japan), a real-time quantitative PCR assay (qPCR) and the Leishmania antigen ELISA (CLIN-TECH, UK) with different sampling techniques and evaluated their prospect to incorporate into post-elimination VL control strategies. Eighty clinically and rK39 rapid diagnostic test confirmed VL cases and 80 endemic healthy controls were enrolled in the study. Peripheral blood and dried blood spots (DBS) were collected from all the participants at the time of diagnosis. DNA was extracted from whole blood (WB) and DBS via silica columns (QIAGEN) and boil & spin (B&S) methods and tested with qPCR and Loopamp. Urine was collected from all participants at the time of diagnosis and was directly subjected to the Leishmania antigen ELISA. 41 patients were followed up and urine samples were collected at day 30 and day 180 after treatment and ELISA was performed. The sensitivities of the Loopamp-WB(B&S) and Loopamp-WB(QIA) were 96.2% (95% CI 89·43-99·22) and 95% (95% CI 87·69-98·62) respectively. The sensitivity of Loopamp- DBS(QIA) was 85% (95% CI 75·26- 92·00). The sensitivities of the qPCR-WB(QIA) and qPCR-DBS(QIA) were 93.8% (95% CI 86·01-97·94) and 72.5% (95% CI 61·38-81·90) respectively. The specificity of all molecular assays was 100%. The sensitivity and specificity of the Leishmania antigen ELISA were 97.5% (95% CI 91·47-99·70) and 91.95% (95% CI 84·12-96·70) respectively. The Leishmania antigen ELISA depicted clinical cure at day 180 in all the followed-up cases. Efficacy and sustainability identify the Loopamp-WB(B&S) and the Leishmania antigen ELISA as promising and minimally invasive VL diagnostic tools to support VL diagnostic and surveillance activities respectively in the post-elimination era.

Made available in DSpace on 2016-12-23T13:55:59Z (GMT). No. of bitstreams: 1 Giuliana Schmidt Franca Fonseca.pdf: 1055751 bytes, checksum: 050d4de10b5fae8001c2b5f264473b60 (MD5) Previous issue date: 2013-08-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O diagnóstico de rotina da leishmaniose visceral (LV) humana é usualmente baseado em parâmetros clínicos e epidemiológicos, associado a exames parasitológicos e/ou imunológicos. Tendo em vista que a doença é fatal se não tratada, a busca por métodos diagnósticos mais efetivos, que sejam de fácil execução, simples, acessíveis, menos invasivos, e rápidos, se faz necessário, diminuindo o tempo de obtenção dos resultados. Portanto, neste estudo foi avaliado o desempenho de diferentes métodos já utilizados na rotina ou propostas como ferramentas alternativas para o diagnóstico da LV, incluindo o exame direto de punção de medula óssea, a reação de imunofluorescência indireta (RIFI), o teste rápido com rK39 (Kalazar Detect®), a ELISA com antígeno solúvel de L. chagasi e a imunofluorescência baseada em citometria de fluxo (FC-AFPA). Para isso foram avaliadas 77 amostras biológicas (punção de medula óssea e soro) de pacientes com diagnóstico clínico de LV, tratados e curados. A sensibilidade dos testes avaliados foi de 48% para o exame parasitológico direto, 74% para RIFI, 79% para o teste rápido com rK39, 88% para o teste ELISA-ASL e 94% para a FC-AFPA. A análise comparativa dos testes avaliados demonstrou que há maior concordância entre os testes sorológicos entre si, do que entre os testes sorológicos e o exame direto, devido a sua baixa sensibilidade. Foi também realizada a comparação entre os resultados dos testes sorológicos em relação ao resultado do teste parasitológico direto. Entretanto, nossos resultados mostraram que o desempenho dos testes foi semelhante independente do resultado do exame direto. Além disso, nosso estudo avaliou o desempenho de dois algoritmos para diagnóstico da LV baseados apenas em testes sorológicos. O primeiro deles utilizando a RIFI como teste de inicial, uma vez que este teste é disponibilizado pelo Ministério da Saúde (MS) para os laboratórios de referência em diagnóstico de LV e um segundo utilizando o teste rápido rK39, que tem sido recentemente sugerido como teste de triagem pelo MS. A análise dos dados demonstrou que o algoritmo para o diagnóstico da LV humana que apresentou melhor desempenho, ou seja, todos os casos foram detectados, foi aquele que utilizou o teste rápido como teste inicial, seguido de FC-AFPA / The routine diagnosis of human visceral leishmaniasis (VL) is usually based on clinical and epidemiologic parameters associated to parasitological and/or immunological tests. Being a fatal disease if not treated, the search for more effective, easy to perform, simple, affordable, and fast diagnostic methods, is necessary, decreasing the time to obtain results. Therefore, in this study the performance of different methods already used in the routine or proposed as alternative tools to the diagnose of VL was evaluated, which included the direct parasite detection (DPD) on bone marrow aspirates, indirect immunofluorescent assay (IFA), rK39 rapid test (Kalazar Detect®), ELISA test using L.chagasi soluble antigen, and immunofluorescence by flow cytometry (FC-AFPA). Seventy-seven biological specimens (bone marrow and serum) from patients with clinical diagnosis of VL, treated, and cured were assessed. The sensitivity of evaluated tests was 48% for DPD, 74% for IFA, 79% for rK39 rapid test, 88% for ELISA-SLA, and 94% for FC-AFPA. The comparative analysis demonstrated higher concordance among serological tests in comparison to serological tests and DPD, due to the low sensitivity of the latter. It was also done the comparison between the results of serological tests and direct examination. However, our results showed that the performance of tests was similar regardless of DPD results. In addition, our study evaluated the performance of two algorithms for the diagnosis of VL based only on serological tests. The first of them using IFA as a initial test, since this is the test provided by the Ministry of Health (MH) for reference laboratories for diagnosis of VL, and a second algorithm using the rK39 rapid test, that has recently been suggested as a screening test by the MH. It was demonstrated that the algorithm presenting the best performance, that is, all the cases were detected, was the one using rapid test as initial test followed by FC-AFPA