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Lessons Learned From Developing an Eradication Investment Case for Lymphatic Filariasis. ADVANCES IN PARASITOLOGY 2016; 94:393-417. [PMID: 27756458 DOI: 10.1016/bs.apar.2016.08.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the last few years, the concepts of disease elimination and eradication have again gained consideration from the global health community, with Guinea worm disease (dracunculiasis) on track to become the first parasitic disease to be eradicated. Given the many complex and interlinking issues involved in committing to a disease eradication initiative, such commitments must be based on a solid assessment of a broad range of factors. In this chapter, we discuss the value and implications of undertaking a systematic and fact-based analysis of the overall situation prior to embarking on an elimination or eradication programme. As an example, we draw upon insights gained from a series of lymphatic filariasis (LF) studies from our research group that adopted an eradication investment case (EIC) framework. The justification for EICs, and related epidemiological, geospatial and other mathematical/operational research modelling, stems from the necessity for proper planning prior to committing to disease eradication. Across all considerations for LF eradication, including: time, treatments, level of investments necessary, health impact, cost-effectiveness, and broader economic benefits, scaling-up mass drug administration coverage to all endemic communities immediately provided the most favourable results. The coherent and consistent pursuit of eradication goals, operationally tailored to a given socioecological system and based on integrated measures of available tools will lead relatively rapidly to elimination in many parts of endemic areas and provide the cornerstone towards eradication.
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Controlling Neglected Tropical Diseases (NTDs) in Haiti: Implementation Strategies and Evidence of Their Success. PLoS Negl Trop Dis 2016; 10:e0004954. [PMID: 27706162 PMCID: PMC5051938 DOI: 10.1371/journal.pntd.0004954] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 08/05/2016] [Indexed: 12/04/2022] Open
Abstract
Lymphatic filariasis (LF) and soil-transmitted helminths (STH) have been targeted since 2000 in Haiti, with a strong mass drug administration (MDA) program led by the Ministry of Public Health and Population and its collaborating international partners. By 2012, Haiti’s neglected tropical disease (NTD) program had reached full national scale, and with such consistently good epidemiological coverage that it is now able to stop treatment for LF throughout almost all of the country. Essential to this success have been in the detail of how MDAs were implemented. These key programmatic elements included ensuring strong community awareness through an evidence-based, multi-channel communication and education campaign facilitated by voluntary drug distributors; strengthening community trust of the drug distributors by ensuring that respected community members were recruited and received appropriate training, supervision, identification, and motivation; enforcing a “directly observed treatment” strategy; providing easy access to treatment though numerous distribution posts and a strong drug supply chain; and ensuring quality data collection that was used to guide and inform MDA strategies. The evidence that these strategies were effective lies in both the high treatment coverage obtained– 100% geographical coverage reached in 2012, with almost all districts consistently achieving well above the epidemiological coverage targets of 65% for LF and 75% for STH—and the significant reduction in burden of infection– 45 communes having reached the target threshold for stopping treatment for LF. By taking advantage of sustained international financial and technical support, especially during the past eight years, Haiti’s very successful MDA campaign resulted in steady progress toward LF elimination and development of a strong foundation for ongoing STH control. These efforts, as described, have not only helped establish the global portfolio of “best practices” for NTD control but also are poised to help solve two of the most important future NTD challenges—how to maintain control of STH infections after the community-based LF “treatment platform” ceases and how to ensure appropriate morbidity management for patients currently suffering from lymphatic filarial disease. We present evidence of Haiti’s successful neglected tropical disease (NTD) program targeting lymphatic filariasis and soil-transmitted helminths and the methods used to achieve this success. By 2012, Haiti’s NTD program had reached full national scale, with such consistently good treatment coverage that the program is now able to stop treatment for lymphatic filariasis in much of the country. These findings are in line with the predictions and expectations of the global community for countries where high coverage is achieved for program implementation. In addition to the evidence of successful program outcomes, we present a detailed description of how the program was implemented—from facilitating the effectiveness of the drug distributors to improving drug logistics and supporting a well-informed population. These methods described can be used to inform the design of other mass drug administration programs and enhance the development of global “best practices” guidance.
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Damgaard J, Meyrowitsch DW, Rwegoshora RT, Magesa SM, Mukoko DA, Simonsen PE. Assessing drivers of the IgG4 antibody reactivity to recombinant antigen Bm14 in Wuchereria bancrofti endemic populations in East Africa. Acta Trop 2016; 161:26-32. [PMID: 27172877 DOI: 10.1016/j.actatropica.2016.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 03/31/2016] [Accepted: 05/06/2016] [Indexed: 11/27/2022]
Abstract
A high proportion of the human population in lymphatic filariasis (LF) endemic areas is positive for filarial specific IgG4 antibodies, including many individuals without microfilariae (mf; circulating larvae in the human blood) or circulating filarial antigens (CFA; marker of adult worm infection). The antibodies are commonly regarded as markers of infection and/or exposure to filarial larvae, but a direct association between the antibodies and these indices has not been well documented. The present study assessed the role and relative effect of potential drivers of the human IgG4 antibody reactivity to the recombinant filarial antigen Bm14 in Wuchereria bancrofti endemic populations in East Africa. Sera collected during previous studies from 395 well characterized individuals with regard to age, sex, mf, CFA, household vector biting and household exposure to infective filarial larvae were tested for IgG4 antibodies to Bm14, and associations between antibody reactivity and the different variables were statistically analyzed. IgG4 reactivity to Bm14 was highly positively associated with CFA, and to a lesser extent with age. However, an expected association with household exposure to infective filarial larvae was not found. Bm14 antibody reactivity thus appeared mainly to reflect actual infection of individuals with adult filarial worms rather than ongoing exposure to transmission. The analyses moreover suggested that many of the CFA negative but Bm14 positive individuals had early or low level infections where antibodies had been induced but where CFA was not (yet?) measurable. Although the study indicated that IgG4 reactivity to Bm14 is a marker of filarial infection, assessment of this reactivity, especially in children, will still be useful for indirect monitoring of changes in transmission intensity, including break of transmission and post-elimination surveillance, in LF control.
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DILEMMAS OF COMMUNITY-DIRECTED MASS DRUG ADMINISTRATION FOR LYMPHATIC FILARIASIS CONTROL: A QUALITATIVE STUDY FROM URBAN AND RURAL TANZANIA. J Biosoc Sci 2016; 49:447-462. [PMID: 27470198 DOI: 10.1017/s0021932016000365] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
There has in recent years been a growing interest in the social significance of global health policy and associated interventions. This paper is concerned with neglected tropical disease control, which prescribes annual mass drug administration to interrupt transmission of, among others, lymphatic filariasis. In Tanzania, this intervention is conducted through community-directed distribution, which aims to improve drug uptake by promoting community participation and local ownership in the intervention. However, the average uptake of drugs often remains too low to achieve the intended interruption of transmission. The qualitative research presented here followed the implementation of mass drug administration in Lindi and Morogoro Regions, Tanzania, in 2011 to understand the different forms of involvement in the campaign and the experiences of stakeholders of their part in community-directed distribution. Some health care workers, community leaders and drug distributors were generally positive about the intervention, emphasizing that the drugs were welcome. Other stakeholders, including the drug-receiving population, reported facing a number of dilemmas of uncertainty, authority and exclusion pertaining to their roles in the intervention. These dilemmas should be of interest to donors, policymakers and implementers. Community-directed distribution relies on social relations between the many different stakeholders. Successful and justifiable interventions for lymphatic filariasis require implementers to recognize the central role of sociality and that the voices and priorities of people count.
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Chand G, Kaushal LS, Choudhari NK, Singh N. Mapping is a prerequisite for elimination of filariasis and effective targeting of filarial 'hot spots'. Pathog Glob Health 2016; 110:157-63. [PMID: 27413817 DOI: 10.1080/20477724.2016.1205302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
OBJECTIVE This study was undertaken to determine the prevalence of filarial infection in the districts of Madhya Pradesh, which were classified as non-endemic by the national program for control of filariasis. These districts showed evidence of clinical symptoms related to filariasis. To confirm the presence of filariasis, night blood surveys and entomological surveys were carried out to detect microfilaria in humans and filarial infection in vectors. MATERIALS AND METHODS For microfilaria surveys, thick blood smears were prepared by taking 60 μL of blood between 8.00 and 11.00 pm and examined under a microscope. Vectors Culex quinquefasciatus were dissected for the filarial infection from the affected villages of four non-endemic districts. RESULTS Prevalence of microfilaria in the four districts ranged from 3.8% in district Shivpuri to 11.2% in district Bhind (overall mf rate 6.9%, 95% CI = 6.2-7.7). Infection and infectivity rates among vectors were recorded from three districts which varied from 2 to 13% and from 1.3 to 3.6%. CONCLUSION The study confirmed the presence of circulating microfilaria in non-endemic population of four districts, which has significant public health implications. To assess filarial endemicity and hot spots, precise filarial risk mapping using new efficient diagnostic tools is needed to reinforce and extend the strategy in other areas to achieve elimination of lymphatic filariasis.
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Affiliation(s)
- Gyan Chand
- a Department of Public Health Entomology , National Institute for Research in Tribal Health (ICMR) , Jabalpur , India
| | - Laxman Singh Kaushal
- a Department of Public Health Entomology , National Institute for Research in Tribal Health (ICMR) , Jabalpur , India
| | - Narendra Kumar Choudhari
- a Department of Public Health Entomology , National Institute for Research in Tribal Health (ICMR) , Jabalpur , India
| | - Neeru Singh
- b Department of Epidemiology and Vector Control , National Institute for Research in Tribal Health (ICMR) , Jabalpur , India
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Wolstenholme AJ, Maclean MJ, Coates R, McCoy CJ, Reaves BJ. How do the macrocyclic lactones kill filarial nematode larvae? INVERTEBRATE NEUROSCIENCE 2016; 16:7. [PMID: 27279086 DOI: 10.1007/s10158-016-0190-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/30/2016] [Indexed: 12/17/2022]
Abstract
The macrocyclic lactones (MLs) are one of the few classes of drug used in the control of the human filarial infections, onchocerciasis and lymphatic filariasis, and the only one used to prevent heartworm disease in dogs and cats. Despite their importance in preventing filarial diseases, the way in which the MLs work against these parasites is unclear. In vitro measurements of nematode motility have revealed a large discrepancy between the maximum plasma concentrations achieved after drug administration and the amounts required to paralyze worms. Recent evidence has shed new light on the likely functions of the ML target, glutamate-gated chloride channels, in filarial nematodes and supports the hypothesis that the rapid clearance of microfilariae that follows treatment involves the host immune system.
