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Ramesh A, Oliveira P, Cameron M, Castanha PMS, Walker T, Lenhart A, Impoinvil L, Alexander N, Medeiros Z, Sá A, Rocha A, Souza WV, Maciel A, Braga C. Postintervention Immunological and Entomological Survey of Lymphatic Filariasis in the City of Olinda, Brazil, 2015-2016. Am J Trop Med Hyg 2024; 110:470-482. [PMID: 38350158 PMCID: PMC10919178 DOI: 10.4269/ajtmh.23-0174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 11/05/2023] [Indexed: 02/15/2024] Open
Abstract
Lymphatic filariasis (LF) is a leading cause of disability due to infectious disease worldwide. The Recife Metropolitan Region (RMR) is the only remaining focus of LF in Brazil, where the parasite Wuchereria bancrofti is transmitted solely by the mosquito Culex quinquefasciatus. This study reports the results of transmission assessment surveys and molecular xenomonitoring in the city of Olinda, RMR, after nearly 15 years (2015-2016) of interventions for LF elimination. Participants were screened for W. bancrofti antigen via immunochromatographic card tests (ICT) in: 1) door-to-door surveys conducted for all children aged 5-7 years from 4 out of 17 intervention areas treated with at least five annual doses of mass drug administration (MDA), and 2) a two-stage cluster sampling survey of residents aged 5 years and older in non-MDA areas. Mosquitoes were collected via handheld aspirators in four MDA areas, differentiated by species, sex, and physiological status, pooled into groups of up to 10 blood-fed, semigravid, and gravid mosquitoes, and screened for W. bancrofti infection by real-time quantitative polymerase chain reaction (RT-qPCR). All 1,170 children from MDA areas and the entire population sample of 990 residents in non-MDA areas were ICT negative. In MDA areas, a total of 3,152 female Cx. quinquefasciatus mosquitoes in 277 households (range, 0-296 mosquitoes per house) were collected via aspiration. RT-qPCR of 233 pools of mosquitos were negative for W. bancrofti RNA; an independent reference laboratory confirmed these results. These results provide evidence that LF transmission has been halted in this setting.
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Affiliation(s)
- Anita Ramesh
- Department of Parasitology, Instituto Aggeu Magalhães/Fundação Oswaldo Cruz (FIOCRUZ), Recife, Brazil
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Paula Oliveira
- National Reference Service for Lymphatic Filariasis, Department of Parasitology, Instituto Aggeu Magalhães/FIOCRUZ, Recife, Brazil
| | - Mary Cameron
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Priscila M. S. Castanha
- Faculty of Medical Science, University of Pernambuco, Recife, Brazil
- School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Thomas Walker
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom
- School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| | - Audrey Lenhart
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Lucy Impoinvil
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Neal Alexander
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Zulma Medeiros
- Department of Parasitology, Instituto Aggeu Magalhães/Fundação Oswaldo Cruz (FIOCRUZ), Recife, Brazil
| | - André Sá
- Collective Health Department, Instituto Aggeu Magalhães/FIOCRUZ
| | - Abraham Rocha
- National Reference Service for Lymphatic Filariasis, Department of Parasitology, Instituto Aggeu Magalhães/FIOCRUZ, Recife, Brazil
| | - Wayner V. Souza
- Collective Health Department, Instituto Aggeu Magalhães/FIOCRUZ
| | - Amélia Maciel
- Department of Tropical Medicine, Federal University of Pernambuco, Recife, Brazil
| | - Cynthia Braga
- Department of Parasitology, Instituto Aggeu Magalhães/Fundação Oswaldo Cruz (FIOCRUZ), Recife, Brazil
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Hedtke SM, Zendejas-Heredia PA, Graves PM, Sheridan S, Sheel M, Fuimaono SD, Lau CL, Grant WN. Genetic epidemiology of lymphatic filariasis in American Samoa after mass drug administration. Int J Parasitol 2020; 51:137-147. [PMID: 33166540 DOI: 10.1016/j.ijpara.2020.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 08/05/2020] [Accepted: 08/09/2020] [Indexed: 11/18/2022]
Abstract
Over 892 million people in 48 countries are at risk of infection by nematodes that cause lymphatic filariasis. As part of the Global Programme to Eliminate Lymphatic Filariasis, mass drug administration is distributed to communities until surveillance indicates infection rates are below target prevalence thresholds. In some countries, including American Samoa, lymphatic filariasis transmission persists despite years of mass drug administration and/or has resurged after cessation. Nothing is known about the population genetics of Wuchereria bancrofti worms in Polynesia, or whether local transmission is persisting and/or increasing due to inadequate mass drug administration coverage, expansion from residual hotspots, reintroduction from elsewhere, or a combination. We extracted DNA from microfilariae on blood slides collected during prevalence surveys in 2014 and 2016, comprising 31 pools of five microfilariae from 22 persons living in eight villages. We sequenced 1104 bp across three mitochondrial markers (ND4, COI, CYTB). We quantified parasite genetic differentiation using variant calls and estimated haplotypes using principal components analysis, F-statistics, and haplotype networks. Of the variants called, all but eight were shared across the main island of Tutuila, and three of those were from a previously described hotspot village, Fagali'i. Genotypic data did not support population genetic structure among regions or villages in 2016, although differences were observed between worms collected in Fagali'i in 2014 and those from 2016. Because estimated haplotype frequency varied between villages, these statistics suggested genetic differentiation, but were not consistent among villages. Finally, haplotype networks demonstrated American Samoan sequence clusters were related to previously published sequences from Papua New Guinea. These are, to our knowledge, the first reports of W. bancrofti genetic variation in Polynesia. The resurgent parasites circulating on the main island of American Samoa represent a single population. This study is the first step towards investigating how parasite population structure might inform strategies to manage resurgence and elimination of lymphatic filariasis.
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Affiliation(s)
- Shannon M Hedtke
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, Australia; Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, Victoria, Australia.
