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Velleman Y, Blair L, Fleming F, Fenwick A. Water-, Sanitation-, and Hygiene-Related Diseases. Infect Dis (Lond) 2023. [DOI: 10.1007/978-1-0716-2463-0_547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
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Swart Z, Duong TA, Wingfield BD, Postma A, Slippers B. The relevance of studying insect-nematode interactions for human disease. Pathog Glob Health 2022; 116:140-145. [PMID: 34726122 PMCID: PMC9090338 DOI: 10.1080/20477724.2021.1996796] [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] [Indexed: 10/19/2022] Open
Abstract
Vertebrate-parasitic nematodes cause debilitating, chronic infections in millions of people worldwide. The burden of these so-called 'neglected tropical diseases' is often carried by poorer socioeconomic communities in part because research on parasitic nematodes and their vertebrate hosts is challenging and costly. However, complex biological and pathological processes can be modeled in simpler organisms. Here, we consider how insight into the interactions between entomopathogenic nematodes (EPN), their insect hosts and bacterial symbionts may reveal novel treatment targets for parasitic nematode infections. We argue that a combination of approaches that target nematodes, as well as the interaction of pathogens with insect vectors and bacterial symbionts, offer potentially effective, but underexplored opportunities.
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Affiliation(s)
- Zorada Swart
- Department of Biochemistry Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa
| | - Tuan A. Duong
- Department of Biochemistry Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa
| | - Brenda D. Wingfield
- Department of Biochemistry Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa
| | - Alisa Postma
- Department of Biochemistry Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa
| | - Bernard Slippers
- Department of Biochemistry Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa
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Mwingira VS, Mboera LEG, Takken W. Synergism between nonane and emanations from soil as cues in oviposition-site selection of natural populations of Anopheles gambiae and Culex quinquefasciatus. Malar J 2021; 20:52. [PMID: 33478526 PMCID: PMC7819190 DOI: 10.1186/s12936-020-03575-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 12/31/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Olfactory cues have been shown to have an important role in guiding gravid mosquito females to selected sites for egg laying. The objective of this study was to determine the influence of emanations from soil from a breeding site and the putative oviposition pheromone nonane on oviposition-site selection of natural populations of Anopheles gambiae sensu lato (s.l.) and Culex quinquefasciatus. METHODS This field-based study was conducted in Mvomero District in East-central Tanzania. In a dual-choice experimental set up, clay bowls were dug into the ground and filled with one of the following treatments: (i) distilled water + autoclaved soil (control), (ii) distilled water + soil from a natural mosquito breeding site, (iii) distilled water + nonane and (iv) distilled water + nonane + soil from a natural breeding site. Soil was dried and autoclaved or dried only before use. After five days of incubation, larvae were collected daily for 10 days. The median number of larvae per bowl per day was used as outcome measure. RESULTS Autoclaved soil had a significant attractive effect on oviposition behaviour of Cx. quinquefasciatus (median values ± s.e: 8.0 ± 1.1; P < 0.005) but no effect on An. gambiae (median value ± s.e: 0.0 ± 0.2; P = 0.18). Nonane and emanations from untreated soil significantly and positively influenced the selection of oviposition sites by both An. gambiae s.l. (median values ± s.e.: 12.0 ± 2.0 and 4.5 ± 1.5, respectively; P < 0.0001) and Cx. quinquefasciatus (median values ± s.e.: 19.0 ± 1.3 and 17.0 ± 2.0, respectively; P < 0.0001). A mixture of nonane and untreated soil caused a synergistic effect on oviposition behaviour in An. gambiae s.l. (median value ± s.e.: 23.5 ± 2.5; P < 0.0001) compared to either nonane (median values ± s.e.: 12.0 ± 2.0; P < 0.0001) or untreated soil alone (median value ± s.e.: 4.5 ± 1.5; P < 0.0001). A synergistic effect of nonane mixed with untreated soil was also found in Cx. quinquefasciatus (median value ± s.e.: 41.0 ± 2.1; P < 0.0001) compared to either nonane (median value ± s.e. 19.0 ± 1.3; P < 0.0001) or untreated soil alone (median value ± s.e.: 17.0 ± 2.0; P < 0.0001). The oviposition activity index for An. gambiae was 0.56 (P < 0.001) and for Cx. quinquefasciatus 0.59 (P < 0.0001). CONCLUSIONS The larval pheromone nonane and emanations from breeding-site soil both induced oviposition in wild An. gambiae s.l. and Cx. quinquefasciatus, with a synergistic effect when both stimuli were present simultaneously. This is the first study in which nonane is shown to cause oviposition under natural conditions, suggesting that this compound can potentially be exploited for the management of mosquito vectors.
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Affiliation(s)
- Victor S Mwingira
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands.,SACIDS Foundation for One Health, Sokoine University of Agriculture, Chuo Kikuu, P.O. Box 3297, Morogoro, Tanzania
| | - Leonard E G Mboera
- SACIDS Foundation for One Health, Sokoine University of Agriculture, Chuo Kikuu, P.O. Box 3297, Morogoro, Tanzania
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands.
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Wilson AL, Courtenay O, Kelly-Hope LA, Scott TW, Takken W, Torr SJ, Lindsay SW. The importance of vector control for the control and elimination of vector-borne diseases. PLoS Negl Trop Dis 2020; 14:e0007831. [PMID: 31945061 PMCID: PMC6964823 DOI: 10.1371/journal.pntd.0007831] [Citation(s) in RCA: 270] [Impact Index Per Article: 67.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Vector-borne diseases (VBDs) such as malaria, dengue, and leishmaniasis exert a huge burden of morbidity and mortality worldwide, particularly affecting the poorest of the poor. The principal method by which these diseases are controlled is through vector control, which has a long and distinguished history. Vector control, to a greater extent than drugs or vaccines, has been responsible for shrinking the map of many VBDs. Here, we describe the history of vector control programmes worldwide from the late 1800s to date. Pre 1940, vector control relied on a thorough understanding of vector ecology and epidemiology, and implementation of environmental management tailored to the ecology and behaviour of local vector species. This complex understanding was replaced by a simplified dependency on a handful of insecticide-based tools, particularly for malaria control, without an adequate understanding of entomology and epidemiology and without proper monitoring and evaluation. With the rising threat from insecticide-resistant vectors, global environmental change, and the need to incorporate more vector control interventions to eliminate these diseases, we advocate for continued investment in evidence-based vector control. There is a need to return to vector control approaches based on a thorough knowledge of the determinants of pathogen transmission, which utilise a range of insecticide and non-insecticide-based approaches in a locally tailored manner for more effective and sustainable vector control.
