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Roy L, Cloots K, Uranw S, Rai K, Bhattarai NR, Smekens T, Hendrickx R, Caljon G, Hasker E, Das ML, Van Bortel W. The ongoing risk of Leishmania donovani transmission in eastern Nepal: an entomological investigation during the elimination era. Parasit Vectors 2023; 16:404. [PMID: 37932813 PMCID: PMC10629032 DOI: 10.1186/s13071-023-05986-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 09/27/2023] [Indexed: 11/08/2023] Open
Abstract
BACKGROUND Visceral leishmaniasis (VL), a life-threatening neglected tropical disease, is targeted for elimination from Nepal by the year 2026. The national VL elimination program is still confronted with many challenges including the increasingly widespread distribution of the disease over the country, local resurgence and the questionable efficacy of the key vector control activities. In this study, we assessed the status and risk of Leishmania donovani transmission based on entomological indicators including seasonality, natural Leishmania infection rate and feeding behavior of vector sand flies, Phlebotomus argentipes, in three districts that had received disease control interventions in the past several years in the context of the disease elimination effort. METHODS We selected two epidemiologically contrasting settings in each survey district, one village with and one without reported VL cases in recent years. Adult sand flies were collected using CDC light traps and mouth aspirators in each village for 12 consecutive months from July 2017 to June 2018. Leishmania infection was assessed in gravid sand flies targeting the small-subunit ribosomal RNA gene of the parasite (SSU-rRNA) and further sequenced for species identification. A segment (~ 350 bp) of the vertebrate cytochrome b (cytb) gene was amplified from blood-fed P. argentipes from dwellings shared by both humans and cattle and sequenced to identify the preferred host. RESULTS Vector abundance varied among districts and village types and peaks were observed in June, July and September to November. The estimated Leishmania infection rate in vector sand flies was 2.2% (1.1%-3.7% at 95% credible interval) and 0.6% (0.2%-1.3% at 95% credible interval) in VL and non-VL villages respectively. The common source of blood meal was humans in both VL (52.7%) and non-VL (74.2%) villages followed by cattle. CONCLUSIONS Our findings highlight the risk of ongoing L. donovani transmission not only in villages with VL cases but also in villages not reporting the presence of the disease over the past several years within the districts having disease elimination efforts, emphasize the remaining threats of VL re-emergence and inform the national program for critical evaluation of disease elimination strategies in Nepal.
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Affiliation(s)
- Lalita Roy
- Tropical and Infectious Disease Centre, BP Koirala Institute of Health Sciences, Dharan, Nepal.
- Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium.
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Antwerp, Belgium.
| | - Kristien Cloots
- Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
| | - Surendra Uranw
- Department of Internal Medicine, BP Koirala Institute of Health Sciences, Dharan, Nepal
| | - Keshav Rai
- Department of Microbiology, BP Koirala Institute of Health Sciences, Dharan, Nepal
| | - Narayan R Bhattarai
- Department of Microbiology, BP Koirala Institute of Health Sciences, Dharan, Nepal
| | - Tom Smekens
- Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
| | - Rik Hendrickx
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Antwerp, Belgium
| | - Guy Caljon
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Antwerp, Belgium
| | - Epco Hasker
- Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
| | - Murari L Das
- Department of Microbiology, BP Koirala Institute of Health Sciences, Dharan, Nepal
| | - Wim Van Bortel
- Department of Biomedical Sciences and Outbreak Research Team, Institute of Tropical Medicine, Antwerp, Belgium
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Joshi AB, Banjara MR, Chuke S, Kroeger A, Jain S, Aseffa A, Reeder JC. Assessment of the impact of implementation research on the Visceral Leishmaniasis (VL) elimination efforts in Nepal. PLoS Negl Trop Dis 2023; 17:e0011714. [PMID: 37943733 PMCID: PMC10635428 DOI: 10.1371/journal.pntd.0011714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023] Open
Abstract
Nepal, Bangladesh, and India signed a Memorandum of Understanding (MoU) in 2005 to eliminate visceral leishmaniasis (VL) as a public health problem from the Indian subcontinent by 2015. By 2021, the number of reported VL cases in these countries had declined by over 95% compared to 2007. This dramatic success was achieved through an elimination programme that implemented early case detection and effective treatment, vector control, disease surveillance, community participation, and operational research that underpinned these strategies. The experience offered an opportunity to assess the contribution of implementation research (IR) to VL elimination in Nepal. Desk review and a stakeholder workshop was conducted to analyse the relationship between key research outputs, major strategic decisions in the national VL elimination programme, and annual number of reported new cases over time between 2005 and 2023. The results indicated that the key decisions across the strategic elements, throughout the course of the elimination programme (such as on the most appropriate tools for diganostics and treatment, and on best strategies for case finding and vector management), were IR informed. IR itself responded dynamically to changes that resulted from interventions, addressing new questions that emerged from the field. Close collaboration between researchers, programme managers, and implementers in priority setting, design, conduct, and review of studies facilitated uptake of evidence into policy and programmatic activities. VL case numbers in Nepal are now reduced by 90% compared to 2005. Although direct attribution of disease decline to research outputs is difficult to establish, the Nepal experience demonstrates that IR can be a critical enabler for disease elimination. The lessons can potentially inform IR strategies in other countries with diseases targeted for elimination.