| | - Patsy A Zendejas-Heredia
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, Australia
| | - Patricia M Graves
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, Queensland, Australia
| | - Sarah Sheridan
- Department of Global Health, Research School of Population Health, The Australian National University, Acton, Australian Capital Territory, Australia
| | - Meru Sheel
- National Centre for Epidemiology and Population Health, Research School of Population Health, The Australian National University, Acton, Australian Capital Territory, Australia
| | | | - Colleen L Lau
- Department of Global Health, Research School of Population Health, The Australian National University, Acton, Australian Capital Territory, Australia
| | - Warwick N Grant
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, Australia; Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, Victoria, Australia
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Molecular xenomonitoring of diurnally subperiodic Wuchereria bancrofti infection in Aedes (Downsiomyia) niveus (Ludlow, 1903) after nine rounds of Mass Drug Administration in Nancowry Islands, Andaman and Nicobar Islands, India. PLoS Negl Trop Dis 2020; 14:e0008763. [PMID: 33095805 PMCID: PMC7641468 DOI: 10.1371/journal.pntd.0008763] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 11/04/2020] [Accepted: 09/01/2020] [Indexed: 11/27/2022] Open
Abstract
A group of four human inhabited Nancowry Islands in Nicobar district in the Andaman and Nicobar Islands, India having a population of 7674 is the lone focus of diurnally sub-periodic Wuchereria bancrofti (DspWB) that is transmitted by Aedes niveus (Ludlow). Microfilaria (Mf) prevalence was above 1% even after nine rounds of Mass Drug Administration (MDA) with DEC and albendazole. Molecular xenomonitoring (MX) was conducted to identify appropriate vector sampling method and assess the impact. BioGents Sentinel traps, gravid traps and human baited double bed nettraps were used in three locations in each village to collect Aedes niveus female mosquitoes. Subsequently daytime man landing collections (MLC) were carried out in all the 25 villages in the islands. Collections were compared in terms of the number of vector mosquitoes captured per trap collection. Females of Ae. niveus were pooled, dried and processed for detecting filarial parasite DNA using RT-PCR assay. Vector infection rate was estimated using PoolScreen software. Only 393 female mosquitoes including 44 Ae. niveus (11.2%) were collected from 459 trap collections using three trapping devices. From 151 MLCs, 2170 Ae. niveus female mosquitoes were collected. The average prevalence of W. bancrofti DNA was 0.43%. Estimated upper 95% CI exceeded the provisional prevalence threshold of 0.1% in all the villages, indicating continued transmission as observed in Mf survey. MLCs could be the choice, for now, to sample Ae. niveus mosquitoes. The PCR assay used in MX for nocturnally periodic bancroftian filariasis could be adopted for DspWB. The vector-parasite MX, can be used to evaluate interventions in this area after further standardization of the protocol. Lymphatic filariasis (LF), caused by nematode parasite–Wuchereria bancrofti, is prevalent in 72 countries with about 1.39 billion people facing the risk of infection. In India LF is endemic in 256 districts. A physiological variant of the parasite, the diurnally sub-periodic Wb (DspWb) is confined to a small pocket of four remotely located isles, in Nicobar district in the Andaman and Nicobar Islands. The parasite is transmitted by a day-biting and forest dwelling mosquito, Aedes niveus. Even after 9 rounds of Mass Drug Administration under the National Programme for LF elimination, microfilaria prevalence was above transmission threshold level (1%), indicating continued transmission. We studied filarial infection in Ae. niveus using molecular xenomonitoring (MX). The vector mosquito was sampled using BioGents Sentinel, Gravid and human baited double bed net-traps. Since the traps did not yield adequate numbers, man landing collections were carried out. The prevalence filarial infection in mosquitoes assessed by molecular assay was above the provisional threshold level (<0.1%.), confirming that the transmission has not been interrupted. MX protocol can further be standardised for use as a surveillance tool in assessing the impact of MDA in this vector-parasite combination.
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Smith MM, Van Hemert C, Handel CM. Evidence of Culiseta mosquitoes as vectors for Plasmodium parasites in Alaska. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2019; 44:68-75. [PMID: 31124235 DOI: 10.1111/jvec.12330] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 01/28/2019] [Indexed: 06/09/2023]
Abstract
Mosquito vectors play a crucial role in the distribution of avian Plasmodium parasites worldwide. At northern latitudes, where climate warming is most pronounced, there are questions about possible changes in the abundance and distribution of Plasmodium parasites, their vectors, and their impacts to avian hosts. To better understand the transmission of Plasmodium among local birds and to gather baseline data on potential vectors, we sampled a total of 3,909 mosquitoes from three locations in south-central Alaska during the summer of 2016. We screened mosquitoes for the presence of Plasmodium parasites using molecular techniques and estimated Plasmodium infection rates per 1,000 mosquitoes using maximum likelihood methods. We found low estimated infection rates across all mosquitoes (1.28 per 1,000), with significantly higher rates in Culiseta mosquitoes (7.91 per 1,000) than in Aedes mosquitoes (0.57 per 1,000). We detected Plasmodium in a single head/thorax sample of Culiseta, indicating potential for transmission of these parasites by mosquitoes of this genus. Plasmodium parasite DNA isolated from mosquitoes showed a 100% identity match to the BT7 Plasmodium lineage that has been detected in numerous avian species worldwide. Additionally, microscopic analysis of blood smears collected from black-capped chickadees (Poecile atricapillus) at the same locations revealed infection by parasites preliminarily identified as Plasmodium circumflexum. Results from our study provide the first information on Plasmodium infection rates in Alaskan mosquitoes and evidence that Culiseta species may play a role in the transmission and maintenance of Plasmodium parasites in this region.
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Affiliation(s)
- Matthew M Smith
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, U.S.A
| | - Caroline Van Hemert
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, U.S.A
| | - Colleen M Handel
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, U.S.A
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Pi-Bansa S, Osei JHN, Kartey-Attipoe WD, Elhassan E, Agyemang D, Otoo S, Dadzie SK, Appawu MA, Wilson MD, Koudou BG, de Souza DK, Utzinger J, Boakye DA. Assessing the Presence of Wuchereria bancrofti Infections in Vectors Using Xenomonitoring in Lymphatic Filariasis Endemic Districts in Ghana. Trop Med Infect Dis 2019; 4:tropicalmed4010049. [PMID: 30884886 PMCID: PMC6473662 DOI: 10.3390/tropicalmed4010049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/10/2019] [Accepted: 03/13/2019] [Indexed: 11/23/2022] Open
Abstract
Mass drug administration (MDA) is the current mainstay to interrupt the transmission of lymphatic filariasis. To monitor whether MDA is effective and transmission of lymphatic filariasis indeed has been interrupted, rigorous surveillance is required. Assessment of transmission by programme managers is usually done via serology. New research suggests that xenomonitoring holds promise for determining the success of lymphatic filariasis interventions. The objective of this study was to assess Wuchereria bancrofti infection in mosquitoes as a post-MDA surveillance tool using xenomonitoring. The study was carried out in four districts of Ghana; Ahanta West, Mpohor, Kassena Nankana West and Bongo. A suite of mosquito sampling methods was employed, including human landing collections, pyrethrum spray catches and window exit traps. Infection of W. bancrofti in mosquitoes was determined using dissection, conventional and real-time polymerase chain reaction and loop mediated isothermal amplification assays. Aedes, Anopheles coustani, An. gambiae, An. pharoensis, Culex and Mansonia mosquitoes were sampled in each of the four study districts. The dissected mosquitoes were positive for filarial infection using molecular assays. Dissected An. melas mosquitoes from Ahanta West district were the only species found positive for filarial parasites. We conclude that whilst samples extracted with Trizol reagent did not show any positives, molecular methods should still be considered for monitoring and surveillance of lymphatic filariasis transmission.
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Affiliation(s)
- Sellase Pi-Bansa
- Swiss Tropical and Public Health Institute, CH-4002 Basel, Switzerland.
- University of Basel, CH-4003 Basel, Switzerland.
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, LG 581 Legon, Ghana.
| | - Joseph H N Osei
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, LG 581 Legon, Ghana.