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Affiliation(s)
- Anne L. Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Louise A. Kelly-Hope
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Thomas W. Scott
- Department of Entomology and Nematology, University of California Davis, Davis, California, United States of America
| | - Willem Takken
- Department of Plant Sciences, Wageningen University and Research, Wageningen, the Netherlands
| | - Steve J. Torr
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Steve W. Lindsay
- Department of Biosciences, Durham University, Durham, United Kingdom
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Mwingira U, Chikawe M, Mandara WL, Mableson HE, Uisso C, Mremi I, Malishee A, Malecela M, Mackenzie CD, Kelly-Hope LA, Stanton MC. Lymphatic filariasis patient identification in a large urban area of Tanzania: An application of a community-led mHealth system. PLoS Negl Trop Dis 2017; 11:e0005748. [PMID: 28708825 PMCID: PMC5529014 DOI: 10.1371/journal.pntd.0005748] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 07/26/2017] [Accepted: 06/25/2017] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Lymphatic filariasis (LF) is best known for the disabling and disfiguring clinical conditions that infected patients can develop; providing care for these individuals is a major goal of the Global Programme to Eliminate LF. Methods of locating these patients, knowing their true number and thus providing care for them, remains a challenge for national medical systems, particularly when the endemic zone is a large urban area. METHODOLOGY/PRINCIPLE FINDINGS A health community-led door-to-door survey approach using the SMS reporting tool MeasureSMS-Morbidity was used to rapidly collate and monitor data on LF patients in real-time (location, sex, age, clinical condition) in Dar es Salaam, Tanzania. Each stage of the phased study carried out in the three urban districts of city consisted of a training period, a patient identification and reporting period, and a data verification period, with refinements to the system being made after each phase. A total of 6889 patients were reported (133.6 per 100,000 population), of which 4169 were reported to have hydrocoele (80.9 per 100,000), 2251 lymphoedema-elephantiasis (LE) (43.7 per 100,000) and 469 with both conditions (9.1 per 100,000). Kinondoni had the highest number of reported patients in absolute terms (2846, 138.9 per 100,000), followed by Temeke (2550, 157.3 per 100,000) and Ilala (1493, 100.5 per 100,000). The number of hydrocoele patients was almost twice that of LE in all three districts. Severe LE patients accounted for approximately a quarter (26.9%) of those reported, with the number of acute attacks increasing with reported LE severity (1.34 in mild cases, 1.78 in moderate cases, 2.52 in severe). Verification checks supported these findings. CONCLUSIONS/SIGNIFICANCE This system of identifying, recording and mapping patients affected by LF greatly assists in planning, locating and prioritising, as well as initiating, appropriate morbidity management and disability prevention (MMDP) activities. The approach is a feasible framework that could be used in other large urban environments in the LF endemic areas.
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Affiliation(s)
- Upendo Mwingira
- Neglected Tropical Diseases Control Programme, Ministry of Health and Social Welfare, Dar es Salaam, Tanzania
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Maria Chikawe
- Neglected Tropical Diseases Control Programme, Ministry of Health and Social Welfare, Dar es Salaam, Tanzania
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Wilfred Lazarus Mandara
- Neglected Tropical Diseases Control Programme, Ministry of Health and Social Welfare, Dar es Salaam, Tanzania
| | - Hayley E. Mableson
- Centre for Neglected Tropical Diseases (CNTD), Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Cecilia Uisso
- Neglected Tropical Diseases Control Programme, Ministry of Health and Social Welfare, Dar es Salaam, Tanzania
| | - Irene Mremi
- Neglected Tropical Diseases Control Programme, Ministry of Health and Social Welfare, Dar es Salaam, Tanzania
| | - Alpha Malishee
- Neglected Tropical Diseases Control Programme, Ministry of Health and Social Welfare, Dar es Salaam, Tanzania
| | - Mwele Malecela
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Charles D. Mackenzie
- Centre for Neglected Tropical Diseases (CNTD), Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, Michigan, United States of America
| | - Louise A. Kelly-Hope
- Centre for Neglected Tropical Diseases (CNTD), Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Michelle C. Stanton
- Centre for Neglected Tropical Diseases (CNTD), Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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Emidi B, Kisinza WN, Mmbando BP, Malima R, Mosha FW. Effect of physicochemical parameters on Anopheles and Culex mosquito larvae abundance in different breeding sites in a rural setting of Muheza, Tanzania. Parasit Vectors 2017. [PMID: 28645303 PMCID: PMC5482952 DOI: 10.1186/s13071-017-2238-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Basiliana Emidi
- Kilimanjaro Christian Medical University College, P.O. Box 2240, Moshi, Tanzania. .,National Institute for Medical Research, Headquarters, P.O. Box 9653, Dar es Salaam, Tanzania.