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Affiliation(s)
- Anand Ballabh Joshi
- Public Health and Infectious Disease Research Center (PHIDReC), Kathmandu, Nepal
| | - Megha Raj Banjara
- Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu, Nepal
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), Geneva, Switzerland
| | - Sachi Chuke
- Public Health and Infectious Disease Research Center (PHIDReC), Kathmandu, Nepal
| | - Axel Kroeger
- Freiburg University, Centre for Medicine and Society, Freiburg, Germany
| | - Saurabh Jain
- Department of Control of Neglected Tropical Diseases, WHO, Geneva, Switzerland
| | - Abraham Aseffa
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), Geneva, Switzerland
| | - John C. Reeder
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), Geneva, Switzerland
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Susceptibility status of the wild-caught Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), the sand fly vector of visceral leishmaniasis, to different insecticides in Nepal. PLoS Negl Trop Dis 2022; 16:e0010304. [PMID: 35834563 PMCID: PMC9321455 DOI: 10.1371/journal.pntd.0010304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 07/26/2022] [Accepted: 06/28/2022] [Indexed: 11/24/2022] Open
Abstract
Background Visceral leishmaniasis (VL) is targeted for elimination as a public health problem in Nepal by 2023. For nearly three decades, the core vector control intervention in Nepal has been indoor residual spraying (IRS) with pyrethroids. Considering the long-term use of pyrethroids and the possible development of resistance in the vector Phlebotomus argentipes sand flies, we monitored the susceptibility status of their field populations to the insecticides of different classes, in villages with and without IRS activities in recent years. Methodology/Principal findings Sand flies were collected from villages with and without IRS in five VL endemic districts from August 2019 to November 2020. The WHO susceptibility test procedure was adopted using filter papers impregnated at the discriminating concentrations of insecticides of the following classes: pyrethroids (alpha-cypermethrin 0.05%, deltamethrin 0.05%, and lambda-cyhalothrin 0.05%), carbamates (bendiocarb 0.1%) and organophosphates (malathion 5%). Pyrethroid resistance intensity bioassays with papers impregnated with 5× of the discriminating concentrations, piperonyl butoxide (PBO) synergist-pyrethroid bioassays, and DDT cross-resistance bioassays were also performed. In the IRS villages, the vector sand flies were resistant (mortality rate <90%) to alpha-cypermethrin and possibly resistant (mortality rate 90–97%) to deltamethrin and lambda-cyhalothrin, while susceptibility to these insecticides was variable in the non-IRS villages. The vector was fully susceptible to bendiocarb and malathion in all villages. A delayed knockdown time (KDT50) with pyrethroids was observed in all villages. The pyrethroid resistance intensity was low, and the susceptibility improved at 5× of the discriminating concentrations. Enhanced pyrethroid susceptibility after pre-exposure to PBO and the DDT-pyrethroid cross-resistance were evident. Conclusions/Significance Our investigation showed that P. argentipes sand flies have emerged with pyrethroid resistance, suggesting the need to switch to alternative classes of insecticides such as organophosphates for IRS. We strongly recommend the regular and systematic monitoring of insecticide resistance in sand flies to optimize the efficiency of vector control interventions to sustain VL elimination efforts in Nepal. Visceral leishmaniasis (VL), transmitted by P. argentipes sand flies, is endemic in South-East Asian countries such as Bangladesh, India, and Nepal, and is on the verge of elimination as a public health problem in Nepal by 2023. As part of the WHO Global Vector Control Response, entomological surveillance including insecticide resistance monitoring is one of the four main pillars of this strategy. In the early 1990s, the historical use of DDT for sand fly vector control was replaced with deltamethrin or alpha-cypermethrin, which have now been in use for almost three decades in Nepal. Suspecting that this long-term use of pyrethroids might have selected resistance in sand fly populations which would jeopardize control efforts, we conducted the first comprehensive survey to generate contemporary evidence of insecticide resistance in Nepal. For this, we performed WHO susceptibility tests in five VL endemic districts and found strong evidence of pyrethroid resistance in vector populations from the areas receiving IRS. Resistance mechanisms involved would probably be kdr mutations and monooxygenase. This study also endorses regular insecticide resistance monitoring to inform evidence-based decisions on insecticide use for vector control and to maintain the effectiveness of vector control measures as a core intervention in the fight against VL.
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Faber C, Montenegro Quiñonez C, Horstick O, Rahman KM, Runge-Ranzinger S. Indoor residual spraying for the control of visceral leishmaniasis: A systematic review. PLoS Negl Trop Dis 2022; 16:e0010391. [PMID: 35587498 PMCID: PMC9159594 DOI: 10.1371/journal.pntd.0010391] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 06/01/2022] [Accepted: 04/03/2022] [Indexed: 11/19/2022] Open
Abstract
Indoor Residual Spraying (IRS) is one of the interventions to control the vectors of Visceral Leishmaniasis (VL). Different insecticides are used in affected countries, also in the Regional Initiative for the Elimination of VL in South-East Asia. This systematic review assesses all available studies analysing the effectiveness of IRS on the key vectors of VL. The systematic review followed PRISMA guidelines, with a broad search strategy, applied to seven key databases. Inclusion criteria were studies focusing on 1) Visceral leishmaniasis 2) Indoor Residual Spraying (IRS) or synonyms, and 3) all primary research methods. 21 studies were included, five cluster randomised controlled trials (cRCTs), one randomised controlled trial (RCT), 11 intervention studies, also included were three modelling studies and one survey. 19 out of 21 included studies were published between 2009 and 2020. 18 of the studies were conducted in the context of the Regional Initiative. Effects of IRS on vector populations are positive, confirmed in terms of effectiveness and by the availability of studies. Deltamethrin and alpha-Cypermethrin reduce total sandfly counts, and/or Phlebotomus argentipes counts by up to 95% with an effect of a minimum of one month. Prolonged effects are not regularly seen. DDT has been used in India only: whereas in the 1990s a good effect could be measured, this effect waned over time. Two intervention studies, embedded in larger programmes in 2019 and 2020, replaced DDT with alpha-Cypermethrin throughout the study. Combinations of different interventions are not systematically researched, however showing some promising results, for example for the combination of IRS and Temephos. Constant monitoring of insecticide resistancies and quality delivery of IRS are confirmed as key issues for programmes. No human transmission data are available to directly relate an effect of IRS-although modelling studies confirm the effect of IRS on human transmission. Concluding, IRS continues to be an effective intervention for Phlebotomus argentipes control. Delivery requires constant monitoring and quality assurance. Further studies need to assess IRS in different geographical areas affected by VL and combinations of interventions.