- Department of Animal Biology and Conservation Science, University of Ghana, LG 67 Legon, Ghana.
| | - Worlasi D Kartey-Attipoe
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, LG 581 Legon, Ghana.
| | | | | | - Sampson Otoo
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, LG 581 Legon, Ghana.
| | - Samuel K Dadzie
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, LG 581 Legon, Ghana.
| | - Maxwell A Appawu
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, LG 581 Legon, Ghana.
| | - Michael D Wilson
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, LG 581 Legon, Ghana.
| | - Benjamin G Koudou
- Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK.
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire.
| | - Dziedzom K de Souza
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, LG 581 Legon, Ghana.
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, CH-4002 Basel, Switzerland.
- University of Basel, CH-4003 Basel, Switzerland.
| | - Daniel A Boakye
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, LG 581 Legon, Ghana.
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Musso D. Infections in French Polynesia. New Microbes New Infect 2019; 27:27-28. [PMID: 30534384 PMCID: PMC6278714 DOI: 10.1016/j.nmni.2018.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 10/31/2018] [Accepted: 11/07/2018] [Indexed: 11/22/2022] Open
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Development of an urban molecular xenomonitoring system for lymphatic filariasis in the Recife Metropolitan Region, Brazil. PLoS Negl Trop Dis 2018; 12:e0006816. [PMID: 30325933 PMCID: PMC6203399 DOI: 10.1371/journal.pntd.0006816] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 10/26/2018] [Accepted: 09/05/2018] [Indexed: 12/02/2022] Open
Abstract
Introduction Molecular xenomonitoring (MX)—pathogen detection in the mosquito rather than human—is a promising tool for lymphatic filariasis (LF) surveillance. In the Recife Metropolitan Region (RMR), the last LF focus in Brazil, Culex quinquefasciatus mosquitoes have been implicated in transmitting Wuchereria bancrofti parasites. This paper presents findings on the ideal mosquito collection method, mosquito dispersion, W. bancrofti infection in mosquitoes and W. bancrofti antigen in humans to aid MX development. Methods Experiments occurred within two densely populated urban areas of Olinda, RMR, in July and August 2015. U.S. Centers for Disease Control and Prevention (CDC) light traps were compared to battery-powered aspirators as collection methods, and mosquito dispersion was measured by mosquito mark release recapture (MMRR). Female Cx. quinquefasciatus were tested by PCR for W. bancrofti infection, and study area residents were screened by rapid tests for W. bancrofti antigen. Results Aspirators caught 2.6 times more total Cx. quinquefasciatus, including 38 times more blood-fed and 5 times more gravid stages, than CDC light traps. They also collected 123 times more Aedes aegypti. Of the 9,644 marked mosquitoes released, only ten (0.01%) were recaptured, nine of which were < 50m (34.8m median, 85.4m maximum) from the release point. Of 9,169 unmarked mosquitoes captured in the MMR, 38.3% were unfed, 48.8% blood-fed, 5.5% semi-gravid, and 7.3% gravid. PCR on 182 pools (1,556 mosquitoes) found no evidence of W. bancrofti infection in Cx. quinquefasciatus. Rapid tests on 110 of 111 eligible residents were all negative for W. bancrofti antigen. Conclusions Aspirators were more effective than CDC light traps at capturing Ae. aegypti and all but unfed stages of Cx. quinquefasciatus. Female Cx. quinquefasciatus traveled short (< 86m) distances in this urban area. Lack of evidence for W. bancrofti infection in mosquitoes and antigen in humans in these fine-scale studies does not indicate that LF transmission has ceased in the RMR. A MX surveillance system should consider vector-specific collection methods, mosquito dispersion, and spatial scale but also local context, environmental factors such as sanitation, and host factors such as infection prevalence and treatment history. Lymphatic filariasis (LF) is a parasitic disease transmitted by mosquitoes, and can cause elephantiasis. It is the world’s leading cause of disability due to infectious diseases, affects over 120 million people globally, and is scheduled for global elimination via mass drug administration (MDA) and mosquito control. Molecular xenomonitoring (MX) is a process of screening mosquitoes—not humans—for parasites to estimate whether they are circulating in human populations. MX is especially useful during and following MDA, when new case detection becomes difficult, but is challenging to design and conduct in cities. Using two study sites in the Recife Metropolitan Region, Brazil, we investigated two crucial questions for urban MX development—“What is the best operationally feasible tool to catch adult mosquitoes?” and “How far do mosquitoes disperse in cities?”—in order to determine placement of future surveillance sites. We also screened a proportion of mosquitoes and all eligible residents from the study sites for LF infection. We determined that handheld battery powered aspirators were the best mosquito collection tool; that mosquitoes flew no more than about 85m; and—in this small sample of mosquitoes and very small sample of humans—there was no evidence of LF infection in mosquitoes or study area residents.
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Kinyatta NM, Ng'ang'a ZW, Kamau L, Kagai JM. Comparison of Indoor Mosquito Collection Methods in the Assessment of Lymphatic Filariasis Transmission Dynamics in Mosquito Vectors in Tana River County, Kenya. East Afr Health Res J 2018; 2:58-66. [PMID: 34308176 PMCID: PMC8279214 DOI: 10.24248/eahrj-d-16-00401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 11/03/2017] [Indexed: 11/20/2022] Open
Abstract
Background Lymphatic filariasis (LF) is a parasitic infectious disease that is transmitted by several species of mosquitoes. Diagnosis of LF is done in both human hosts and vectors. Effective mosquito collection method(s) is/are required in order to collect large numbers of mosquitoes with high chances of infectivity. Methods In this study, 3 mosquito sampling methods were compared. Mosquitoes were collected from 6 randomly selected villages of Tana River County, Kenya. The effectiveness of CDC light traps, gravid traps, and pyrethrum spray methods in collecting mosquitoes were compared. Mosquitoes were morphologically identified into genera and species level, and mosquito dissection was done in search of microfilariae larvae to assess the infection and infectivity rates. Data was analysed by SPSS version 15.0 and analysis of variance (ANOVA). Results A total of 1632 female mosquitoes were collected belonging to 5 mosquito genera: Culex, Anopheles, Aedes, Mansonia, and Ficalbia. The most abundant mosquito genera was Culex. Light traps obtained the most blood-fed mosquitoes. Conclusion Light traps were found to be the most effective method of mosquito collection in terms of high catches and high infectivities.
