title: Understanding the transmission dynamics of Leishmania donovani to provide robust evidence for interventions to eliminate visceral leishmaniasis in Bihar, India.
abstract: Visceral Leishmaniasis (VL) is a neglected vector-borne disease. In India, it is transmitted to humans by Leishmania donovani-infected Phlebotomus argentipes sand flies. In 2005, VL was targeted for elimination by the governments of India, Nepal and Bangladesh by 2015. The elimination strategy consists of rapid case detection, treatment of VL cases and vector control using indoor residual spraying (IRS). However, to achieve sustained elimination of VL, an appropriate post elimination surveillance programme should be designed, and crucial knowledge gaps in vector bionomics, human infection and transmission need to be addressed. This review examines the outstanding knowledge gaps, specifically in the context of Bihar State, India.The knowledge gaps in vector bionomics that will be of immediate benefit to current control operations include better estimates of human biting rates and natural infection rates of P. argentipes, with L. donovani, and how these vary spatially, temporally and in response to IRS. The relative importance of indoor and outdoor transmission, and how P. argentipes disperse, are also unknown. With respect to human transmission it is important to use a range of diagnostic tools to distinguish individuals in endemic communities into those who: 1) are to going to progress to clinical VL, 2) are immune/refractory to infection and 3) have had past exposure to sand flies.It is crucial to keep in mind that close to elimination, and post-elimination, VL cases will become infrequent, so it is vital to define what the surveillance programme should target and how it should be designed to prevent resurgence. Therefore, a better understanding of the transmission dynamics of VL, in particular of how rates of infection in humans and sand flies vary as functions of each other, is required to guide VL elimination efforts and ensure sustained elimination in the Indian subcontinent. By collecting contemporary entomological and human data in the same geographical locations, more precise epidemiological models can be produced. The suite of data collected can also be used to inform the national programme if supplementary vector control tools, in addition to IRS, are required to address the issues of people sleeping outside.
authors.affiliation: London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. Mary.Cameron@lshtm.ac.uk.
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authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. alvaro.acosta-serrano@lstmed.ac.uk.
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authors.lastname: Acosta-Serrano
authors.affiliation: UCSF School of Medicine, 550 16th Street, San Francisco, 94158, CA, USA. Caryn.Bern2@ucsf.edu.
authors.forename: Caryn
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authors.affiliation: Institute of Tropical Medicine, Antwerp, Belgium. mboelaert@itg.be.
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authors.affiliation: KalaCORE, London, Uk. margrietdenboer@gmail.com.
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authors.affiliation: London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. sakib.burza@kalacore.org.
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authors.affiliation: European Biological Control Laboratory, USDA-ARS, Tsimiski 43 Street, Thessaloniki, 54623, Greece. achaskopoulou@ars-ebcl.org.
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authors.affiliation: University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK. Erin.Dilger@warwick.ac.uk.
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authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. Geraldine.Foster@lstmed.ac.uk.
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authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. Lee.Haines@lstmed.ac.uk.
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authors.affiliation: Bill and Melinda Gates Foundation, Seattle, USA. Angi.Harris@gatesfoundation.org.
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authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. Janet.Hemingway@lstmed.ac.uk.
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authors.affiliation: University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK. deirdre.hollingsworth@warwick.ac.uk.
authors.forename: T Déirdre
authors.initials: TD
authors.lastname: Hollingsworth
authors.affiliation: University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK. s.jervis@warwick.ac.uk.
authors.forename: Sarah
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authors.affiliation: London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. Graham.Medley@lshtm.ac.uk.
authors.forename: Graham
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authors.lastname: Medley
authors.affiliation: London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. Michael.Miles@lshtm.ac.uk.
authors.forename: Michael
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authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. Mark.Paine@lstmed.ac.uk.
authors.forename: Mark
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authors.affiliation: FIND, Campus Biotech, Chemin des Mines 9, 1202, Geneva, Switzerland. Albert.Picado@finddx.org.
authors.forename: Albert
authors.initials: A
authors.lastname: Picado
authors.affiliation: Genesis Laboratories, Inc., Wellington, CO, 80549, USA. richard@genesislabs.com.
authors.forename: Richard
authors.initials: R
authors.lastname: Poché
authors.affiliation: London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. Paul.Ready@lshtm.ac.uk.
authors.forename: Paul
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authors.lastname: Ready
authors.affiliation: London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. Matthew.Rogers@lshtm.ac.uk.
authors.forename: Matthew
authors.initials: M
authors.lastname: Rogers
authors.affiliation: London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. Mark.Rowland@lshtm.ac.uk.
authors.forename: Mark
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authors.affiliation: Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221005, India. drshyamsundar@hotmail.com.
authors.forename: Shyam
authors.initials: S
authors.lastname: Sundar
authors.affiliation: Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands. s.devlas@erasmusmc.nl.
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authors.initials: SJ
authors.lastname: de Vlas
authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. David.Weetman@lstmed.ac.uk.
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mesh_terms: D000818:Animals; D060740:Disease Eradication; D006801:Humans; D007194:India / Q000453:epidemiology; D007893:Leishmania donovani / Q000502:physiology*; D007898:Leishmaniasis, Visceral / Q000453:epidemiology / Q000635:transmission*; D010691:Phlebotomus / Q000469:parasitology* / Q000502:physiology
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