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Affiliation(s)
- Claudia Faber
- Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany
| | - Carlos Montenegro Quiñonez
- Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany
- Instituto de Investigaciones, Centro Universitario de Zacapa, Universidad de San Carlos de Guatemala, Zacapa, Guatemala
| | - Olaf Horstick
- Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany
| | - Kazi Mizanur Rahman
- The University of Sydney, University Centre for Rural Health, Lismore, New South Wales, Australia
| | - Silvia Runge-Ranzinger
- Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany
- * E-mail:
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Montenegro-Quiñonez CA, Buhler C, Horstick O, Runge-Ranzinger S, Rahman KM. Efficacy and community-effectiveness of insecticide treated nets for the control of visceral leishmaniasis: A systematic review. PLoS Negl Trop Dis 2022; 16:e0010196. [PMID: 35235556 PMCID: PMC8890655 DOI: 10.1371/journal.pntd.0010196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 01/24/2022] [Indexed: 12/28/2022] Open
Abstract
Visceral leishmaniasis (VL) has been targeted for elimination from Southeast Asia (SEA). The disease has been endemic in SEA, and in other parts of the world involving both humans and animals. One of the key strategies for combating VL is controlling for the vector sandfly. There are a few vector control strategies that are currently in practice. We sought to assess the efficacy and community effectiveness of insecticide treated nets (ITNs) in controlling the burden of sandfly and the occurrence of VL among humans. We conducted a systematic review following a study protocol and the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) criteria. 6331 initial hits were retrieved from Google Scholar, Lilacs, PubMed, Science Direct, WHOlis, WHOiris and PAHOiris. 25 met the full inclusion criteria. Findings show that the insecticide impregnated bednets and the commercially treated long lasting insecticidal nets (LLINs) are effective in controlling sandflies, with mortalities as high as 75% lasting over a year; although their role in controlling VL in the community was not extensively studied, since effectiveness was usually measured with sandflies densities. Findings also show that insecticide impregnated bednets are low cost and well accepted in the community, however, early erosion of insecticides from nets could occur. Some studies also showed that killing of sandflies may not translate into reduction of VL, therefore sandfly knock down and killing data needs to be interpreted with caution. Conclusions of this review are (1) combining insecticide impregnated bednets, as targeted interventions, with another vector control measure, particularly indoor residual spraying, and in conjunction with case detection, could be the way forward to controlling VL in resource limited settings. (2) Given the current low incidence of VL in SEA, it can be difficult to further research the community effectiveness of those control measures in reducing VL. Visceral leishmaniasis (VL) is a vector borne disease endemic in Southeast Asia (SEA) and present in other regions of the world. In SEA the disease has been targeted for elimination. VL is transmitted by different species of sandflies and key strategies against VL rely on the control of the vectors. This systematic review assesses the efficacy and community effectiveness of insecticide treated nets (ITNs) in controlling sandflies and VL occurrence among humans. After a revision of 6331 initial hits, 25 studies were included in this systematic review. Main findings indicated that insecticide impregnated bednets and long-lasting insecticidal nets (LLINs) can effectively control sandflies, however, it was not possible to fully assess the role of ITNs in controlling VL transmission. Additional results showed that insecticide impregnated bednets are low cost and well accepted in the community, however early erosion of insecticides from the nets could occur. If insecticide impregnated bednets are combined with other vector control measures, such as indoor residual spraying, and together with case detection, it could be an important strategy to control VL in resource limited settings.
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Affiliation(s)
- Carlos Alberto Montenegro-Quiñonez
- Heidelberg Institute of Global Health, Research to Practice Group, Heidelberg University, Heidelberg, Germany
- Instituto de Investigaciones, Centro Universitario de Zacapa, Universidad de San Carlos de Guatemala, Zacapa, Guatemala
- * E-mail:
| | - Claudia Buhler
- Heidelberg Institute of Global Health, Research to Practice Group, Heidelberg University, Heidelberg, Germany
| | - Olaf Horstick
- Heidelberg Institute of Global Health, Research to Practice Group, Heidelberg University, Heidelberg, Germany
| | - Silvia Runge-Ranzinger
- Heidelberg Institute of Global Health, Research to Practice Group, Heidelberg University, Heidelberg, Germany
| | - Kazi Mizanur Rahman
- The University of Sydney, University Centre for Rural Health, Lismore, New South Wales, Australia
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Balaska S, Fotakis EA, Chaskopoulou A, Vontas J. Chemical control and insecticide resistance status of sand fly vectors worldwide. PLoS Negl Trop Dis 2021; 15:e0009586. [PMID: 34383751 PMCID: PMC8360369 DOI: 10.1371/journal.pntd.0009586] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Phlebotomine sand flies are prominent vectors of Leishmania parasites that cause leishmaniasis, which comes second to malaria in terms of parasitic causative fatalities globally. In the absence of human vaccines, sand fly chemical-based vector control is a key component of leishmaniasis control efforts. METHODS AND FINDINGS We performed a literature review on the current interventions, primarily, insecticide-based used for sand fly control, as well as the global insecticide resistance (IR) status of the main sand fly vector species. Indoor insecticidal interventions, such as residual spraying and treated bed nets are the most widely deployed, while several alternative control strategies are also used in certain settings and/or are under evaluation. IR has been sporadically detected in sand flies in India and other regions, using non-standardized diagnostic bioassays. Molecular studies are limited to monitoring of known pyrethroid resistance mutations (kdr), which are present at high frequencies in certain regions. CONCLUSIONS As the leishmaniasis burden remains a major problem at a global scale, evidence-based rational use of insecticidal interventions is required to meet public health demands. Standardized bioassays and molecular markers are a prerequisite for this task, albeit are lagging behind. Experiences from other disease vectors underscore the need for the implementation of appropriate IR management (IRM) programs, in the framework of integrated vector management (IVM). The implementation of alternative strategies seems context- and case-specific, with key eco-epidemiological parameters yet to be investigated. New biotechnology-based control approaches might also come into play in the near future to further reinforce sand fly/leishmaniasis control efforts.