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Affiliation(s)
- Nancy Mutanu Kinyatta
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | | | - Luna Kamau
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Jim Mwaniki Kagai
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
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Tahir D, Almeras L, Varloud M, Raoult D, Davoust B, Parola P. Assessment of MALDI-TOF mass spectrometry for filariae detection in Aedes aegypti mosquitoes. PLoS Negl Trop Dis 2017; 11:e0006093. [PMID: 29261659 PMCID: PMC5754087 DOI: 10.1371/journal.pntd.0006093] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 01/04/2018] [Accepted: 11/02/2017] [Indexed: 11/28/2022] Open
Abstract
Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) is an emerging tool for routine identification of bacteria, archaea and fungi. It has also been recently applied as an accurate approach for arthropod identification. Preliminary studies have shown that the MALDI-TOF MS was able to differentiate whether ticks and mosquitoes were infected or not with some bacteria and Plasmodium parasites, respectively. The aim of the present study was to test the efficiency of MALDI-TOF MS tool in distinguishing protein profiles between uninfected mosquitoes from specimens infected by filarioid helminths. Aedes aegypti mosquitoes were engorged on microfilaremic blood infected with Dirofilaria immitis, Brugia malayi or Brugia pahangi. Fifteen days post-infective blood feeding, a total of 534 mosquitoes were killed by freezing. To assess mass spectra (MS) profile changes following filariae infections, one compartment (legs, thorax, head or thorax and head) per mosquito was submitted for MALDI-TOF MS analysis; the remaining body parts were used to establish filariae infectious status by real-time qPCR. A database of reference MS, based on the mass profiles of at least two individual mosquitoes per compartment, was created. Subsequently, the remaining compartment spectra (N = 350) from Ae. aegypti infected or not infected by filariae were blind tested against the spectral database. In total, 37 discriminating peak masses ranging from 2062 to 14869 daltons were identified, of which 17, 11, 12 and 7 peak masses were for legs, thorax, thorax-head and head respectively. Two peak masses (4073 and 8847 Da) were specific to spectra from Ae. aegypti infected with filariae, regardless of nematode species or mosquito compartment. The thorax-head part provided better classification with a specificity of 94.1% and sensitivity of 86.6, 71.4 and 68.7% of D. immitis, B. malayi and B. pahangi respectively. This study presents the potential of MALDI-TOF MS as a reliable tool for differentiating non-infected and filariae-infected Ae. aegypti mosquitoes. Considering that the results might vary in other mosquito species, further studies are needed to consolidate the obtained preliminary results before applying this tool in entomological surveillance as a fast mass screening method of filariosis vectors in endemic areas. Filariosis is a disease group affecting humans and animals, caused by nematode parasites of the family Onchocercidae, superfamily Filarioidea. These parasites can be transmitted, essentially, by mosquitoes during blood meals of infected female specimens. Screening vectors for these filariae currently relies on time- and resource-consuming methods such as dissection and polymerase chain reaction-based methods. Here, we applied matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) to assess whether this tool can detect changes in the protein profiles of Aedes aegypti infected with filarioid helminths compared to those uninfected by testing different parts of mosquitoes. First a reference mass spectra database from Ae. aegypti infected or not infected by filariae was created using MS from 47 specimen compartments. Then we tested the remaining mass spectra (350 x 4) in a blind validation test. Regardless of filariae species, the best correct classification rate was obtained from the thorax-head part with a specificity of 94.1% and sensitivity of 86.6, 71.4 and 68.7% for non-infected and D. immitis, B. malayi and B. pahangi infected mosquitoes respectively. The results indicated that MALDI-TOF MS is potentially able to screen Aedes aegypti mosquitoes as being non-infected or filariae-infected. Furthermore, complementary works using other mosquito species infected with different filarioids are needed to reinforce these preliminary results prior to apply this tool on field samples.
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Affiliation(s)
- Djamel Tahir
- Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille Université, UM63, CNRS 7278, IRD 198 (Dakar), Inserm 1095, AP-HM Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
| | - Lionel Almeras
- Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille Université, UM63, CNRS 7278, IRD 198 (Dakar), Inserm 1095, AP-HM Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
- Unité de Parasitologie et Entomologie, Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, Marseille, France
| | | | - Didier Raoult
- Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille Université, UM63, CNRS 7278, IRD 198 (Dakar), Inserm 1095, AP-HM Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
| | - Bernard Davoust
- Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille Université, UM63, CNRS 7278, IRD 198 (Dakar), Inserm 1095, AP-HM Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
| | - Philippe Parola
- Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille Université, UM63, CNRS 7278, IRD 198 (Dakar), Inserm 1095, AP-HM Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
- * E-mail:
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Pilotte N, Unnasch TR, Williams SA. The Current Status of Molecular Xenomonitoring for Lymphatic Filariasis and Onchocerciasis. Trends Parasitol 2017; 33:788-798. [PMID: 28756911 DOI: 10.1016/j.pt.2017.06.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 06/19/2017] [Accepted: 06/21/2017] [Indexed: 10/19/2022]
Abstract
The capacity of vector insect surveillance to provide estimates of pathogen prevalence and transmission potential has long been recognized within the global communities tasked with eliminating lymphatic filariasis (LF), the underlying cause of elephantiasis and hydrocele, and onchocerciasis (river blindness). Initially restricted to the practice of dissection, the potential of vector monitoring has grown due to the advent of molecular methods capable of increasing the sensitivity and throughput of testing. However, despite such advancement, operational research gaps remain. If insufficiently addressed, these gaps will reduce the utility of molecular xenomonitoring (MX) for onchocerciasis as elimination efforts expand into Africa. Similarly, such shortcomings will limit the programmatic usefulness of MX for LF, resulting in this technique's significant underutilization.
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Affiliation(s)
- Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, MA, USA; Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA, USA; These authors contributed equally to this work
| | - Thomas R Unnasch
- Department of Global Health, University of South Florida, Tampa, FL, USA; These authors contributed equally to this work
| | - Steven A Williams
- Department of Biological Sciences, Smith College, Northampton, MA, USA; Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA, USA.