| | - William N Kisinza
- National Institute for Medical Research, Amani Centre, P.O. Box 81, Muheza, Tanzania
| | - Bruno P Mmbando
- National Institute for Medical Research, Tanga Centre, P.O. Box 5004, Tanga, Tanzania
| | - Robert Malima
- National Institute for Medical Research, Amani Centre, P.O. Box 81, Muheza, Tanzania
| | - Franklin W Mosha
- Kilimanjaro Christian Medical University College, P.O. Box 2240, Moshi, Tanzania
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Hiscox A, Hirooka R, Vongphayloth K, Hill N, Lindsay SW, Grandadam M, Brey PT. Armigeres subalbatus colonization of damaged pit latrines: a nuisance and potential health risk to residents of resettlement villages in Laos. MEDICAL AND VETERINARY ENTOMOLOGY 2016; 30:95-100. [PMID: 26508317 DOI: 10.1111/mve.12142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 07/06/2015] [Accepted: 07/17/2015] [Indexed: 06/05/2023]
Abstract
During the resettlement of 6500 persons living around the Nam Theun 2 hydroelectric project in Laos, more than 1200 pour-flush latrines were constructed. To assess the role of these latrines as productive larval habitats for mosquitoes, entomological investigations using Centers for Disease Control (CDC) light traps, visual inspection and emergence trapping were carried out in over 300 latrines during the rainy seasons of 2008-2010. Armigeres subalbatus (Diptera: Culicidae) were nine times more likely to be found in latrines (mean catch: 3.09) than in adjacent bedrooms (mean catch: 0.37) [odds ratio (OR) 9.08, 95% confidence interval (CI) 6.74-15.11] and mosquitoes were active in and around 59% of latrines at dusk. Armigeres subalbatus was strongly associated with latrines with damaged or improperly sealed septic tank covers (OR 5.44, 95% CI 2.02-14.67; P < 0.001). Armigeres subalbatus is a nuisance biter and a putative vector of Japanese encephalitis and dengue viruses. Dengue virus serotype 3 was identified from a single pool of non-blood-fed female A. subalbatus using reverse transcription polymerase chain reaction. Maintaining a good seal around septic tanks by covering them with a layer of soil is a simple intervention to block mosquito exit/entry and contribute to vector control in resettlement villages. The scale-up of this simple, cheap intervention would have global impact in preventing the colonization of septic tanks by nuisance biting and disease-transmitting mosquitoes.
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Affiliation(s)
- A Hiscox
- Laboratory of Vector-Borne Diseases, Institut Pasteur du Laos, Vientiane, Laos
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, U.K
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, the Netherlands
| | - R Hirooka
- Laboratory of Vector-Borne Diseases, Institut Pasteur du Laos, Vientiane, Laos
| | - K Vongphayloth
- Laboratory of Vector-Borne Diseases, Institut Pasteur du Laos, Vientiane, Laos
| | - N Hill
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, U.K
| | - S W Lindsay
- School of Biological and Biomedical Sciences, Durham University, Durham, U.K
| | - M Grandadam
- Laboratory of Arbovirology and Emerging Viruses, Institut Pasteur du Laos, Vientiane, Laos
| | - P T Brey
- Laboratory of Vector-Borne Diseases, Institut Pasteur du Laos, Vientiane, Laos
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Ganapathy M, Perumal A, Mohan C, Palaniswamy H, Perumal K. Immunogenicity of Brugia malayi Abundant Larval Transcript-2, a potential filarial vaccine candidate expressed in tobacco. PLANT CELL REPORTS 2014; 33:179-88. [PMID: 24277081 DOI: 10.1007/s00299-013-1521-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 10/01/2013] [Accepted: 10/01/2013] [Indexed: 06/02/2023]
Abstract
KEY MESSAGE Transgenic tobacco plants with Bm ALT-2, a filarial vaccine candidate, were developed. The plant-produced antigen showed immunogenicity on par with the E.coli product. Transgenic tobacco plants were developed using Brugia malayi Abundant Larval Transcript-2 (Bm ALT-2), a major antigen produced from recombinant E.coli found to be experimentally successful as potential vaccine candidate against lymphatic filariasis. Results of experiments on the transformation and expression of the Bm ALT-2 in tobacco plant to produce plant-based vaccine are presented here. We have successfully transformed the tobacco plant with Bm ALT-2 and confirmed that the plants expressed the filarial protein by PCR analysis and Western blotting. The level of expression varied from 50 to 90 ng/μg of total soluble protein for ALT-2. Immunization of mice with plant-extracted protein indicated that the plant-produced protein had immunological characteristics similar to the E.coli-produced protein. Antibody titres produced by plant-produced recombinant ALT 2-immunized mice were on par with those immunized with recombinant protein produced by E.coli. Antibody isotype assay showed that plant-produced recombinant ALT-2 induced significant IgG1, whereas E.coli-produced recombinant ALT-2 induced IgG3. This result is a step forward towards the development of a model eukaryotic system for the production of recombinant filarial proteins, which can be utilized to produce therapeutic and diagnostic molecules against lymphatic filariasis, a neglected tropical infectious disease which has a negative impact on socioeconomic development. In addition, this is the first report of the immunogenicity of a plant-derived filarial antigen.
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Affiliation(s)
- Mathangi Ganapathy
- Centre for Biotechnology, Anna University, Guindy, Chennai, 600025, Tamil Nadu, India,
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Boatin BA, Basáñez MG, Prichard RK, Awadzi K, Barakat RM, García HH, Gazzinelli A, Grant WN, McCarthy JS, N'Goran EK, Osei-Atweneboana MY, Sripa B, Yang GJ, Lustigman S. A research agenda for helminth diseases of humans: towards control and elimination. PLoS Negl Trop Dis 2012; 6:e1547. [PMID: 22545161 PMCID: PMC3335858 DOI: 10.1371/journal.pntd.0001547] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human helminthiases are of considerable public health importance in sub-Saharan Africa, Asia, and Latin America. The acknowledgement of the disease burden due to helminth infections, the availability of donated or affordable drugs that are mostly safe and moderately efficacious, and the implementation of viable mass drug administration (MDA) interventions have prompted the establishment of various large-scale control and elimination programmes. These programmes have benefited from improved epidemiological mapping of the infections, better understanding of the scope and limitations of currently available diagnostics and of the relationship between infection and morbidity, feasibility of community-directed or school-based interventions, and advances in the design of monitoring and evaluation (M&E) protocols. Considerable success has been achieved in reducing morbidity or suppressing transmission in a number of settings, whilst challenges remain in many others. Some of the obstacles include the lack of diagnostic tools appropriate to the changing requirements of ongoing interventions and elimination settings; the reliance on a handful of drugs about which not enough is known regarding modes of action, modes of resistance, and optimal dosage singly or in combination; the difficulties in sustaining adequate coverage and compliance in prolonged and/or integrated programmes; an incomplete understanding of the social, behavioural, and environmental determinants of infection; and last, but not least, very little investment in research and development (R&D). The Disease Reference Group on Helminth Infections (DRG4), established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR), was given the mandate to undertake a comprehensive review of recent advances in helminthiases research, identify research gaps, and rank priorities for an R&D agenda for the control and elimination of these infections. This review presents the processes undertaken to identify and rank ten top research priorities; discusses the implications of realising these priorities in terms of their potential for improving global health and achieving the Millennium Development Goals (MDGs); outlines salient research funding needs; and introduces the series of reviews that follow in this PLoS Neglected Tropical Diseases collection, "A Research Agenda for Helminth Diseases of Humans."