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Affiliation(s)
- Sofia Balaska
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Greece
| | - Emmanouil Alexandros Fotakis
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, Heraklion, Greece
- Department of Crop Science, Agricultural University of Athens, Athens, Greece
| | | | - John Vontas
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, Heraklion, Greece
- Department of Crop Science, Agricultural University of Athens, Athens, Greece
- * E-mail:
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Santamaría E, Cabrera OL, Pardo RH. Efficacy of factory-treated and dip-it-yourself long lasting insecticide-treated bednets against cutaneous leishmaniasis vectors in the sub-Andean region of Colombia: results after two years of use. Mem Inst Oswaldo Cruz 2020; 115:e190431. [PMID: 32935748 PMCID: PMC7491276 DOI: 10.1590/0074-02760190431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 08/17/2020] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Long lasting insecticide-treated nets (LLINs) may be effective for vector control of cutaneous leishmaniasis (CL). Their efficacy, however, has not been sufficiently evaluated. OBJECTIVE To evaluate the large-scale efficacy of LLINs on Lutzomyia longiflocosa entomological parameters up to two years post-intervention in the sub-Andean region of Colombia. METHODS A matched-triplet cluster-randomised study of 21 rural settlements, matched by pre-intervention L. longiflocosa indoor density was used to compare three interventions: dip it yourself (DIY) lambda-cyhalothrin LLIN, deltamethrin LLIN, and untreated nets (control). Sand fly indoor density, feeding success, and parity were recorded using CDC light trap collections at 1, 6, 12, and 24 months post-intervention. FINDINGS Both LLINs reduced significantly (74-76%) the indoor density and the proportion of fully engorged sand flies up to two years post-intervention without differences between them. Residual lethal effects of both LLINs and the use of all nets remained high throughout the two-year evaluation period. CONCLUSIONS Both LLINs demonstrated high efficacy against L. longiflocosa indoors. Therefore, the deployment of these LLINs could have a significant impact on the reduction of CL transmission in the sub-Andean region. The DIY lambda-cyhalothrin kit may be used to convert untreated nets to LLINs increasing coverage.
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Affiliation(s)
- Erika Santamaría
- Instituto Nacional de Salud, Grupo de Entomología, Bogotá, Colombia
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Calderon-Anyosa R, Galvez-Petzoldt C, Garcia PJ, Carcamo CP. Housing Characteristics and Leishmaniasis: A Systematic Review. Am J Trop Med Hyg 2019; 99:1547-1554. [PMID: 30382013 DOI: 10.4269/ajtmh.18-0037] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Leishmaniasis is a major neglected tropical disease associated with high rates of disability and death. This disease is associated with poverty, which can be reflected in housing quality, especially in rural areas. This systematic review found that mud walls with cracks and holes, damp, and dark houses were risk factors for transmission of leishmaniasis. These characteristics create favorable conditions for sand fly breeding and resting as sand flies prefer humidity, warmth, and protection from sunlight during the day. Housing interventions might be a promising research area with a special focus on education as individual and collective protection for the effective control of leishmaniasis.
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Affiliation(s)
- Renzo Calderon-Anyosa
- Kuskaya Program, School of Public Health and Administration, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Camila Galvez-Petzoldt
- Kuskaya Program, School of Public Health and Administration, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Patricia J Garcia
- Kuskaya Program, School of Public Health and Administration, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Cesar P Carcamo
- Kuskaya Program, School of Public Health and Administration, Universidad Peruana Cayetano Heredia, Lima, Peru
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Hirve S, Kroeger A, Matlashewski G, Mondal D, Banjara MR, Das P, Be-Nazir A, Arana B, Olliaro P. Towards elimination of visceral leishmaniasis in the Indian subcontinent-Translating research to practice to public health. PLoS Negl Trop Dis 2017; 11:e0005889. [PMID: 29023446 PMCID: PMC5638223 DOI: 10.1371/journal.pntd.0005889] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The decade following the Regional Strategic Framework for Visceral Leishmaniasis (VL) elimination in 2005 has shown compelling progress in the reduction of VL burden in the Indian subcontinent. The Special Programme for Research and Training in Tropical Diseases (TDR), hosted by the World Health Organization (WHO) and other stakeholders, has coordinated and financed research for the development of new innovative tools and strategies to support the regional VL elimination initiative. This paper describes the process of the TDR's engagement and contribution to this initiative. METHODOLOGY/PRINCIPAL FINDINGS Multiple databases were searched to identify 152 scientific papers and reports with WHO funding or authorship affiliation around the following 3 framework strategies: detection of new cases, morbidity reduction, and prevention of infection. TDR has played a critical role in the evaluation and subsequent use of the 39-aminoacid-recombinant kinesin antigen (rK39) rapid diagnostic test (RDT) as a confirmatory test for VL in the national program. TDR has supported the clinical research and development of miltefosine and single-dose liposomal amphotericin B as a first-line treatment against VL. TDR has engaged with in-country researchers, national programme managers, and partners to generate evidence-based interventions for early detection and treatment of VL patients. TDR evaluated the quality, community acceptance, and cost effectiveness of indoor residual spraying, insecticide-treated bed nets, insecticide-impregnated durable wall linings, insecticidal paint, and environmental management as tools for integrated vector management in reducing sandfly density. CONCLUSIONS/SIGNIFICANCE TDR's engagement with country policy makers, scientists, and clinicians in the development of effective diagnosis, treatment, case detection, and vector control represents an important example of TDR's stewardship toward the elimination of VL in the Indian subcontinent.