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Subramanian S, Jambulingam P, Chu BK, Sadanandane C, Vasuki V, Srividya A, Mohideen AbdulKader MS, Krishnamoorthy K, Raju HK, Laney SJ, Williams SA, Henderson RH. Application of a household-based molecular xenomonitoring strategy to evaluate the lymphatic filariasis elimination program in Tamil Nadu, India. PLoS Negl Trop Dis 2017; 11:e0005519. [PMID: 28406927 PMCID: PMC5404881 DOI: 10.1371/journal.pntd.0005519] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 04/25/2017] [Accepted: 03/21/2017] [Indexed: 11/24/2022] Open
Abstract
Background The monitoring and evaluation of lymphatic filariasis (LF) has largely relied on the detection of antigenemia and antibodies in human populations. Molecular xenomonitoring (MX), the detection of parasite DNA/RNA in mosquitoes, may be an effective complementary method, particularly for detecting signals in low-level prevalence areas where Culex is the primary mosquito vector. This paper investigated the application of a household-based sampling method for MX in Tamil Nadu, India. Methods MX surveys were conducted in 2010 in two evaluation units (EUs): 1) a hotspot area, defined as sites with community microfilaria prevalence ≥1%, and 2) a larger area that also encompassed the hotspots. Households were systematically selected using a sampling interval proportional to the number of households in the EU. Mosquito pools were collected and analyzed by real-time polymerase chain reaction (qPCR). Two independent samples were taken in each EU to assess reproducibility of results. Follow-up surveys were conducted in 2012. Results In 2010, the proportion of positive pools in the hotspot EU was 49.3% compared to 23.4% in the overall EU. In 2012, pool positivity was significantly reduced to 24.3% and 6.5%, respectively (p<0.0001). Pool positivity based on independent samples taken from each EU in 2010 and 2012 were not significantly different except for the hotspot EU in 2012 (p = 0.009). The estimated prevalence of infection in mosquitoes, measured by PoolScreen, declined from 2.2–2.7% in 2010 to 0.6–1.2% in 2012 in the hotspot area and from 0.9–1.1% to 0.2–0.3% in the larger area. Conclusions The household-based sampling strategy for MX led to mostly reproducible results and supported the observed LF infection trends found in humans. MX has the potential to be a cost-effective, non-invasive monitoring and evaluation tool with sensitive detection of infection signals in low prevalence settings. Further investigation and application of this sampling strategy for MX are recommended to support its adoption as a standardized method for global LF elimination programs. Lymphatic filariasis (LF) is one of the world’s foremost debilitating infectious diseases with nearly 800 million people at risk of infection. Given that LF is a mosquito-borne disease, the use of molecular xenomonitoring (MX) to detect parasite DNA/RNA in mosquitoes can serve as a valuable tool for LF monitoring and evaluation, particularly in Culex vector areas. We investigated using MX in a low-level prevalence district of Tamil Nadu, India by applying a household-based sampling strategy to determine trap location sites. Two independent mosquito samples were collected in each of a higher human infection hotspot area (sites with community microfilaria prevalence ≥1%) and across a larger evaluation area that also encompassed the hotspots. Pooled results showed mostly reproducible outcomes in both settings and a significant higher pool positivity in the hotspot area. A follow-up survey conducted two years later reconfirmed these findings while also showing a reduction in pool positivity and estimated prevalence of infection in mosquitoes in both settings. The utilization of a household-based sampling strategy for MX proved effective and should be further validated in wider epidemiological settings.
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Affiliation(s)
- Swaminathan Subramanian
- Vector Control Research Centre (Indian Council of Medical Research), Indira Nagar, Puducherry, India
- * E-mail:
| | - Purushothaman Jambulingam
- Vector Control Research Centre (Indian Council of Medical Research), Indira Nagar, Puducherry, India
| | - Brian K. Chu
- Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, Georgia, United States of America
| | - Candasamy Sadanandane
- Vector Control Research Centre (Indian Council of Medical Research), Indira Nagar, Puducherry, India
| | - Venkatesan Vasuki
- Vector Control Research Centre (Indian Council of Medical Research), Indira Nagar, Puducherry, India
| | - Adinarayanan Srividya
- Vector Control Research Centre (Indian Council of Medical Research), Indira Nagar, Puducherry, India
| | | | | | - Harikishan K. Raju
- Vector Control Research Centre (Indian Council of Medical Research), Indira Nagar, Puducherry, India
| | - Sandra J. Laney
- SJL Global Consulting, Seattle, Washington, United States of America
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Ralph H. Henderson
- Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, Georgia, United States of America
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Moustafa MA, Salamah MMI, Thabet HS, Tawfik RA, Mehrez MM, Hamdy DM. Molecular xenomonitoring (MX) and transmission assessment survey (TAS) of lymphatic filariasis elimination in two villages, Menoufyia Governorate, Egypt. Eur J Clin Microbiol Infect Dis 2017; 36:1143-1150. [PMID: 28155014 DOI: 10.1007/s10096-017-2901-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/04/2017] [Indexed: 11/30/2022]
Abstract
Lymphatic filariasis (LF) is focally endemic in Egypt where the female mosquito, Culex pipiens, is responsible for its transmission. The aim of the study was to investigate the impact of implementation of the 13th round of MDA in two Egyptian villages in the Menoufyia Governorate area after failing the transmission assessment survey (TAS) in 2005 using two methods, and to decide whether it is safe to stop MDA in these, as well as in similar implementation units (IUs). To achieve this aim, both the immunochromatographic card test (ICT) and molecular xenomonitoring (MX) techniques were employed. A cross-sectional study was carried out in the villages in 2014 with two sections: Section (1): a school-based survey where all the primary school entrants (6-7) years of age were tested by ICT. Section (2): a mosquito-based survey where a total of 152 mosquito pools collected from Samalay and 167 from Kafr El-Tarainah were tested for the presence of the gDNA of Wuchereria bancrofti microfilaria by real-time PCR assays. The results revealed that all primary school children in both villages were 100% negative for antigenemia. Also, all mosquito pools were 100% negative for the microfilarial gDNA.
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Affiliation(s)
- M A Moustafa
- Department of Parasitology, Faculty of Medicine, Ain Shams University, Abbassia, 11566, Cairo, Egypt
| | - M M I Salamah
- Department of Parasitology, Faculty of Medicine, Ain Shams University, Abbassia, 11566, Cairo, Egypt
| | - H S Thabet
- Department of Parasitology, Faculty of Medicine, Ain Shams University, Abbassia, 11566, Cairo, Egypt
| | - R A Tawfik
- Department of Parasitology, Faculty of Medicine, Ain Shams University, Abbassia, 11566, Cairo, Egypt.