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Affiliation(s)
- Boakye A. Boatin
- Lymphatic Filariasis Support Centre, Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
- Institute of Parasitology, McGill University, Montreal, Canada
| | - María-Gloria Basáñez
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, United Kingdom
| | | | - Kwablah Awadzi
- Onchocerciasis Chemotherapy Research Centre, Hohoe Hospital, Hohoe, Ghana
| | - Rashida M. Barakat
- High Institute of Public Health, Alexandria University, Alexandria, Egypt
| | - Héctor H. García
- Department of Microbiology, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Andrea Gazzinelli
- Department of Maternal and Child Nursing and Public Health, School of Nursing, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Warwick N. Grant
- The Nematode Functional Genomics Laboratory, La Trobe University, Victoria, Australia
| | - James S. McCarthy
- Queensland Institute of Medical Research, University of Queensland, Herston, Australia
| | - Eliézer K. N'Goran
- Laboratoire de Zoologie et de Biologie Animale, Université de Cocody, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Mike Y. Osei-Atweneboana
- Council for Scientific and Industrial Research (CSIR), Department of Environmental Biology and Health, Water Research Institute, Accra, Ghana
| | - Banchob Sripa
- Tropical Disease Research Laboratory, Division of Experimental Pathology, Department of Pathology, Khon Kaen University, Khon Kaen, Thailand
| | - Guo-Jing Yang
- Department of Schistosomiasis Control, Jiangsu Institute of Parasitic Diseases, Meiyuan Yangxiang, Wuxi, People's Republic of China
| | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
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Prichard RK, Basáñez MG, Boatin BA, McCarthy JS, García HH, Yang GJ, Sripa B, Lustigman S. A research agenda for helminth diseases of humans: intervention for control and elimination. PLoS Negl Trop Dis 2012; 6:e1549. [PMID: 22545163 PMCID: PMC3335868 DOI: 10.1371/journal.pntd.0001549] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recognising the burden helminth infections impose on human populations, and particularly the poor, major intervention programmes have been launched to control onchocerciasis, lymphatic filariasis, soil-transmitted helminthiases, schistosomiasis, and cysticercosis. The Disease Reference Group on Helminth Infections (DRG4), established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR), was given the mandate to review helminthiases research and identify research priorities and gaps. A summary of current helminth control initiatives is presented and available tools are described. Most of these programmes are highly dependent on mass drug administration (MDA) of anthelmintic drugs (donated or available at low cost) and require annual or biannual treatment of large numbers of at-risk populations, over prolonged periods of time. The continuation of prolonged MDA with a limited number of anthelmintics greatly increases the probability that drug resistance will develop, which would raise serious problems for continuation of control and the achievement of elimination. Most initiatives have focussed on a single type of helminth infection, but recognition of co-endemicity and polyparasitism is leading to more integration of control. An understanding of the implications of control integration for implementation, treatment coverage, combination of pharmaceuticals, and monitoring is needed. To achieve the goals of morbidity reduction or elimination of infection, novel tools need to be developed, including more efficacious drugs, vaccines, and/or antivectorial agents, new diagnostics for infection and assessment of drug efficacy, and markers for possible anthelmintic resistance. In addition, there is a need for the development of new formulations of some existing anthelmintics (e.g., paediatric formulations). To achieve ultimate elimination of helminth parasites, treatments for the above mentioned helminthiases, and for taeniasis and food-borne trematodiases, will need to be integrated with monitoring, education, sanitation, access to health services, and where appropriate, vector control or reduction of the parasite reservoir in alternative hosts. Based on an analysis of current knowledge gaps and identification of priorities, a research and development agenda for intervention tools considered necessary for control and elimination of human helminthiases is presented, and the challenges to be confronted are discussed.
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Jones CM, Machin C, Mohammed K, Majambere S, Ali AS, Khatib BO, McHa J, Ranson H, Kelly-Hope LA. Insecticide resistance in Culex quinquefasciatus from Zanzibar: implications for vector control programmes. Parasit Vectors 2012; 5:78. [PMID: 22520274 PMCID: PMC3349604 DOI: 10.1186/1756-3305-5-78] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Accepted: 04/21/2012] [Indexed: 11/10/2022] Open
Abstract
Background Zanzibar has a long history of lymphatic filariasis (LF) caused by the filarial parasite Wuchereria bancrofti, and transmitted by the mosquito Culex quinquefasciatus Say. The LF Programme in Zanzibar has successfully implemented mass drug administration (MDA) to interrupt transmission, and is now in the elimination phase. Monitoring infections in mosquitoes, and assessing the potential role of interventions such as vector control, is important in case the disease re-emerges as a public health problem. Here, we examine Culex mosquito species from the two main islands to detect W. bancrofti infection and to determine levels of susceptibility to the insecticides used for vector control. Methods Culex mosquitoes collected during routine catches in Vitongoji, Pemba Island, and Makadara, Unguja Island were tested for W. bancrofti infection using PCR. Insecticide bioassays on Culex mosquitoes were performed to determine susceptibility to permethrin, deltamethrin, lambda-cyhalothrin, DDT and bendiocarb. Additional synergism assays with piperonyl butoxide (PBO) were used for lambda-cyhalothrin. Pyrosequencing was used to determine the kdr genotype and sequencing of the mitochondrial cytochrome oxidase I (mtCOI) subunit performed to identify ambiguous Culex species. Results None of the wild-caught Culex mosquitoes analysed were found to be positive for W. bancrofti. High frequencies of resistance to all insecticides were found in Wete, Pemba Island, whereas Culex from the nearby site of Tibirinzi (Pemba) and in Kilimani, Unguja Island remained relatively susceptible. Species identification confirmed that mosquitoes from Wete were Culex quinquefasciatus. The majority of the Culex collected from Tibirinzi and all from Kilimani could not be identified to species by molecular assays. Two alternative kdr alleles, both resulting in a L1014F substitution were detected in Cx. quinquefasciatus from Wete with no homozygote susceptible detected. Metabolic resistance to pyrethroids was also implicated by PBO synergism assays. Conclusions Results from the xenomonitoring are encouraging for the LF programme in Zanzibar. However, the high levels of pyrethroid resistance found in the principle LF vector in Pemba Island will need to be taken into consideration if vector control is to be implemented as part of the elimination programme.
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Hamilton CE, Beresford DV, Sutcliffe JF. Effects of natal habitat odour, reinforced by adult experience, on choice of oviposition site in the mosquito Aedes aegypti. MEDICAL AND VETERINARY ENTOMOLOGY 2011; 25:428-435. [PMID: 21605148 DOI: 10.1111/j.1365-2915.2011.00964.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The effects of natal experience on the oviposition behaviour of adult female mosquitoes were investigated in the laboratory using Aedes aegypti (L.) (Diptera: Culicidae). 'Treatment' mosquitoes were exposed to a dilute repellent (inducing stimulus) in their breeding water (aquatic stages) and/or in the air (adults) during various combinations of life stages [larval only (L regime); larval and pupal (LP regime); larval, pupal and emergent adult (LPE regime); larval, pupal, emergent adult and adult (LPEA regime); pupal, emergent adult and adult (PEA regime); adult only (A regime)]. 'Control' mosquitoes were raised in an identical manner, but were not exposed to the inducing stimulus. The oviposition behaviour of treatment and control females was assessed in an oviposition assay that presented a choice of water with or without the inducing stimulus. Of the 435 mosquitoes tested in the experiment, 176 were non-distributors (i.e. laid all of their eggs in only one of the choices). Treatment females (distributors plus non-distributors) reared in the presence of the inducing stimulus throughout their lives (LPEA regime) showed a significant preference for the oviposition option containing the inducing stimulus (24/36 females) compared with corresponding controls (5/39 females). Distributors reared under the LPEA and PEA regimes also showed this preference (6/6 treatment vs. 2/29 control females, and 13/18 treatment vs. 7/23 control females, respectively). Females that had been exposed to the inducing stimulus as either immatures or adults only showed no preference for, and some showed an aversion to, the treatment oviposition option. This is interpreted as evidence for a natal habitat preference induction (NHPI) in this species, albeit one that requires extensive reinforcement in the adult stage. This adult experience-reinforced NHPI (AER-NHPI) is discussed in terms of its adaptive significance for container breeders, the possible timing mechanism and sensory basis of induction and potential practical consequences.
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Affiliation(s)
- C E Hamilton
- Department of Biology, Trent University, Peterborough, ON, Canada
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Kudom AA, Mensah BA, Botchey MA. Aqueous neem extract versus neem powder on Culex quinquefasciatus: implications for control in anthropogenic habitats. JOURNAL OF INSECT SCIENCE (ONLINE) 2011; 11:142. [PMID: 22233153 PMCID: PMC3281371 DOI: 10.1673/031.011.14201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 04/02/2011] [Indexed: 05/26/2023]
Abstract
Control programs using conventional insecticides to target anthropogenic mosquito habitats are very expensive because these habitats are widespread, particularly in cities of most African countries. Additionally, there are serious environmental concerns regarding large-scale application of most conventional insecticides. Clearly there is a need for alternative methods that are more effective, less expensive, and environmentally friendly. One such method would be the application of preparations made from parts of the neem tree, Azadirachta indica A. Jussieu (Sapindales: Meliaceae). In this study, aqueous crude extracts and crude powder were prepared from different parts of neem, and the efficacies of the preparations on juvenile stages of Culex quinquefasciatus Say (Diptera: Culicidae) were evaluated in the laboratory. When larvae were exposed to a concentration of 0.1 g/mL extract for 24 hours, percent mean mortality (± SE) was 72.7 plusmn; 1.8 for the bark, 68.7 ± 1.6 for fruits and 60 ± 1.6 for leaves. These means were not significantly different (χ(2) = 4.12; df = 2; p = 0.127). At a concentration of 0.01 g/mL, > 95% of the larvae died within 24 hours of exposure to powdered neem leaf, but it took 120 hours to reach the same level of larval mortality in aqueous leaf extract. The crude extract slowly inhibited the growth and development of mosquitoes while the crude powder acted more as a barrier; the mosquitoes probably died from suffocation. However, both types of preparations can be made and used by local people to control mosquito breeding in anthropogenic habitats, especially in urbanized areas.
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Affiliation(s)
- Andreas A. Kudom
- Department of Entomology and Wildlife, University of Cape Coast, Cape Coast, Ghana
| | - Ben A. Mensah
- Department of Entomology and Wildlife, University of Cape Coast, Cape Coast, Ghana
| | - Mary A. Botchey
- Department of Entomology and Wildlife, University of Cape Coast, Cape Coast, Ghana
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Abstract
Lymphatic filariasis and onchocerciasis are parasitic helminth diseases that constitute a serious public health issue in tropical regions. The filarial nematodes that cause these diseases are transmitted by blood-feeding insects and produce chronic and long-term infection through suppression of host immunity. Disease pathogenesis is linked to host inflammation invoked by the death of the parasite, causing hydrocoele, lymphoedema, and elephantiasis in lymphatic filariasis, and skin disease and blindness in onchocerciasis. Most filarial species that infect people co-exist in mutualistic symbiosis with Wolbachia bacteria, which are essential for growth, development, and survival of their nematode hosts. These endosymbionts contribute to inflammatory disease pathogenesis and are a target for doxycycline therapy, which delivers macrofilaricidal activity, improves pathological outcomes, and is effective as monotherapy. Drugs to treat filariasis include diethylcarbamazine, ivermectin, and albendazole, which are used mostly in combination to reduce microfilariae in blood (lymphatic filariasis) and skin (onchocerciasis). Global programmes for control and elimination have been developed to provide sustained delivery of drugs to affected communities to interrupt transmission of disease and ultimately eliminate this burden on public health.
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Affiliation(s)
- Mark J Taylor
- Liverpool School of Tropical Medicine, Liverpool, UK.