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Affiliation(s)
| | - Axel Kroeger
- Centre for Medicine and Society and Centre for Anthropology, Freiburg University, Freiburg, Germany
- Special Programme for Research and Training in Tropical Diseases (TDR), hosted by the World Health Organization, Geneva, Switzerland
| | - Greg Matlashewski
- Department of Microbiology and Immunology, McGill University, Montreal, Canada
| | - Dinesh Mondal
- Nutrition and Clinical Services division, International Center for Diarrheal Disease Research Bangladesh, Dhaka, Bangladesh
| | - Megha Raj Banjara
- Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
| | - Pradeep Das
- Rajendra Memorial Research Institute of Medical Sciences, Indian Council of Medical Research, Patna, India
| | - Ahmed Be-Nazir
- Department of Microbiology and Parasitology, National Institute of Preventive and Social Medicine, Dhaka, Bangladesh
| | - Byron Arana
- Cutaneous Leishmaniasis unit, Drugs for Neglected Diseases Initiative, Geneva, Switzerland
| | - Piero Olliaro
- Special Programme for Research and Training in Tropical Diseases (TDR), hosted by the World Health Organization, Geneva, Switzerland
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Dhiman RC, Yadav RS. Insecticide resistance in phlebotomine sandflies in Southeast Asia with emphasis on the Indian subcontinent. Infect Dis Poverty 2016; 5:106. [PMID: 27817749 PMCID: PMC5098277 DOI: 10.1186/s40249-016-0200-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 10/12/2016] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Visceral leishmaniasis, commonly known as kala-azar in India, is a global public health problem. In Southeast Asia, Bangladesh, Bhutan, India, Nepal, Sri Lanka and Thailand are endemic for visceral leishmaniasis. The role of sandflies as the vector of kala-azar was first confirmed in 1942 in India. Insecticide resistance in Phlebotomus argentipes Annandale and Brunetti, the vector of kala-azar in the Indian subcontinent, was first reported in 1987 in Bihar, India. This article provides a scoping review of the studies undertaken from 1959 to 2015 on insecticide resistance in P. argentipes and P. papatasi (Scopoli), the vectors of visceral and cutaneous leishmaniasis respectively, in Southeast Asia, mainly in Bangladesh, India, Nepal and Sri Lanka. RESULTS Studies undertaken in areas of Bihar and West Bengal in India where kala-azar is endemic have reported resistance of P. argentipes to DDT, while in non-endemic areas it has been reported to be susceptible. In areas of Nepal bordering India, there are indications of resistance to DDT; biochemical resistance has been reported in Sri Lanka. No laboratory studies have been undertaken in Bangladesh; however, the sandfly vector is reported to be still susceptible to pyrethroids in all kala-azar endemic areas in the aforementioned countries. CONCLUSIONS Studies are needed to determine the resistance of sandfly vectors to all available classes of potential insecticides in kala-azar endemic areas. There is a need to assess the impact of indoor residual spraying with DDT and pyrethroids on the incidence of kala-azar in India where 54 districts remain endemic for the disease, strengthen entomological surveillance capacity, and develop and implement an insecticide management plan. Alpha-cypermethrin indoor residual spraying has been introduced in 33 kala-azar endemic districts in Bihar State of India in a pilot trial; the outcomes should be used to inform decisions on expanding coverage with alpha-cypermethrin in all remaining endemic districts to achieve the revised goal of elimination of visceral leishmaniasis by 2020.
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Affiliation(s)
- Ramesh C. Dhiman
- National Institute of Malaria Research (ICMR), Delhi, 110077 India
| | - Rajpal S. Yadav
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
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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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Le Rutte EA, Coffeng LE, Bontje DM, Hasker EC, Postigo JAR, Argaw D, Boelaert MC, De Vlas SJ. Feasibility of eliminating visceral leishmaniasis from the Indian subcontinent: explorations with a set of deterministic age-structured transmission models. Parasit Vectors 2016; 9:24. [PMID: 26787302 PMCID: PMC4717541 DOI: 10.1186/s13071-016-1292-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/31/2015] [Indexed: 02/02/2023] Open
Abstract
Background Visceral leishmaniasis (VL) is a neglected tropical disease transmitted by sandflies. On the Indian subcontinent (ISC), VL is targeted for elimination as a public health problem by 2017. In the context of VL, the elimination target is defined as an annual VL incidence of <1 per 10,000 capita at (sub-)district level. Interventions focus on vector control, surveillance and on diagnosing and treating VL cases. Many endemic areas have not yet achieved optimal control due to logistical, biological as well as technical challenges. We used mathematical modelling to quantify VL transmission dynamics and predict the feasibility of achieving the VL elimination target with current control strategies under varying assumptions about the reservoir of infection in humans. Methods We developed three deterministic age-structured transmission models with different main reservoirs of infection in humans: asymptomatic infections (model 1), reactivation of infection after initial infection (model 2), and post kala-azar dermal leishmaniasis (PKDL; model 3). For each model, we defined four sub-variants based on different assumptions about the duration of immunity and age-patterns in exposure to sandflies. All 12 model sub-variants were fitted to data from the KalaNet study in Bihar (India) and Nepal, and the best sub-variant was selected per model. Predictions were made for optimal and sub-optimal indoor residual spraying (IRS) effectiveness for three different levels of VL endemicity. Results Structurally different models explained the KalaNet data equally well. However, the predicted impact of IRS varied substantially between models, such that a conclusion about reaching the VL elimination targets for the ISC heavily depends on assumptions about the main reservoir of infection in humans: asymptomatic cases, recovered (immune) individuals that reactivate, or PKDL cases. Conclusions Available data on the impact of IRS so far suggest one model is probably closest to reality (model 1). According to this model, elimination of VL (incidence of <1 per 10,000) by 2017 is only feasible in low and medium endemic settings with optimal IRS. In highly endemic settings and settings with sub-optimal IRS, additional interventions will be required. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1292-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Epke A Le Rutte
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
| | - Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
| | - Daniel M Bontje
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
| | - Epco C Hasker
- Institute of Tropical Medicine, Nationalestraat 155, 2000, Antwerp, Belgium.