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Affiliation(s)
- Adrian J Wolstenholme
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA. .,Department of Infectious Diseases, College of Veterinary Medicine, 501 D. W. Brooks Drive, Athens, GA, 30602, USA.
| | - Mary J Maclean
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Ruby Coates
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.,Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK
| | - Ciaran J McCoy
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.,School of Biological Sciences, Medical Biology Centre, Queen's University, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Barbara J Reaves
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
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Turner HC, Bettis AA, Chu BK, McFarland DA, Hooper PJ, Ottesen EA, Bradley MH. The health and economic benefits of the global programme to eliminate lymphatic filariasis (2000-2014). Infect Dis Poverty 2016; 5:54. [PMID: 27388873 PMCID: PMC4937583 DOI: 10.1186/s40249-016-0147-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 05/18/2016] [Indexed: 10/25/2022] Open
Abstract
BACKGROUND Lymphatic filariasis (LF), also known as elephantiasis, is a neglected tropical disease (NTD) targeted for elimination through a Global Programme to Eliminate LF (GPELF). Between 2000 and 2014, the GPELF has delivered 5.6 billion treatments to over 763 million people. Updating the estimated health and economic benefits of this significant achievement is important in justifying the resources and investment needed for eliminating LF. METHOD We combined previously established models to estimate the number of clinical manifestations and disability-adjusted life years (DALYs) averted from three benefit cohorts (those protected from acquiring infection, those with subclinical morbidity prevented from progressing and those with clinical disease alleviated). The economic savings associated with this disease prevention was then analysed in the context of prevented medical expenses incurred by LF clinical patients, potential income loss through lost-labour, and prevented costs to the health system to care for affected individuals. The indirect cost estimates were calculated using the human capital approach. A combination of four wage sources was used to estimate the fair market value of time for an agricultural worker with LF infection (to ensure a conservative estimate, the lowest wage value was used). RESULTS We projected that due to the first 15 years of the GPELF 36 million clinical cases and 175 (116-250) million DALYs will potentially be averted. It was estimated that due to this notable health impact, US$100.5 billion will potentially be saved over the lifetimes of the benefit cohorts. This total amount results from summing the medical expenses incurred by LF patients (US$3 billion), potential income loss (US$94 billion), and costs to the health system (US$3.5 billion) that were projected to be prevented. The results were subjected to sensitivity analysis and were most sensitive to the assumed percentage of work hours lost for those suffering from chronic disease (changing the total economic benefit between US$69.30-150.7 billion). CONCLUSIONS Despite the limitations of any such analysis, this study identifies substantial health and economic benefits that have resulted from the first 15 years of the GPELF, and it highlights the value and importance of continued investment in the GPELF.
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Affiliation(s)
- Hugo C Turner
- London Centre for Neglected Tropical Disease Research, London, UK.
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Marys Campus, Imperial College London, Norfolk Place, London, W2 1PG, UK.
| | - Alison A Bettis
- London Centre for Neglected Tropical Disease Research, London, UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Marys Campus, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - Brian K Chu
- Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, GA, USA
| | | | - Pamela J Hooper
- Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, GA, USA
| | - Eric A Ottesen
- Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, GA, USA
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Sharma OP, Kumar MS. Essential proteins and possible therapeutic targets of Wolbachia endosymbiont and development of FiloBase--a comprehensive drug target database for Lymphatic filariasis. Sci Rep 2016; 6:19842. [PMID: 26806463 PMCID: PMC4726333 DOI: 10.1038/srep19842] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 10/27/2015] [Indexed: 11/26/2022] Open
Abstract
Lymphatic filariasis (Lf) is one of the oldest and most debilitating tropical diseases. Millions of people are suffering from this prevalent disease. It is estimated to infect over 120 million people in at least 80 nations of the world through the tropical and subtropical regions. More than one billion people are in danger of getting affected with this life-threatening disease. Several studies were suggested its emerging limitations and resistance towards the available drugs and therapeutic targets for Lf. Therefore, better medicine and drug targets are in demand. We took an initiative to identify the essential proteins of Wolbachia endosymbiont of Brugia malayi, which are indispensable for their survival and non-homologous to human host proteins. In this current study, we have used proteome subtractive approach to screen the possible therapeutic targets for wBm. In addition, numerous literatures were mined in the hunt for potential drug targets, drugs, epitopes, crystal structures, and expressed sequence tag (EST) sequences for filarial causing nematodes. Data obtained from our study were presented in a user friendly database named FiloBase. We hope that information stored in this database may be used for further research and drug development process against filariasis. URL: http://filobase.bicpu.edu.in.
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Affiliation(s)
- Om Prakash Sharma
- Centre for Bioinformatics, School of Life Science, Pondicherry University, Pondicherry-605014, India
| | - Muthuvel Suresh Kumar
- Centre for Bioinformatics, School of Life Science, Pondicherry University, Pondicherry-605014, India
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Brugia malayi Asparaginyl-tRNA Synthetase Stimulates Endothelial Cell Proliferation, Vasodilation and Angiogenesis. PLoS One 2016; 11:e0146132. [PMID: 26751209 PMCID: PMC4709172 DOI: 10.1371/journal.pone.0146132] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 12/14/2015] [Indexed: 11/24/2022] Open
Abstract
A hallmark of chronic infection with lymphatic filarial parasites is the development of lymphatic disease which often results in permanent vasodilation and lymphedema, but all of the mechanisms by which filarial parasites induce pathology are not known. Prior work showed that the asparaginyl-tRNA synthetase (BmAsnRS) of Brugia malayi, an etiological agent of lymphatic filariasis, acts as a physiocrine that binds specifically to interleukin-8 (IL-8) chemokine receptors. Endothelial cells are one of the many cell types that express IL-8 receptors. IL-8 also has been reported previously to induce angiogenesis and vasodilation, however, the effect of BmAsnRS on endothelial cells has not been reported. Therefore, we tested the hypothesis that BmAsnRS might produce physiological changes in endothelial by studying the in vitro effects of BmAsnRS using a human umbilical vein cell line EA.hy926 and six different endothelial cell assays. Our results demonstrated that BmAsnRS produces consistent and statistically significant effects on endothelial cells that are identical to the effects of VEGF, vascular endothelial growth factor. This study supports the idea that new drugs or immunotherapies that counteract the adverse effects of parasite-derived physiocrines may prevent or ameliorate the vascular pathology observed in patients with lymphatic filariasis.
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Lau YL, Lee WC, Xia J, Zhang G, Razali R, Anwar A, Fong MY. Draft genome of Brugia pahangi: high similarity between B. pahangi and B. malayi. Parasit Vectors 2015; 8:451. [PMID: 26350613 PMCID: PMC4562187 DOI: 10.1186/s13071-015-1064-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 09/01/2015] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Efforts to completely eradicate lymphatic filariasis from human population may be challenged by the emergence of Brugia pahangi as another zoonotic lymphatic filarial nematode. In this report, a genomic study was conducted to understand this species at molecular level. METHODS After blood meal on a B. pahangi-harbouring cat, the Aedes togoi mosquitoes were maintained to harvest infective third stage larvae, which were then injected into male Mongolian gerbils. Subsequently, adult B. pahangi were obtained from the infected gerbil for genomic DNA extraction. Sequencing and subsequently, construction of genomic libraries were performed. This was followed by genomic analyses and gene annotation analysis. By using archived protein sequences of B. malayi and a few other nematodes, clustering of gene orthologs and phylogenetics were conducted. RESULTS A total of 9687 coding genes were predicted. The genome of B. pahangi shared high similarity to that B. malayi genome, particularly genes annotated to fundamental processes. Nevertheless, 166 genes were considered to be unique to B. pahangi, which may be responsible for the distinct properties of B. pahangi as compared to other filarial nematodes. In addition, 803 genes were deduced to be derived from Wolbachia, an endosymbiont bacterium, with 44 of these genes intercalate into the nematode genome. CONCLUSIONS The reporting of B. pahangi draft genome contributes to genomic archive. Albeit with high similarity to B. malayi genome, the B. pahangi-unique genes found in this study may serve as new focus to study differences in virulence, vector selection and host adaptability among different Brugia spp.
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Affiliation(s)
- Yee-Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.
| | - Wenn-Chyau Lee
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore, 138648, Singapore
| | | | | | - Rozaimi Razali
- Sengenics HIR, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Arif Anwar
- Sengenics HIR, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Mun-Yik Fong
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
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Coulibaly YI, Dembele B, Diallo AA, Konaté S, Dolo H, Coulibaly SY, Doumbia SS, Soumaoro L, Coulibaly ME, Bockarie MJ, Molyneux D, Nutman TB, Klion AD, Toure YT, Traore SF. The Impact of Six Annual Rounds of Mass Drug Administration on Wuchereria bancrofti Infections in Humans and in Mosquitoes in Mali. Am J Trop Med Hyg 2015; 93:356-60. [PMID: 26033027 PMCID: PMC4530761 DOI: 10.4269/ajtmh.14-0516] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 02/16/2015] [Indexed: 11/07/2022] Open
Abstract
Wuchereria bancrofti prevalence and transmission were assessed in six endemic villages in Sikasso, Mali prior to and yearly during mass drug administration (MDA) with albendazole and ivermectin from 2002 to 2007. Microfilaremia was determined by calibrated thick smear of night blood in adult volunteers and circulating filarial antigen was measured using immunochromatographic card test in children < 5 years of age. Mosquitoes were collected by human landing catch from July to December. None of the 686 subjects tested were microfilaremic 12 months after the sixth MDA round. More importantly, circulating antigen was not detected in any of the 120 children tested, as compared with 53% (103/194) before the institution of MDA. The number of infective bites/human/year decreased from 4.8 in 2002 to 0.04 in 2007, and only one mosquito containing a single infective larva was observed 12 months after the final MDA round. Whether this dramatic reduction in transmission will be sustained following cessation of MDA remains to be seen.
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Affiliation(s)
- Yaya I Coulibaly
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Benoit Dembele
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Abdallah Amadou Diallo
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Siaka Konaté
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Houseini Dolo
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Siaka Yamoussa Coulibaly
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Salif Seriba Doumbia
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Lamine Soumaoro
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Michel Emmanuel Coulibaly
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Moses J Bockarie
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - David Molyneux
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Thomas B Nutman
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Amy D Klion
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Yeya T Toure
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
| | - Sekou F Traore
- International Center of Excellence in Research (ICER-Mali), Filariasis Research and Training Unit, Bamako, Mali; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; University of Liverpool, Liverpool Liverpool School of Tropical Medicine, Centre for Neglected Tropical Diseases, Liverpool, United Kingdom; National Institutes of Health, Laboratory of Parasitic Diseases, Helminth Immunology Section, Bethesda, Maryland; National Institutes of Health, Laboratory of Parasitic Diseases, Eosinophil Pathology Section, Bethesda, Maryland; World Health Organization, Vectors, Environment and Society Research, Geneva, Switzerland
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Impact of socioeconomic factors on the prevalence of lymphatic filariasis in Andhra Pradesh, India. J Public Health (Oxf) 2015. [DOI: 10.1007/s10389-015-0673-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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COMMUNITY MEMBERS' PERCEPTIONS OF MASS DRUG ADMINISTRATION FOR CONTROL OF LYMPHATIC FILARIASIS IN RURAL AND URBAN TANZANIA. J Biosoc Sci 2015; 48:94-112. [PMID: 25790081 PMCID: PMC4668335 DOI: 10.1017/s0021932015000024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lymphatic filariasis is one of several neglected tropical diseases with severely disabling and stigmatizing manifestations that are referred to as ‘neglected diseases of poverty’. It is a mosquito-borne disease found endemically and exclusively in low-income contexts where, concomitantly, general public health care is often deeply troubled and fails to meet the basic health needs of impoverished populations. This presents particular challenges for the implementation of mass drug administration (MDA), which currently is the principal means of control and eventual elimination. Several MDA programmes face the dilemma that they are unable to attain and maintain the required drug coverage across target groups. In recognition of this, a qualitative study was conducted in the Morogoro and Lindi regions of Tanzania to gain an understanding of community experiences with, and perceptions of, the MDA campaign implemented in 2011 by the National Lymphatic Filariasis Elimination Programme. The study revealed a wide variation of perceptions and experiences regarding the aim, rationale and justification of MDA. There were positive sentiments about the usefulness of the drugs, but many study participants were sceptical about the manner in which MDA is implemented. People were particularly disappointed with the limited attempts by implementers to share information and mobilize residents. In addition, negative sentiments towards MDA for lymphatic filariasis reflected a general feeling of desertion and marginalization by the health care system and political authorities. However, the results suggest that if the communities are brought on board with genuine respect for their integrity and informed self-determination, there is scope for major improvements in community support for MDA-based control activities.