| | - M M Mehrez
- General Department for Malaria, Filariasis & Leishmaniasis Control, Endemic Diseases Control Sector, Ministry of Health and Population, Cairo, Egypt
| | - D M Hamdy
- Department of Parasitology, Faculty of Medicine, Ain Shams University, Abbassia, 11566, Cairo, Egypt
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Lymphatic Filariasis Elimination in American Samoa: Evaluation of Molecular Xenomonitoring as a Surveillance Tool in the Endgame. PLoS Negl Trop Dis 2016; 10:e0005108. [PMID: 27802280 PMCID: PMC5089733 DOI: 10.1371/journal.pntd.0005108] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 10/13/2016] [Indexed: 11/19/2022] Open
Abstract
The Global Programme to Eliminate Lymphatic Filariasis has made significant progress toward interrupting transmission of lymphatic filariasis (LF) through mass drug administration (MDA). Operational challenges in defining endpoints of elimination programs include the need to determine appropriate post-MDA surveillance strategies. As humans are the only reservoirs of LF parasites, one such strategy is molecular xenomonitoring (MX), the detection of filarial DNA in mosquitoes using molecular methods (PCR), to provide an indirect indicator of infected persons nearby. MX could potentially be used to evaluate program success, provide support for decisions to stop MDA, and conduct post-MDA surveillance. American Samoa has successfully completed MDA and passed WHO recommended Transmission Assessment Surveys in 2011 and 2015, but recent studies using spatial analysis of antigen (Ag) and antibody (Ab) prevalence in adults (aged ≥18 years) and entomological surveys showed evidence of possible ongoing transmission. This study evaluated MX as a surveillance tool in American Samoa by linking village-level results of published human and mosquito studies. Of 32 villages, seropositive persons for Og4C3 Ag were identified in 11 (34.4%), for Wb123 Ab in 18 (56.3%) and for Bm14 Ab in 27 (84.4%) of villages. Village-level seroprevalence ranged from 0–33%, 0–67% and 0–100% for Og4C3 Ag, Wb123 Ab and Bm14 Ab respectively. PCR-positive Aedes polynesiensis mosquitoes were found in 15 (47%) villages, and their presence was significantly associated with seropositive persons for Og4C3 Ag (67% vs 6%, p<0.001) and Wb123 Ab (87% vs 29%, p = 0.001), but not Bm14 Ab. In villages with persons seropositive for Og4C3 Ag and Wb123 Ab, PCR-positive Ae. polynesiensis were found in 90.9% and 72.2% respectively. In villages without seropositive persons for Og4C3 Ag or Wb123 Ab, PCR-positive Ae. polynesiensis were also absent in 94.1% and 70.6% of villages respectively. Our study provides promising evidence to support the potential usefulness of MX in post-MDA surveillance in an Aedes transmission area in the Pacific Islands setting. Lymphatic filariasis (LF) is caused by infection with filarial worms that are transmitted by mosquito bites. Globally, 36 million are disfigured and disabled by complications such as severe swelling of the legs (elephantiasis) or scrotum (hydrocele). The Global Programme to Eliminate LF (GPELF) aims to interrupt disease transmission through mass drug administration (MDA), and to control illness and suffering in affected persons. Significant progress has been made toward eliminating LF from many parts of the world, including the Pacific Islands. Current challenges of the GPELF include identification of any residual hotspots of ongoing transmission, and effective strategies for early identification of any resurgence of infections. As humans are the only reservoirs of LF parasites and mosquitoes have short flight ranges, one such strategy is to monitor LF infection in mosquitoes as an indicator of ongoing transmission nearby. Mosquito monitoring could potentially be used to evaluate program success, provide support for decisions to stop MDA, and conduct post-MDA surveillance. Our study evaluated mosquito monitoring as a surveillance tool in American Samoa by linking village-level results of published studies of LF in humans and mosquitoes, and provides promising evidence to support the potential usefulness of mosquito monitoring in post-MDA surveillance the Pacific Islands.
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Kouassi BL, de Souza DK, Goepogui A, Narh CA, King SA, Mamadou BS, Diakité L, Dadzie SK, Boakye DA, Utzinger J, Bockarie MJ, Koudou BG. Assessing the presence of Wuchereria bancrofti in vector and human populations from urban communities in Conakry, Guinea. Parasit Vectors 2015; 8:492. [PMID: 26410739 PMCID: PMC4583765 DOI: 10.1186/s13071-015-1077-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 09/08/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Global Programme to Eliminate Lymphatic Filariasis was launched in 2000 with the goal of interrupting transmission of lymphatic filariasis (LF) through multiple rounds of mass drug administration (MDA). In Guinea, there is evidence of ongoing LF transmission, but little is known about the most densely populated parts of the country, including the capital Conakry. In order to guide the LF control and elimination efforts, serological and entomological surveys were carried out to determine whether or not LF transmission occurs in Conakry. METHODS The prevalence of circulating filarial antigen (CFA) of Wuchereria bancrofti was assessed by an immuno-chromatography test (ICT) in people recruited from all five districts of Conakry. Mosquitoes were collected over a 1-year period, in 195 households in 15 communities. A proportion of mosquitoes were analysed for W. bancrofti, using dissection, loop-mediated isothermal amplification (LAMP) assay and conventional polymerase chain reaction (PCR). RESULTS CFA test revealed no infection in the 611 individuals examined. A total of 14,334 mosquitoes were collected; 14,135 Culex (98.6 %), 161 Anopheles (1.1 %) and a few other species. Out of 1,312 Culex spp. (9.3 %) and 51 An. gambiae (31.7 %) dissected, none was infected with any stage of the W. bancrofti parasite. However, the LAMP assay revealed that 1.8 % of An. gambiae and 0.31 % of Culex spp. were positive, while PCR determined respective prevalences of 0 % and 0.19 %. CONCLUSIONS This study revealed the presence of W. bancrofti DNA in mosquitoes, despite the apparent absence of infection in the human population. Although MDA interventions are not recommended where the prevalence of ICT is below 1 %, the entomological results are suggestive of the circulation of the parasite in the population of Conakry. Therefore, rigorous surveillance is still warranted so that LF transmission in Conakry would be identified rapidly and adequate responses being implemented.
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Affiliation(s)
- Bernard L Kouassi
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire.,Unité de Formation et de Recherche Science de la Nature, Université Nangui Abrogoua, Abidjan, Côte d'Ivoire.,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Dziedzom K de Souza
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Andre Goepogui
- Programme National de Lutte contre l'Onchocercose, le Trachome et les autres Maladies Tropicales Négligées, Ministère de la Santé Publique, Conakry, Guinea
| | - Charles A Narh
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Sandra A King
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Baldé S Mamadou
- Programme National de Lutte contre l'Onchocercose, le Trachome et les autres Maladies Tropicales Négligées, Ministère de la Santé Publique, Conakry, Guinea
| | - Lamia Diakité
- Programme National de Lutte contre l'Onchocercose, le Trachome et les autres Maladies Tropicales Négligées, Ministère de la Santé Publique, Conakry, Guinea
| | - Samuel K Dadzie
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Daniel A Boakye
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Jürg Utzinger
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Moses J Bockarie
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Benjamin G Koudou
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire. .,Unité de Formation et de Recherche Science de la Nature, Université Nangui Abrogoua, Abidjan, Côte d'Ivoire. .,Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Liverpool, UK.
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Schmaedick MA, Koppel AL, Pilotte N, Torres M, Williams SA, Dobson SL, Lammie PJ, Won KY. Molecular xenomonitoring using mosquitoes to map lymphatic filariasis after mass drug administration in American Samoa. PLoS Negl Trop Dis 2014; 8:e3087. [PMID: 25122037 PMCID: PMC4133231 DOI: 10.1371/journal.pntd.0003087] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 06/24/2014] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Mass drug administration (MDA) programs have dramatically reduced lymphatic filariasis (LF) incidence in many areas around the globe, including American Samoa. As infection rates decline and MDA programs end, efficient and sensitive methods for detecting infections are needed to monitor for recrudescence. Molecular methods, collectively termed 'molecular xenomonitoring,' can identify parasite DNA or RNA in human blood-feeding mosquitoes. We tested mosquitoes trapped throughout the inhabited islands of American Samoa to identify areas of possible continuing LF transmission after completion of MDA. METHODOLOGY/PRINCIPLE FINDINGS Mosquitoes were collected using BG Sentinel traps from most of the villages on American Samoa's largest island, Tutuila, and all major villages on the smaller islands of Aunu'u, Ofu, Olosega, and Ta'u. Real-time PCR was used to detect Wuchereria bancrofti DNA in pools of ≤ 20 mosquitoes, and PoolScreen software was used to infer territory-wide prevalences of W. bancrofti DNA in the mosquitoes. Wuchereria bancrofti DNA was found in mosquitoes from 16 out of the 27 village areas sampled on Tutuila and Aunu'u islands but none of the five villages on the Manu'a islands of Ofu, Olosega, and Ta'u. The overall 95% confidence interval estimate for W. bancrofti DNA prevalence in the LF vector Ae. polynesiensis was 0.20-0.39%, and parasite DNA was also detected in pools of Culex quinquefasciatus, Aedes aegypti, and Aedes (Finlaya) spp. CONCLUSIONS/SIGNIFICANCE Our results suggest low but widespread prevalence of LF on Tutuila and Aunu'u where 98% of the population resides, but not Ofu, Olosega, and Ta'u islands. Molecular xenomonitoring can help identify areas of possible LF transmission, but its use in the LF elimination program in American Samoa is limited by the need for more efficient mosquito collection methods and a better understanding of the relationship between prevalence of W. bancrofti DNA in mosquitoes and infection and transmission rates in humans.