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15
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Abstract
The planning and evaluation of parasitic control programmes are complicated by the many interacting population dynamic and programmatic factors that determine infection trends under different control options. A key need is quantification about the status of the parasite system state at any one given timepoint and the dynamic change brought upon that state as an intervention program proceeds. Here, we focus on the control and elimination of the vector-borne disease, lymphatic filariasis, to show how mathematical models of parasite transmission can provide a quantitative framework for aiding the design of parasite elimination and monitoring programs by their ability to support (1) conducting rational analysis and definition of endpoints for different programmatic aims or objectives, including transmission endpoints for disease elimination, (2) undertaking strategic analysis to aid the optimal design of intervention programs to meet set endpoints under different endemic settings and (3) providing support for performing informed evaluations of ongoing programs, including aiding the formation of timely adaptive management strategies to correct for any observed deficiencies in program effectiveness. The results also highlight how the use of a model-based framework will be critical to addressing the impacts of ecological complexities, heterogeneities and uncertainties on effective parasite management and thereby guiding the development of strategies to resolve and overcome such real-world complexities. In particular, we underscore how this approach can provide a link between ecological science and policy by revealing novel tools and measures to appraise and enhance the biological controllability or eradicability of parasitic diseases. We conclude by emphasizing an urgent need to develop and apply flexible adaptive management frameworks informed by mathematical models that are based on learning and reducing uncertainty using monitoring data, apply phased or sequential decision-making to address extant uncertainty and focus on developing ecologically resilient management strategies, in ongoing efforts to control or eliminate filariasis and other parasitic diseases in resource-poor communities.
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16
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Castro MC, Kanamori S, Kannady K, Mkude S, Killeen GF, Fillinger U. The importance of drains for the larval development of lymphatic filariasis and malaria vectors in Dar es Salaam, United Republic of Tanzania. PLoS Negl Trop Dis 2010; 4:e693. [PMID: 20520797 PMCID: PMC2876116 DOI: 10.1371/journal.pntd.0000693] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 03/31/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Dar es Salaam has an extensive drain network, mostly with inadequate water flow, blocked by waste, causing flooding after rainfall. The presence of Anopheles and Culex larvae is common, which is likely to impact the transmission of lymphatic filariasis and malaria by the resulting adult mosquito populations. However, the importance of drains as larval habitats remains unknown. METHODOLOGY Data on mosquito larval habitats routinely collected by the Urban Malaria Control Program (UMCP) and a special drain survey conducted in 2006 were used to obtain a typology of habitats. Focusing on drains, logistic regression was used to evaluate potential factors impacting the presence of mosquito larvae. Spatial variation in the proportion of habitats that contained larvae was assessed through the local Moran's I indicator of spatial association. PRINCIPAL FINDINGS More than 70% of larval habitats in Dar es Salaam were human-made. Aquatic habitats associated with agriculture had the highest proportion of Anopheles larvae presence and the second highest of Culex larvae presence. However, the majority of aquatic habitats were drains (42%), and therefore, 43% (1,364/3,149) of all culicine and 33% (320/976) of all anopheline positive habitats were drains. Compared with drains where water was flowing at normal velocity, the odds of finding Anopheles and Culex larvae were 8.8 and 6.3 (p<0.001) times larger, respectively, in drains with stagnant water. There was a positive association between vegetation and the presence of mosquito larvae (p<0.001). The proportion of habitats with mosquito larvae was spatially correlated. CONCLUSION Restoring and maintaining drains in Dar es Salaam has the potential to eliminate more than 40% of all potential mosquito larval habitats that are currently treated with larvicides by the UMCP. The importance of human-made larval habitats for both lymphatic filariasis and malaria vectors underscores the need for a synergy between on-going control efforts of those diseases.
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Affiliation(s)
- Marcia C Castro
- Department of Global Health and Population, Harvard School of Public Health, Boston, Massachusetts, USA.
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17
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Bockarie MJ, Pedersen EM, White GB, Michael E. Role of vector control in the global program to eliminate lymphatic filariasis. ANNUAL REVIEW OF ENTOMOLOGY 2009; 54:469-487. [PMID: 18798707 DOI: 10.1146/annurev.ento.54.110807.090626] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Lymphatic filariasis (LF) is a major cause of acute and chronic morbidity in the tropical and subtropical parts of the world. The availability of safe, single-dose, drug treatment regimens capable of suppressing microfilaremia to very low levels, along with improvements in techniques for diagnosing infection, has resulted in the targeting of this major mosquito-borne disease for global elimination. The Global Program to Eliminate Lymphatic Filariasis (GPELF) was launched in 2000 with the principal objective of breaking the cycles of transmission of Wuchereria bancrofti and Brugia spp. through the application of annual mass drug administrations (MDAs) to entire at-risk populations. Although significant progress in initiating MDA programs in endemic countries has been made, emerging challenges to this approach have raised questions regarding the effectiveness of using MDA alone to eliminate LF without the inclusion of supplementary vector control. Here, we review advances in knowledge of vector ecology, vector-parasite relationships, and both empirical and theoretical evidence regarding vector management to assess the feasibility and strategic value of including vector control in the GPELF initiative to achieve the global elimination of LF.
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Affiliation(s)
- Moses J Bockarie
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, United Kingdom.
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18
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van den Berg H, Takken W. A framework for decision-making in integrated vector management to prevent disease. Trop Med Int Health 2007; 12:1230-8. [PMID: 17956506 DOI: 10.1111/j.1365-3156.2007.01905.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Integrated vector management (IVM) aims to extend the basis of disease control by involving other sectors and local communities in control action. It is vital that decisions on IVM are made locally for two reasons: first, the epidemiology of disease can vary at a small spatial scale, suggesting the need for precise targeting and second, a number of disease determinants relate to the actions and conditions of local communities, suggesting the need for their increased participation. This requires a shift from centrally managed, sector-specific operations to the facilitation of multi-partner programmes at the district and local level. We propose a methodology for involving local partners outside the health sector in describing and mapping the local determinants and conditions of disease, analysing control options, and consolidating a joint strategy of control. Thus determinants that often lie outside the domain of the health sector are tackled.
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Affiliation(s)
- Henk van den Berg
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands.