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Pion SDS, Chesnais CB, Bopda J, Louya F, Fischer PU, Majewski AC, Weil GJ, Boussinesq M, Missamou F. The impact of two semiannual treatments with albendazole alone on lymphatic filariasis and soil-transmitted helminth infections: a community-based study in the Republic of Congo. Am J Trop Med Hyg 2015; 92:959-66. [PMID: 25758650 DOI: 10.4269/ajtmh.14-0661] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 12/09/2014] [Indexed: 11/07/2022] Open
Abstract
Implementation of mass drug administration (MDA) with ivermectin plus albendazole (ALB) for lymphatic filariasis (LF) has been delayed in central Africa because of the risk of serious adverse events in subjects with high Loa loa microfilaremia. We conducted a community trial to assess the impact of semiannual MDA with ALB (400 mg) alone on LF and soil-transmitted helminth (STH) infections in the Republic of Congo. Evaluation at 12 months showed that ALB MDA had not significantly reduced Wuchereria bancrofti antigenemia or microfilaria (mf) rates in the community (from 17.3% to 16.6% and from 5.3% to 4.2%, respectively). However, the geometric mean mf count in mf-positive subjects was reduced from 202.2 to 80.9 mf/mL (60% reduction, P = 0.01). The effect of ALB was impressive in 38 subjects who were mf-positive at baseline and retested at 12 months: 37% had total mf clearance, and individual mf densities were reduced by 73.0%. MDA also dramatically reduced the hookworm infection rate in the community from 6.5% to 0.6% (91% reduction), with less impressive effects on Ascaris and Trichuris. These preliminary results suggest that semiannual community MDA with ALB is a promising strategy for controlling LF and STH in areas with coendemic loiasis.
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Affiliation(s)
- Sébastien D S Pion
- Unité Mixte Internationale 233, Institut de Recherche pour le Développement and University of Montpellier 1, Montpellier, France; Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon; Programme National de Lutte contre l'Onchocercose, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo; Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Cédric B Chesnais
- Unité Mixte Internationale 233, Institut de Recherche pour le Développement and University of Montpellier 1, Montpellier, France; Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon; Programme National de Lutte contre l'Onchocercose, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo; Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Jean Bopda
- Unité Mixte Internationale 233, Institut de Recherche pour le Développement and University of Montpellier 1, Montpellier, France; Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon; Programme National de Lutte contre l'Onchocercose, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo; Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Frédéric Louya
- Unité Mixte Internationale 233, Institut de Recherche pour le Développement and University of Montpellier 1, Montpellier, France; Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon; Programme National de Lutte contre l'Onchocercose, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo; Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Peter U Fischer
- Unité Mixte Internationale 233, Institut de Recherche pour le Développement and University of Montpellier 1, Montpellier, France; Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon; Programme National de Lutte contre l'Onchocercose, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo; Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Andrew C Majewski
- Unité Mixte Internationale 233, Institut de Recherche pour le Développement and University of Montpellier 1, Montpellier, France; Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon; Programme National de Lutte contre l'Onchocercose, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo; Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Gary J Weil
- Unité Mixte Internationale 233, Institut de Recherche pour le Développement and University of Montpellier 1, Montpellier, France; Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon; Programme National de Lutte contre l'Onchocercose, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo; Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Michel Boussinesq
- Unité Mixte Internationale 233, Institut de Recherche pour le Développement and University of Montpellier 1, Montpellier, France; Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon; Programme National de Lutte contre l'Onchocercose, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo; Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - François Missamou
- Unité Mixte Internationale 233, Institut de Recherche pour le Développement and University of Montpellier 1, Montpellier, France; Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon; Programme National de Lutte contre l'Onchocercose, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo; Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
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How effective is integrated vector management against malaria and lymphatic filariasis where the diseases are transmitted by the same vector? PLoS Negl Trop Dis 2014; 8:e3393. [PMID: 25501002 PMCID: PMC4263402 DOI: 10.1371/journal.pntd.0003393] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 11/05/2014] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The opportunity to integrate vector management across multiple vector-borne diseases is particularly plausible for malaria and lymphatic filariasis (LF) control where both diseases are transmitted by the same vector. To date most examples of integrated control targeting these diseases have been unanticipated consequences of malaria vector control, rather than planned strategies that aim to maximize the efficacy and take the complex ecological and biological interactions between the two diseases into account. METHODOLOGY/PRINCIPAL FINDINGS We developed a general model of malaria and LF transmission and derived expressions for the basic reproductive number (R0) for each disease. Transmission of both diseases was most sensitive to vector mortality and biting rate. Simulating different levels of coverage of long lasting-insecticidal nets (LLINs) and larval control confirms the effectiveness of these interventions for the control of both diseases. When LF was maintained near the critical density of mosquitoes, minor levels of vector control (8% coverage of LLINs or treatment of 20% of larval sites) were sufficient to eliminate the disease. Malaria had a far greater R0 and required a 90% population coverage of LLINs in order to eliminate it. When the mosquito density was doubled, 36% and 58% coverage of LLINs and larval control, respectively, were required for LF elimination; and malaria elimination was possible with a combined coverage of 78% of LLINs and larval control. CONCLUSIONS/SIGNIFICANCE Despite the low level of vector control required to eliminate LF, simulations suggest that prevalence of LF will decrease at a slower rate than malaria, even at high levels of coverage. If representative of field situations, integrated management should take into account not only how malaria control can facilitate filariasis elimination, but strike a balance between the high levels of coverage of (multiple) interventions required for malaria with the long duration predicted to be required for filariasis elimination.
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Ximenes C, Brandão E, Oliveira P, Rocha A, Rego T, Medeiros R, Aguiar-Santos A, Ferraz J, Reis C, Araujo P, Carvalho L, Melo FL. Detection of Wuchereria bancrofti DNA in paired serum and urine samples using polymerase chain reaction-based systems. Mem Inst Oswaldo Cruz 2014; 109:978-83. [PMID: 25424447 PMCID: PMC4325614 DOI: 10.1590/0074-0276140155] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 10/31/2014] [Indexed: 11/23/2022] Open
Abstract
The Global Program for the Elimination of Lymphatic Filariasis (GPELF) aims to
eliminate this disease by the year 2020. However, the development of more specific
and sensitive tests is important for the success of the GPELF. The present study
aimed to standardise polymerase chain reaction (PCR)-based systems for the diagnosis
of filariasis in serum and urine. Twenty paired biological urine and serum samples
from individuals already known to be positive for Wuchereria bancrofti
were collected during the day. Conventional PCR and semi-nested PCR assays
were optimised. The detection limit of the technique for purified W.
bancrofti DNA extracted from adult worms was 10 fg for the internal
systems (WbF/Wb2) and 0.1 fg by using semi-nested PCR. The specificity of the primers
was confirmed experimentally by amplification of 1 ng of purified genomic DNA from
other species of parasites. Evaluation of the paired urine and serum samples by the
semi-nested PCR technique indicated only two of the 20 tested individuals were
positive, whereas the simple internal PCR system (WbF/Wb2), which has highly
promising performance, revealed that all the patients were positive using both
samples. This study successfully demonstrated the possibility of using the PCR
technique on urine for the diagnosis of W. bancrofti infection.
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Affiliation(s)
- Camila Ximenes
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - Eduardo Brandão
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - Paula Oliveira
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - Abraham Rocha
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - Tamisa Rego
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - Rafael Medeiros
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - Ana Aguiar-Santos
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - João Ferraz
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - Christian Reis
- Departamento de Microbiologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - Paulo Araujo
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
| | - Luiz Carvalho
- Laboratório de Imunopatologia Keizo Asami, Universidade Federal de Pernambuco, Recife, PE, Brasil
| | - Fabio L Melo
- Serviço de Referência Nacional em Filarioses, Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Recife, PE, Brasil
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Simonsen PE, Derua YA, Magesa SM, Pedersen EM, Stensgaard AS, Malecela MN, Kisinza WN. Lymphatic filariasis control in Tanga Region, Tanzania: status after eight rounds of mass drug administration. Parasit Vectors 2014; 7:507. [PMID: 25387483 PMCID: PMC4233105 DOI: 10.1186/s13071-014-0507-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 10/28/2014] [Indexed: 11/13/2022] Open
Abstract
Background Lymphatic filariasis (LF) control started in Tanga Region of Tanzania in 2004, with annual ivermectin/albendazole mass drug administration (MDA). Since then, the current project has monitored the effect in communities and schools in rural areas of Tanga District. In 2013, after 8 rounds of MDA, spot check surveys were added in the other 7 districts of Tanga Region, to assess the regional LF status. Methods LF vector and transmission surveillance, and human cross sectional surveys in communities and schools, continued in Tanga District as previously reported. In each of the other 7 districts, 2–3 spot check sites were selected and about 200 schoolchildren were examined for circulating filarial antigens (CFA). At 1–2 of the sites in each district, additional about 200 community volunteers were examined for CFA and chronic LF disease, and the CFA positives were re-examined for microfilariae (mf). Results The downward trend in LF transmission and human infection previously reported for Tanga District continued, with prevalences after MDA 8 reaching 15.5% and 3.5% for CFA and mf in communities (decrease by 75.5% and 89.6% from baseline) and 2.3% for CFA in schoolchildren (decrease by 90.9% from baseline). Surprisingly, the prevalence of chronic LF morbidity after MDA 8 was less than half of baseline records. No infective vector mosquitoes were detected after MDA 7. Spot checks in the other districts after MDA 8 showed relatively high LF burdens in the coastal districts. LF burdens gradually decreased when moving to districts further inland and with higher altitudes. Conclusion LF was still widespread in many parts of Tanga Region after MDA 8, in particular in the coastal areas. This calls for intensified control, which should include increased MDA treatment coverage, strengthening of bed net usage, and more male focus in LF health information dissemination. The low LF burdens observed in some inland districts suggest that MDA in these could be stepped down to provide more resources for upscale of control in the coastal areas. Monitoring should continue to guide the programme to ensure that the current major achievements will ultimately lead to successful LF elimination.
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Affiliation(s)
- Paul E Simonsen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, 1870, Frederiksberg C, Denmark.
| | - Yahya A Derua
- National Institute for Medical Research, Amani Medical Research Centre, P.O. Box 81, Muheza, Tanzania.
| | - Stephen M Magesa
- RTI International, Global Health Division, Dar es Salaam, Tanzania.
| | - Erling M Pedersen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, 1870, Frederiksberg C, Denmark.
| | - Anna-Sofie Stensgaard
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, 1870, Frederiksberg C, Denmark. .,Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen Ø, Denmark.
| | - Mwelecele N Malecela
- National Institute for Medical Research, P.O. Box 9653, Dar es Salaam, Tanzania.
| | - William N Kisinza
- National Institute for Medical Research, Amani Medical Research Centre, P.O. Box 81, Muheza, Tanzania.