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Affiliation(s)
- Mark A. Schmaedick
- Division of Community and Natural Resources, American Samoa Community College, Pago Pago, American Samoa
| | - Amanda L. Koppel
- Department of Entomology, College of Agriculture, University of Kentucky, Lexington, Kentucky, United States of America
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Melissa Torres
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Stephen L. Dobson
- Department of Entomology, College of Agriculture, University of Kentucky, Lexington, Kentucky, United States of America
| | - Patrick J. Lammie
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Kimberly Y. Won
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
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Sim S, Ramirez JL, Dimopoulos G. Molecular discrimination of mosquito vectors and their pathogens. Expert Rev Mol Diagn 2014; 9:757-65. [DOI: 10.1586/erm.09.56] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Plichart C, Lemoine A. Monitoring and evaluation of lymphatic filariasis interventions: an improved PCR-based pool screening method for high throughput Wuchereria bancrofti detection using dried blood spots. Parasit Vectors 2013; 6:110. [PMID: 23597068 PMCID: PMC3637190 DOI: 10.1186/1756-3305-6-110] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 04/14/2013] [Indexed: 11/29/2022] Open
Abstract
Background Effective diagnostic tools are necessary to monitor and evaluate interruption of Lymphatic Filariasis (LF) transmission. Accurate detection of Wuchereria bancrofti (Wb) microfilaria (mf) is essential to measure the impact of community treatment programmes. PCR-based assays are specific, highly sensitive tools allowing the detection of Wuchereria bancrofti DNA in human blood samples. However, current protocols describing the pool screening approach, use samples of less than 60 μl of blood, which limits the sensitivity of the pool-screen PCR assay. The purpose of this study was to improve the pool-screen PCR protocol to enhance its sensitivity and usefulness for population scale studies. Findings DNA extractions were performed with the DNeasy kit, the PCR with the Wb LDR primers and the SYBR-Green dye. Improvements of our pool-screen real-time PCR (qPCR) assay allowed the detection of as little as one Wb microfilaria diluted in a pool of at least 12 blood samples of 60 μl each. Using this assay, mf burdens can be predicted using a standard curve derived from mf spiked dried blood samples. The sensitivity achieved is equivalent to the detection of a single LF positive individual carrying a mf burden as low as 18 mf/ml, in a pool of blood samples from at least 12 individuals. Conclusions Due to its sensitivity, rapidity and cost-effectiveness, we suggest this qPCR pool-screening assay could be used as a diagnostic tool for population- scale filariasis elimination monitoring and evaluation.
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Bataille A, Fournié G, Cruz M, Cedeño V, Parker PG, Cunningham AA, Goodman SJ. Host selection and parasite infection in Aedes taeniorhynchus, endemic disease vector in the Galápagos Islands. INFECTION GENETICS AND EVOLUTION 2012; 12:1831-41. [PMID: 22921730 DOI: 10.1016/j.meegid.2012.07.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 06/29/2012] [Accepted: 07/18/2012] [Indexed: 11/25/2022]
Abstract
Host selection in blood-sucking arthropods has important evolutionary and ecological implications for the transmission dynamics, distribution and host-specificity of the parasites they transmit. The black salt-marsh mosquito (Aedes taeniorhynchus Wiedemann) is distributed throughout tropical to temperate coastal zones in the Americas, and continental populations are primarily mammalphilic. It is the only indigenous mosquito in the Galápagos Islands, having colonised the archipelago around 200,000 years ago, potentially adapting its host selection, and in the process, altering the dynamics of vector mediated pathogen interactions in the archipelago. Here, we use blood-meal analysis and PCR-based parasite screening approach to determine the blood-feeding patterns of A. taeniorhynchus in the Galápagos Islands and identify potential parasite transmission with which this mosquito could be involved. Our results show that A. taeniorhynchus feeds equally on mammals and reptiles, and only one avian sample was observed in 190 successful PCR amplifications from blood meals. However, we detected endemic filarial worms and Haemoproteus parasites known to infect various Galápagos bird species in mosquito thoraces, suggesting that feeding on birds must occur at low frequency, and that A. taeniorhynchus may play a role in maintaining some avian vector-borne pathogens, although more work is needed to explore this possibility. We also isolated three different DNA sequences corresponding to hemogregarine parasites of the genus Hepatozoon from mosquito and iguana blood samples, suggesting that more than one species of Hepatozoon parasites are present in Galápagos. Phylogenetic analysis of Hepatozoon 18sRNA sequences indicates that A. taeniorhynchus may have facilitated a recent breakdown in host-species association of formerly isolated Hepatozoon spp. infecting the reptile populations in the Galápagos Islands.
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Affiliation(s)
- Arnaud Bataille
- Institute of Integrative and Comparative Biology, University of Leeds, Leeds LS2 9JT, UK.
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Mercer DR, Bossin H, Sang MC, O'Connor L, Dobson SL. Monitoring temporal abundance and spatial distribution of Aedes polynesiensis using BG-Sentinel traps in neighboring habitats on Raiatea, Society Archipelago, French Polynesia. JOURNAL OF MEDICAL ENTOMOLOGY 2012; 49:51-60. [PMID: 22308771 PMCID: PMC3313484 DOI: 10.1603/me11087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Adult numbers and sizes of mosquitoes were monitored for 2 yr in neighboring habitats on the western coast of Raiatea (Society Archipelago) in anticipation of testing new vector control technologies. Aedes polynesiensis Marks females comprised the overwhelming majority (approximately 99%) of the three species of mosquitoes captured in Biogent Sentinel traps placed at fixed sites on three small satellite islands (motus) of the western lagoon and on the shoreline of Raiatea. Aedes polynesiensis males, Aedes aegypti (L.), and Culex quinquefasciatus Say rarely were collected. Numbers of Ae. polynesiensis females per collection differed among trapping dates and locations, with the majority of females captured on two motus, Horea and Toamaro. Shoreline and Horea females had significantly longer mean wing lengths than females from Tiano and Toamaro. Thus, wing lengths were influenced more by local developmental conditions than overall numbers of adults. Significantly more females were captured during the wet season than the dry season. Nonetheless, at least on the two highly productive motus, dry-season females had larger wing lengths than their wet season counterparts. Local weather patterns predicted about half the variation in mosquito numbers. Differences in vector abundance observed when comparing neighboring motus are likely because of differences in human activity and mosquito suppression.