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Sunish IP, Rajendran R, Mani TR, Munirathinam A, Dash AP, Tyagi BK. Vector control complements mass drug administration against bancroftian filariasis in Tirukoilur, India. Bull World Health Organ 2007; 85:138-45. [PMID: 17308735 PMCID: PMC2636282 DOI: 10.2471/blt.06.029389] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Accepted: 10/12/2006] [Indexed: 10/22/2022] Open
Abstract
OBJECTIVE To determine the role of vector control in further decreasing the transmission of bancroftian filariasis achieved by mass drug administration and the long-term impact on filariometric indices. METHODS Three rounds of annual mass drug administration, with diethylcarbamazine and ivermectin, were complemented by vector control (mainly using polystyrene beads) in villages of Tirukoilur, south India, during 1995-99. Subsequently, drug administration is being carried out with diethylcarbamazine and albendazole or diethylcarbamazine alone. We evaluated the impact of mass drug administration used alone or in conjunction with vector control (from 1995 to 2005) on vector transmission indices (such as transmission intensity index, monthly biting rate, monthly transmission potential and annual transmission potential). We analysed data on filarial infection in the community to estimate the prevalence of microfilaraemia and antigenaemia using chi2 analysis and Fisher's exact test. FINDINGS Vector density greatly decreased in villages where vector control was used as an adjunct to mass drug administration and almost no infective mosquitoes were found in the small numbers still remaining. Filarial antigenaemia was low and continued to decrease significantly in the age group 15-25 years in villages receiving mass drug administration with vector control in contrast to villages receiving only mass drug administration. CONCLUSION The gains of mass drug administration were sustained only with the integration of vector control measures. We advocate the incorporation of vector control in the Global Programme to Eliminate Lymphatic Filariasis as it can potentially decrease the time required for eliminating lymphatic filariasis.
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Affiliation(s)
- I P Sunish
- Centre for Research in Medical Entomology, Tamil Nadu, India.
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20
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Thirugnanam S, Pandiaraja P, Ramaswamy K, Murugan V, Gnanasekar M, Nandakumar K, Reddy MVR, Kaliraj P. Brugia malayi: comparison of protective immune responses induced by Bm-alt-2 DNA, recombinant Bm-ALT-2 protein and prime-boost vaccine regimens in a jird model. Exp Parasitol 2007; 116:483-91. [PMID: 17442307 PMCID: PMC2763209 DOI: 10.1016/j.exppara.2007.02.017] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2006] [Revised: 02/28/2007] [Accepted: 02/28/2007] [Indexed: 11/30/2022]
Abstract
Immunization of jirds with Bm-alt-2 elicited partial protection against challenge infection with the filarial parasite Brugia malayi. In this study, we initially compared the protective immune responses elicited following immunization with recombinant Bm-ALT-2 protein regimen and Bm-alt-2 DNA regimen. These studies showed that protein vaccination conferred approximately 75% protection compared to DNA vaccination that conferred only 57% protection. Analysis of the protective immune responses showed that the protein immunization promoted a Th2-biased response with an increase in IL-4, IL-5 and IgG1 responses, whereas, the DNA vaccine promoted a Th1-biased response with profound IFN-gamma and IgG2a responses. Since protein vaccination gave better results than DNA vaccination, we then wanted to evaluate whether a prime-boost vaccination that combined DNA prime and protein boost will significantly increase the protective responses induced by the protein vaccine. Our results suggest that prime-boost vaccination had no added advantage and was comparatively less effective (64% protection) than the Bm-ALT-2 protein alone vaccination. Prime boost vaccination generated mixed Th1/Th2 responses with a slightly diminished Th2 responses compared to protein vaccination. Thus, our results suggest that Bm-ALT-2 protein vaccination regimen may be slightly better than prime-boost vaccine regimen and the mechanism of protection appears to be largely mediated by a Th2-biased response.
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MESH Headings
- Animals
- Antibodies, Helminth/biosynthesis
- Antibodies, Helminth/blood
- Antigens, Helminth/genetics
- Antigens, Helminth/immunology
- Brugia malayi/immunology
- Cytokines/biosynthesis
- Cytokines/genetics
- DNA, Helminth/immunology
- Diffusion Chambers, Culture
- Disease Models, Animal
- Elephantiasis, Filarial/prevention & control
- Gerbillinae
- Helminth Proteins/genetics
- Helminth Proteins/immunology
- Immunity, Cellular
- Immunization/methods
- Lymphocyte Activation
- Male
- Recombinant Proteins/genetics
- Recombinant Proteins/immunology
- Th2 Cells/immunology
- Vaccines/immunology
- Vaccines, DNA/immunology
- Vaccines, Synthetic/immunology
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Affiliation(s)
| | | | - Kalyanasundaram Ramaswamy
- Department of Biomedical Sciences, University of Illinois, College of Medicine, Rockford, IL 61107, USA
| | - Vadivel Murugan
- Centre for Biotechnology, Anna University, Chennai 600 025, India
| | - Munirathinam Gnanasekar
- Department of Biomedical Sciences, University of Illinois, College of Medicine, Rockford, IL 61107, USA
| | - Krithika Nandakumar
- Jamnalal Bajaj Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram, India
| | - Maryada Venkata Rami Reddy
- Jamnalal Bajaj Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram, India
- Corresponding authors. Fax: +91 44 22542299. (M.V.R. Reddy), (P. Kaliraj)
| | - Perumal Kaliraj
- Centre for Biotechnology, Anna University, Chennai 600 025, India
- Corresponding authors. Fax: +91 44 22542299. (M.V.R. Reddy), (P. Kaliraj)
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Burkot TR, Durrheim DN, Melrose WD, Speare R, Ichimori K. The argument for integrating vector control with multiple drug administration campaigns to ensure elimination of lymphatic filariasis. FILARIA JOURNAL 2006; 5:10. [PMID: 16914040 PMCID: PMC1560133 DOI: 10.1186/1475-2883-5-10] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Accepted: 08/16/2006] [Indexed: 11/22/2022]
Abstract
BACKGROUND There is a danger that mass drug administration campaigns may fail to maintain adequate treatment coverage to achieve lymphatic filariasis elimination. Hence, additional measures to suppress transmission might be needed to ensure the success of the Global Program for the Elimination of Lymphatic Filariasis. DISCUSSION Vector control successfully eliminated lymphatic filariasis when implemented alone or with mass drug administration. Challenges to lymphatic filariasis elimination include uncertainty of the exact level and duration of microfilarial suppression required for elimination, the mobility of infected individuals, consistent non-participation of some infected individuals with mass drug administration, the possible development of anti-filarial drug resistance and treatment strategies in areas co-endemic with loasis. Integration of vector control with mass drug administration can address some of these challenges. The potential benefits of vector control would include: (1) the ability to suppress filariasis transmission without the need to identify all individual 'foci of infection'; (2) minimizing the risk of reestablishment of transmission from imported microfilaria positive individuals; and (3) decreasing the risk of dengue or malaria transmission where, respectively, Aedes or Anopheles are lymphatic filariasis vectors. SUMMARY With adequate sustained treatment coverage, mass drug administration should meet the criteria for elimination of lymphatic filariasis. However, it may be difficult to sustain sufficiently high mass drug administration coverage to achieve lymphatic filariasis elimination in some areas, particularly, where Aedes species are the vectors. Since vector control was effective in controlling and even eliminating lymphatic filariasis transmission, integration of vector control with mass drug administration will ensure the sustainability of transmission suppression and thereby better ensure the success of national filariasis elimination programs. Although trials of some vector control interventions are needed, proven vector control strategies are ready for immediate integration with mass drug administration for many important vectors. Vector control is the only presently available additional lymphatic filariasis control measure with the potential for immediate implementation.
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Affiliation(s)
- TR Burkot
- Centers for Disease Prevention and Control, Division of Parasitic Diseases, 4770 Buford Highway, Mailstop F42, Atlanta, Georgia 03041, USA
| | - DN Durrheim
- WHO Lymphatic Filariasis Collaborating Center, James Cook University, Townsville, QLD, 4811, Australia
- Hunter New England Population Health, Locked Bag 10, Wallsend New South Wales 2287, Australia
| | - WD Melrose
- WHO Lymphatic Filariasis Collaborating Center, James Cook University, Townsville, QLD, 4811, Australia
| | - R Speare
- WHO Lymphatic Filariasis Collaborating Center, James Cook University, Townsville, QLD, 4811, Australia
| | - K Ichimori
- PacELF, World Health Organization, PO Box 113, Suva, Fiji Islands
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Michael E, Malecela-Lazaro MN, Kabali C, Snow LC, Kazura JW. Mathematical models and lymphatic filariasis control: endpoints and optimal interventions. Trends Parasitol 2006; 22:226-33. [PMID: 16564745 DOI: 10.1016/j.pt.2006.03.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2005] [Revised: 02/02/2006] [Accepted: 03/08/2006] [Indexed: 11/25/2022]
Abstract
The current global initiative to eliminate lymphatic filariasis is a major renewed commitment to reduce or eliminate the burden of one of the major helminth infections from resource-poor communities of the world. Mathematical models of filariasis transmission can serve as an effective tool for guiding the scientific development and management of successful community-level intervention programmes by acting as analytical frameworks for integrating knowledge regarding parasite transmission dynamics with programmatic factors. However, the power of these tools for supporting control interventions will be realized fully only if researchers address the current uncertainties and gaps in data and knowledge of filarial population dynamics and the effectiveness of currently proposed filariasis intervention options.
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Affiliation(s)
- Edwin Michael
- Department of Infectious Disease Epidemiology, Imperial College School of Medicine, Norfolk Place, London W2 1PG, UK.
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Abstract
Lymphatic filariasis (LF) is a disease not just treatable or controllable; it is a disease that can be eliminated. Indeed, LF is currently the target of a major global initiative to do just that; a few visionaries of the past 50 years did hypothesize that LF elimination was feasible. However, for most of the scientific and global health communities, the elimination of such a broadly disseminated, mosquito-borne disease has seemed highly unlikely. During the past decade, however, both the treatment strategies and the control strategies for LF have undergone profound paradigm shifts-all because of a rapid increase in knowledge and understanding of LF that derived directly from a series of remarkable achievements by the scientific and medical research communities. As a result, a public health dimension with a focus on affected populations, now supplements the earlier, predominantly patient-oriented clinical approach to LF. The early uncertainties, then the essential steps leading to this change in outlook are outlined below, followed by descriptions of the new strategy for LF elimination, the Global Programme created to attain this goal and the successes achieved to date.
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Affiliation(s)
- Eric A Ottesen
- Lymphatic Filariasis Support Centre, The Task Force for Child Survival and Development, 750 Commerce Drive Decatur, GA 30030, USA
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Michael E, Malecela-Lazaro MN, Simonsen PE, Pedersen EM, Barker G, Kumar A, Kazura JW. Mathematical modelling and the control of lymphatic filariasis. THE LANCET. INFECTIOUS DISEASES 2004; 4:223-34. [PMID: 15050941 DOI: 10.1016/s1473-3099(04)00973-9] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The current global initiative to eliminate lymphatic filariasis represents one of the largest mass drug administration programmes ever conceived for the control of a parasitic disease. Yet, it is still not known whether the WHO-recommended primary strategy of applying annual single-dose mass chemotherapy with a combination of two drugs for 4-6 years will effectively break parasite transmission from all endemic communities. Here we review recent work on the development and application of a deterministic mathematical model of filariasis transmission, to show how models of parasite transmission will help resolve the key currently debated questions regarding the ultimate effectiveness of the global strategy to control filariasis. These critical questions include the required duration of mass treatment in different endemic areas, the optimal drug coverage required to meet control targets within prescribed timeframes, the impact and importance of adding vector control to mass chemotherapy regimens, and the likelihood of the development of drug resistance by treated worm populations. The results demonstrate the vital role that integrating these models into control programming can have in providing effective decision-support frameworks for undertaking the optimal design and monitoring of regional and global filariasis-control programmes. Operationally, the models show that the effectiveness of the strategy to achieve filariasis control will be determined by successfully addressing two key factors: the need to maintain high community treatment coverages, and the need to include vector control measures especially in areas of high endemicity.
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Affiliation(s)
- Edwin Michael
- Department of Infectious Disease Epidemiology, Imperial College School of Medicine, London, UK.
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