| | | | - Daniel Argaw
- World Health Organization, Avenue Appia 20, 1211, Geneva, Switzerland.
| | - Marleen C Boelaert
- Institute of Tropical Medicine, Nationalestraat 155, 2000, Antwerp, Belgium.
| | - Sake J De Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
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Gorahava KK, Rosenberger JM, Mubayi A. Optimizing insecticide allocation strategies based on houses and livestock shelters for visceral leishmaniasis control in Bihar, India. Am J Trop Med Hyg 2015; 93:114-22. [PMID: 25940194 DOI: 10.4269/ajtmh.14-0612] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 03/19/2015] [Indexed: 11/07/2022] Open
Abstract
Visceral leishmaniasis (VL) is the most deadly form of the leishmaniasis family of diseases, which affects numerous developing countries. The Indian state of Bihar has the highest prevalence and mortality rate of VL in the world. Insecticide spraying is believed to be an effective vector control program for controlling the spread of VL in Bihar; however, it is expensive and less effective if not implemented systematically. This study develops and analyzes a novel optimization model for VL control in Bihar that identifies an optimal (best possible) allocation of chosen insecticide (dichlorodiphenyltrichloroethane [DDT] or deltamethrin) based on the sizes of human and cattle populations in the region. The model maximizes the insecticide-induced sandfly death rate in human and cattle dwellings while staying within the current state budget for VL vector control efforts. The model results suggest that deltamethrin might not be a good replacement for DDT because the insecticide-induced sandfly deaths are 3.72 times more in case of DDT even after 90 days post spray. Different insecticide allocation strategies between the two types of sites (houses and cattle sheds) are suggested based on the state VL-control budget and have a direct implication on VL elimination efforts in a resource-limited region.
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Affiliation(s)
- Kaushik K Gorahava
- Industrial and Manufacturing Systems Engineering Department, The University of Texas at Arlington, Arlington, Texas; Department of Mathematics, Northeastern Illinois University, Chicago, Illinois; Department of Mathematics, The University of Texas at Arlington, Arlington, Texas; SAL Mathematical Computational and Modeling Science Center, Tempe, Arizona; School of Mathematical and Natural Sciences, Arizona State University, Phoenix, Arizona
| | - Jay M Rosenberger
- Industrial and Manufacturing Systems Engineering Department, The University of Texas at Arlington, Arlington, Texas; Department of Mathematics, Northeastern Illinois University, Chicago, Illinois; Department of Mathematics, The University of Texas at Arlington, Arlington, Texas; SAL Mathematical Computational and Modeling Science Center, Tempe, Arizona; School of Mathematical and Natural Sciences, Arizona State University, Phoenix, Arizona
| | - Anuj Mubayi
- Industrial and Manufacturing Systems Engineering Department, The University of Texas at Arlington, Arlington, Texas; Department of Mathematics, Northeastern Illinois University, Chicago, Illinois; Department of Mathematics, The University of Texas at Arlington, Arlington, Texas; SAL Mathematical Computational and Modeling Science Center, Tempe, Arizona; School of Mathematical and Natural Sciences, Arizona State University, Phoenix, Arizona
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Gunay F, Karakus M, Oguz G, Dogan M, Karakaya Y, Ergan G, Kaynas S, Kasap OE, Ozbel Y, Alten B. Evaluation of the efficacy of Olyset® Plus in a village-based cohort study in the Cukurova Plain, Turkey, in an area of hyperendemic cutaneous leishmaniasis. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2014; 39:395-405. [PMID: 25424269 DOI: 10.1111/jvec.12115] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 08/21/2014] [Indexed: 06/04/2023]
Abstract
The aim of this study was to measure the protective efficacy of Olyset(®) Plus, a new long-lasting factory-treated insecticidal net (LLIN) incorporated with 2% permethrin and 1% of the synergist piperonyl butoxide (PBO), against cutaneous leishmaniasis (CL) transmission under field conditions. A village-scale trial, promoting the use of LLIN by the local inhabitants of the study area was conducted as a pilot study in a new hyperendemic focus of CL caused by a Leishmania infantum/L. donovani hybrid parasite transmitted by proven vector species Phlebotomus tobbi in Cukurova Plain, Adana, Turkey, between May, 2013 and May, 2014. The study area comprised eight villages; two of them were selected as an intervention village with Olyset(®) Plus net (Kizillar) and a control village without net application (Malihidirli). Six villages with surrounding allopatric barriers were utilized as a buffer zone cluster between intervention and control villages. Monthly entomological surveys were performed in the intervention and control villages and Damyeri, representing the other six villages, to collect adults of Phlebotomus tobbi. Results showed a significant reduction in cutaneous leishmaniasis incidence in the intervention village from 4.78% to 0.37%. The protective efficacy rate of LLIN was 92.2%. In contrast, incidence rates increased in the control village from 3.67% to 4.69%. We also evaluated residual insecticide levels of used nets after six and 12 months of usage. It was determined that the nets had retained full insecticidal strength. These results highlight the value of real-world data on bed net effectiveness and longevity to guide decisions regarding sand fly control strategies. To the best of our knowledge, this is the first field study to evaluate Olyset(®) Plus efficacy in a hyperendemic cutaneous leishmaniasis area.