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Affiliation(s)
- David R Mercer
- Department of Entomology, University of Kentucky, Lexington, KY, USA.
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Vezzani D, Mesplet M, Eiras DF, Fontanarrosa MF, Schnittger L. PCR detection of Dirofilaria immitis in Aedes aegypti and Culex pipiens from urban temperate Argentina. Parasitol Res 2010; 108:985-9. [PMID: 21072539 DOI: 10.1007/s00436-010-2142-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 10/28/2010] [Indexed: 11/29/2022]
Abstract
Dirofilariasis, a mosquito-borne disease of dogs caused by the nematode Dirofilaria immitis (Leidy; Spirurida: Onchocercidae), has now become a growing zoonotic concern. Based on direct microscopical observation, Aedes aegypti (L.) and Culex pipiens L. (Diptera: Culicidae) have been previously incriminated as potential vectors of D. immitis in urban temperate Argentina. In this study, an effort was made to provide evidence for this assumption by screening of mosquitoes for D. immitis infection using a polymerase chain reaction (PCR) assay. PCR primers were developed to specifically amplify the D. immitis-16S rRNA gene and to reliably detect 100th of the genomic equivalent (10 pg) of the infective third-stage larvae in mosquito pools of up to 30 individuals. Collection of mosquitoes was performed between September 2007 and April 2008 in premises known to be inhabited by D. immitis-infected dogs in Greater Buenos Aires. The final collection comprised 453 specimens belonging to 11 mosquito species of the genera Aedes, Culex, Ochlerotatus, and Psorophora. PCR assays were performed on 82 pools (n ≤ 20) of heads and abdomens separately, as this allows differentiating infective and non-infective stages of the parasite, respectively. Identification of the non-infective stage of D. immitis in A. aegypti and C. pipiens provided additional strong support of transmission of the parasite by these species. To our knowledge, this was the first PCR screening for D. immitis-infected mosquitoes in South America.
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Affiliation(s)
- Darío Vezzani
- Unidad de Ecología de Reservorios y Vectores de Parásitos, Facultad de Cs. Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, 4º piso, (C1428EHA), Buenos Aires, Argentina.
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Boyd A, Won KY, McClintock SK, Donovan CV, Laney SJ, Williams SA, Pilotte N, Streit TG, Beau de Rochars MVE, Lammie PJ. A community-based study of factors associated with continuing transmission of lymphatic filariasis in Leogane, Haiti. PLoS Negl Trop Dis 2010; 4:e640. [PMID: 20351776 PMCID: PMC2843627 DOI: 10.1371/journal.pntd.0000640] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 02/04/2010] [Indexed: 11/30/2022] Open
Abstract
Seven rounds of mass drug administration (MDA) have been administered in Leogane, Haiti, an area hyperendemic for lymphatic filariasis (LF). Sentinel site surveys showed that the prevalence of microfilaremia was reduced to <1% from levels as high as 15.5%, suggesting that transmission had been reduced. A separate 30-cluster survey of 2- to 4-year-old children was conducted to determine if MDA interrupted transmission. Antigen and antifilarial antibody prevalence were 14.3% and 19.7%, respectively. Follow-up surveys were done in 6 villages, including those selected for the cluster survey, to assess risk factors related to continued LF transmission and to pinpoint hotspots of transmission. One hundred houses were mapped in each village using GPS-enabled PDAs, and then 30 houses and 10 alternates were chosen for testing. All individuals in selected houses were asked to participate in a short survey about participation in MDA, history of residence in Leogane and general knowledge of LF. Survey teams returned to the houses at night to collect blood for antigen testing, microfilaremia and Bm14 antibody testing and collected mosquitoes from these communities in parallel. Antigen prevalence was highly variable among the 6 villages, with the highest being 38.2% (Dampus) and the lowest being 2.9% (Corail Lemaire); overall antigen prevalence was 18.5%. Initial cluster surveys of 2- to 4-year-old children were not related to community antigen prevalence. Nearest neighbor analysis found evidence of clustering of infection suggesting that LF infection was focal in distribution. Antigen prevalence among individuals who were systematically noncompliant with the MDAs, i.e. they had never participated, was significantly higher than among compliant individuals (p<0.05). A logistic regression model found that of the factors examined for association with infection, only noncompliance was significantly associated with infection. Thus, continuing transmission of LF seems to be linked to rates of systematic noncompliance. Lymphatic filariasis (LF) is a mosquito-borne parasitic disease that affects an estimated 120 million people worldwide with over 1 billion at risk for infection. LF is considered to be a leading cause of permanent disability worldwide due to the clinical manifestations of the disease. A global effort was established to eliminate LF by 2020 through interruption of transmission by annual mass administrations of anti-parasitic drugs. In Leogane, Haiti, seven rounds of drug administration have been administered and, though infection levels have dropped, transmission has not been interrupted. In this study the authors examined factors that could contribute to continuing transmission of LF in Haiti. Ongoing transmission was confirmed by high infection rates among young children. Infection was found to cluster at the household level within communities. The factor most associated with this transmission was systematic noncompliance with drug administration (i.e. never taking the medication). While increased health education and awareness campaigns may improve noncompliance, new tools and approaches may be needed to stop transmission of LF in Haiti. Understanding obstacles and solutions from the Haiti program could aid elimination programs in other countries.
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Affiliation(s)
- Alexis Boyd
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Kimberly Y. Won
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- * E-mail:
| | - Shannon K. McClintock
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Catherine V. Donovan
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Sandra J. Laney
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Thomas G. Streit
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | | | - Patrick J. Lammie
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
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Laney SJ, Ramzy RMR, Helmy HH, Farid HA, Ashour AA, Weil GJ, Williams SA. Detection of Wuchereria bancrofti L3 larvae in mosquitoes: a reverse transcriptase PCR assay evaluating infection and infectivity. PLoS Negl Trop Dis 2010; 4:e602. [PMID: 20169115 PMCID: PMC2821903 DOI: 10.1371/journal.pntd.0000602] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 12/18/2009] [Indexed: 11/20/2022] Open
Abstract
Background Detection of filarial DNA in mosquitoes by PCR cannot differentiate infective mosquitoes from infected mosquitoes. In order to evaluate transmission risk an assay is needed that can specifically detect infective L3 stage parasites. We now report the development of an assay that specifically detects the infective stage of Wuchereria bancrofti in mosquitoes. The assay detects an L3-activated mRNA transcript by reverse-transcriptase PCR (RT-PCR). Methodology/Principal Findings W. bancrofti cuticle-related genes were selected using bioinformatics and screened as potential diagnostic target genes for L3 detection in mosquitoes. Expression profiles were determined using RT-PCR on RNA isolated from mosquitoes collected daily across a two-week period after feeding on infected blood. