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Dahal P, Singh-Phulgenda S, Naylor C, Brack M, Chatterjee M, Alves F, Guerin PJ, Stepniewska K. Design, Conduct, Analysis, and Reporting of Therapeutic Efficacy Studies in Visceral Leishmaniasis: A Systematic Review of Published Reports, 2000-2021. Am J Trop Med Hyg 2024; 111:365-376. [PMID: 38955166 PMCID: PMC11310606 DOI: 10.4269/ajtmh.23-0458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 02/19/2024] [Indexed: 07/04/2024] Open
Abstract
A systematic review (SR) of published efficacy studies in visceral leishmaniasis (VL) was undertaken to describe methodological aspects of design, conduct, analysis, and reporting. Studies published during 2000-2021 and indexed in the Infectious Diseases Data Observatory VL library of clinical studies were eligible for inclusion (N = 89 studies). Of the 89 studies, 40 (44.9%) were randomized, 33 (37.1%) were single-armed, 14 (15.7%) were nonrandomized multiarmed studies, and randomization status was unclear in two (2.2%). After initial screening, disease confirmation was done by microscopy in 26 (29.2%) and by a combination of serology and microscopy in 63 (70.8%). Post-treatment follow-up duration was <6 months in three (3.3%) studies, 6 months in 75 (84.3%), and >6 months in 11 (12.4%) studies. Confirmation of relapse was solely based on clinical suspicion in four (4.5%) studies, parasitological demonstration in 64 (71.9%), using molecular/serological/parasitological method in 6 (6.7%), and there was no information in 15 (16.9%). Of the 40 randomized studies, sample size calculation was reported in only 22 (55.0%) studies. This review highlights substantial variations in definitions adopted for disease diagnosis and therapeutic outcomes suggesting a need for a harmonized trials protocol.
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Affiliation(s)
- Prabin Dahal
- Infectious Diseases Data Observatory, Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Sauman Singh-Phulgenda
- Infectious Diseases Data Observatory, Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Caitlin Naylor
- Infectious Diseases Data Observatory, Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Matthew Brack
- Infectious Diseases Data Observatory, Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Mitali Chatterjee
- Institute of Postgraduate Medical Education & Research, Kolkata, India
| | - Fabiana Alves
- Drugs for Neglected Diseases initiative, Geneva, Switzerland
| | - Philippe J. Guerin
- Infectious Diseases Data Observatory, Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Kasia Stepniewska
- Infectious Diseases Data Observatory, Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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Ivănescu L, Andronic BL, Grigore-Hristodorescu S, Martinescu GV, Mîndru R, Miron L. The immune response in canine and human leishmaniasis and how this influences the diagnosis- a review and assessment of recent research. Front Cell Infect Microbiol 2023; 13:1326521. [PMID: 38149009 PMCID: PMC10749942 DOI: 10.3389/fcimb.2023.1326521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 11/22/2023] [Indexed: 12/28/2023] Open
Abstract
Leishmaniasis is a widespread but still underdiagnosed parasitic disease that affects both humans and animals. There are at least 20 pathogenic species of Leishmania, most of them being zoonotic. The diagnosis of leishmaniasis remains a major challenge, with an important role being played by the species of parasites involved, the genetic background, the immunocompetence of the host. This paper brings to the fore the sensitivity of the balance in canine and human leishmaniasis and addresses the importance of the host's immune response in establishing a correct diagnosis, especially in certain cases of asymptomatic leishmaniasis, or in the situation the host is immunosuppressed or acquired leishmaniasis through vertical transmission. The methods considered as a reference in the diagnosis of leishmaniasis no longer present certainty, the diagnosis being influenced mostly by the immune response of the host, which differs according to the presence of other associated diseases or even according to the breed in dogs. Consequently, the diagnosis and surveillance of leishmaniasis cases remains an open topic, requiring new diagnostic methods adapted to the immunological state of the host.
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Affiliation(s)
- Larisa Ivănescu
- Clinics Department, Faculty of Veterinary Medicine, Iasi University of Life Sciences, Iaşi, Romania
| | - Bianca Lavinia Andronic
- Clinics Department, Faculty of Veterinary Medicine, Iasi University of Life Sciences, Iaşi, Romania
| | | | | | - Raluca Mîndru
- Clinics Department, Faculty of Veterinary Medicine, Iasi University of Life Sciences, Iaşi, Romania
| | - Liviu Miron
- Clinics Department, Faculty of Veterinary Medicine, Iasi University of Life Sciences, Iaşi, Romania
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Takamiya NT, Rogerio LA, Torres C, Leonel JAF, Vioti G, de Sousa Oliveira TMF, Valeriano KC, Porcino GN, de Miranda Santos IKF, Costa CHN, Costa DL, Ferreira TS, Gurgel-Gonçalves R, da Silva JS, Teixeira FR, De Almeida RP, Ribeiro JMC, Maruyama SR. Parasite Detection in Visceral Leishmaniasis Samples by Dye-Based qPCR Using New Gene Targets of Leishmania infantum and Crithidia. Trop Med Infect Dis 2023; 8:405. [PMID: 37624343 PMCID: PMC10457869 DOI: 10.3390/tropicalmed8080405] [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: 07/03/2023] [Revised: 07/26/2023] [Accepted: 07/31/2023] [Indexed: 08/26/2023] Open
Abstract
Visceral leishmaniasis (VL) is a neglected disease considered a serious public health problem, especially in endemic countries. Several studies have discovered monoxenous trypanosomatids (Leptomonas and Crithidia) in patients with VL. In different situations of leishmaniasis, investigations have examined cases of co-infection between Leishmania spp. and Crithidia spp. These coinfections have been observed in a wide range of vertebrate hosts, indicating that they are not rare. Diagnostic techniques require improvements and more robust tools to accurately detect the causative agent of VL. This study aimed to develop a real-time quantitative dye-based PCR (qPCR) assay capable of distinguishing Leishmania infantum from Crithidia-related species and to estimate the parasite load in samples of VL from humans and animals. The primer LinJ31_2420 targets an exclusive phosphatase of L. infantum; the primer Catalase_LVH60-12060_1F targets the catalase gene of Crithidia. Therefore, primers were designed to detect L. infantum and Crithidia sp. LVH60A (a novel trypanosomatid isolated from VL patients in Brazil), in samples related to VL. These primers were considered species-specific, based on sequence analysis using genome data retrieved from the TriTryp database and the genome assembling of Crithidia sp. LVH60A strain, in addition to experimental and clinical data presented herein. This novel qPCR assay was highly accurate in identifying and quantifying L. infantum and Crithidia sp. LVH60A in samples obtained experimentally (in vitro and in vivo) or collected from hosts (humans, dogs, cats, and vectors). Importantly, the screening of 62 cultured isolates from VL patients using these primers surprisingly revealed that 51 parasite cultures were PCR+ for Crithidia sp. In addition, qPCR assays identified the co-infection of L. infantum with Crithidia sp. LVH60A in two new VL cases in Brazil, confirming the suspicion of co-infection in a previously reported case of fatal VL. We believe that the species-specific genes targeted in this study can be helpful for the molecular diagnosis of VL, as well as for elucidating suspected co-infections with monoxenous-like trypanosomatids, which is a neglected fact of a neglected disease.
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Affiliation(s)
- Nayore Tamie Takamiya
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
| | - Luana Aparecida Rogerio
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
| | - Caroline Torres
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
| | - João Augusto Franco Leonel
- Post-Graduate Program in Experimental Epidemiology Applied to Zoonoses at the Faculty of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
| | - Geovanna Vioti
- Post-Graduate Program in Experimental Epidemiology Applied to Zoonoses at the Faculty of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
| | - Tricia Maria Ferreira de Sousa Oliveira
- Post-Graduate Program in Experimental Epidemiology Applied to Zoonoses at the Faculty of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | - Karoline Camila Valeriano
- Ribeirão Preto Medical School, University of São Paulo, FMRP-USP, Ribeirão Preto 14049-900, SP, Brazil
| | | | | | - Carlos H. N. Costa
- Natan Portela Institute of Tropical Diseases, Teresina 64002-510, PI, Brazil
| | | | - Tauana Sousa Ferreira
- Laboratory of Medical Parasitology and Vector Biology, Faculty of Medicine, University of Brasília, Brasília 70910-900, DF, Brazil
| | - Rodrigo Gurgel-Gonçalves
- Laboratory of Medical Parasitology and Vector Biology, Faculty of Medicine, University of Brasília, Brasília 70910-900, DF, Brazil
| | - João Santana da Silva
- Fiocruz-Bi-Institutional Translational Medicine Project, Oswaldo Cruz Foundation, Ribeirão Preto 14040-900, SP, Brazil
| | - Felipe Roberti Teixeira
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
| | - Roque Pacheco De Almeida
- Department of Medicine, Center for Biology and Health Sciences, Federal University of Sergipe (UFS), Aracaju 49060-108, SE, Brazil
| | - José M. C. Ribeiro
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, NIH/NIAID, Rockville, MD 20892, USA
| | - Sandra Regina Maruyama
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
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Pereira LQ, Tanaka SCSV, Ferreira-Silva MM, Gomes FVBAF, Santana MP, Aguiar PR, de Araújo Pereira G, Gómez-Hernández C, Junior VR, De Vito FB, Moraes-Souza H. Leukoreduction as a control measure in transfusion transmission of visceral leishmaniasis. Transfusion 2023; 63:1044-1049. [PMID: 36929836 DOI: 10.1111/trf.17308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 01/18/2023] [Accepted: 01/30/2023] [Indexed: 03/18/2023]
Abstract
BACKGROUND Asymptomatic visceral leishmaniasis (VL) infection is a risk for transfusion safety. Leukoreduction has been an alternative for the prevention of some blood-borne diseases, including VL. This study aimed to evaluate the role of leukoreduction of cellular blood components as a control measure for transfusional VL transmission. RESEARCH DESIGN AND METHODS A total of 161 polytransfused patients with non-leukoreduced blood components (HNL), 95 polytransfused with leukoreduced blood components (LH), and 202 non-transfused (NT) from endemic regions for VL and with a similar epidemiological profile. The detection of antibodies against VL was performed by ELISA and the presence of the parasite was investigated by real-time PCR. Statistical significance was defined as p < .05. RESULTS When comparing three groups, ELISA results were statistically significant (p = .0065). The residual analysis of ELISA showed statistically significant for the HNL group compared to the general group (p = .002; OR: 5.6; CI: 1.7-25.8), demonstrating that individuals who received non-leukoreduced transfusions are five times more likely to acquire Leishmania infantum infection than the general. DISCUSSION Higher prevalence in the group with HNL and low prevalence in those who received LH, similar to NT patients, highlight the risk of transfusional VL transmission and reinforce the role of leukoreduction in its prevention.