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Affiliation(s)
- Filiz Gunay
- Hacettepe University, Faculty of Science, Department of Biology, Ankara, Turkey
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Model-based investigations of different vector-related intervention strategies to eliminate visceral leishmaniasis on the Indian subcontinent. PLoS Negl Trop Dis 2014; 8:e2810. [PMID: 24762676 PMCID: PMC3998939 DOI: 10.1371/journal.pntd.0002810] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 03/10/2014] [Indexed: 01/19/2023] Open
Abstract
The elimination of infectious diseases requires reducing transmission below a certain threshold. The Visceral Leishmaniasis (VL) Elimination Initiative in Southeast Asia aims to reduce the annual VL incidence rate below 1 case per 10,000 inhabitants in endemic areas by 2015 via a combination of case management and vector control. Using a previously developed VL transmission model, we investigated transmission thresholds dependent on measures reducing the sand fly density either by killing sand flies (e.g., indoor residual spraying and long-lasting insecticidal nets) or by destroying breeding sites (e.g., environmental management). Model simulations suggest that elimination of VL is possible if the sand fly density can be reduced by 67% through killing sand flies, or if the number of breeding sites can be reduced by more than 79% through measures of environmental management. These results were compared to data from two recent cluster randomised controlled trials conducted in India, Nepal and Bangladesh showing a 72% reduction in sand fly density after indoor residual spraying, a 44% and 25% reduction through the use of long-lasting insecticidal nets and a 42% reduction after environmental management. Based on model predictions, we identified the parameters within the transmission cycle of VL that predominantly determine the prospects of intervention success. We suggest further research to refine model-based predictions into the elimination of VL. Visceral leishmaniasis is suspected to be the second largest parasitic killer in the world after malaria. On the Indian subcontinent, the vector-borne disease is caused by the protozoan flagellate Leishmania donovani and transmitted by the sand fly Phlebotomus argentipes. The regional elimination programme has suggested as a target line to reduce the annual incidence below 1 case in 10,000 by 2015. Using a previously developed mathematical model, we investigated to what extent the sand fly population must be controlled to achieve elimination. These calculated thresholds were compared to data from two recent trials conducted in India, Nepal and Bangladesh to evaluate the efficacy of different vector control measures. Our results indicate that elimination should be feasible because the evaluated effect of indoor residual spraying exceeds the threshold. However, emerging insecticide resistance may compromise the effectiveness of this measure. The observed effects of long lasting insecticidal nets and environmental management do not seem to be sufficient to reach either threshold. Integrated vector management based on indoor residual spraying combined with long lasting insecticidal nets and more effective environmental management may allow overcoming the limitations of the current vector control methods and should also prevent re-emergence of the infection after local extinction.
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Bray DP, Hamilton JGC. Insecticide-impregnated netting as a potential tool for long-lasting control of the leishmaniasis vector Lutzomyia longipalpis in animal shelters. Parasit Vectors 2013; 6:133. [PMID: 23642213 PMCID: PMC3658972 DOI: 10.1186/1756-3305-6-133] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 04/30/2013] [Indexed: 11/23/2022] Open
Abstract
Background Leishmaniasis remains a serious neglected disease, with more than 350 million people potentially at risk worldwide. Control strategies often rely on spraying residual insecticides to target populations of the sand fly vectors that transmit Leishmania parasites when blood-feeding. These programmes are often difficult to sustain effectively, as sand fly resting sites must be resprayed on a regular basis. Here, we investigate whether application of insecticide-impregnated netting to a surface could act as an alternative to residual spraying for controlling the American visceral leishmaniasis vector Lutzomyia longipalpis. Methods Female L. longipalpis from our laboratory colony were exposed for 1 h to three treatments applied to plywood surfaces: 2% permethrin-impregnated netting (Olyset®), 20 mg a.i.m-2 micro-encapsulated lambda-cyhalothrin (Demand CS®) and a no-treatment control. We compared the speed at which these treatments acted, by measuring the percentage of sand flies killed both immediately after exposure to the treatment for 1 hour, as well as the number that had died 24 h after the 1 hour exposure. We repeated the experiment at 6 and 12 months following application to test the effectiveness of each treatment over time. Results When first applied, the lambda-cyhalothrin killed more sand flies in the first hour than the permethrin-impregnated netting. However, the effectiveness of the lambda-cyhalothrin diminished over time, so that there was no difference between the two treatments at 12 months. Both killed more sand flies than the control. When measured 24 h following exposure, both test treatments had killed close to 100% of sand flies when first applied, but while the lethal effect of the netting was maintained at close to 100% over 12 months, the effectiveness of the residual insecticide diminished to approximately 80% after 6 months. Conclusions The results of these initial laboratory experiments indicate that covering surfaces with insecticide impregnated netting material may provide a longer-lasting solution for killing sand flies than residual spraying. Field trials are needed to identify the feasibility of treating surfaces with netting or similar impregnated materials as part of a control program. In targeting L. longipalpis, the greatest benefits may be seen in treating animal sheds with netting, where these sand flies aggregate in large numbers, and which can be difficult to treat repeatedly by conventional spraying.
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Bhunia GS, Kesari S, Chatterjee N, Kumar V, Das P. Telehealth: a perspective approach for visceral leishmaniasis (kala-azar) control in India. Pathog Glob Health 2012; 106:150-8. [PMID: 23265372 PMCID: PMC4001574 DOI: 10.1179/2047773212y.0000000014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Visceral leishmaniasis, also known as kala-azar, is a vector borne disease caused by the protozoan parasite, L. donovani. Poor and neglected populations in Indian sub-continent are particularly affected by this disease. Due to the diversity of epidemiological situations, no single diagnosis, treatment, or control will be suitable for all. Control measures through case findings, treatment, and vector control are seldom used, even where they could be useful. Modern tools like telehealth, using space technology, have now come in handy to address issues of disease surveillance, control checking, and evaluation. The present study focuses on telehealth as a current vector control strategy, perspectives on diagnosis, treatment, and control of visceral leishmaniasis as these deserve more attention and research.
