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Kumar A, Singh VK, Madhukar P, Tiwari R, Roy R, Rajneesh, Mehrotra S, Sundar S, Kumar R. Evaluation of blood based quantitative PCR as a molecular diagnostic tool for post kala-azar dermal leishmaniasis (PKDL). Mol Biol Rep 2024; 51:716. [PMID: 38824237 DOI: 10.1007/s11033-024-09640-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 05/13/2024] [Indexed: 06/03/2024]
Abstract
BACKGROUND Post kala-azar dermal leishmaniasis (PKDL) is a consequential dermal manifestation of visceral leishmaniasis (VL), serving as a parasite reservoir. The traditional diagnostic approach, which requires an invasive skin biopsy is associated with inherent risks and necessitates skilled healthcare practitioners in sterile settings. There is a critical need for a rapid, less invasive method for Leishmania detection. The main objective of this study was to evaluate and compare the diagnostic efficacy of PCR and qPCR in detecting PKDL, utilizing both skin and blood samples and to assess the utility of blood samples for molecular diagnosis. METHODS AND RESULTS 73 individuals exhibiting clinical symptoms of PKDL and who had tested positive for rK39 rapid diagnostic test (RDT) were enrolled in this study. For the diagnosis of PKDL, both PCR and real-time quantitative PCR (qPCR), employing SYBR Green and TaqMan assays, were performed on blood and skin matched samples. qPCR results using both TaqMan and SYBR Green assay, indicated higher parasite loads in the skin compared to blood, as evident by the Ct values. Importantly, when blood samples were used for PKDL diagnosis by qPCR, an encouraging sensitivity of 69.35% (TaqMan assay) and 79.36% (SYBR Green) were obtained, compared to 8.2% with conventional PCR. CONCLUSION The findings of the study suggest the potential utility of blood for molecular diagnosis by qPCR, offering a less invasive alternative to skin biopsies in field setting for the early detection of parasitaemia in PKDL patients and effective management and control of the disease.
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Affiliation(s)
- Awnish Kumar
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Vishal K Singh
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Prasoon Madhukar
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Rahul Tiwari
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Ritirupa Roy
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Rajneesh
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Sanjana Mehrotra
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Shyam Sundar
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Rajiv Kumar
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221005, India.
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2
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Ghosh P, Chowdhury R, Faisal K, Khan MAA, Hossain F, Rahat MA, Chowdhury MAA, Mithila NT, Kamal M, Maruf S, Nath R, Kobialka RM, Ceruti A, Cameron M, Duthie MS, Wahed AAE, Mondal D. Evaluation of a Point-of-Need Molecular Diagnostic Tool Coupled with Rapid DNA Extraction Methods for Visceral Leishmaniasis. Diagnostics (Basel) 2023; 13:3639. [PMID: 38132223 PMCID: PMC10742398 DOI: 10.3390/diagnostics13243639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/23/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023] Open
Abstract
A rapid, cost-effective, and simple nucleic acid isolation technique coupled with a point-of-need DNA amplification assay is a desirable goal for programmatic use. For diagnosis of Visceral Leishmaniasis (VL), Recombinase Polymerase Amplification (RPA) rapid tests for the detection of Leishmania DNA are versatile and have operational advantages over qPCR. To facilitate the delivery of the RPA test at point-of-need for VL diagnosis, we compared two rapid DNA extraction methods, SwiftDx (SX) and an in-house Boil and Spin (BS) method, coupled with RPA amplification, versus more widely used methods for DNA extraction and amplification, namely Qiagen (Q) kits and qPCR, respectively. A total of 50 confirmed VL patients and 50 controls, matched for age and gender, were recruited from Mymensingh, Bangladesh, a region highly endemic for VL. Blood samples were collected from each participant and DNA was extracted using Q, SX and BS methods. Following DNA extraction, qPCR and RPA assays were performed to detect L. donovani in downstream analysis. No significant differences in sensitivity of the RPA assay were observed between DNA extraction methods, 94.00% (95% CI: 83.45-98.75%), 90% (95% CI: 78.19-96.67%), and 88% (95% CI: 75.69-95.47%) when using Q, SX, and BS, respectively. Similarly, using qPCR, no significant differences in sensitivity were obtained when using Q or SX for DNA extraction, 94.00% (95% CI: 83.45-98.75%) and 92.00% (80.77-97.78%), respectively. It is encouraging that RPA and qPCR showed excellent agreement (k: 0.919-0.980) when different extraction methods were used and that the DNA impurities using BS had no inhibitory effect on the RPA assay. Furthermore, significantly higher DNA yields were obtained using SX and BS versus Q; however, a significantly higher parasite load was detected using qPCR when DNA was extracted using Q versus SX. Considering the cost, execution time, feasibility, and performance of RPA assay, rapid extraction methods such as the Boil and Spin technique appear to have the potential for implementation in resource-limited endemic settings. Further clinical research is warranted prior to broader application.
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Affiliation(s)
- Prakash Ghosh
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Rajashree Chowdhury
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Khaledul Faisal
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Md. Anik Ashfaq Khan
- Institute of Animal Hygiene and Veterinary Public Health, Leipzig University, D-04103 Leipzig, Germany; (M.A.A.K.); (R.M.K.); (A.C.)
| | - Faria Hossain
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Md. Abu Rahat
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Md. Arko Ayon Chowdhury
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Nishad Tasnim Mithila
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Mostafa Kamal
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Shomik Maruf
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Rupen Nath
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
| | - Rea Maja Kobialka
- Institute of Animal Hygiene and Veterinary Public Health, Leipzig University, D-04103 Leipzig, Germany; (M.A.A.K.); (R.M.K.); (A.C.)
| | - Arianna Ceruti
- Institute of Animal Hygiene and Veterinary Public Health, Leipzig University, D-04103 Leipzig, Germany; (M.A.A.K.); (R.M.K.); (A.C.)
| | - Mary Cameron
- London School of Hygiene and Tropical Medicine, University of London, London WC1E 7HT, UK;
| | | | - Ahmed Abd El Wahed
- Institute of Animal Hygiene and Veterinary Public Health, Leipzig University, D-04103 Leipzig, Germany; (M.A.A.K.); (R.M.K.); (A.C.)
| | - Dinesh Mondal
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh; (R.C.); (K.F.); (F.H.); (M.A.R.); (M.A.A.C.).; (N.T.M.); (M.K.); (S.M.); (R.N.); (D.M.)
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3
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Ghosh D, Rashid MU, Sagar SK, Uddin MR, Maruf S, Ghosh P, Chowdhury R, Rahat MA, Islam MN, Aktaruzzaman MM, Sohel ANM, Banjara MR, Kroeger A, Aseffa A, Mondal D. Epidemiological, serological, and entomological aspects of visceral leishmaniasis (VL) in suspected new VL foci in Bangladesh. Acta Trop 2023; 248:107021. [PMID: 37716668 DOI: 10.1016/j.actatropica.2023.107021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/14/2023] [Accepted: 09/13/2023] [Indexed: 09/18/2023]
Abstract
The study aimed to explore epidemiological, serological, and entomological aspects of visceral leishmaniasis (VL) in suspected new VL foci and assess the knowledge, attitude, and practices of the community living in the alleged new VL foci. The study investigated new visceral leishmaniasis (VL) cases reported between 2019 and 2020 in four sub-districts (Dharmapasha, Hakimpur, Islampur and Savar) where we tested 560 members using the rK39 rapid test and conducted vector collections in six neighbouring houses of the index cases to assess sandfly density and distribution, examined sandflies' infection, and determined the spatial relationship with VL infection. Furthermore, we highlighted the importance of early detection, and community awareness in controlling the spread of the disease. The study screened 1078 people from 231 households in the four sub-districts for fever, history of visceral leishmaniasis (VL), and PKDL-like skin lesions. Among sub-districts, positivity rate for rK39 rapid test was highest (3.5 %) in Savar. Sandflies were present across all areas except in Dharmapasha, but all 21 collected female P. argentipes sandflies were negative for Leishmania parasite DNA. We found one person from Islampur with a history of VL, and one from Islampur and another one from Savar had PKDL. After the awareness intervention, more people became familiar with VL infection (91.2 %), and their knowledge concerning sandflies being the vector of the disease and the risk of having VL increased significantly (30.1 %). The study found no active case in the suspected new foci, but some asymptomatic individuals were present. As sandfly vectors exist in these areas, the National Kala-azar Elimination Programme (NKEP) should consider these areas as kala-azar endemic and initiate control activities as per national guidelines.
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Affiliation(s)
- Debashis Ghosh
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka 1212, Bangladesh
| | - Md Utba Rashid
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka 1212, Bangladesh
| | - Soumik Kha Sagar
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka 1212, Bangladesh
| | - Md Rasel Uddin
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka 1212, Bangladesh
| | - Shomik Maruf
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka 1212, Bangladesh
| | - Prakash Ghosh
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka 1212, Bangladesh
| | - Rajashree Chowdhury
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka 1212, Bangladesh
| | - Md Abu Rahat
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka 1212, Bangladesh
| | - Md Nazmul Islam
- Communicable Disease Control (CDC), Directorate General of Health Services (DGHS), Mohakhali, Dhaka 1212, Bangladesh
| | - M M Aktaruzzaman
- Communicable Disease Control (CDC), Directorate General of Health Services (DGHS), Mohakhali, Dhaka 1212, Bangladesh
| | - Abu Nayeem Mohammad Sohel
- Communicable Disease Control (CDC), Directorate General of Health Services (DGHS), Mohakhali, Dhaka 1212, Bangladesh
| | - Megha Raj Banjara
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, Geneva, Switzerland; Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu, Nepal
| | - Axel Kroeger
- University of Freiburg, Centre for Medicine and Society, Freiburg, Germany
| | - Abraham Aseffa
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, Geneva, Switzerland
| | - Dinesh Mondal
- Nutrition Research Division (NRD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka 1212, Bangladesh.
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4
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Louizi C, Khan MAA, Faisal K, Chowdhury R, Ghosh P, Hossain F, Nisansala T, Ranasinghe S, Moreno J, Alvar J, Mondal D, Buhl T, Lüder CGK, Abd El Wahed A. Assessment of pan-Leishmania detection by recombinase polymerase amplification assay. Diagn Microbiol Infect Dis 2023; 105:115862. [PMID: 36493571 DOI: 10.1016/j.diagmicrobio.2022.115862] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 11/08/2022] [Accepted: 11/12/2022] [Indexed: 11/18/2022]
Abstract
The spread of vector habitats along with increasing human mobility can introduce atypical Leishmania species and hence can challenge existing diagnostic practices for rapid detection of active infection with species outside the narrow target range. Here we assessed the pan-Leishmania detection ability of isothermal recombinase polymerase amplification (RPA) assays targeting 18S rRNA gene, cathepsin L-like cysteine proteinase B (Cpb) gene, and kinetoplast minicircle DNA (kDNA) regions. While the lowest limit of detection of the 18S rRNA-RPA and Cpb-RPA assays were estimated as 12 and 17 standard DNA molecules, respectively, both assays could amplify genomic DNA of 7 pathogenic Leishmania species. Evaluation of 18S rRNA-RPA and our previously developed kDNA-RPA assays on 70 real-time PCR-positive leishmaniasis samples of varying pathologies resulted in sensitivity rates of 35.71% and 88.57%, respectively, while the combined sensitivity was 98.57%. Combinatorial application of 18S rRNA-RPA and kDNA-RPA assays can be recommended for further diagnostic assessments.
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Affiliation(s)
- Chiheb Louizi
- Institute for Medical Microbiology and Virology, University Medical Center Goettingen, Georg-August University, Göttingen, Germany
| | - Md Anik Ashfaq Khan
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, Leipzig, Germany; Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, Dhaka, Bangladesh.
| | - Khaledul Faisal
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, Dhaka, Bangladesh
| | - Rajashree Chowdhury
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, Dhaka, Bangladesh
| | - Prakash Ghosh
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, Dhaka, Bangladesh
| | - Faria Hossain
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, Dhaka, Bangladesh
| | - Thilini Nisansala
- Faculty of Veterinary Medicine, Universiti Malaysia Kelantan, Pengkalan Chepa, Kota Baru, Kelantan, Malaysia; Faculty of Medical Sciences, University of Sri Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka
| | - Shalindra Ranasinghe
- Faculty of Medical Sciences, University of Sri Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka
| | - Javier Moreno
- WHO Collaborating Center for Leishmaniasis, National Center for Microbiology, Instituto de Salud Carlos III, Madrid, Spain
| | - Jorge Alvar
- Royal Academy of Medicine of Spain, Madrid, Spain
| | - Dinesh Mondal
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, Dhaka, Bangladesh; Laboratory Sciences and Services Division, International Centre for Diarrheal Disease Research Bangladesh, Dhaka, Bangladesh
| | - Timo Buhl
- Department of Dermatology, Venereology and Allergology, University Medical Centre Göttingen, Georg-August University, Göttingen, Germany
| | - Carsten G K Lüder
- Institute for Medical Microbiology and Virology, University Medical Center Goettingen, Georg-August University, Göttingen, Germany
| | - Ahmed Abd El Wahed
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, Leipzig, Germany
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Sereno D, Oury B, Geiger A, Vela A, Karmaoui A, Desquesnes M. Isothermal Nucleic Acid Amplification to Detect Infection Caused by Parasites of the Trypanosomatidae Family: A Literature Review and Opinion on the Laboratory to Field Applicability. Int J Mol Sci 2022; 23:ijms23147543. [PMID: 35886895 PMCID: PMC9322063 DOI: 10.3390/ijms23147543] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/03/2022] [Accepted: 07/04/2022] [Indexed: 12/13/2022] Open
Abstract
Isothermal amplification of nucleic acids has the potential to be applied in resource-limited areas for the detection of infectious agents, as it does not require complex nucleic purification steps or specific and expensive equipment and reagents to perform the reaction and read the result. Since human and animal infections by pathogens of the Tryponasomatidae family occur mainly in resource-limited areas with scant health infrastructures and personnel, detecting infections by these methodologies would hold great promise. Here, we conduct a narrative review of the literature on the application of isothermal nucleic acid amplification for Trypanosoma and Leishmania infections, which are a scourge for human health and food security. We highlight gaps and propose ways to improve them to translate these powerful technologies into real-world field applications for neglected human and animal diseases caused by Trypanosomatidae.
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Affiliation(s)
- Denis Sereno
- Institut de Recherche pour le Développement, Université de Montpellier, UMR INTERTRYP IRD, CIRAD, Parasite Infectiology and Public Health Group, 34032 Montpellier, France;
- Correspondence:
| | - Bruno Oury
- Institut de Recherche pour le Développement, Université de Montpellier, UMR INTERTRYP IRD, CIRAD, Parasite Infectiology and Public Health Group, 34032 Montpellier, France;
| | - Anne Geiger
- Centre International de Recherche en Agronomie pour le Développement, Institut de Recherche pour le Développement, Université de Montpellier, UMR INTERTRYP IRD, 34032 Montpellier, France;
| | - Andrea Vela
- One Health Research Group, Facultad de Ciencias de la Salud, Universidad de las Américas-Quito, Calle de los Colimes y Avenida De los Granados, Quito 170513, Ecuador;
| | - Ahmed Karmaoui
- Bioactives (Health and Environmental, Epigenetics Team), Faculty of Sciences and Techniques, Errachidia (UMI), Moroccan Center for Culture and Sciences, University Moulay Ismail, Meknes 50000, Morocco;
| | - Marc Desquesnes
- CIRAD, UMR INTERTRYP, 31076 Toulouse, France;
- INTERTRYP, Université de Montpellier, CIRAD, IRD, 34032 Montpellier, France
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Development of Quantitative Rapid Isothermal Amplification Assay for Leishmania donovani. Diagnostics (Basel) 2021; 11:diagnostics11111963. [PMID: 34829309 PMCID: PMC8625035 DOI: 10.3390/diagnostics11111963] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/12/2021] [Accepted: 10/18/2021] [Indexed: 11/20/2022] Open
Abstract
Quantification of pathogen load, although challenging, is of paramount importance for accurate diagnosis and clinical management of a range of infectious diseases in a point-of-need testing (PONT) scenario such as in resource-limited settings. We formulated a quantification approach to test the standard-curve based absolute quantification ability of isothermal recombinase polymerase amplification (RPA) assay. As a test of principle, a 10-fold dilution series of Leishmania donovani (LD) genomic DNA prepared in nuclease-free-water (NFW), and from culture-spiked-blood (CSB) were tested, and a 15 min assay was performed. A modified algorithm was formulated to derive the detection outcome. The threshold-record times (Tr) in seconds thus obtained were plotted against the initial load of parasite genomes for log-linear regression analysis. The quantitative RPA (Q-RPA) assay was further evaluated against a LD quantitative (q)-PCR assay with DNA extracted from visceral and post-Kala-azar dermal leishmaniasis case specimens and stratified into different ranges of threshold cycle (Ct). The best-fitted regression models were found linear with mean r2/root mean square error (RMSE) values of residual points (in seconds) estimated as 0.996/8.063 and 0.992/7.46 for replicated series of NFW and CSB, respectively. In both series, the lower limit of detection reached less than 0.1 parasite genome equivalent DNA. Absolute agreement between Q-RPA and LD-qPCR was found for test positivity, and strong positive correlations were observed between the Tr and Ct values (r = 0.89; p < 0.0001) as well as between the absolute parasite loads (r = 0.87; p < 0.0001) quantified by respective assays. The findings in this very first Q-RPA assay for leishmaniasis are suggestive of its potential in monitoring LD load in clinical specimens, and the development of rapid Q-RPA assays for other infectious diseases.
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Khan MAA, Faisal K, Chowdhury R, Nath R, Ghosh P, Ghosh D, Hossain F, Abd El Wahed A, Mondal D. Evaluation of molecular assays to detect Leishmania donovani in Phlebotomus argentipes fed on post-kala-azar dermal leishmaniasis patients. Parasit Vectors 2021; 14:465. [PMID: 34503557 PMCID: PMC8428120 DOI: 10.1186/s13071-021-04961-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/17/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Post-kala-azar dermal leishmaniasis (PKDL) caused by Leishmania donovani (LD) is a skin disorder that often appears after treatment of visceral leishmaniasis (VL) patients. PKDL patients are potential reservoirs of LD parasites, which can initiate a new epidemic of anthroponotic VL. Therefore, host infectiousness to its sand fly vector is a critical factor for transmission, and its accurate estimation can facilitate control strategies. At present, conventional microscopy serves as the reference method to detect parasites in its vector. However, low sensitivity of microscopy can be a limiting factor. METHODS In this study, real-time quantitative PCR (LD-qPCR) and recombinase polymerase amplification (LD-RPA) assays were evaluated against microscopy for the detection of LD DNA extracted from live sand flies five days after controlled feeding on PKDL cases. RESULTS The sensitivity of LD-qPCR and LD-RPA assays were found to be 96.43 and 100%, respectively, against microscopy for the selected fed sand flies (n = 28), and an absolute specificity of both molecular tools for apparently unfed sand flies (n = 30). While the proportion of infectious cases among 47 PKDL patients was estimated as 46.81% as defined by microscopic detection of LD in at least one fed sand fly per case, LD-RPA assay evaluation of only the microscopy negative sand flies fed to those 47 PKDL cases estimated an even greater proportion of infectious cases (51.06%). In overall estimation of the infectious cases in retrospective manner, discordance in positivity rate was observed (p < 0.05) between LD-RPA (59.57%) assay and microscopy (46.81%), while LD-RPA had slightly better positivity rate than LD-qPCR (55.32%) as well. CONCLUSIONS Considering the sensitivity, cost, detection time, and field applicability, RPA assay can be considered as a promising single molecular detection tool for investigations pertaining to LD infections in sand flies and/or host infectiousness in PKDL, while it can also be useful in confirmation of microscopy negative sand fly samples.
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Affiliation(s)
- Md Anik Ashfaq Khan
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, An den Tierkliniken 43, 04103, Leipzig, Germany.,Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, 1212, Dhaka, Bangladesh
| | - Khaledul Faisal
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, 1212, Dhaka, Bangladesh
| | - Rajashree Chowdhury
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, 1212, Dhaka, Bangladesh
| | - Rupen Nath
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, 1212, Dhaka, Bangladesh
| | - Prakash Ghosh
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, 1212, Dhaka, Bangladesh
| | - Debashis Ghosh
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, 1212, Dhaka, Bangladesh
| | - Faria Hossain
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, 1212, Dhaka, Bangladesh
| | - Ahmed Abd El Wahed
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, An den Tierkliniken 43, 04103, Leipzig, Germany.
| | - Dinesh Mondal
- Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research Bangladesh, 1212, Dhaka, Bangladesh. .,Laboratory Sciences and Services Division, International Centre for Diarrheal Disease Research Bangladesh, 1212, Dhaka, Bangladesh.
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