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Affiliation(s)
- Loren Queli Pereira
- Laboratory of Hematological Research, Triângulo Mineiro Federal University, Uberaba, Brazil
| | | | | | | | - Melissa Palis Santana
- Government of Piauí, Hemopi - Hematology and Hemotherapy Center of the State of Piauí, Teresina, Brazil
| | - Paulo Roberto Aguiar
- Hemominas Foundation, Regional Blood Center of Montes Claros (Minas Gerais), Montes Claros, Brazil
| | - Gilberto de Araújo Pereira
- Department of Nursing in Education and Community Health, Federal University of Triângulo Mineiro, Uberaba, Brazil
| | | | | | | | - Helio Moraes-Souza
- Laboratory of Hematological Research, Triângulo Mineiro Federal University, Uberaba, Brazil
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Laboratory diagnostics for human Leishmania infections: a polymerase chain reaction-focussed review of detection and identification methods. Parasit Vectors 2022; 15:412. [PMID: 36335408 PMCID: PMC9636697 DOI: 10.1186/s13071-022-05524-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/02/2022] [Indexed: 11/08/2022] Open
Abstract
Leishmania infections span a range of clinical syndromes and impact humans from many geographic foci, but primarily the world's poorest regions. Transmitted by the bite of a female sand fly, Leishmania infections are increasing with human movement (due to international travel and war) as well as with shifts in vector habitat (due to climate change). Accurate diagnosis of the 20 or so species of Leishmania that infect humans can lead to the successful treatment of infections and, importantly, their prevention through modelling and intervention programs. A multitude of laboratory techniques for the detection of Leishmania have been developed over the past few decades, and although many have drawbacks, several of them show promise, particularly molecular methods like polymerase chain reaction. This review provides an overview of the methods available to diagnostic laboratories, from traditional techniques to the now-preferred molecular techniques, with an emphasis on polymerase chain reaction-based detection and typing methods.
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Diagnosis of Visceral Leishmaniasis in an Elimination Setting: A Validation Study of the Diagnostic Algorithm in India. Diagnostics (Basel) 2022; 12:diagnostics12030670. [PMID: 35328223 PMCID: PMC8947297 DOI: 10.3390/diagnostics12030670] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/02/2022] [Accepted: 03/07/2022] [Indexed: 02/01/2023] Open
Abstract
Visceral leishmaniasis (VL) is on the verge of elimination on the Indian subcontinent. Nonetheless, the currently low VL-incidence setting brings along new challenges, one of which is the validity of the diagnostic algorithm, based on a combination of suggestive clinical symptoms in combination with a positive rK39 Rapid Diagnostic Test (RDT). With this study, we aimed to assess the positive predictive value of the diagnostic algorithm in the current low-endemic setting in India by re-assessing newly diagnosed VL patients with a qPCR analysis on venous blood as the reference test. In addition, we evaluated the specificity of the rK39 RDT by testing non-VL cases with the rK39 RDT. Participants were recruited in Bihar and Uttar Pradesh, India. VL patients diagnosed based on the diagnostic algorithm were recruited through six primary health care centers (PHCs); non-VL cases were identified through a door-to-door survey in currently endemic, previously endemic, and non-endemic clusters, and tested with rK39 RDT, as well as—if positive—with qPCR on peripheral blood. We found that 95% (70/74; 95% CI 87–99%) of incident VL cases diagnosed at the PHC level using the current diagnostic algorithm were confirmed by qPCR. Among 15,422 non-VL cases, 39 were rK39 RDT positive, reflecting a specificity of the test of 99.7% (95% CI 99.7–99.8%). The current diagnostic algorithm combining suggestive clinical features with a positive rK39 RDT still seems valid in the current low-endemic setting in India.
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Ibarra-Meneses AV, Corbeil A, Wagner V, Onwuchekwa C, Fernandez-Prada C. Identification of asymptomatic Leishmania infections: a scoping review. Parasit Vectors 2022; 15:5. [PMID: 34983616 PMCID: PMC8727076 DOI: 10.1186/s13071-021-05129-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/11/2021] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Asymptomatic Leishmania infection may play an important role in the transmission of the parasite in endemic areas. At present there is no consensus on the definition of asymptomatic Leishmania infection, nor is there a safe and accessible gold standard test for its identification. METHODS This paper presents a scoping review to summarize definitions of asymptomatic Leishmania infection found in the literature, as well as to detail the approach (molecular, serological, cellular, and/or parasitological tests) used by researchers to identify this asymptomatic population. A scoping review of published and gray literature related to asymptomatic Leishmania infection was conducted; retrieved citations were screened based on predefined eligibility criteria, and relevant data items were extracted from eligible articles. The analysis is descriptive and is presented using tables, figures, and thematic narrative synthesis. RESULTS We conducted a screening of 3008 articles, of which 175 were selected for the full review. Of these articles, we selected 106 that met the inclusion criteria. These articles were published between 1991 and 2021, and in the last 5 years, up to 38 articles were reported. Most of the studies were conducted in Brazil (26%), Spain (14%), India (12%), Bangladesh (10%), and Ethiopia (7%). Of the studies, 84.9% were conducted in the immunocompetent population, while 15.1% were conducted in the immunosuppressed population (HIV, immunosuppressive drugs, and organ transplantation population). We report 14 different techniques and 10 strategies employed by researchers to define asymptomatic Leishmania infection in an endemic area. CONCLUSIONS The definition of asymptomatic Leishmania infection is not unified across the literature, but often includes the following criteria: residence (or extended stay) in a Leishmania-endemic area, no reported signs/symptoms compatible with leishmaniasis, and positive on a combination of serological, molecular, cellular, and/or parasitological tests. Caution is recommended when comparing results of different studies on the subject of asymptomatic infections, as the reported prevalence cannot be confidently compared between areas due to the wide variety of tests employed by research groups. More research on the importance of asymptomatic immunosuppressed and immunocompetent Leishmania-positive populations in leishmaniasis epidemiology is required.
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Affiliation(s)
- Ana Victoria Ibarra-Meneses
- Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada.,The Research Group on Infectious Diseases in Production Animals (GREMIP), Faculty of Veterinary Medicine, Université de Montréal, Saint Hyacinthe, Canada
| | - Audrey Corbeil
- Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada.,The Research Group on Infectious Diseases in Production Animals (GREMIP), Faculty of Veterinary Medicine, Université de Montréal, Saint Hyacinthe, Canada
| | - Victoria Wagner
- Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada.,The Research Group on Infectious Diseases in Production Animals (GREMIP), Faculty of Veterinary Medicine, Université de Montréal, Saint Hyacinthe, Canada
| | - Chukwuemeka Onwuchekwa
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic, University of Barcelona, Barcelona, Spain
| | - Christopher Fernandez-Prada
- Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada. .,The Research Group on Infectious Diseases in Production Animals (GREMIP), Faculty of Veterinary Medicine, Université de Montréal, Saint Hyacinthe, Canada.
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Mediterranean visceral leishmaniasis : update on biological diagnosis. LA TUNISIE MEDICALE 2022; 100:13-26. [PMID: 35822327 PMCID: PMC8996314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/29/2022]
Abstract
Visceral leishmaniasis (VL) is a severe life threatening parasitosis requiring early management of cases. It is an emerging disease in the Mediterranean region with a spread of endemic areas and an increase in case incidence. The patient profile has also evolved with more affected adults, presenting generally non-specific symptoms. Hence the interest of a systematic biological confirmation. The microscopic detection of Leishmania amastigotes in bone marrow aspirates (BMA) smears is the gold standard diagnostic technique. However, it requires invasive sampling. Serological tests searching for specific antibodies remain highly contributory, but their interpretation must always take into account the epidemiological context and the patient's clinical and biological features. Currently, the Western-Blot represents the most specific serological technique for diagnostic confirmation. VL diagnosis has greatly improved by the introduction of both rapid diagnostic tests (RDTs) and molecular biological techniques. RDTs using recombinant rk39 antigen are easy to perform and deliver results in less than 30 minutes. Real-time PCR (Polymerase Chain Reaction) is currently retained as the best technique for VL diagnosis. It is efficient on simple blood samples, allowing to avoid invasive BMA needed for microscopy. In addition, real time PCR estimates parasite load which is helpful for the post-treatment follow-up. In any case, the choice of techniques to be used should be strategic and adapted to the local epidemiology as well as to the means available.
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Castelli G, Bruno F, Reale S, Catanzaro S, Valenza V, Vitale F. Molecular Diagnosis of Leishmaniasis: Quantification of Parasite Load by a Real-Time PCR Assay with High Sensitivity. Pathogens 2021; 10:pathogens10070865. [PMID: 34358015 PMCID: PMC8308825 DOI: 10.3390/pathogens10070865] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/05/2021] [Accepted: 07/06/2021] [Indexed: 12/21/2022] Open
Abstract
Real-time PCR was developed to quantify Leishmania infantum kinetoplast DNA and optimized to achieve a sensitivity of 1 parasite/mL. For this purpose, we cloned the conserved kDNA fragment of 120 bp into competent cells and correlated them with serial dilutions of DNA extracted from reference parasite cultures calculating that a parasite cell contains approximately 36 molecules of kDNA. This assay was applied to estimate parasite load in clinical samples from visceral, cutaneous leishmaniasis patients and infected dogs and cats comparing with conventional diagnosis. The study aimed to propose a real-time PCR for the detection of Leishmania DNA from clinical samples trying to solve the diagnostic problems due to the low sensitivity of microscopic examination or the low predictive values of serology and resolve problems related to in vitro culture. The quantitative PCR assay in this study allowed detection of Leishmania DNA and quantification of considerably low parasite loads in samples that had been diagnosed negative by conventional techniques. In conclusion, this quantitative PCR can be used for the diagnosis of both human, canine and feline Leishmaniasis with high sensitivity and specificity, but also for evaluating treatment and the endpoint determination of leishmaniasis.
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Affiliation(s)
- Germano Castelli
- Centro di Referenza Nazionale per le Leishmaniosi (C.Re.Na.L.), OIE Leishmania Reference Laboratory, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (G.C.); (S.C.); (V.V.); (F.V.)
| | - Federica Bruno
- Centro di Referenza Nazionale per le Leishmaniosi (C.Re.Na.L.), OIE Leishmania Reference Laboratory, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (G.C.); (S.C.); (V.V.); (F.V.)
- Correspondence: ; Tel.: +39-0916565368
| | - Stefano Reale
- Laboratorio di Tecnologie Diagnostiche Innovative (TDI), Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy;
| | - Simone Catanzaro
- Centro di Referenza Nazionale per le Leishmaniosi (C.Re.Na.L.), OIE Leishmania Reference Laboratory, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (G.C.); (S.C.); (V.V.); (F.V.)
| | - Viviana Valenza
- Centro di Referenza Nazionale per le Leishmaniosi (C.Re.Na.L.), OIE Leishmania Reference Laboratory, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (G.C.); (S.C.); (V.V.); (F.V.)
| | - Fabrizio Vitale
- Centro di Referenza Nazionale per le Leishmaniosi (C.Re.Na.L.), OIE Leishmania Reference Laboratory, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (G.C.); (S.C.); (V.V.); (F.V.)
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Pediatric visceral leishmaniasis: a retrospective study to propose the diagnostic tests algorithm in southern Iran. Parasitol Res 2021; 120:1447-1453. [PMID: 33576903 DOI: 10.1007/s00436-021-07067-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 01/20/2021] [Indexed: 10/22/2022]
Abstract
Leishmania infantum is the most common cause of visceral leishmaniasis (VL) in Iran, where mainly the patients are children under the age of 5 years. Timely, less invasive, and accurate diagnosis and proper treatment of the disease are necessary. This retrospective study aimed to search for a less invasive but robust algorithm on VL diagnostic tests in children. Four hundred and fifteen patients with clinical suspicion of VL, 50 healthy children from VL endemic areas, 46 healthy individuals from non-endemic VL areas, and 47 non-VL diseases were tested using three diagnostic tests: indirect immunofluorescent antibody test (IFAT), rK39-rapid diagnostic test (rK39-RDT), and quantitative PCR (qPCR). One hundred and two suspected VL cases were positive in at least one test and were cured after receiving appropriate treatment. Of these 102 VL patients, 94 were positive in qPCR, 84 in IFAT, and 79 in rK39-RDT. None of the tests detected all the patients, but overall, qPCR is capable of detecting more VL patients than serological tests, i.e., 92.2%, compared to IFAT, 82.4%, and rK39, 77.5%. There was only a significant difference between the sensitivity of qPCR and rK39-RDT (p = 0.024). The specificity was 100% for qPCR and IFAT (≥128) and 98.6% for rK39-RDT. qPCR alone is capable of detecting most of the VL-suspected children. Serological tests like IFAT and rk39-RDT are recommended to increase the overall sensitivity of detection in patients with a negative molecular test. Combining qPCR with a serological test (IFAT or rK39-RDT) can help diagnose 98% of VL. In laboratories without molecular facilities, we recommend testing with the combination of rK39-RDT and IFAT yielding a combined sensitivity of 93.1% equivalent to that of qPCR in our study.
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Pereira LQ, Ferreira-Silva MM, Ratkevicius CMA, Gómez-Hérnandez C, De Vito FB, Tanaka SCSV, Rodrigues Júnior V, Moraes-Souza H. Identification of Leishmania infantum in blood donors from endemic regions for visceral leishmaniasis. Parasitology 2021; 148:110-114. [PMID: 33143775 PMCID: PMC11010041 DOI: 10.1017/s0031182020001936] [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: 06/19/2020] [Revised: 09/06/2020] [Accepted: 10/11/2020] [Indexed: 11/05/2022]
Abstract
Visceral leishmaniasis is an endemic protozoonosis observed in over 60 countries, with over 500 000 new cases recorded annually. Although the diagnostic procedure of its symptomatic forms is well established, for asymptomatic patients, who represent about 85% of those infected, there is no consensus on the best method for its identification. Recent studies have presented molecular techniques as viable identification methods, with good sensitivity and specificity indices in asymptomatic individuals. Therefore, we aimed to use molecular methods to assess their effectiveness in identifying the presence of asymptomatic infection by Leishmania infantum (L. infantum) individuals from endemic regions of Brazil. Screening was performed by real-time polymerase chain reaction (qPCR) and confirmed by sequencing the cytochrome B gene. Of the 127 samples [from 608 blood donors who had participated in a previous study, of which 34 were positive by the enzyme-linked immunosorbent assay (ELISA) rK39] tested by qPCR, 31 (24.4%) were positive. In the sequencing of 10 qPCR-positive samples, five were identified as L. infantum. Complimentary samples of the ELISA rK39 and conventional PCR showed only reasonable and low agreement with qPCR, respectively. The qPCR confirmed the presence of infection in five of the 10 sequenced samples, ELISA confirmed three, and the conventional PCR confirmed none.
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Affiliation(s)
- Loren Queli Pereira
- Laboratory of Hematological Research of the Triângulo Mineiro Federal University and Uberaba Regional Blood Center – Hemominas Fundation, Uberaba, Minas Gerais, Brazil
| | - Márcia Maria Ferreira-Silva
- Laboratory of Hematological Research of the Triângulo Mineiro Federal University and Uberaba Regional Blood Center – Hemominas Fundation, Uberaba, Minas Gerais, Brazil
| | | | - César Gómez-Hérnandez
- Laboratory of Immunology, Triângulo Mineiro Federal University, Uberaba, Minas Gerais, Brazil
| | - Fernanda Bernadelli De Vito
- Laboratory of Hematological Research of the Triângulo Mineiro Federal University and Uberaba Regional Blood Center – Hemominas Fundation, Uberaba, Minas Gerais, Brazil
| | - Sarah Cristina Sato Vaz Tanaka
- Laboratory of Hematological Research of the Triângulo Mineiro Federal University and Uberaba Regional Blood Center – Hemominas Fundation, Uberaba, Minas Gerais, Brazil
| | | | - Helio Moraes-Souza
- Laboratory of Hematological Research of the Triângulo Mineiro Federal University and Uberaba Regional Blood Center – Hemominas Fundation, Uberaba, Minas Gerais, Brazil
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Wu Y, Tian X, Song N, Huang M, Wu Z, Li S, Waterfield NR, Zhan B, Wang L, Yang G. Application of Quantitative PCR in the Diagnosis and Evaluating Treatment Efficacy of Leishmaniasis. Front Cell Infect Microbiol 2020; 10:581639. [PMID: 33117735 PMCID: PMC7575730 DOI: 10.3389/fcimb.2020.581639] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 09/11/2020] [Indexed: 11/21/2022] Open
Abstract
Leishmaniasis is still a serious neglected tropical disease that may cause death in infected individuals. At present, the clinical diagnosis and treatment monitoring still rely on parasitological culture and microscopy that needs experienced technicians. The low sensitivity and inconvenience of microscopic examination could cause misdiagnosis and relapse of leishmaniasis. There is an urgent need for developing a sensitive and easily operated diagnostic method for the diagnosis and disease management of leishmaniasis. Thus, a quantitative real-time PCR (qPCR) based on the conversed regions of kinetoplast minicircle DNA (mkDNA) of Leishmania spp. was developed to detect different species of Leishmania. The designed mkDNA-based qPCR was able to detect as low as one copy of Leishmania mkDNA or DNA from single parasite. It also detected Pan-Leishmania protozoa including Leishmania donovani, Leishmania infantum and Leishmania major without cross-reaction with other pathogen DNAs available in our lab. This method was clinically applied to quantitatively detect skin lesion samples from 20 cutaneous leishmaniasis (CL) and bone marrow and/or PBMC samples from 30 current and cured visceral leishmaniasis (VL) patients, and blood samples from 11 patients with other infections and 5 normal donors as well. Total 20 skin lesion samples from current CL patients and 20 bone marrow and/or PBMC samples from current VL patients were all detected as positive with qPCR without cross-reaction with samples from patients with malaria, brucellosis and dengue or normal donors. Two VL patients with parasite converted to microscopically negative after treatment were detected positive with qPCR. The patients with bigger skin lesion in CL and higher level of immunoglobulin or splenomegaly in VL, had the higher parasite load detected by qPCR. The parasite load was significantly reduced after treatment. In conclusion, the mkDNA-based qPCR assay that we developed in this study can be used not only for diagnosis of both cutaneous and visceral leishmaniasis with high sensitivity and specificity, but also for evaluating the severity and treatment efficacy of this disease, presenting a rapid and accurate tool for clinical surveillance, treatment monitoring and the end point determination of leishmaniasis.
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Affiliation(s)
- Yun Wu
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Beijing Institute of Tropical Medicine, Beijing, China
| | - Xiaojun Tian
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Beijing Institute of Tropical Medicine, Beijing, China
| | - Nan Song
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Beijing Institute of Tropical Medicine, Beijing, China
| | - Minjun Huang
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Beijing Institute of Tropical Medicine, Beijing, China
| | - Zhaoyong Wu
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Beijing Institute of Tropical Medicine, Beijing, China
| | - Shaogang Li
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Beijing Institute of Tropical Medicine, Beijing, China
| | | | - Bin Zhan
- Department of Pediatrics and National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, United States
| | - Lei Wang
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Beijing Institute of Tropical Medicine, Beijing, China
| | - Guowei Yang
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Beijing Institute of Tropical Medicine, Beijing, China
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Leishmania ITS1 Is Genetically Divergent in Asymptomatic and Symptomatic Visceral Leishmaniasis: Results of a Study in Southern Iran. J Trop Med 2020; 2020:5351098. [PMID: 32908548 PMCID: PMC7474766 DOI: 10.1155/2020/5351098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 07/13/2020] [Indexed: 11/18/2022] Open
Abstract
It has been documented that the genotypic traits in symptomatic and asymptomatic cases of visceral leishmaniasis (VL) may be different. The current study aimed to find out and compare the genotype and intraspecies diversity of Leishmania Internal Transcribed Spacer 1 (ITS1) from asymptomatic and symptomatic VL cases in southern Iran. Methods. Buffy coat samples from seven VL patients, with clinical signs and symptoms, and seven asymptomatic VL cases, were evaluated in this study. Samples of asymptomatic individuals were obtained from children living in a VL endemic area in southern Iran, while the samples of symptomatic subjects were obtained from patients admitted to hospitals with a diagnosis of VL. DNA was extracted from the buffy coats of the samples and PCR-amplified, targeting the ITS1of Leishmania. The PCR products were sequenced, and the consensus sequences were assembled and multiple-aligned with a set of Leishmania strains retrieved from the GenBank, using Clustal W. The phylogenetic tree was rooted, using MEGAX software, and the diversities based on haplotype and nucleotides, as well as the number of polymorphic sites, were measured using DnaSP v5.0 software. The results of ITS1 sequencing in 5 out of 7 asymptomatic VL cases showed 99.25% to 100% similarity with the Leishmania infantum ITS1 sequence (accessed number: MN648746), and one isolate was considered as just Leishmania sp. In one sample, 99.75% similarity was seen with the ITS1 sequence of Crithidia fasciculata. Of the symptomatic VL patients, the PCR product revealed a 340 bp band corresponding to L. infantum in all of the samples. By analyzing the ITS1 sequences, all seven sequences formed a clade somewhat different from other Leishmania species and considered as Leishmania sp. Haplotype and nucleotide diversity were much more prevalent in symptomatic cases where six haplotypes were seen in the ITS1 of Leishmania from symptomatic patients and only two haplotypes were observed in the samples from asymptomatic cases. The findings of the current study showed that the Leishmania ITS1 from symptomatic VL and asymptomatic cases has significant genetic differences. Besides, infection with Crithidia fasciculata was reported, for the first time, in an asymptomatic case, which deserves further study.
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Conversion of asymptomatic infection to symptomatic visceral leishmaniasis: A study of possible immunological markers. PLoS Negl Trop Dis 2020; 14:e0008272. [PMID: 32555598 PMCID: PMC7326279 DOI: 10.1371/journal.pntd.0008272] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 06/30/2020] [Accepted: 04/07/2020] [Indexed: 12/31/2022] Open
Abstract
Introduction Presence of asymptomatic individuals in endemic areas is common. The possible biomarkers in asymptomatic individuals once they get exposed to infection as well as following conversion to symptomatic disease are yet to be identified.We identified asymptomatic Visceral leishmaniasis (VL) infection amongst rK39+sorted direct agglutination test positive (DAT+) endemic healthy population and confirmed it by quantitative PCR(qPCR).The immunological determinants such as Adenosine deaminase (ADA), Interferon gamma (IFN-γ), Tumour Necrosis Factor alpha (TNF-α) and Interleukin 10 (IL-10)were examined to predict probable biomarkers for conversion to symptomatic VL. Methods Sample size was 5794 healthy individuals from VL endemic region. Antibody tests(DAT &rK39) were performed and later a qPCR assay was employed using kDNA specific primers and probes. Immunological biomarkers examined were ADA level by ADA–MTP kit and quantitative cytokines(IFN-γ, IL-10 and TNF-α) by ELISA. Results 120 asymptomatic individuals of 308 rK39 sero-positives were DAT positive comprising of 56 with previous history and 64 with no history of VL. RT-PCR confirmed asymptomatic VL in 42 sero-positives. These were followed up through repeated qPCR and evaluation of immunological determinants. We observed10 symptomatic cases converted from a total of 42 asymptomatic individuals identified at base-line. The level of ADA, IL-10 and IFN-γ remained consistently high in asymptomatic cases and amongst these, ADA and IL-10 but not IFN-γ remained higher at the development of clinical symptoms into active VL. On the contrary, there was no significant change in the mean concentration of TNF-α at both stages of the disease. Discussion We surmise from our data that considerable proportion of asymptomatic cases can be a reservoir and may play a crucial role in transmission of visceral leishmaniasis in endemic areas. The data also suggests that ADA and IL-10 can serve as a potential biomarker during the conversion of asymptomatic into symptomatic VL. The most threatening form of leishmaniasis is human visceral leishmaniasis, which is caused by L. donovani in Indian subcontinent. The disease accounts for huge annual burden of infectious disease in India. Efforts towards disease elimination programme are far beyond satisfaction and there is need to re-strengthen health monitoring, surveillance programme in endemic areas. There is a greater need to identify asymptomatic individuals amongst endemic healthy control by active surveillance programme. Further, except a few, many asymptomatic subjects become sero-negative without developing VL due to strong inherent cellular immunity possessed by them. This study enumerates use of rK39, DAT and quantitative PCR(qPCR) in asymptomatic detection and then evaluate immunological biomarkers(Adenosine deaminase, IFN-γ, TNF-α and IL-10) which help in disease conversion to symptomatic VL, at 6 month follow- up. Follow–up analysis revealed that antibody testing with rK39 (3.24%), DAT (8.33%) had poor agreement with disease conversion. By qPCR, we could identify the level of parasitemia, and collectively with serology, the test detected 23.80% of asymptomatic cases converted into disease. The level of ADA and IL-10 remained consistently high during conversion. IFN-γ became high in asymptomatic infection but became low on conversion, whereas, no significant change in level of TNF-α was observed at both stages of disease. Thus by use of qPCR, concomitantly with DAT over rK39+ sorted endemic healthy control may be employed for early case detection. Adenosine is produced by ecto-nucleotide during L.donovaniinfection, has been previously reported and in parallel to this study we conclude that determination of adenosine deaminase level (ADA) might help identify early cases with more tendency to convert into disease. This will help to boost health monitoring programme to eradicate Kala-azar in Bihar, India.
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Thakur S, Joshi J, Kaur S. Leishmaniasis diagnosis: an update on the use of parasitological, immunological and molecular methods. J Parasit Dis 2020; 44:253-272. [PMID: 32419743 PMCID: PMC7223249 DOI: 10.1007/s12639-020-01212-w] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 03/07/2020] [Indexed: 12/24/2022] Open
Abstract
Diagnosis of leishmaniasis has always been a major challenge as its clinical features resemble some other commonly occurring diseases such as tuberculosis, typhoid, and malaria. Reliable laboratory methods become important for differential diagnosis. Demonstration of the parasites in stained preparations of bone marrow and splenic aspirates being risky and invasive is still the gold standard for diagnosis. Serological tests utilizing rapid immunochromatographic formats or rK39 in enzyme linked immune sorbent assay, immunoblotting, direct agglutination test have complications related to high proportions of positive asymptomatic individuals and the inability to diagnose a relapse. Among the molecular techniques, polymerase chain reaction is the most commonly used technique that is successfully implied for diagnosis. This review provides updated information on the recent developments in the field of diagnosis in leishmaniasis, various methods utilized with their advantages and limitations.
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Affiliation(s)
- Shivani Thakur
- Parasitology Laboratory, Department of Zoology, Panjab University, Chandigarh, 160014 India
| | - Jyoti Joshi
- Parasitology Laboratory, Department of Zoology, Panjab University, Chandigarh, 160014 India
| | - Sukhbir Kaur
- Parasitology Laboratory, Department of Zoology, Panjab University, Chandigarh, 160014 India
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Kumar A, Pandey SC, Samant M. A spotlight on the diagnostic methods of a fatal disease Visceral Leishmaniasis. Parasite Immunol 2020; 42:e12727. [PMID: 32378226 DOI: 10.1111/pim.12727] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 04/30/2020] [Accepted: 05/01/2020] [Indexed: 01/26/2023]
Abstract
Leishmania donovani (a causative agent of visceral leishmaniasis) poses a serious health threat to the human population which is fatal if left untreated. The life cycle of Leishmania alternates between vertebrate host and Phlebotomine fly as intermediate ones. Due to the difficulties linked to vector (sandfly) control and the lack of an effective vaccine, the control of leishmaniasis relies mostly on chemotherapy. Unfortunately, the prevalence of parasites becoming resistant to the first-line drug pentavalent antimonial (SbV )/sodium antimony gluconate (SAG) and some other anti-leishmanial drug is increasing in several parts of the world. With the alarming rise of drug resistance and other issues related to VL, there is an urgent need to focus on early detection and quick diagnosis of VL case. Therefore, we have reviewed most of the methods used in the diagnostic process of VL. Along with existing diagnostic methods, developing more effective and sensitive diagnostic methods and biomarkers is also vital for enhancing VL identification and control programs. This review gathers the comprehensive information on diagnostics methods of VL under a single umbrella that could be the prominent tools for the development of rapid, accurate and cost-effective diagnostic kits for VL which can be used in field conditions.
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Affiliation(s)
- Awanish Kumar
- Department of Biotechnology, National Institute of Technology, Raipur, India
| | - Satish Chandra Pandey
- Cell and Molecular Biology Laboratory, Department of Zoology, Kumaun University, Almora, India.,Department of Biotechnology, Kumaun University, Nainital, India
| | - Mukesh Samant
- Cell and Molecular Biology Laboratory, Department of Zoology, Kumaun University, Almora, India
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Moulik S, Chaudhuri SJ, Sardar B, Ghosh M, Saha B, Das NK, Chatterjee M. Monitoring of Parasite Kinetics in Indian Post-Kala-azar Dermal Leishmaniasis. Clin Infect Dis 2019; 66:404-410. [PMID: 29020350 DOI: 10.1093/cid/cix808] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 09/12/2017] [Indexed: 12/13/2022] Open
Abstract
Background The potential reservoirs of leishmaniasis in South Asia include relapsed cases of visceral leishmaniasis (VL), patients with post-kala-azar dermal leishmaniasis (PKDL), and an asymptomatically infected population. Therefore, assessment of cure in terms of parasite clearance, early detection of PKDL, and asymptomatic VL are pivotal for ensuring elimination. This study aimed to monitor the efficacy of miltefosine and liposomal amphotericin B (LAmB) in PKDL based on parasite load. Methods Patients with PKDL were recruited from the dermatology outpatient departments or during active field surveys. Skin biopsies were collected at disease presentation, immediately at the end of treatment, and 6 months later. The presence of parasite DNA was assessed by internal transcribed spacer-1 polymerase chain reaction, and quantified by amplification of parasite kinetoplastid DNA. Results At disease presentation (n = 184), the median parasite load was 5229 (interquartile range [IQR], 896-50898)/μg genomic DNA (gDNA). Miltefosine cleared the parasites to <10 in the macular (n = 17) and polymorphic (n = 21) variants, and remained so up to 6 months later (<10 parasites). LAmB reduced the parasite burden substantially in macular (n = 34; 2128 [IQR, 544-5763]/µg gDNA) and polymorphic PKDL (n = 36; 2541 [IQR, 650-9073]/µg gDNA). Importantly, in patients who returned 6 months later (n = 38), a resurgence of parasites was evident, as the parasites increased to 5665 (IQR, 1840-17067)/µg gDNA. Conclusions This study established that quantifying parasite load is an effective approach for monitoring patients with PKDL, wherein miltefosine demonstrated near-total parasite clearance and resolution of symptoms. However, in cases treated with LAmB, the persistence of parasites suggested treatment inadequacy. This needs immediate redressal in view of the leishmaniasis elimination program targeted for 2020.
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Affiliation(s)
- Srija Moulik
- Department of Pharmacology, Institute of Postgraduate Medical Education and Research, Kolkata, India
| | | | - Bikash Sardar
- Department of Tropical Medicine, School of Tropical Medicine, Kolkata, India
| | - Manab Ghosh
- Department of Tropical Medicine, School of Tropical Medicine, Kolkata, India
| | - Bibhuti Saha
- Department of Tropical Medicine, School of Tropical Medicine, Kolkata, India
| | - Nilay Kanti Das
- Department of Dermatology, Calcutta Medical College, Kolkata, India
| | - Mitali Chatterjee
- Department of Pharmacology, Institute of Postgraduate Medical Education and Research, Kolkata, India
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Evaluation of methods for detection of asymptomatic individuals infected with Leishmania infantum in the state of Piauí, Brazil. PLoS Negl Trop Dis 2019; 13:e0007493. [PMID: 31260440 PMCID: PMC6625727 DOI: 10.1371/journal.pntd.0007493] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 07/12/2019] [Accepted: 05/24/2019] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Visceral Leishmaniasis in humans presents with fever, anemia, and splenomegaly and can be lethal if not treated. Nevertheless, the majority of Leishmania infantum-infected individuals does not manifest symptoms and remain so provided they are not immunosuppressed. In this work, the performance of different tests was evaluated to detect asymptomatic individuals who were living in Teresina, Piauí state, Brazil, an endemic area for VL. METHODOLOGY L. infantum-specific antibodies were detected by ELISA and two different rapid immunochromatographic (IC) diagnostic tests, Kalazar Detect and OnSite, and parasitic loads were detected by real time PCR [qPCR]. Additionally, we measured levels of the biomarkers monokine induced by IFN-γ (MIG) and IFN-γ-induced protein 10 (IP-10) before and after stimulation of whole blood with soluble Leishmania antigen [SLA]. PRINCIPAL FINDINGS Kalazar Detect and OnSite detected, respectively, 76% and 64% of patients presenting with active Visceral Leishmaniasis; 50% and 57% of patients remained positive in these tests, respectively, after treatment. Of the healthy participants in the study who were living in the endemic area, only 1.7% were positive with both of the IC tests. On the other hand, reactivity in ELISA tests revealed that 13% of these individuals presented asymptomatic infections; among VL patients, 84% presenting with active disease were reactive in ELISA, and after treatment, 55.5% were seropositive. L. infantum DNA was present in the blood of 37.9% of infected individuals living in the endemic area, while IP-10 and MIG biomarkers were detected in 26.7% of them. The greatest concordance of positivity occurred between ELISA and qPCR. CONCLUSION The association of different techniques can detect asymptomatic infections, however, more research is necessary to develop ideal biomarkers that are simple to use in the clinic and in field studies in areas endemic for Visceral Leishmaniasis.
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Sengupta R, Chaudhuri SJ, Moulik S, Ghosh MK, Saha B, Das NK, Chatterjee M. Active surveillance identified a neglected burden of macular cases of Post Kala-azar Dermal Leishmaniasis in West Bengal. PLoS Negl Trop Dis 2019; 13:e0007249. [PMID: 30856178 PMCID: PMC6428339 DOI: 10.1371/journal.pntd.0007249] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 03/21/2019] [Accepted: 02/18/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Post Kala-azar Dermal Leishmaniasis (PKDL) develops in patients apparently cured of Visceral Leishmaniasis (VL), and is the strongest contender for being the disease reservoir. Therefore, existence of a few cases is sufficient to trigger an epidemic of VL in a given community, emphasizing the need for its active detection and in turn ensuring success of the current elimination program. This study explored the impact of active surveillance on the demographic profile of PKDL patients in West Bengal. METHODOLOGY/PRINCIPAL FINDINGS Patients with PKDL were recruited through passive (2003-date, n = 100) and active surveillance (2015-date, n = 202), the former from outpatient departments of dermatology in medical colleges in West Bengal and the latter through an active door-to-door survey in four VL hyper-endemic districts of West Bengal. Passive surveillance indicated a male preponderance and a predominance of polymorphic lesions, whereas active surveillance indicated absence of any gender bias and more importantly, macular PKDL constituted almost 50% of the population burden. In terms of polymorphic vs. macular PKDL, the former appeared at a later age, their disease duration was longer and had a higher parasite burden. In the polymorphic variant, the lesional distribution was asymmetrical, comprised of papules/nodules/macules that were present mainly in sun-exposed areas whereas in macular cases, the hypopigmented patches were diffusely present all over the body. CONCLUSIONS/SIGNIFICANCE Active surveillance unraveled a disease component whose demographic profile showed important differences with PKDL cases who sought treatment in government hospitals. Detection of a higher proportion of macular cases indicates that this variant is not an uncommon presentation as conventionally stated in text books, and should be studied in greater detail to ensure success of the ongoing Leishmaniasis elimination programme.
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Affiliation(s)
- Ritika Sengupta
- Department of Pharmacology, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
| | | | - Srija Moulik
- Department of Pharmacology, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
| | - Manab Kumar Ghosh
- Department of Tropical Medicine, School of Tropical Medicine, Kolkata, West Bengal, India
| | - Bibhuti Saha
- Department of Tropical Medicine, School of Tropical Medicine, Kolkata, West Bengal, India
| | - Nilay Kanti Das
- Department of Dermatology, Bankura Sammilani Medical College, Bankura, West Bengal, India
| | - Mitali Chatterjee
- Department of Pharmacology, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
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Ferreira GR, Castelo Branco Ribeiro JC, Meneses Filho A, de Jesus Cardoso Farias Pereira T, Parente DM, Pereira HF, Carlos da Silva J, Zacarias DA, Vieira da Silva L, Medeiros Faustino SK, Almeida Neto WS, Costa DL, Lopes de Mendonça I, Nery Costa CH. Human Competence to Transmit Leishmania infantum to Lutzomyia longipalpis and the Influence of Human Immunodeficiency Virus Infection. Am J Trop Med Hyg 2018; 98:126-133. [PMID: 29141704 DOI: 10.4269/ajtmh.16-0883] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Visceral leishmaniasis (VL) caused by Leishmania infantum is a lethal disease transmitted by sand flies. Although, considered a zoonosis with dogs held as the main reservoirs, humans are also sources of infection. Therefore, control policies currently focused on dog culling may need to consider that VL and human immunodeficiency virus (HIV)/VL patients may also be infectious, contributing to transmission. Reservoir competence of patients with VL without and with HIV infection and of persons asymptomatically infected with Leishmania was assessed by xenodiagnosis with the vector Lutzomyia longipalpis. Parasites in sand fly's guts were identified by using optical microscopy and by conventional polymerase chain reaction (PCR). Leishmania infantum blood parasite burden was determined by quantitative PCR. Among the 61 participants, 27 (44%) infected sand flies as seen by microscopy or PCR. When infectiousness was assessed by microscopy, xenodiagnosis was positive in five (25%) patients not infected with HIV, whereas nine (45%) of those harboring HIV were positive. Among the 19 asymptomatic patients four (21%) infected sand flies only demonstrated by PCR. One (50%) asymptomatic patient with HIV had a positive xenodiagnosis by microscopy. 9/372 (2.4%) and 37/398 (9.2%) sand flies were infected when feeding in patients without and with HIV, respectively. Infectiousness was poorly correlated with quantitative PCR. The study shows that asymptomatic humans are capable of transmitting L. infantum, that ill persons with HIV infection are more infectious to sand flies, and that humans are more important reservoirs than previously thought. This fact may be considered when designing control policies for zoonotic VL.
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Affiliation(s)
- Gabriel Reis Ferreira
- Leishmaniasis Research Laboratory at Natan Portella Tropical Diseases Institute, Teresina, Brazil.,Graduation Program in Sciences and Health, Federal University of Piauí, Teresina, Brazil
| | - José Carlos Castelo Branco Ribeiro
- Leishmaniasis Research Laboratory at Natan Portella Tropical Diseases Institute, Teresina, Brazil.,Graduation Program in Sciences and Health, Federal University of Piauí, Teresina, Brazil
| | - Antônio Meneses Filho
- Leishmaniasis Research Laboratory at Natan Portella Tropical Diseases Institute, Teresina, Brazil
| | | | - Daniela Moura Parente
- Leishmaniasis Research Laboratory at Natan Portella Tropical Diseases Institute, Teresina, Brazil
| | - Humberto Feitosa Pereira
- Leishmaniasis Research Laboratory at Natan Portella Tropical Diseases Institute, Teresina, Brazil
| | - Jailthon Carlos da Silva
- Leishmaniasis Research Laboratory at Natan Portella Tropical Diseases Institute, Teresina, Brazil.,Graduation Program in Sciences and Health, Federal University of Piauí, Teresina, Brazil
| | - Danielle Alves Zacarias
- Leishmaniasis Research Laboratory at Natan Portella Tropical Diseases Institute, Teresina, Brazil
| | | | | | | | - Dorcas Lamounier Costa
- Graduation Program in Sciences and Health, Federal University of Piauí, Teresina, Brazil.,Maternal and Child Department, Federal University of Piauí, Teresina, Brazil.,Leishmaniasis Research Laboratory at Natan Portella Tropical Diseases Institute, Teresina, Brazil
| | | | - Carlos Henrique Nery Costa
- Graduation Program in Sciences and Health, Federal University of Piauí, Teresina, Brazil.,Department of Community Medicine, Federal University of Piauí, Teresina, Brazil.,Leishmaniasis Research Laboratory at Natan Portella Tropical Diseases Institute, Teresina, Brazil
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Duthie MS, Lison A, Courtenay O. Advances toward Diagnostic Tools for Managing Zoonotic Visceral Leishmaniasis. Trends Parasitol 2018; 34:881-890. [PMID: 30131210 PMCID: PMC6168404 DOI: 10.1016/j.pt.2018.07.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 11/20/2022]
Abstract
Visceral leishmaniasis (VL) is a life-threatening outcome of Leishmania infantum or Leishmania donovani infection. Dogs are the primary domestic reservoir of L. infantum parasites, and ownership of infected dogs increases the risk of human VL. Controlling infection within dog populations is regarded as critical to VL management in endemic countries, both preventing progression of canine disease and limiting parasite transmission to humans and dogs. Here we discuss various strategies that are used to diagnose canine visceral leishmaniasis (CVL) and the possibilities of adapting these for use within population screening and control programs. In addition, given the variable transmissibility of L. infantum to the sand fly vector, we outline some possibilities for the preferential identification of 'super-spreader' dogs among the overall infected population.
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Affiliation(s)
- Malcolm S Duthie
- Infectious Disease Research Institute, 1616 Eastlake Ave E, Suite 400, Seattle, WA 98102, USA.
| | - Aurore Lison
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Orin Courtenay
- School of Life Sciences, University of Warwick, Coventry, UK
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Chapman LAC, Jewell CP, Spencer SEF, Pellis L, Datta S, Chowdhury R, Bern C, Medley GF, Hollingsworth TD. The role of case proximity in transmission of visceral leishmaniasis in a highly endemic village in Bangladesh. PLoS Negl Trop Dis 2018; 12:e0006453. [PMID: 30296295 PMCID: PMC6175508 DOI: 10.1371/journal.pntd.0006453] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/13/2018] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Visceral leishmaniasis (VL) is characterised by a high degree of spatial clustering at all scales, and this feature remains even with successful control measures. VL is targeted for elimination as a public health problem in the Indian subcontinent by 2020, and incidence has been falling rapidly since 2011. Current control is based on early diagnosis and treatment of clinical cases, and blanket indoor residual spraying of insecticide (IRS) in endemic villages to kill the sandfly vectors. Spatially targeting active case detection and/or IRS to higher risk areas would greatly reduce costs of control, but its effectiveness as a control strategy is unknown. The effectiveness depends on two key unknowns: how quickly transmission risk decreases with distance from a VL case and how much asymptomatically infected individuals contribute to transmission. METHODOLOGY/PRINCIPAL FINDINGS To estimate these key parameters, a spatiotemporal transmission model for VL was developed and fitted to geo-located epidemiological data on 2494 individuals from a highly endemic village in Mymensingh, Bangladesh. A Bayesian inference framework that could account for the unknown infection times of the VL cases, and missing symptom onset and recovery times, was developed to perform the parameter estimation. The parameter estimates obtained suggest that, in a highly endemic setting, VL risk decreases relatively quickly with distance from a case-halving within 90m-and that VL cases contribute significantly more to transmission than asymptomatic individuals. CONCLUSIONS/SIGNIFICANCE These results suggest that spatially-targeted interventions may be effective for limiting transmission. However, the extent to which spatial transmission patterns and the asymptomatic contribution vary with VL endemicity and over time is uncertain. In any event, interventions would need to be performed promptly and in a large radius (≥300m) around a new case to reduce transmission risk.
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Affiliation(s)
- Lloyd A. C. Chapman
- Zeeman Institute, University of Warwick, Coventry, UK
- School of Life Sciences, University of Warwick, Coventry, UK
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Chris P. Jewell
- Centre for Health Informatics, Computing And Statistics, Lancaster University, Lancaster, UK
| | - Simon E. F. Spencer
- Zeeman Institute, University of Warwick, Coventry, UK
- Department of Statistics, University of Warwick, Coventry, UK
| | | | - Samik Datta
- Zeeman Institute, University of Warwick, Coventry, UK
- National Institute of Water and Atmospheric Research, Wellington, New Zealand
| | - Rajib Chowdhury
- National Institute of Preventive and Social Medicine (NIPSOM), Mohakhali, Dhaka, Bangladesh
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Caryn Bern
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA
| | - Graham F. Medley
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - T. Déirdre Hollingsworth
- Zeeman Institute, University of Warwick, Coventry, UK
- School of Life Sciences, University of Warwick, Coventry, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
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Abstract
Visceral leishmaniasis (VL), a deadly parasitic disease, is a major public health concern globally. Countries affected by VL have signed the London Declaration on Neglected Tropical Diseases and committed to eliminate VL as a public health problem by 2020. To achieve and sustain VL elimination, it will become progressively important not to miss any remaining cases in the community who can maintain transmission. This requires accurate identification of symptomatic and asymptomatic carriers using highly sensitive diagnostic tools at the primary health service setting. The rK39 rapid diagnostic test (RDT) is the most widely used tool and with its good sensitivity and specificity is the first choice for decentralized diagnosis of VL in endemic areas. However, this test cannot discriminate between current, subclinical, or past infections and is useless for diagnosis of relapses and as a prognostic (cure) test. Importantly, as the goal of elimination of VL as a public health problem is approaching, the number of people susceptible to infection will increase. Therefore, correct diagnosis using a highly sensitive diagnostic test is crucial for applying appropriate treatment and management of cases. Recent advances in molecular techniques have improved Leishmania detection and quantification, and therefore this technology has become increasingly relevant due to its possible application in a variety of clinical sample types. Most importantly, given current problems in identifying asymptomatic individuals because of poor correlation between the main methods of detection, molecular tests are valuable for VL elimination programs, especially to monitor changes in burden of infection in specific communities. This review provides a comprehensive overview of the available VL diagnostics and discusses the usefulness of molecular methods in the diagnosis, quantification, and species differentiation as well as their clinical applications.
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Affiliation(s)
- Shyam Sundar
- Infectious Disease Research Laboratory, Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, 221 005, India
| | - Om Prakash Singh
- Infectious Disease Research Laboratory, Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, 221 005, India.
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Courtenay O, Peters NC, Rogers ME, Bern C. Combining epidemiology with basic biology of sand flies, parasites, and hosts to inform leishmaniasis transmission dynamics and control. PLoS Pathog 2017; 13:e1006571. [PMID: 29049371 PMCID: PMC5648254 DOI: 10.1371/journal.ppat.1006571] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Quantitation of the nonlinear heterogeneities in Leishmania parasites, sand fly vectors, and mammalian host relationships provides insights to better understand leishmanial transmission epidemiology towards improving its control. The parasite manipulates the sand fly via production of promastigote secretory gel (PSG), leading to the “blocked sand fly” phenotype, persistent feeding attempts, and feeding on multiple hosts. PSG is injected into the mammalian host with the parasite and promotes the establishment of infection. Animal models demonstrate that sand flies with the highest parasite loads and percent metacyclic promastigotes transmit more parasites with greater frequency, resulting in higher load infections that are more likely to be both symptomatic and efficient reservoirs. The existence of mammalian and sand fly “super-spreaders” provides a biological basis for the spatial and temporal clustering of clinical leishmanial disease. Sand fly blood-feeding behavior will determine the efficacies of indoor residual spraying, topical insecticides, and bed nets. Interventions need to have sufficient coverage to include transmission hot spots, especially in the absence of field tools to assess infectiousness. Interventions that reduce sand fly densities in the absence of elimination could have negative consequences, for example, by interfering with partial immunity conferred by exposure to sand fly saliva. A deeper understanding of both sand fly and host biology and behavior is essential to ensuring effectiveness of vector interventions. We review recent research that sheds light on the quantitative biology of leishmanial transmission between sand flies and mammalian hosts and use these insights to better understand transmission, the observed epidemiology of the disease, and their implications in choice of control strategy. Using animal models, we show how the parasite-induced processes manipulate sand fly blood-feeding behavior and the infectious metacyclic dose to promote host infection and to differentially regulate the onward transmission potential of individual vectors and hosts. The existence of subpopulations of mammalian and sand fly “super-spreaders” provides a biological basis for the spatial and temporal clustering of clinical leishmanial disease. While tools are unavailable to distinguish these individuals in mixed populations, blanket interventions will be necessary to ensure inclusion of transmission hot spots. Interventions that reduce sand fly densities without elimination could interfere with vector—host dynamics and conferred partial immunity to host populations.
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Affiliation(s)
- Orin Courtenay
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
- Zeeman Institute, University of Warwick, Coventry, United Kingdom
- * E-mail:
| | - Nathan C. Peters
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Matthew E. Rogers
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Caryn Bern
- Department of Epidemiology and Biostatistics, School of Medicine, University of California San Francisco, San Francisco, California, United States of America
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Jara M, Berg M, Caljon G, de Muylder G, Cuypers B, Castillo D, Maes I, Orozco MDC, Vanaerschot M, Dujardin JC, Arevalo J. Macromolecular biosynthetic parameters and metabolic profile in different life stages of Leishmania braziliensis: Amastigotes as a functionally less active stage. PLoS One 2017; 12:e0180532. [PMID: 28742826 PMCID: PMC5526552 DOI: 10.1371/journal.pone.0180532] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 05/26/2017] [Indexed: 12/04/2022] Open
Abstract
It was recently hypothesized that Leishmania amastigotes could constitute a semi-quiescent stage characterized by low replication and reduced metabolic activity. This concept developed with Leishmania (Leishmania) mexicana and Leishmania (Leishmania) major models might explain numerous clinical and sub-clinical features of Leishmania (Viannia) braziliensis infections, like reactivation of the disease, non-response to chemotherapy or asymptomatic infections. We compared here in vitro the proliferative capability of L. (V.) braziliensis amastigotes and promastigotes, assessed the expression of key molecular parameters and performed metabolomic analysis. We found that contrary to the highly proliferative promastigotes, amastigotes (axenic and intracellular) do not show evidence of extensive proliferation. In parallel, amastigotes showed a significant decrease of (i) the kDNA mini-circle abundance, (ii) the intracellular ATP level, (iii) the ribosomal components: rRNA subunits 18S and 28S α and ribosomal proteins RPS15 and RPL19, (iv) total RNA and protein levels. An untargeted metabolomic study identified clear differences between the different life stages: in comparison to logarithmic promastigotes, axenic amastigotes showed (a) a strong decrease of 14 essential and non-essential amino acids and eight metabolites involved in polyamine synthesis, (b) extensive changes in the phospholipids composition and (c) increased levels of several endogenous and exogenous sterols. Altogether, our results show that L. (V.) braziliensis amastigotes can show a phenotype with negligible rate of proliferation, a lower capacity of biosynthesis, a reduced bio-energetic level and a strongly altered metabolism. Our results pave the way for further exploration of quiescence among amastigotes of this species.
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Affiliation(s)
- Marlene Jara
- Instituto de Medicina Tropical “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Perú
- Institute of Tropical Medicine Antwerp, Molecular Parasitology Unit, Antwerp, Belgium
| | - Maya Berg
- Institute of Tropical Medicine Antwerp, Molecular Parasitology Unit, Antwerp, Belgium
| | - Guy Caljon
- Institute of Tropical Medicine Antwerp, Molecular Parasitology Unit, Antwerp, Belgium
| | - Geraldine de Muylder
- Institute of Tropical Medicine Antwerp, Molecular Parasitology Unit, Antwerp, Belgium
| | - Bart Cuypers
- Institute of Tropical Medicine Antwerp, Molecular Parasitology Unit, Antwerp, Belgium
- University of Antwerp, Antwerp, Belgium
| | - Denis Castillo
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Ilse Maes
- Institute of Tropical Medicine Antwerp, Molecular Parasitology Unit, Antwerp, Belgium
| | - María del Carmen Orozco
- Instituto de Medicina Tropical “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Manu Vanaerschot
- Institute of Tropical Medicine Antwerp, Molecular Parasitology Unit, Antwerp, Belgium
| | - Jean-Claude Dujardin
- Institute of Tropical Medicine Antwerp, Molecular Parasitology Unit, Antwerp, Belgium
- University of Antwerp, Antwerp, Belgium
| | - Jorge Arevalo
- Instituto de Medicina Tropical “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Perú
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
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Zacarias DA, Rolão N, de Pinho FA, Sene I, Silva JC, Pereira TC, Costa DL, Costa CHN. Causes and consequences of higher Leishmania infantum burden in patients with kala-azar: a study of 625 patients. Trop Med Int Health 2017; 22:679-687. [PMID: 28380279 DOI: 10.1111/tmi.12877] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND An infected host's Leishmania infantum load in blood is considered to be an estimate of his or her total parasite burden. Therefore, the measurement of blood parasite burden is important in the identification of factors involved in parasite control. METHODS Quantitative polymerase chain reaction was performed on blood samples from 625 patients with kala-azar consecutively admitted to a reference hospital in Teresina, Brazil. Primers were used to amplify a segment of kDNA using the TaqMan system. Non-parametric statistical tests were applied. RESULTS The median blood parasite burden was 499.2 amastigote equivalents (AE)/ml. Children <1 year old (yo) had a high parasite burden, which dropped sharply after the first year of life (192.8, AE/ml at 1 < 2 yo) and remained lower until adolescence. Following adolescence, the parasite burden increased with age, peaking among elderly individuals. Men had a higher parasite burden than women. HIV-infected patients had a much higher parasite burden than non-infected patients. The parasite burden of children under 5 years with acute moderate to severe malnourishment (weight-for-age and body mass index z-scores <-2) was almost three times greater than that of better-nourished children. The parasite burden identified in deceased patients was more than twice that of surviving patients; those with a higher risk of death, sepsis, pneumonia and jaundice also had increased parasite burdens. All of these differences were statistically significant at P-values <0.05. CONCLUSIONS These data indicate that the parasite burden in patients with kala-azar was associated with age- and gender-associated factors and with HIV infection status. Acute malnutrition could be either a cause or a consequence of a higher parasite burden. An individual's parasite burden influences his or her clinical profile, disease severity and mortality risk. The best explanation for the presence of a higher parasite burden in individuals with these immunoregulatory conditions and severe disease is the occurrence of acquired immunosuppression followed by heightened innate immunity.
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Affiliation(s)
- Danielle A Zacarias
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
| | - Nuno Rolão
- Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Flaviane A de Pinho
- Setor de Patologia Animal, Centro de Ciências Agrárias, Universidade Federal do Piauí, Teresina, Brazil
| | - Ingridi Sene
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
| | - Jailthon C Silva
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
| | - Teresinha C Pereira
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
| | - Dorcas L Costa
- Departamento Materno-Infantil, Universidade Federal do Piauí, Teresina, Brazil
| | - Carlos H N Costa
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
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Das VNR, Pandey RN, Siddiqui NA, Chapman LAC, Kumar V, Pandey K, Matlashewski G, Das P. Longitudinal Study of Transmission in Households with Visceral Leishmaniasis, Asymptomatic Infections and PKDL in Highly Endemic Villages in Bihar, India. PLoS Negl Trop Dis 2016; 10:e0005196. [PMID: 27974858 PMCID: PMC5156552 DOI: 10.1371/journal.pntd.0005196] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 11/17/2016] [Indexed: 12/13/2022] Open
Abstract
Background Visceral Leishmaniasis (VL) is a neglected tropical disease that afflicts some of the poorest populations in the world including people living in the Bihar state of India. Due to efforts from local governments, NGOs and international organizations, the number of VL cases has declined in recent years. Despite this progress, the reservoir for transmission remains to be clearly defined since it is unknown what role post kala-azar dermal leishmaniasis (PKDL) and asymptomatic infections play in transmission. This information is vital to establish effective surveillance and monitoring to sustainably eliminate VL. Methodology/Principal Findings We performed a longitudinal study over a 24-month period to examine VL transmission and seroconversion in households with VL, PKDL and asymptomatic infections in the Saran and Muzaffarpur districts of Bihar. During the initial screening of 5,144 people in 16 highly endemic villages, 195 cases of recently treated VL, 116 healthy rK39 positive cases and 31 PKDL cases were identified. Approximately half of the rK39-positive healthy cases identified during the initial 6-month screening period were from households (HHs) where a VL case had been identified. During the 18-month follow-up period, seroconversion of family members in the HHs with VL cases, PKDL cases, and rK39-positive individuals was similar to control HHs. Therefore, seroconversion was highest in HHs closest to the time of VL disease of a household member and there was no evidence of higher transmission in households with PKDL or healthy rK39-positive HHs. Moreover, within the PKDL HHs, (the initial 31 PKDL cases plus an additional 66 PKDL cases), there were no cases of VL identified during the initial screen or the 18-month follow-up. Notably, 23% of the PKDL cases had no prior history of VL suggesting that infection resulting directly in PKDL is more common than previously estimated. Conclusions/Significance These observations argue that acute VL cases represent the major reservoir for transmission in these villages and early identification and treatment of VL cases should remain a priority for VL elimination. We were unable to obtain evidence that transmission occurs in HHs with a PKDL case. Visceral leishmaniasis (also known as kala-azar) caused by infection with L. donovani is a deadly parasitic disease that afflicts some of world’s poorest populations, including the people of the northern Bihar State of India. Once transmitted to a human by an infected sandfly, the L. donovani parasite migrates from the site of the sandfly bite throughout the reticuloendothelial system, resulting in high levels of infection in the spleen, liver and bone marrow that eventually lead to organ failure and death if not treated effectively. India, Nepal and Bangladesh are currently engaged in a program to eliminate visceral leishmaniasis, principally through early case detection, treatment and vector control. As humans are the only reservoir for L. donovani, it is necessary to understand how the disease is transmitted and specifically what role acute visceral leishmaniasis (VL) cases, asymptomatic infections and post kala-azar dermal leishmaniasis (PKDL) cases play in transmission. We therefore performed a study to determine seroconversion for antibodies against the L. donovani rK39 antigen as a surrogate for transmission in households with VL cases, asymptomatic infections and PKDL cases in 16 highly endemic villages over a 2-year period in Bihar, India. We observed that most transmission occurred in the VL households and further that it occurred closest to the time of acute disease. We were unable to confirm that transmission occurred in the households with either asymptomatic infections or PKDL cases. These observations argue that active surveillance to diagnose and treat VL cases as soon as possible to reduce transmission should remain a priority for VL elimination.
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Affiliation(s)
- Vidya Nand Ravi Das
- Rajendra Memorial Research Institute of Medical Sciences (ICMR), Patna, India
| | | | | | | | - Vijay Kumar
- Rajendra Memorial Research Institute of Medical Sciences (ICMR), Patna, India
| | - Krishna Pandey
- Rajendra Memorial Research Institute of Medical Sciences (ICMR), Patna, India
| | - Greg Matlashewski
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
- * E-mail: (PD); (GM)
| | - Pradeep Das
- Rajendra Memorial Research Institute of Medical Sciences (ICMR), Patna, India
- * E-mail: (PD); (GM)
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Rock KS, Quinnell RJ, Medley GF, Courtenay O. Progress in the Mathematical Modelling of Visceral Leishmaniasis. ADVANCES IN PARASITOLOGY 2016; 94:49-131. [PMID: 27756459 DOI: 10.1016/bs.apar.2016.08.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The leishmaniases comprise a complex of diseases characterized by clinical outcomes that range from self-limiting to chronic, and disfiguring and stigmatizing to life threatening. Diagnostic methods, treatments, and vector and reservoir control options exist, but deciding the most effective interventions requires a quantitative understanding of the population level infection and disease dynamics. The effectiveness of any set of interventions has to be determined within the context of operational conditions, including economic and political commitment. Mathematical models are the best available tools for studying quantitative systems crossing disciplinary spheres (biology, medicine, economics) within environmental and societal constraints. In 2005, the World Health Assembly and government health ministers of India, Nepal, and Bangladesh signed a Memorandum of Understanding to eliminate the life threatening form of leishmaniasis, visceral leishmaniasis (VL), on the Indian subcontinent by 2015 through a combination of early case detection, improved treatments, and vector control. The elimination target is <1 case/10,000 population at the district or subdistrict level compared to the current 20/10,000 in the regions of highest transmission. Towards this goal, this chapter focuses on mathematical models of VL, and the biology driving those models, to enable realistic predictions of the best combination of interventions. Several key issues will be discussed which have affected previous modelling of VL and the direction future modelling may take. Current understanding of the natural history of disease, immunity (and loss of immunity), and stages of infection and their durations are considered particularly for humans, and also for dogs. Asymptomatic and clinical infection are discussed in the context of their relative roles in Leishmania transmission, as well as key components of the parasite-sandfly-vector interaction and intervention strategies including diagnosis, treatment and vector control. Gaps in current biological knowledge and potential avenues to improve model structures and mathematical predictions are identified. Underpinning the marriage between biology and mathematical modelling, the content of this chapter represents the first step towards developing the next generation of models for VL.
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Affiliation(s)
- K S Rock
- University of Warwick, Coventry, United Kingdom
| | | | - G F Medley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - O Courtenay
- University of Warwick, Coventry, United Kingdom
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A Correlative Study of Splenic Parasite Score and Peripheral Blood Parasite Load Estimation by Quantitative PCR in Visceral Leishmaniasis. J Clin Microbiol 2016; 53:3905-7. [PMID: 26400788 DOI: 10.1128/jcm.01465-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Parasitological diagnosis of visceral leishmaniasis (VL) by splenic smear is highly sensitive, but it is associated with the risk of severe hemorrhage. In this study, the diagnosis of VL using quantitative PCR (qPCR) in peripheral blood was evaluated in 100 patients with VL. Blood parasitemia ranged from 5 to 93,688 leishmania parasite genomes/ml of blood and positively correlated with splenic score (P<0.0001; r2=0.58). Therefore, quantification of parasite genomes by qPCR can replace invasive procedures for diagnostic and prognostic evaluations.