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Benefit of insecticide-treated nets, curtains and screening on vector borne diseases, excluding malaria: a systematic review and meta-analysis. PLoS Negl Trop Dis 2014; 8:e3228. [PMID: 25299481 PMCID: PMC4191944 DOI: 10.1371/journal.pntd.0003228] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 08/28/2014] [Indexed: 11/19/2022] Open
Abstract
Introduction Insecticide-treated nets (ITNs) are one of the main interventions used for malaria control. However, these nets may also be effective against other vector borne diseases (VBDs). We conducted a systematic review and meta-analysis to estimate the efficacy of ITNs, insecticide-treated curtains (ITCs) and insecticide-treated house screening (ITS) against Chagas disease, cutaneous and visceral leishmaniasis, dengue, human African trypanosomiasis, Japanese encephalitis, lymphatic filariasis and onchocerciasis. Methods MEDLINE, EMBASE, LILACS and Tropical Disease Bulletin databases were searched using intervention, vector- and disease-specific search terms. Cluster or individually randomised controlled trials, non-randomised trials with pre- and post-intervention data and rotational design studies were included. Analysis assessed the efficacy of ITNs, ITCs or ITS versus no intervention. Meta-analysis of clinical data was performed and percentage reduction in vector density calculated. Results Twenty-one studies were identified which met the inclusion criteria. Meta-analysis of clinical data could only be performed for four cutaneous leishmaniasis studies which together showed a protective efficacy of ITNs of 77% (95%CI: 39%–91%). Studies of ITC and ITS against cutaneous leishmaniasis also reported significant reductions in disease incidence. Single studies reported a high protective efficacy of ITS against dengue and ITNs against Japanese encephalitis. No studies of Chagas disease, human African trypanosomiasis or onchocerciasis were identified. Conclusion There are likely to be considerable collateral benefits of ITN roll out on cutaneous leishmaniasis where this disease is co-endemic with malaria. Due to the low number of studies identified, issues with reporting of entomological outcomes, and few studies reporting clinical outcomes, it is difficult to make strong conclusions on the effect of ITNs, ITCs or ITS on other VBDs and therefore further studies be conducted. Nonetheless, it is clear that insecticide-treated materials such as ITNs have the potential to reduce pathogen transmission and morbidity from VBDs where vectors enter houses. Malaria is a deadly disease caused by a parasite which is transmitted by anopheline mosquitoes. Bednets treated with insecticide are one of the key tools used to prevent malaria and they have been distributed on a large scale in many countries, particularly in Africa. It may be possible to control other diseases transmitted by insects using insecticide-treated bednets because many of these insects also enter houses. We did a review of studies looking at the effectiveness of insecticide-treated bednets, curtains and house screening against nine major diseases transmitted by insects. We assessed the effect these tools had on reducing numbers of the insects and disease in humans. Insecticide-treated bednets were found to be effective in preventing cutaneous leishmaniasis—a disease transmitted by sandflies—and insecticide-treated curtains and screening showed potential in preventing other insect borne diseases. Although further studies are required, it is clear that insecticide-treated bednets, curtains and screening have the potential to prevent transmission of insect-transmitted diseases.
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Factors influencing drug uptake during mass drug administration for control of lymphatic filariasis in rural and urban Tanzania. PLoS One 2014; 9:e109316. [PMID: 25296034 PMCID: PMC4190414 DOI: 10.1371/journal.pone.0109316] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 09/08/2014] [Indexed: 11/19/2022] Open
Abstract
Background In most countries of Sub-Saharan Africa, control of lymphatic filariasis (LF) is based on annual mass drug administration (MDA) with a combination of ivermectin and albendazole. Treatment coverages are however often suboptimal for programmes to reach the goal of transmission interruption within reasonable time. The present study aimed to identify predictors and barriers to individual drug uptake during MDA implementation by the National LF Elimination Programme in Tanzania. Methods A questionnaire based cross sectional household survey was carried out in two rural and two urban districts in Lindi and Morogoro regions shortly after the 2011 MDA. 3279 adults (≥15 years) were interviewed about personal characteristics, socio-economic status, MDA drug uptake among themselves and their children, reasons for taking/not taking drugs, and participation in previous MDA activities for LF control. Findings The overall drug uptake rate was 55.1% (range of 44.5–75.6% between districts). There was no overall major difference between children (54.8%) and adults (55.2%) or between females (54.9%) and males (55.8%), but the role of these and other predictors varied to some extent between study sites. Major overall predictors of drug uptake among the interviewed adults were increasing age and history of previous drug uptake. Being absent from home during drug distribution was the main reason for not taking the drugs (50.2%) followed by clinical contraindications to treatment (10.8%), missing household visits of drug distributors (10.6%), and households not being informed about the distribution (9.0%). Conclusion Drug uptake relied more on easily modifiable provider-related factors than on individual perceptions and practices in the target population. Limited investments in appropriate timing, dissemination of accurate timing information to recipients and motivation of drug distributors to visit all households (repeatedly when residents are absent) are likely to have considerable potential for increasing drug uptake, in support of successful LF transmission elimination.
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Helminth parasites alter protection against Plasmodium infection. BIOMED RESEARCH INTERNATIONAL 2014; 2014:913696. [PMID: 25276830 PMCID: PMC4170705 DOI: 10.1155/2014/913696] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 08/06/2014] [Indexed: 12/17/2022]
Abstract
More than one-third of the world's population is infected with one or more helminthic parasites. Helminth infections are prevalent throughout tropical and subtropical regions where malaria pathogens are transmitted. Malaria is the most widespread and deadliest parasitic disease. The severity of the disease is strongly related to parasite density and the host's immune responses. Furthermore, coinfections between both parasites occur frequently. However, little is known regarding how concomitant infection with helminths and Plasmodium affects the host's immune response. Helminthic infections are frequently massive, chronic, and strong inductors of a Th2-type response. This implies that infection by such parasites could alter the host's susceptibility to subsequent infections by Plasmodium. There are a number of reports on the interactions between helminths and Plasmodium; in some, the burden of Plasmodium parasites increased, but others reported a reduction in the parasite. This review focuses on explaining many of these discrepancies regarding helminth-Plasmodium coinfections in terms of the effects that helminths have on the immune system. In particular, it focuses on helminth-induced immunosuppression and the effects of cytokines controlling polarization toward the Th1 or Th2 arms of the immune response.
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Bisanzio D, Mutuku F, Bustinduy AL, Mungai PL, Muchiri EM, King CH, Kitron U. Cross-sectional study of the burden of vector-borne and soil-transmitted polyparasitism in rural communities of Coast Province, Kenya. PLoS Negl Trop Dis 2014; 8:e2992. [PMID: 25057825 PMCID: PMC4109907 DOI: 10.1371/journal.pntd.0002992] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Accepted: 05/20/2014] [Indexed: 11/18/2022] Open
Abstract
Background In coastal Kenya, infection of human populations by a variety of parasites often results in co-infection or poly-parasitism. These parasitic infections, separately and in conjunction, are a major cause of chronic clinical and sub-clinical human disease and exert a long-term toll on economic welfare of affected populations. Risk factors for these infections are often shared and overlap in space, resulting in interrelated patterns of transmission that need to be considered at different spatial scales. Integration of novel quantitative tools and qualitative approaches is needed to analyze transmission dynamics and design effective interventions. Methodology Our study was focused on detecting spatial and demographic patterns of single- and co-infection in six villages in coastal Kenya. Individual and household level data were acquired using cross-sectional, socio-economic, and entomological surveys. Generalized additive models (GAMs and GAMMs) were applied to determine risk factors for infection and co-infections. Spatial analysis techniques were used to detect local clusters of single and multiple infections. Principal findings Of the 5,713 tested individuals, more than 50% were infected with at least one parasite and nearly 20% showed co-infections. Infections with Schistosoma haematobium (26.0%) and hookworm (21.4%) were most common, as was co-infection by both (6.3%). Single and co-infections shared similar environmental and socio-demographic risk factors. The prevalence of single and multiple infections was heterogeneous among and within communities. Clusters of single and co-infections were detected in each village, often spatially overlapped, and were associated with lower SES and household crowding. Conclusion Parasitic infections and co-infections are widespread in coastal Kenya, and their distributions are heterogeneous across landscapes, but inter-related. We highlighted how shared risk factors are associated with high prevalence of single infections and can result in spatial clustering of co-infections. Spatial heterogeneity and synergistic risk factors for polyparasitism need to be considered when designing surveillance and intervention strategies. In Coast Province, Kenya, infections with Schistosoma haematobium, Plasmodium spp., filarial nematodes, and geohelminths are common, resulting in high levels of both single infections and polyparasitism. The long-term effect of these infections, separately or in combination, has a major impact on human health and on the economic welfare of affected populations. The transmission dynamics of these parasitic infections can be linked to shared risk factors that often overlap in space. We studied human and environmental factors driving transmission and the resulting spatial pattern of infections in six communities, using cross-sectional, socio-economic and entomological surveys. Single and co-infections were widespread in the communities, and were associated with environmental, demographic and socio-economic risk factors, including distance of community from the coast, sanitation and human age and crowding. The spatial patterns of single and co-infections were heterogeneous among and within communities, with overlapping clusters of single and multiple infections in areas where houses with lower socio-economic status and more crowding were located. The heterogeneities among and within communities can provide important insights when designing surveillance and intervention strategies when planning appropriate surveillance and control strategies targeting polyparasitism.
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Affiliation(s)
- Donal Bisanzio
- Department of Environmental Sciences, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
| | - Francis Mutuku
- Department of Environmental Sciences, Emory University, Atlanta, Georgia, United States of America
- Department of Environment and Health Sciences, Technical University of Mombasa, Mombasa, Kenya
| | - Amaya L. Bustinduy
- Parasitology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Peter L. Mungai
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Eric M. Muchiri
- Division of Vector-Borne and Neglected Tropical Diseases, Ministry of Public Health and Sanitation, Nairobi, Kenya
| | - Charles H. King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Uriel Kitron
- Department of Environmental Sciences, Emory University, Atlanta, Georgia, United States of America
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Synthesis and antifilarial activity of chalcone-thiazole derivatives against a human lymphatic filarial parasite, Brugia malayi. Eur J Med Chem 2014; 81:473-80. [PMID: 24863844 DOI: 10.1016/j.ejmech.2014.05.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 05/07/2014] [Accepted: 05/10/2014] [Indexed: 01/07/2023]
Abstract
Here we report the synthesis of novel chalcone-thiazole compounds and their antifilarial activity. The antifilarial properties of these hybrids were assessed against microfilariae as well as adult worms of Brugia malayi. Among all the synthesized compounds, only two compounds, namely 4g and 4n were identified to be promising in vitro. These active compounds were tested in B. malayi-jird (Meriones unguiculatus) and B. malayi-Mastomys coucha models. Compound 4n showed 100% embryostatic effect and 49% macrofilaricidal in jirds and M. coucha models, respectively. This study provides a new structural clue for the development of novel antifilarial lead molecules.
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73
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Filaria zoogeography in Africa: ecology, competitive exclusion, and public health relevance. Trends Parasitol 2014; 30:163-9. [PMID: 24636357 DOI: 10.1016/j.pt.2014.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 02/04/2014] [Accepted: 02/09/2014] [Indexed: 11/20/2022]
Abstract
Six species of filariae infect humans in sub-Saharan Africa. We hypothesise that these nematodes are able to polyparasitise human hosts by having successfully, through competitive exclusion, adapted to distinct niches. Despite inhabiting the same host, adult stages reside in different tissue sites. Microfilariae of some species exhibit temporal separation by reaching peak levels in the blood at specific times of day. Spatial and temporal distributions in microfilaria location are exploited by the vector feeding-behaviour whereas adult survival is enhanced by occupying exclusive 'ecological' niches of the body. We present specific examples to demonstrate this concept, which is not only important from the biological aspect but important in the context of elimination programmes.
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Transmission assessment surveys (TAS) to define endpoints for lymphatic filariasis mass drug administration: a multicenter evaluation. PLoS Negl Trop Dis 2013; 7:e2584. [PMID: 24340120 PMCID: PMC3855047 DOI: 10.1371/journal.pntd.0002584] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 10/29/2013] [Indexed: 11/19/2022] Open
Abstract
Background Lymphatic filariasis (LF) is targeted for global elimination through treatment of entire at-risk populations with repeated annual mass drug administration (MDA). Essential for program success is defining and confirming the appropriate endpoint for MDA when transmission is presumed to have reached a level low enough that it cannot be sustained even in the absence of drug intervention. Guidelines advanced by WHO call for a transmission assessment survey (TAS) to determine if MDA can be stopped within an LF evaluation unit (EU) after at least five effective rounds of annual treatment. To test the value and practicality of these guidelines, a multicenter operational research trial was undertaken in 11 countries covering various geographic and epidemiological settings. Methodology The TAS was conducted twice in each EU with TAS-1 and TAS-2 approximately 24 months apart. Lot quality assurance sampling (LQAS) formed the basis of the TAS survey design but specific EU characteristics defined the survey site (school or community), eligible population (6–7 year olds or 1st–2nd graders), survey type (systematic or cluster-sampling), target sample size, and critical cutoff (a statistically powered threshold below which transmission is expected to be no longer sustainable). The primary diagnostic tools were the immunochromatographic (ICT) test for W. bancrofti EUs and the BmR1 test (Brugia Rapid or PanLF) for Brugia spp. EUs. Principal Findings/Conclusions In 10 of 11 EUs, the number of TAS-1 positive cases was below the critical cutoff, indicating that MDA could be stopped. The same results were found in the follow-up TAS-2, therefore, confirming the previous decision outcome. Sample sizes were highly sex and age-representative and closely matched the target value after factoring in estimates of non-participation. The TAS was determined to be a practical and effective evaluation tool for stopping MDA although its validity for longer-term post-MDA surveillance requires further investigation. Lymphatic filariasis (LF) is targeted for global elimination through a strategy of repeated annual mass drug administration (MDA) to entire at-risk populations. A transmission assessment survey (TAS) is designed to evaluate whether transmission of LF is presumed to have reached a level low enough that it cannot be sustained in the absence of drug intervention and, therefore, MDA can be stopped. This multicenter operational research trial examines the value and practicality of the TAS guidelines through its implementation in 11 countries of diverse geographical and epidemiologic profiles. The field experiences support the TAS survey design methodology with particular respect to school and cluster-based sampling strategies. We found that sample sizes were age and sex representative and met the target values after factoring in estimates of non-participation rates. In 10 of 11 countries, the TAS found the number of positive cases in the evaluation unit to be no more than the statistically powered critical threshold. These results were corroborated in a follow-up TAS approximately 24 months later. We conclude the TAS is a valuable and effective tool for stopping MDA but its utility for longer-term post-MDA surveillance needs further empirical evidence and may be best supported with complementary tools and methods.
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75
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Bruyère F, Desoubeaux G, Malavaud S, Fourcade C, Chandenier J, Lachaud L, Guy L, Karsenty G, Bastide C, Lavigne JP, Sotto A. [Non-antibiotic anti-infectious treatments in urology]. Prog Urol 2013; 23:1342-56. [PMID: 24183092 DOI: 10.1016/j.purol.2013.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 09/05/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To define the terms of use of pesticides, antifungal, antiviral and antiseptic treatments in urology. MATERIALS AND METHODS A literature search was conducted on MEDLINE for all these treatments used in urology. The molecules were classified by family. Modes of action, indications in urology and adverse effects have been detailed. Authorisation files were consulted and then complemented by a literature analysis. RESULTS Although parasitic or viral diseases are uncommon in urology, their specific treatment deserves a thorough knowledge of pesticide and antiviral molecules. Antifungal treatments are regularly used in urology with special features to know to improve the efficacy/safety ratio. Antiseptics are used daily in urology and a better understanding of these molecules allows better use. CONCLUSION Beyond antibiotics, antiviral, antiparasitic and antifungal deserve a thorough knowledge. Antiseptic although used daily have features little known.
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Affiliation(s)
- F Bruyère
- Service d'urologie, CHRU Bretonneau, 2, boulevard Tonnellé, 37044 Tours cedex, France; Université François-Rabelais de Tours, PRES Centre Val-de-Loire université, 37000 Tours, France.
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76
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Surveillance and vector control of lymphatic filariasis in the republic of Korea. Osong Public Health Res Perspect 2013; 3:145-50. [PMID: 24159506 PMCID: PMC3738707 DOI: 10.1016/j.phrp.2012.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 07/19/2012] [Accepted: 07/19/2012] [Indexed: 11/30/2022] Open
Abstract
Objectives Until the early 2000s, lymphatic filariasis would commonly break out in the coastal areas in Korea. Through steady efforts combining investigation and treatment, filariasis was officially declared eradicated in 2008. This study surveyed the density of vector species of filariasis in past endemic areas, and inspected filariasis DNA from collected mosquitoes for protection against the reemergence of filariasis. Methods Between May and October 2009, mosquitoes were caught using the black night trap in past endemic coastal areas: Gyeongsangnam-do, Jeollanamdo, and Jeju-do. The collected mosquitoes were identified, and the extracted DNA from the collected vector mosquitoes was tested by polymerase chain reaction for Brugia malayi filariasis. Results Ochletotatus togoi, Anophel es (Hyrcanus) group and Culex pipiens were most frequently caught in Jeollanam-do (Geomun Island, Bogil Island, Heuksan Island), Jeju-do (Namone-ri, Wimi-ri). and Gyeongsangnam-do (Maemul Island). DNA of B malayi was not found in Och Togoi and An (Hyrcanus) group as main vectors of filariasis. Conclusion Lymphatic filariasis was not found in the vector mosquitoes collected in past endemic areas. However, considering that the proportion of vector species is quite high, there is a potential risk that filariasis could be reemerging through overseas travel or trade. Thus, there is a need to continuously monitor vector mosquitoes of lymphatic filariasis.
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Simonsen PE, Magesa SM, Derua YA, Rwegoshora RT, Malecela MN, Pedersen EM. Monitoring lymphatic filariasis control in Tanzania: effect of repeated mass drug administration on circulating filarial antigen prevalence in young schoolchildren. Int Health 2013; 3:182-7. [PMID: 24038368 DOI: 10.1016/j.inhe.2011.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
In most countries of Sub-Saharan Africa the control of lymphatic filariasis (LF) is based on annual mass drug administration (MDA) with a combination of ivermectin and albendazole, in order to interrupt transmission. We monitored the effect of four repeated MDAs with this combination, as implemented by the Tanzanian National Lymphatic Filariasis Elimination Programme (NLFEP), on the circulating filarial antigen (CFA) status of young schoolchildren. A new batch of Standard 1 pupils from 10 rural primary schools in Tanga Municipality were examined for CFA each year in September/October (691-848 children per survey; mean age of 7.5-8.1 years), from immediately before the first MDA until eight months after the fourth MDA. The overall pre-MDA prevalence of CFA was 25.2%. Only minor and non-significant change in prevalence was seen after the first two MDAs. However, this was followed by substantial and statistically significant decreases in subsequent surveys, and eight months after the fourth MDA the prevalence was only 6.4%. Continuous entomological surveillance in a village accommodating one of the schools showed progressive decrease in transmission right from the first MDA. The usefulness of screening young schoolchildren for CFA as a tool for monitoring the impact of MDA on LF transmission is discussed.
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Affiliation(s)
- Paul E Simonsen
- DBL - Centre for Health Research and Development, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 57, 1871 Frederiksberg C, Denmark
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78
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Hodges ME, Koroma JB, Sonnie M, Kennedy N, Cotter E, Macarthur C. Neglected tropical disease control in post-war Sierra Leone using the Onchocerciasis Control Programme as a platform. Int Health 2013; 3:69-74. [PMID: 24038179 DOI: 10.1016/j.inhe.2011.03.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Strategic investments in the control of neglected tropical diseases (NTD) spearheaded by the US Government, the British Government and other bilateral donors such as foundations and key pharmaceutical partners have enabled the treatment of millions of people for the five targeted debilitating diseases (lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiasis and trachoma), paving the way for the potential elimination as public health problems of some of these diseases. Like many other countries, Sierra Leone has a high burden of these major NTDs. Despite the fragile infrastructure of a health system emerging from a devastating 10-year civil war, the country has successfully implemented the National NTD Control Programme, reaching national coverage in 2010. The NTD Control Programme uses the existing Onchocerciasis Control Programme as a platform and involves primary health workers. The programme has provided extensive training opportunities to health workers at national, district and community levels. The country currently has 31 161 trained community volunteers treating a population of five million people. It is shown that the investments in NTD control are not only to control NTDs but also to strengthen health systems, particularly at the primary level, through extensive capacity building of frontline health workers and community-directed distributors.
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Affiliation(s)
- Mary E Hodges
- Helen Keller International, 35 Nelson Lane, Tengbeh Town, Freetown, Sierra Leone
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Richards FO, Emukah E, Graves PM, Nkwocha O, Nwankwo L, Rakers L, Mosher A, Patterson A, Ozaki M, Nwoke BEB, Ukaga CN, Njoku C, Nwodu K, Obasi A, Miri ES. Community-wide distribution of long-lasting insecticidal nets can halt transmission of lymphatic filariasis in southeastern Nigeria. Am J Trop Med Hyg 2013; 89:578-87. [PMID: 23939708 PMCID: PMC3771303 DOI: 10.4269/ajtmh.12-0775] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 05/17/2013] [Indexed: 11/07/2022] Open
Abstract
Lymphatic filariasis (LF) in rural southeastern Nigeria is transmitted mainly by Anopheles spp. mosquitoes. Potential coinfection with Loa loa in this area has prevented use of ivermectin in the mass drug administration (MDA) strategy for LF elimination because of potential severe adverse L. loa-related reactions. This study determined if long-lasting insecticidal net (LLIN) distribution programs for malaria would interrupt LF transmission in such areas, without need for MDA. Monthly entomologic monitoring was conducted in sentinel villages before and after LLIN distribution to all households and all age groups (full coverage) in two districts, and to pregnant women and children less than five years of age in the other two districts. No change in human LF microfilaremia prevalence was observed, but mosquito studies showed a statistically significant decrease in LF infection and infectivity with full-coverage LLIN distribution. We conclude that LF transmission can be halted in southeastern Nigeria by full-coverage LLIN distribution, without MDA.
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Affiliation(s)
- Frank O Richards
- Malaria, River Blindness, Lymphatic Filariasis, and Schistosomiasis Programs, The Carter Center, 453 Freedom Parkway, Atlanta, GA 30307, USA.
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Mapping, bayesian geostatistical analysis and spatial prediction of lymphatic filariasis prevalence in Africa. PLoS One 2013; 8:e71574. [PMID: 23951194 PMCID: PMC3741112 DOI: 10.1371/journal.pone.0071574] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 07/07/2013] [Indexed: 11/30/2022] Open
Abstract
There is increasing interest to control or eradicate the major neglected tropical diseases. Accurate modelling of the geographic distributions of parasitic infections will be crucial to this endeavour. We used 664 community level infection prevalence data collated from the published literature in conjunction with eight environmental variables, altitude and population density, and a multivariate Bayesian generalized linear spatial model that allows explicit accounting for spatial autocorrelation and incorporation of uncertainty in input data and model parameters, to construct the first spatially-explicit map describing LF prevalence distribution in Africa. We also ran the best-fit model against predictions made by the HADCM3 and CCCMA climate models for 2050 to predict the likely distributions of LF under future climate and population changes. We show that LF prevalence is strongly influenced by spatial autocorrelation between locations but is only weakly associated with environmental covariates. Infection prevalence, however, is found to be related to variations in population density. All associations with key environmental/demographic variables appear to be complex and non-linear. LF prevalence is predicted to be highly heterogenous across Africa, with high prevalences (>20%) estimated to occur primarily along coastal West and East Africa, and lowest prevalences predicted for the central part of the continent. Error maps, however, indicate a need for further surveys to overcome problems with data scarcity in the latter and other regions. Analysis of future changes in prevalence indicates that population growth rather than climate change per se will represent the dominant factor in the predicted increase/decrease and spread of LF on the continent. We indicate that these results could play an important role in aiding the development of strategies that are best able to achieve the goals of parasite elimination locally and globally in a manner that may also account for the effects of future climate change on parasitic infection.
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81
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Small ST, Ramesh A, Bun K, Reimer L, Thomsen E, Baea M, Bockarie MJ, Siba P, Kazura JW, Tisch DJ, Zimmerman PA. Population genetics of the filarial worm wuchereria bancrofti in a post-treatment region of Papua New Guinea: insights into diversity and life history. PLoS Negl Trop Dis 2013; 7:e2308. [PMID: 23875043 PMCID: PMC3708868 DOI: 10.1371/journal.pntd.0002308] [Citation(s) in RCA: 11] [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: 02/11/2013] [Accepted: 05/30/2013] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Wuchereria bancrofti (Wb) is the primary causative agent of lymphatic filariasis (LF). Our studies of LF in Papua New Guinea (PNG) have shown that it is possible to reduce the prevalence of Wb in humans and mosquitoes through mass drug administration (MDA; diethylcarbamazine with/without ivermectin). While MDAs in the Dreikikir region through 1998 significantly reduced prevalence of Wb infection, parasites continue to be transmitted in the area. METHODS We sequenced the Wb mitochondrial Cytochrome Oxidase 1 (CO1) gene from 16 people infected with Wb. Patients were selected from 7 villages encompassing both high and moderate annual transmission potentials (ATP). We collected genetic data with the objectives to (i) document contemporary levels of genetic diversity and (ii) distinguish between populations of parasites and hosts across the study area. PRINCIPLE FINDINGS We discovered 109 unique haplotypes currently segregating in the Wb parasite population, with one common haplotype present in 15 out of 16 infections. We found that parasite diversity was similar among people residing within the same village and clustered within transmission zones. For example, in the high transmission area, diversity tended to be more similar between neighboring villages, while in the moderate transmission area, diversity tended to be less similar. CONCLUSIONS In the Dreikikir region of PNG there are currently high levels of genetic diversity in populations of Wb. High levels of genetic diversity may complicate future MDAs in this region and the presence of dominant haplotypes will require adjustments to current elimination strategies.
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Affiliation(s)
- Scott T. Small
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Akshaya Ramesh
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Krufinta Bun
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Lisa Reimer
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Edward Thomsen
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Manasseh Baea
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Moses J. Bockarie
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Peter Siba
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - James W. Kazura
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Daniel J. Tisch
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Peter A. Zimmerman
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
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Singh BK, Bockarie MJ, Gambhir M, Siba PM, Tisch DJ, Kazura J, Michael E. Sequential modelling of the effects of mass drug treatments on anopheline-mediated lymphatic filariasis infection in Papua New Guinea. PLoS One 2013; 8:e67004. [PMID: 23826185 PMCID: PMC3691263 DOI: 10.1371/journal.pone.0067004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 05/16/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Lymphatic filariasis (LF) has been targeted by the WHO for global eradication leading to the implementation of large scale intervention programs based on annual mass drug administrations (MDA) worldwide. Recent work has indicated that locality-specific bio-ecological complexities affecting parasite transmission may complicate the prediction of LF extinction endpoints, casting uncertainty on the achievement of this initiative. One source of difficulty is the limited quantity and quality of data used to parameterize models of parasite transmission, implying the important need to update initially-derived parameter values. Sequential analysis of longitudinal data following annual MDAs will also be important to gaining new understanding of the persistence dynamics of LF. Here, we apply a Bayesian statistical-dynamical modelling framework that enables assimilation of information in human infection data recorded from communities in Papua New Guinea that underwent annual MDAs, into our previously developed model of parasite transmission, in order to examine these questions in LF ecology and control. RESULTS Biological parameters underlying transmission obtained by fitting the model to longitudinal data remained stable throughout the study period. This enabled us to reliably reconstruct the observed baseline data in each community. Endpoint estimates also showed little variation. However, the updating procedure showed a shift towards higher and less variable values for worm kill but not for any other drug-related parameters. An intriguing finding is that the stability in key biological parameters could be disrupted by a significant reduction in the vector biting rate prevailing in a locality. CONCLUSIONS Temporal invariance of biological parameters in the face of intervention perturbations indicates a robust adaptation of LF transmission to local ecological conditions. The results imply that understanding the mechanisms that underlie locally adapted transmission dynamics will be integral to identifying points of system fragility, and thus countermeasures to reliably facilitate LF extinction both locally and globally.
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Affiliation(s)
- Brajendra K Singh
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America.
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Zeldenryk L, Gray M, Gordon S, Speare R, Hossain M. The use of focus groups to develop a culturally relevant quality of life tool for lymphatic filariasis in Bangladesh. Qual Life Res 2013; 23:299-309. [PMID: 23793443 PMCID: PMC3929034 DOI: 10.1007/s11136-013-0455-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2013] [Indexed: 11/01/2022]
Abstract
PURPOSE The purpose of this study was to conduct focus groups to operationalise the construct of quality of life (QOL) for people living with lymphatic filariasis (LF) in Bangladesh to develop culturally valid items for a Bangladeshi LF QOL tool. METHODS Ten focus groups were conducted with a stratified purposeful sample (n = 60) of LF patients (3 focus groups, n = 17), doctors (1 focus group, n = 5), nurses (1 focus group, n = 6) and other hospital staff (1 focus group, n = 5), community leaders (2 focus groups, n = 14), community volunteer health workers (1 focus group, n = 5) and Bangladeshi LF researchers and planners (1 focus group, n = 8). Focus group methodology was informed by local culture in consultation with cultural mentors and local advisors, often going against standard focus group procedures. Data were collected through note taking, audio taping, transcripts, observational notes and a reflection diary. Open coding of transcript data was completed until data saturation was achieved. RESULTS Forty-three constructs were identified through the focus groups that had not previously been identified in the literature, including constructs relating to environmental supports and barriers, activities, participation and psychological impacts. There were marked differences between the impacts reported by different groups, highlighting the need for a comprehensive purposive sample. In particular, contributions from participants who would not traditionally be viewed as "experts" were vital. CONCLUSIONS The use of focus groups strongly contributed to the operationalisation of the concept of QOL in Bangladesh for people living with LF. Use of literature review or expert opinion alone would have missed vital constructs.
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Affiliation(s)
- Lynne Zeldenryk
- Occupational Therapy, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Douglas, QLD, 4811, Australia,
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Abd Elaziz KM, El-Setouhy M, Bradley MH, Ramzy RMR, Weil GJ. Knowledge and practice related to compliance with mass drug administration during the Egyptian national filariasis elimination program. Am J Trop Med Hyg 2013; 89:260-4. [PMID: 23751402 DOI: 10.4269/ajtmh.12-0491] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Lymphatic filariasis (LF) has been targeted for global elimination by 2020. The primary tool for the program is mass drug administration (MDA) with antifilarial medications to reduce the source of microfilariae required for mosquito transmission of the parasite. This strategy requires high MDA compliance rates. Egypt initiated a national filariasis elimination program in 2000 that targeted approximately 2.7 million persons in 181 disease-endemic localities. This study assessed factors associated with MDA compliance in year three of the Egyptian LF elimination program. 2,859 subjects were interviewed in six villages. The surveyed compliance rate for MDA in these villages was 85.3% (95% confidence interval = 83.9-86.5%). Compliance with MDA was positively associated with LF knowledge scores, male sex, and older age. Adverse events reported by 18.4% of participants were mild and more common in females. This study has provided new information on factors associated with MDA compliance during Egypt's successful LF elimination program.
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Affiliation(s)
- Khaled M Abd Elaziz
- Department of Community, Environmental, and Occupational Medicine, Faculty of Medicine, and Research and Training Center on Vector of Diseases Ain Shams University, Cairo, Egypt.
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85
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Prichard RK. Ivermectin resistance and overview of the Consortium for Anthelmintic Resistance SNPs. Expert Opin Drug Discov 2013; 2:S41-52. [PMID: 23489032 DOI: 10.1517/17460441.2.s1.s41] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Ivermectin (IVM) has transformed nematode parasite control in veterinary medicine and the control of some nematode infections in humans, such as onchocerciasais, lymphatic filariasis in Africa and strongyloidiasis. Unfortunately, IVM resistance is now a serious problem for parasite control in livestock and there is a concern about resistance development and spread in nematode parasites of humans. IVM is believed to act by opening glutamate-gated chloride channels and GABA-gated channels in invertebrate neurons or muscle cells, leading to hyperpolarisation of the cells and to an inhibitory paralysis. However, in the filarial nematodes, it is not altogether clear that the effect of IVM is confined to these actions or even whether these are the most important. Alterations in some ligand-gated ion channel (LGIC) receptor subunits may play a role in the mechanisms of IVM resistance in some nematodes, but the evidence that changes in LGICs are the most important cause of IVM resistance in nematodes is far from clear. What is evident is that IVM is an excellent substrate for some ATP-binding cassette transporters, IVM selects for changes in expression levels of ABC transporters, such as P-glycoproteins, and that altered levels of some ABC transporters contribute to IVM resistance. In addition, there is growing evidence that IVM selects on β-tubulin, at least in some nematodes. Based on these various mechanisms, which contribute to IVM resistance, it may become possible to develop panels of molecular markers for IVM resistance in different nematode parasites. In order to stimulate the development of such markers, an international Consortium for Anthelmintic Resistance SNPs (CARS) has been developed to help coordinate marker development, advance our knowledge of helminth biology and possibly assist with the development of new anthelmintic molecules.
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Affiliation(s)
- Roger K Prichard
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC, H9X3V9, Canada 1 514 398 7729 ; +1 514 398 7594 ;
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Reiner RC, Perkins TA, Barker CM, Niu T, Chaves LF, Ellis AM, George DB, Le Menach A, Pulliam JRC, Bisanzio D, Buckee C, Chiyaka C, Cummings DAT, Garcia AJ, Gatton ML, Gething PW, Hartley DM, Johnston G, Klein EY, Michael E, Lindsay SW, Lloyd AL, Pigott DM, Reisen WK, Ruktanonchai N, Singh BK, Tatem AJ, Kitron U, Hay SI, Scott TW, Smith DL. A systematic review of mathematical models of mosquito-borne pathogen transmission: 1970-2010. J R Soc Interface 2013; 10:20120921. [PMID: 23407571 PMCID: PMC3627099 DOI: 10.1098/rsif.2012.0921] [Citation(s) in RCA: 242] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Mathematical models of mosquito-borne pathogen transmission originated in the early twentieth century to provide insights into how to most effectively combat malaria. The foundations of the Ross–Macdonald theory were established by 1970. Since then, there has been a growing interest in reducing the public health burden of mosquito-borne pathogens and an expanding use of models to guide their control. To assess how theory has changed to confront evolving public health challenges, we compiled a bibliography of 325 publications from 1970 through 2010 that included at least one mathematical model of mosquito-borne pathogen transmission and then used a 79-part questionnaire to classify each of 388 associated models according to its biological assumptions. As a composite measure to interpret the multidimensional results of our survey, we assigned a numerical value to each model that measured its similarity to 15 core assumptions of the Ross–Macdonald model. Although the analysis illustrated a growing acknowledgement of geographical, ecological and epidemiological complexities in modelling transmission, most models during the past 40 years closely resemble the Ross–Macdonald model. Modern theory would benefit from an expansion around the concepts of heterogeneous mosquito biting, poorly mixed mosquito-host encounters, spatial heterogeneity and temporal variation in the transmission process.
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Affiliation(s)
- Robert C Reiner
- Fogarty International Center, National Institutes of Health, Bethesda, MD, USA.
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Waterborne Infectious Diseases, Approaches to Control. Infect Dis (Lond) 2013. [DOI: 10.1007/978-1-4614-5719-0_14] [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: 10/27/2022] Open
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Diagnosis of brugian filariasis by loop-mediated isothermal amplification. PLoS Negl Trop Dis 2012; 6:e1948. [PMID: 23272258 PMCID: PMC3521703 DOI: 10.1371/journal.pntd.0001948] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/25/2012] [Indexed: 11/19/2022] Open
Abstract
In this study we developed and evaluated a Brugia Hha I repeat loop-mediated isothermal amplification (LAMP) assay for the rapid detection of Brugia genomic DNA. Amplification was detected using turbidity or fluorescence as readouts. Reactions generated a turbidity threshold value or a clear visual positive within 30 minutes using purified genomic DNA equivalent to one microfilaria. Similar results were obtained using DNA isolated from blood samples containing B. malayi microfilariae. Amplification was specific to B. malayi and B. timori, as no turbidity was observed using DNA from the related filarial parasites Wuchereria bancrofti, Onchocerca volvulus or Dirofilaria immitis, or from human or mosquito. Furthermore, the assay was most robust using a new strand-displacing DNA polymerase termed Bst 2.0 compared to wild-type Bst DNA polymerase, large fragment. The results indicate that the Brugia Hha I repeat LAMP assay is rapid, sensitive and Brugia-specific with the potential to be developed further as a field tool for diagnosis and mapping of brugian filariasis. Brugian filariasis is a debilitating neglected tropical disease caused by infection with the filarial parasites Brugia malayi or Brugia timori. Adult worms live in the lymphatic system and produce large numbers of microfilariae that predominantly circulate in the blood at night. Bloodsucking mosquitoes spread the disease by ingesting microfilariae that develop into infective stage larvae in the insect. In rural areas, diagnosis still relies largely on microscopic examination of night blood and morphological assessment of stained microfilariae. Loop-mediated isothermal amplification (LAMP) is a technique that can amplify DNA with high specificity, sensitivity and rapidity under isothermal conditions. The operational simplicity, versatility and low-cost of the technique make it particularly appealing for use in diagnosis and geographical mapping of neglected tropical diseases. In the present study, we have developed and evaluated a Brugia Hha I repeat LAMP assay for the rapid detection of B. malayi and B. timori genomic DNA. The results indicate that the Brugia Hha I repeat LAMP diagnostic assay is sensitive and rapid, detecting a single microfilariae in blood within 30 minutes, and Brugia-specific. The test has the potential to be developed further as a field tool for use in the implementation and management of mass drug administration programs for brugian filariasis.
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Kubofcik J, Fink DL, Nutman TB. Identification of Wb123 as an early and specific marker of Wuchereria bancrofti infection. PLoS Negl Trop Dis 2012; 6:e1930. [PMID: 23236529 PMCID: PMC3516582 DOI: 10.1371/journal.pntd.0001930] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 10/16/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The current antibody tests used for monitoring in lymphatic filariasis (LF) elimination programs suffer from poor specificity because of the considerable geographical overlap with other filarial infections such as Loa loa (Ll), Onchocerca volvulus (Ov), and Mansonella perstans (Mp). METHODS Using bioinformatics to assemble into contigs 2048 expressed sequence tags (ESTs) from the L3 infective larvae of W. bancrofti (Wb), these were next assessed for homology to known proteins and nucleotides and to similar assemblies of L3 larval ESTs of B. malayi (Bm - n = 5068), Ov (n = 4166), and Ll (n = 3315). Nineteen potential L3- and Wb- and/or Bm-specific antigens were identified. Sixteen of the 19 antigens could be expressed as fusion proteins with Renilla luciferase (Ruc); these were used in a rapid Luciferase Immunopreciptation System (LIPS) assay. RESULTS One of the 16 expressed antigens (Wb123) was both highly immunogenic and specific for Wb. Using Wb123-based IgG and IgG4 LIPS assays on well-defined sera from normal North Americans and those infected exclusively with intestinal helminths, we could detect all of the Wb-infected individuals (from diverse geographic regions) with 100% sensitivity and 100% specificity. Using sera from exclusively Ll-infected, Ov-infected Mp-infected or Bm-infected subjects as the negative comparator, the sensitivities were between 98-100% and the specificities ranged between 84-100% (for IgG anti-Wb123) and between 98-100% (for IgG4 anti-Wb123). Blinded assessments using panels of sera from various Wb-, Bm- or non-Wb helminth-infected subjects demonstrated equally high degrees of sensitivity and specificity. SIGNIFICANCE We have identified a Wb-encoded antigen that can be used both as a rapid, high throughput tool to diagnose individual Wb infections and as a sensitive method for early detection of recrudescent infections in areas of control and for mapping new areas of Wb transmission.
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Affiliation(s)
- Joseph Kubofcik
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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90
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Antibody to the filarial antigen Wb123 reflects reduced transmission and decreased exposure in children born following single mass drug administration (MDA). PLoS Negl Trop Dis 2012; 6:e1940. [PMID: 23236533 PMCID: PMC3516579 DOI: 10.1371/journal.pntd.0001940] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 10/23/2012] [Indexed: 11/19/2022] Open
Abstract
Background Antibody (Ab) to the Wuchereria bancrofti (Wb) infective larval (L3) antigen Wb123, using a Luciferase Immunoprecipitation System (LIPS) assay, has been shown to be a species-specific, early marker of infection developed for potential use as a surveillance tool following transmission interruption post mass drug administration. To examine its usefulness in a single filarial-endemic island assessed at two time points with markedly different levels of transmission, Ab to Wb123 was measured in sera collected from subjects from Mauke, Cook Islands in 1975 (no previous treatment) and 1992 (5 years after a one time island-wide treatment with diethylcarbamazine [DEC]). Findings Between 1975 and 1992, Wb transmission decreased dramatically as evidenced by reduced prevalences of microfilariae (31% vs. 5%) and circulating Ag (CAg, 49% vs. 16%). Age specific prevalence analysis showed a dramatic reduction in Wb123 Ab positivity from 54% (25/46) in 1975 to 8% (3/38) in 1992 in children 1–5 years (p<0.0001), reflecting the effects of single-dose treatment five years earlier. By 1992, Wb123 Ab prevalence in children 6–10 years had fallen from 75% (42/56) in 1975 to 42% (33/79) consistent with a lower cumulative transmission potential. In the whole population, Wb123 seropositivity decreased from 86% to 60% between 1975 and 1992. In CAg+ subjects the levels of Wb123 Ab were indistinguishable between the 2 time points but differed in those who were CAg− (p<0.0001). In paired sample analysis, individuals who were CAg+ in 1975 but became CAg− in 1992 had significantly lower Ab levels in 1992 (p<0.0001), with 9/40 (23%) becoming seronegative for Wb123. Conclusions The relationship between reduction in Wb123 Ab prevalence and the reduction of transmission, seen most clearly in young children, strongly advocates for the continuing assessment and rapid development of Wb123 as a surveillance tool to detect potential transmission of bancroftian filariasis in treated endemic areas. Lymphatic filariasis (LF) causes an enormous disease burden throughout the tropics and subtropics. The Global Programme to Eliminate Lymphatic Filariasis was begun in 2000 following the advent of large donations from drug companies for treating LF and the development of a rapid antigen assay for detection of infection. As more countries undergo mass drug administration (MDA), the driving need is for development of a highly sensitive and specific antibody assay for detecting ongoing exposure to vector-borne filaria following MDA. The target group for such surveillance is children born during or following MDA. Current assays, while sensitive, are not specific enough where non-LF filaria species are co-endemic. Recently, we developed an antibody assay based upon the highly specific larval antigen Wb123 using the Luciferase Immunoprecipitation System (LIPS). In the current study, we determined that the Wb123 LIPS assay detects a reduction in LF transmission on an endemic island following a one-time island wide MDA with diethylcarbamazine, with the most pronounced reduction in prevalence of antibody to Wb123 occurring in young children born just prior to and following this MDA. We propose that Wb123 can be an extremely useful surveillance tool following MDA and should be developed into a rapid test format.
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91
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de Souza DK, Koudou B, Kelly-Hope LA, Wilson MD, Bockarie MJ, Boakye DA. Diversity and transmission competence in lymphatic filariasis vectors in West Africa, and the implications for accelerated elimination of Anopheles-transmitted filariasis. Parasit Vectors 2012; 5:259. [PMID: 23151383 PMCID: PMC3533928 DOI: 10.1186/1756-3305-5-259] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 11/04/2012] [Indexed: 11/10/2022] Open
Abstract
Lymphatic Filariasis (LF) is targeted for elimination by the Global Programme for the Elimination of Lymphatic Filariasis (GPELF). The strategy adopted is based on the density dependent phenomenon of Facilitation, which hypothesizes that in an area where the vector species transmitting Wuchereria bancrofti are Anopheles mosquitoes, it is feasible to eliminate LF using Mass Drug Administration (MDA) because of the inability of Anopheles species to transmit low-density microfilaraemia. Even though earlier studies have shown Anopheles species can exhibit the process of Facilitation in West Africa, observations point towards the process of Limitation in certain areas, in which case vector control is recommended. Studies on Anopheles species in West Africa have also shown genetic differentiation, cryptic taxa and speciation, insecticide resistance and the existence of molecular and chromosomal forms, all of which could influence the vectorial capacity of the mosquitoes and ultimately the elimination goal. This paper outlines the uniqueness of LF vectors in West Africa and the challenges it poses to the 2020 elimination goal, based on the current MDA strategies.
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Affiliation(s)
- Dziedzom K de Souza
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon-Accra, Ghana
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Scott AL, Ghedin E, Nutman TB, McReynolds LA, Poole CB, Slatko BE, Foster JM. Filarial and Wolbachia genomics. Parasite Immunol 2012; 34:121-9. [PMID: 22098559 DOI: 10.1111/j.1365-3024.2011.01344.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Filarial nematode parasites, the causative agents for a spectrum of acute and chronic diseases including lymphatic filariasis and river blindness, threaten the well-being and livelihood of hundreds of millions of people in the developing regions of the world. The 2007 publication on a draft assembly of the 95-Mb genome of the human filarial parasite Brugia malayi- representing the first helminth parasite genome to be sequenced - has been followed in rapid succession by projects that have resulted in the genome sequencing of six additional filarial species, seven nonfilarial nematode parasites of animals and nearly 30 plant parasitic and free-living species. Parallel to the genomic sequencing, transcriptomic and proteomic projects have facilitated genome annotation, expanded our understanding of stage-associated gene expression and provided a first look at the role of epigenetic regulation of filarial genomes through microRNAs. The expansion in filarial genomics will also provide a significant enrichment in our knowledge of the diversity and variability in the genomes of the endosymbiotic bacterium Wolbachia leading to a better understanding of the genetic principles that govern filarial-Wolbachia mutualism. The goal here is to provide an overview of the trends and advances in filarial and Wolbachia genomics.
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Affiliation(s)
- A L Scott
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MA 21205, USA.
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Knopp S, Steinmann P, Hatz C, Keiser J, Utzinger J. Nematode Infections:. Infect Dis Clin North Am 2012; 26:359-81. [DOI: 10.1016/j.idc.2012.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Arndts K, Deininger S, Specht S, Klarmann U, Mand S, Adjobimey T, Debrah AY, Batsa L, Kwarteng A, Epp C, Taylor M, Adjei O, Layland LE, Hoerauf A. Elevated adaptive immune responses are associated with latent infections of Wuchereria bancrofti. PLoS Negl Trop Dis 2012; 6:e1611. [PMID: 22509424 PMCID: PMC3317915 DOI: 10.1371/journal.pntd.0001611] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Accepted: 02/28/2012] [Indexed: 12/24/2022] Open
Abstract
In order to guarantee the fulfillment of their complex lifecycle, adult filarial nematodes release millions of microfilariae (MF), which are taken up by mosquito vectors. The current strategy to eliminate lymphatic filariasis as a public health problem focuses upon interrupting this transmission through annual mass drug administration (MDA). It remains unclear however, how many rounds of MDA are required to achieve low enough levels of MF to cease transmission. Interestingly, with the development of further diagnostic tools a relatively neglected cohort of asymptomatic (non-lymphedema) amicrofilaremic (latent) individuals has become apparent. Indeed, epidemiological studies have suggested that there are equal numbers of patent (MF+) and latent individuals. Since the latter represent a roadblock for transmission, we studied differences in immune responses of infected asymptomatic male individuals (n = 159) presenting either patent (n = 92 MF+) or latent (n = 67 MF−) manifestations of Wuchereria bancrofti. These individuals were selected on the basis of MF, circulating filarial antigen in plasma and detectable worm nests. Immunological profiles of either Th1/Th17, Th2, regulatory or innate responses were determined after stimulation of freshly isolated PBMCs with either filarial-specific extract or bystander stimuli. In addition, levels of total and filarial-specific antibodies, both IgG subclasses and IgE, were ascertained from plasma. Results from these individuals were compared with those from 22 healthy volunteers from the same endemic area. Interestingly, we observed that in contrast to MF+ patients, latent infected individuals had lower numbers of worm nests and increased adaptive immune responses including antigen-specific IL-5. These data highlight the immunosuppressive status of MF+ individuals, regardless of age or clinical hydrocele and reveal immunological profiles associated with latency and immune-mediated suppression of parasite transmission. The tropical helminth infection lymphatic filariasis affects more than 120 million people worldwide and is considered a major public health concern. Over 90% of infections are elicited by Wucheria bancrofti and adult worms reside in the lymphatic system releasing millions of microfilariae (MF), which periodically circulate in the blood. New diagnostic tools have provided a method to determine asymptomatic patients that are amicrofilaremic: a subset of individuals that have so far been neglected but are of special interest since these patients represent a dead end in terms of parasite transmission. Therefore, we were interested in determining whether the absence of MF was associated with distinct immunological profiles and observed that indeed responses in MF+ patients were dampened. From the viewpoint of the helminth such overall suppression of immune responses may facilitate MF transmission. Latent individuals however, presented elevated filarial specific responses and extrapolating these findings to the host provides novel insight into possible protective mechanisms which either actively hinders the release of MF from worms or their travel to the periphery. Further research into these aspects may broaden the range of strategies currently employed to reduce transmission and in turn eliminate bancroftian filariasis.
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Affiliation(s)
- Kathrin Arndts
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Susanne Deininger
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Sabine Specht
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Ute Klarmann
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- Institute of Medical Biometry, Informatics and Epidemiology, University Hospital Bonn, Bonn, Germany
| | - Sabine Mand
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Tomabu Adjobimey
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Alexander Y. Debrah
- Kumasi Centre for Collaborative Research in Tropical Medicine, Kumasi, Ghana
- Faculty of Allied Health Sciences, Department of Theoretical and Applied Biology, and School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Linda Batsa
- Kumasi Centre for Collaborative Research in Tropical Medicine, Kumasi, Ghana
| | - Alexander Kwarteng
- Kumasi Centre for Collaborative Research in Tropical Medicine, Kumasi, Ghana
| | - Christian Epp
- Department für Infektiologie, Parasitologie, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Mark Taylor
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Ohene Adjei
- Kumasi Centre for Collaborative Research in Tropical Medicine, Kumasi, Ghana
- Faculty of Allied Health Sciences, Department of Theoretical and Applied Biology, and School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Laura E. Layland
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- * E-mail:
| | - Achim Hoerauf
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
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Upadhyayula SM, Mutheneni SR, Kadiri MR, Kumaraswamy S, Nagalla B. A cohort study of lymphatic filariasis on socio economic conditions in Andhra Pradesh, India. PLoS One 2012; 7:e33779. [PMID: 22442721 PMCID: PMC3307764 DOI: 10.1371/journal.pone.0033779] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 02/17/2012] [Indexed: 12/02/2022] Open
Abstract
Background To assess the impact of socioeconomic variables on lymphatic filariasis in endemic villages of Karimnagar district, Andhra Pradesh, India. Methods A pilot scale study was conducted in 30 villages of Karimnagar district from 2004 to 2007. These villages were selected based on previous reports from department of health, Government of Andhra Pradesh, epidemiology, entomology and socioeconomic survey was conducted as per protocol. Collected data were analysed statistically by Chi square test, Principal Component Analysis, Odds ratio, Bivariate, multivariate logistic regression analysis. Results Total of 5,394 blood samples collected and screened for microfilaria, out of which 199 were found to be positive (3.7%). The socioeconomic data of these respondents/participants were correlated with MF prevalence. The socioeconomic variables like educational status (Odds Ratio (OR) = 2.6, 95% Confidence Interval (CI) = 1.1–6.5), house structure (hut OR = 1.9, 95% CI = 1.2–3.1; tiled OR = 1.3, 95% CI = 0.8–2) and participation in mass drug administration program (OR = 1.8, 95% CI = 1.3–2.6) were found to be highly associated with the occurrence of filarial disease. The socioeconomic index was categorized into low (3.6%; OR-1.1, 95% CI: 0.7–1.5) medium (4.9%; OR-1.5, 95% CI = 1–2.1) and high (3.3%) in relation to percentage of filarial parasite prevalence. A significant difference was observed among these three groups while comparing the number of cases of filaria with the type of socioeconomic conditions of the respondents (P = 0.067). Conclusions From this study it is inferred that age, education of family, type of house structure and awareness about the filarial disease directly influenced the disease prevalence. Beside annual mass drug administration program, such type of analysis should be undertaken by health officials to target a few socioeconomic factors to reduce the disease burden. Health education campaigns in the endemic villages and imparting of protection measures against mosquitoes using insecticide treated bed nets would substantially reduce the disease in these villages.
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Affiliation(s)
- Suryanaryana Murty Upadhyayula
- Bioinformatics Group, Biology Division, Indian Institute of Chemical Technology (CSIR), Hyderabad, Andhra Pradesh, India.
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Koroma JB, Bangura MM, Hodges MH, Bah MS, Zhang Y, Bockarie MJ. Lymphatic filariasis mapping by immunochromatographic test cards and baseline microfilaria survey prior to mass drug administration in Sierra Leone. Parasit Vectors 2012; 5:10. [PMID: 22236419 PMCID: PMC3268710 DOI: 10.1186/1756-3305-5-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 01/11/2012] [Indexed: 12/02/2022] Open
Abstract
Background National mapping of lymphatic filariasis (LF) was conducted using Immunochromatographic tests (ICT) in 2005 to determine endemicity and geographic spread of the disease. A baseline microfilaria survey was then conducted to determine LF prevalence and microfilaria intensity. Methods In 2005 1,982 persons of 15 years and over from 14 health districts were selected and fingertip blood samples were tested with ICT cards. In 2007-8 blood samples were taken between 10 p.m. and 2 a.m. and examined for microfilaria (mf) from 9,288 persons from 16 sentinel sites representing each district and 2 additional sites for districts with populations over 500,000 (Bo and Kenema). Results The overall LF prevalence by ICT cards was 21% (males 28%, females 15%). All districts had a prevalence of Wuchereria bancrofti antigen > 1%. Distribution of LF prevalence showed a strong spatial correlation pattern with high prevalence in a large area in the northeast gradually decreasing to a relatively low prevalence in the southwest coast. High prevalence was found in the northeast, Bombali (52%), Koinadugu (46%), Tonkolili (37%) and Kono (30%). Low prevalence was found in the southwest, Bonthe (3%) and Pujehun (4%). The mf prevalence was higher in the northeast: Bombali, 6.7%, Koinadugu 5.7%, Port Loko 4.4% and Kono 2.4%. Overall there was a significant difference in mf prevalence by gender: males 2.9%, females 1.8% (p = 0.0002) and within districts in Kailahun, Kono, Port Loko, Moyamba and Koinadugu (all p < 0.05). The mf prevalence was higher in people > 20 years (2.5%) than in people ≤ 20 years (1.7%) (p = 0.043). The overall arithmetic mean mf density was 50.30 mf/ml among mf-positive individuals and 1.19 mf/ml in the population examined which varied significantly between districts. Conclusions The ICT results showed that LF was endemic nationwide and that preventive chemotherapy (PCT) was justified across the country. Both the ICT and microfilaraemia surveys found that prevalence was greater in males than females. The increase in microfilaraemia prevalence by age was evident when grouped as ≤ 20 versus > 20 years demonstrating early exposure. Baseline LF microfilaria load will be used to monitor PCT program progress.
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Affiliation(s)
- Joseph B Koroma
- National Neglected Tropical Disease Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone.
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Abstract
The World Health Organization has developed a comprehensive plan to deal with neglected tropical diseases (NTDs). Compared with a decade ago, more resources are being spent to address the problem of neglected diseases, and considerable progress has been made. However, NTDs remain neglected, deepening the global inequities in health. The current efforts do not implement a multiprong strategy and are effective in the short term, but do not generate long-term, sustainable solutions. This article discusses the current successes in providing access to medicine for treatment of a multitude of neglected diseases, and the opportunities to achieve global equality in health.
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98
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Zeldenryk LM, Gray M, Speare R, Gordon S, Melrose W. The emerging story of disability associated with lymphatic filariasis: a critical review. PLoS Negl Trop Dis 2011; 5:e1366. [PMID: 22216361 PMCID: PMC3246437 DOI: 10.1371/journal.pntd.0001366] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Globally, 40 million people live with the chronic effects of lymphatic filariasis (LF), making it the second leading cause of disability in the world. Despite this, there is limited research into the experiences of people living with the disease. This review summarises the research on the experiences of people living with LF disability. The review highlights the widespread social stigma and oppressive psychological issues that face most people living with LF-related disability. Physical manifestations of LF make daily activities and participation in community life difficult. The findings confirm the need for the Global Programme to Eliminate Lymphatic Filariasis (GPELF) to support morbidity management activities that address the complex biopsychosocial issues that people living with LF-related disability face.
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Affiliation(s)
- Lynne Michelle Zeldenryk
- School of Public Health Tropical Medicine and Rehabilitation Sciences, James Cook University, Australia.
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99
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Joseph H, Maiava F, Naseri T, Silva U, Lammie P, Melrose W. Epidemiological assessment of continuing transmission of lymphatic filariasis in Samoa. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2011; 105:567-78. [PMID: 22325816 PMCID: PMC4089807 DOI: 10.1179/2047773211y.0000000008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 09/11/2011] [Accepted: 11/02/2011] [Indexed: 12/28/2022]
Abstract
Ongoing transmission of lymphatic filariasis (LF) was assessed in five Samoan villages by measuring microfilaraemia (Mf), circulating filarial antigen (CFA) and antibody prevalence. Compared to the other villages, Fasitoo-Tai had a significantly higher Mf prevalence (3·2%), CFA prevalence (14·6%) and antibody prevalence in children (62·0%) (P<0·05). Puapua had a significantly lower CFA prevalence (2·5%), no detectable Mf-positive individuals and significantly low antibody prevalence in children (7·9%) (P<0·05). Siufaga, previously believed to be LF-free, recorded >1% CFA prevalence and a high antibody prevalence in children (46·6%). Overall, antibody prevalence in children appeared to reflect the transmission dynamics in the villages and, in Siufaga, identified an area of ongoing transmission. The Filariasis Cellabs Enzyme-Linked Immunosorbent Assay (CELISA), based on recombinant antigen Bm14, to detect antibodies, could potentially be a promising diagnostic tool for inclusion in future surveillance in the South Pacific.
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Affiliation(s)
- H Joseph
- James Cook University, Townsville, QLD 4811, Australia.
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100
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Preventive chemotherapy in human helminthiasis: theoretical and operational aspects. Trans R Soc Trop Med Hyg 2011; 105:683-93. [PMID: 22040463 DOI: 10.1016/j.trstmh.2011.08.013] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 04/29/2011] [Accepted: 06/23/2011] [Indexed: 11/21/2022] Open
Abstract
Preventive chemotherapy (PC), the large-scale distribution of anthelminthic drugs to population groups at risk, is the core intervention recommended by the WHO for reducing morbidity and transmission of the four main helminth infections, namely lymphatic filariasis, onchocerciasis, schistosomiasis and soil-transmitted helminthiasis. The strategy is widely implemented worldwide but its general theoretical foundations have not been described so far in a comprehensive and cohesive manner. Starting from the information available on the biological and epidemiological characteristics of helminth infections, as well as from the experience generated by disease control and elimination interventions across the world, we extrapolate the fundamentals and synthesise the principles that regulate PC and justify its implementation as a sound and essential public health intervention. The outline of the theoretical aspects of PC contributes to a thorough understanding of the different facets of this strategy and helps comprehend opportunities and limits of control and elimination interventions directed against helminth infections.
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