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Affiliation(s)
- Gouri Sankar Bhunia
- Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Patna, Bihar, India
| | - Shreekant Kesari
- Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Patna, Bihar, India
| | - Nandini Chatterjee
- Department of Geography, Presidency University, Kolkata, West Bengal, India
| | - Vijay Kumar
- Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Patna, Bihar, India
| | - Pradeep Das
- Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Patna, Bihar, India
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Das M, Roy L, Picado A, Kroeger A, Rijal S, Boelaert M. Deltamethrin and permethrin residue on long-lasting insecticidal nets after 18 months of use in a visceral leishmaniasis-endemic area in Nepal. Trans R Soc Trop Med Hyg 2012; 106:230-4. [PMID: 22381627 DOI: 10.1016/j.trstmh.2012.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Revised: 01/13/2012] [Accepted: 01/13/2012] [Indexed: 12/01/2022] Open
Abstract
The insecticide residue on two types of long-lasting insecticidal nets (LLIN), Olyset Net and PermaNet 2.0, used in a visceral leishmaniasis-endemic village in eastern Nepal was quantified using HPLC. After two washes during 18 months of use the mean insecticide residues on PermaNet 2.0 and Olyset Net were 53.5 mg/m(2) (97.3% of the target dose) of deltamethrin and 911.8 mg/m(2) (91.2% of the target dose) of permethrin, respectively. These residues were close to the insecticide loads specified by the manufacturers of the two LLINs. The use of LLINs has been postulated as an alternative or complementary method to indoor residual spraying. Our results suggest that LLINs should be washed 4-5 times each year throughout their lifespan by specifically requesting villagers to wash nets on certain dates. The insecticide residue on the nets and their bioefficacy against sand fly vectors should be monitored after each wash, in various cultural settings, to assess their durability and long-term retention of the insectide.
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Affiliation(s)
- Murari Das
- BP Koirala Institute of Health Sciences, Dharan, Nepal.
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Visceral leishmaniasis in the Indian subcontinent: modelling epidemiology and control. PLoS Negl Trop Dis 2011; 5:e1405. [PMID: 22140589 PMCID: PMC3226461 DOI: 10.1371/journal.pntd.0001405] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 10/12/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND In the Indian subcontinent, about 200 million people are at risk of developing visceral leishmaniasis (VL). In 2005, the governments of India, Nepal and Bangladesh started the first regional VL elimination program with the aim to reduce the annual incidence to less than 1 per 10,000 by 2015. A mathematical model was developed to support this elimination program with basic quantifications of transmission, disease and intervention parameters. This model was used to predict the effects of different intervention strategies. METHODS AND FINDINGS Parameters on the natural history of Leishmania infection were estimated based on a literature review and expert opinion or drawn from a community intervention trial (the KALANET project). The transmission dynamic of Leishmania donovani is rather slow, mainly due to its long incubation period and the potentially long persistence of parasites in infected humans. Cellular immunity as measured by the Leishmanin skin test (LST) lasts on average for roughly one year, and re-infection occurs in intervals of about two years, with variation not specified. The model suggests that transmission of L. donovani is predominantly maintained by asymptomatically infected hosts. Only patients with symptomatic disease were eligible for treatment; thus, in contrast to vector control, the treatment of cases had almost no effect on the overall intensity of transmission. CONCLUSIONS Treatment of Kala-azar is necessary on the level of the individual patient but may have little effect on transmission of parasites. In contrast, vector control or exposure prophylaxis has the potential to efficiently reduce transmission of parasites. Based on these findings, control of VL should pay more attention to vector-related interventions. Cases of PKDL may appear after years and may initiate a new outbreak of disease; interventions should therefore be long enough, combined with an active case detection and include effective treatment.
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Harhay MO, Olliaro PL, Costa DL, Costa CHN. Urban parasitology: visceral leishmaniasis in Brazil. Trends Parasitol 2011; 27:403-9. [PMID: 21596622 DOI: 10.1016/j.pt.2011.04.001] [Citation(s) in RCA: 146] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 04/04/2011] [Accepted: 04/08/2011] [Indexed: 10/18/2022]
Abstract
Since the early 1980s, visceral leishmaniasis (VL) which is, in general, a rural zoonotic disease, has spread to the urban centers of the north, and now the south and west of Brazil. The principal drivers differ between cities, though human migration, large urban canid populations (animal reservoir), and a decidedly peripatetic and adaptable sand fly vector are the primary forces. The exact number of urban cases remains unclear as a result of challenges with surveillance. However, the number of urban cases registered continues to increase annually. Most control initiatives (e.g. culling infected dogs and household spraying to kill the sand fly) could be effective, but have proven hard to maintain at large scales due to logistical, financial and other reasons. In this article, the urbanization of VL in Brazil is reviewed, touching on these and other topics related to controlling VL within and outside Brazil.
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Affiliation(s)
- Michael O Harhay
- Graduate Program in Public Health Studies, University of Pennsylvania, Philadelphia, USA
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Warburg A, Faiman R. Research priorities for the control of phlebotomine sand flies. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2011; 36 Suppl 1:S10-S16. [PMID: 21366761 DOI: 10.1111/j.1948-7134.2011.00107.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The control of the sand fly vectors of leishmaniasis is problematic because their larvae develop in largely unknown terrestrial habitats making them impervious to available control measures. Furthermore, the behavior patterns of adults of different sand fly species are highly diverse, requiring tailor-made control solutions based upon a profound knowledge of their biology. In this short review, we describe possible lines of research that hold promise for improving our munitions in the battle against the diseases they transmit. The suggested approaches are not necessarily presented in order of importance, but rather in a logical sequence starting in the larval breeding areas where the sand flies originate and culminating with the human environments. Some examples are offered to illustrate the potential efficacy.
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Affiliation(s)
- Alon Warburg
- The Kuvin Centre for the Study of Infectious and Tropical Diseases, The Institute for Medical Research Israel-Canada, The Hebrew University--Hadassah Medical School, The Hebrew University of Jerusalem, Israel
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