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30
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Transmission Dynamics of Visceral Leishmaniasis in the Indian Subcontinent - A Systematic Literature Review. PLoS Negl Trop Dis 2016; 10:e0004896. [PMID: 27490264 PMCID: PMC4973965 DOI: 10.1371/journal.pntd.0004896] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/12/2016] [Indexed: 12/24/2022] Open
Abstract
Background As Bangladesh, India and Nepal progress towards visceral leishmaniasis (VL) elimination, it is important to understand the role of asymptomatic Leishmania infection (ALI), VL treatment relapse and post kala-azar dermal leishmaniasis (PKDL) in transmission. Methodology/ Principal Finding We reviewed evidence systematically on ALI, relapse and PKDL. We searched multiple databases to include studies on burden, risk factors, biomarkers, natural history, and infectiveness of ALI, PKDL and relapse. After screening 292 papers, 98 were included covering the years 1942 through 2016. ALI, PKDL and relapse studies lacked a reference standard and appropriate biomarker. The prevalence of ALI was 4–17-fold that of VL. The risk of ALI was higher in VL case contacts. Most infections remained asymptomatic or resolved spontaneously. The proportion of ALI that progressed to VL disease within a year was 1.5–23%, and was higher amongst those with high antibody titres. The natural history of PKDL showed variability; 3.8–28.6% had no past history of VL treatment. The infectiveness of PKDL was 32–53%. The risk of VL relapse was higher with HIV co-infection. Modelling studies predicted a range of scenarios. One model predicted VL elimination was unlikely in the long term with early diagnosis. Another model estimated that ALI contributed to 82% of the overall transmission, VL to 10% and PKDL to 8%. Another model predicted that VL cases were the main driver for transmission. Different models predicted VL elimination if the sandfly density was reduced by 67% by killing the sandfly or by 79% by reducing their breeding sites, or with 4–6y of optimal IRS or 10y of sub-optimal IRS and only in low endemic setting. Conclusion/ Significance There is a need for xenodiagnostic and longitudinal studies to understand the potential of ALI and PKDL as reservoirs of infection. The role of asymptomatic Leishmania infection (ALI), PKDL and VL relapse in transmission is unclear as VL elimination is achieved in the Indian subcontinent. ALI, PKDL and relapse studies lacked a reference standard and appropriate biomarker. ALI was 4–17-fold more prevalent than VL. The risk of ALI was higher in VL case contacts. Most infections remained asymptomatic or resolved spontaneously. The natural history of PKDL showed variability. Twenty nine percent had no past history of VL treatment. The risk of VL relapse was higher with HIV co-infection. Modelling studies predicted different effects. Early diagnosis was unlikely to eliminate VL in the long term. ALI was predicted to contribute to 82% of the overall transmission, VL to 10% and PKDL to 8%. Another model predicted that VL cases were the main driver for transmission. VL elimination was predicted if the sandfly density was reduced by 67% by killing the sandfly or by 79% by reducing their breeding sites, or with 4–6y of optimal IRS or 10y of sub-optimal IRS and only in low endemic setting. There is a need for more studies to fully understand the potential of ALI and PKDL as reservoirs of infection.
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Abstract
Visceral leishmaniasis (VL or kala-azar) is most endemic in Asia and Africa and commonly affects young children. It is usually caused by Leishmania donovani or Leishmania infantum that are transmitted by Phlebotomine sand flies. Transmission may be anthroponotic or zoonotic or both, depending on the endemic area. Clinical features include fever, hepatosplenomegaly, weight loss and pancytopenia. Younger age, malnutrition and immunosuppression (HIV infection, use of immunosuppressive drugs) are risk factors. Many infections remain asymptomatic. Diagnosis is made by demonstration of the Leishmania parasite in aspirates of lymph node, bone marrow or spleen. Serological tests such as rK39 strip test are widely used but the sensitivity varies. qPCR is useful to detect low numbers of parasites and to monitor treatment. Treatment is with AmBisome monotherapy in most areas but with drug combinations elsewhere. HIV co-infected patients are most difficult to treat and often relapse. Control efforts focus on case finding, availability of diagnostic tools, reservoir control and protection from sand flies (insecticides, bed nets). There is no human vaccine.
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Developments in Diagnosis of Visceral Leishmaniasis in the Elimination Era. J Parasitol Res 2015; 2015:239469. [PMID: 26843964 PMCID: PMC4710934 DOI: 10.1155/2015/239469] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/06/2015] [Accepted: 12/14/2015] [Indexed: 11/29/2022] Open
Abstract
Visceral leishmaniasis (VL) is the most devastating parasitic infection worldwide causing high morbidity and mortality. Clinical presentation of VL ranges from asymptomatic or subclinical infection to severe and complicated symptomatic disease. A major challenge in the clinical management of VL is the weakness of health systems in disease endemic regions. People affected by VL mostly present to primary health care centers (PHCs), often late in their therapeutic itinerary. PHC physicians face a major challenge: they do not deal with a single disease issue but with patients presenting with complaints pointing to several diagnostic possibilities. Risk exists when some patients having less clinical manifestations are misdiagnosed. Therefore, field based accurate, sensitive, and cost effective rapid diagnostic tools that can detect disease in its mildest form are essential for effective control and reaching the goal of VL elimination. In this review, we discuss the current status and challenges of various diagnostic tools for the diagnosis of VL and assess their application in resource poor settings.
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Reed SG, Coler RN, Mondal D, Kamhawi S, Valenzuela JG. Leishmania vaccine development: exploiting the host-vector-parasite interface. Expert Rev Vaccines 2015; 15:81-90. [PMID: 26595093 PMCID: PMC6019289 DOI: 10.1586/14760584.2016.1105135] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Visceral leishmaniasis (VL) is a disease transmitted by phlebotomine sand flies, fatal if untreated, and with no available human vaccine. In rodents, cellular immunity to Leishmania parasite proteins as well as salivary proteins of the sand fly is associated with protection, making them worthy targets for further exploration as vaccines. This review discusses the notion that a combination vaccine including Leishmania and vector salivary antigens may improve vaccine efficacy by targeting the parasite at its most vulnerable stage just after transmission. Furthermore, we put forward the notion that better modeling of natural transmission is needed to test efficacy of vaccines. For example, the fact that individuals living in endemic areas are exposed to sand fly bites and will mount an immune response to salivary proteins should be considered in pre-clinical and clinical evaluation of leishmaniasis vaccines. Nevertheless, despite remaining obstacles there is good reason to be optimistic that safe and effective vaccines against leishmaniasis can be developed.
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Affiliation(s)
- S G Reed
- a Infectious Disease Research Institute , Seattle WA , USA
- b Department of Global Health , University of Washington , Seattle WA , USA
| | - R N Coler
- a Infectious Disease Research Institute , Seattle WA , USA
- b Department of Global Health , University of Washington , Seattle WA , USA
| | - D Mondal
- c International Center for Diarrhoeal Diseases Research, Centre for Nutrition and Food Security , Parasitology Laboratory , Dhaka , Bangladesh
| | - S Kamhawi
- d Vector Molecular Biology Section, LMVR , National Institute of Allergy and Infectious Diseases, NIH , Rockville , MD , USA
| | - J G Valenzuela
- d Vector Molecular Biology Section, LMVR , National Institute of Allergy and Infectious Diseases, NIH , Rockville , MD , USA
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Sudarshan M, Singh T, Singh AK, Chourasia A, Singh B, Wilson ME, Chakravarty J, Sundar S. Quantitative PCR in epidemiology for early detection of visceral leishmaniasis cases in India. PLoS Negl Trop Dis 2014; 8:e3366. [PMID: 25503103 PMCID: PMC4263468 DOI: 10.1371/journal.pntd.0003366] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 10/23/2014] [Indexed: 12/04/2022] Open
Abstract
Introduction Studies employing serological, DTH or conventional PCR techniques suggest a vast proportion of Leishmania infected individuals living in regions endemic for Visceral Leishmaniasis (VL) remain asymptomatic. This study was designed to assess whether quantitative PCR (qPCR) can be used for detection of asymptomatic or early Leishmania donovani infection and as a predictor of progression to symptomatic disease. Methods The study included 1469 healthy individuals living in endemic region (EHC) including both serology-positive and -negative subjects. TaqMan based qPCR assay was done on peripheral blood of each subject using kDNA specific primers and probes. Results A large proportion of EHC 511/1469 (34.78%) showed qPCR positivity and 56 (3.81% of 1469 subjects) had more than 1 calculated parasite genome/ml of blood. However, the number of individuals with parasite load above 5 genomes/ml was only 20 (1.36% of 1469). There was poor agreement between serological testing and qPCR (k = 0.1303), and 42.89% and 31.83% EHC were qPCR positive in seropositive and seronegative groups, respectively. Ten subjects had developed to symptomatic VL after 12 month of their follow up examination, of which eight were initially positive according to qPCR and among these, five had high parasite load. Discussion Thus, qPCR can help us to detect significant early parasitaemia, thereby assisting us in recognition of potential progressors to clinical disease. This test could facilitate early intervention, decreased morbidity and mortality, and possibly interruption of disease transmission. Anthroponotic VL caused by Leishmania donovani in the Indian subcontinent accounts for 70% of the world burden of VL. Among the estimated 100,000 cases of VL acquired annually in India, 90% occur in the state of Bihar. Leishmania infection can result in either symptomatic or asymptomatic infection. L. donovani infection can also manifest as post-kala azar dermal leishmaniasis, a chronic cutaneous form thought to provide the reservoir for anthroponotic transmission of VL in regions endemic for this parasite species. We hypothesized that, in areas endemic for L. donovani, asymptomatic infections might also play a crucial role in disease transmission. This study describes use of quantitative PCR (qPCR) to determine the infection status in individuals living in an endemic region of India. We hypothesized that parasite load estimation by qPCR of peripheral blood cells among healthy individuals living in the endemic region might reveal the true frequency of infections through direct evidence of parasitemia. We reasoned this test would detect both asymptomatic non-progressors as well as asymptomatic individuals who will progress to fully symptomatic VL. Serologic testing by ELISA or DAT showed poor agreement with molecular detection of parasite DNA by qPCR, suggesting the tests differentiate between infection and immune response. Amongst ten healthy individuals who progressed to VL, only six were serologically positive whereas eight were initially qPCR positive, among whom five had high parasite loads in their blood. Thus, deployment of qPCR technique to estimate the presence and level of parasitemia in healthy individuals from Leishmania endemic regions may contribute to early case detection, thereby reducing morbidity and mortality. Consistent with the goals of the VL control and elimination program, this early intervention approach could help interrupt disease transmission.
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Affiliation(s)
- Medhavi Sudarshan
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Toolika Singh
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Abhishek Kumar Singh
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Ankita Chourasia
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Bhawana Singh
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Mary E Wilson
- Departments of Internal Medicine and Microbiology, University of Iowa and the VA Medical Center, Iowa City, Iowa, United States of America
| | - Jaya Chakravarty
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Shyam Sundar
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
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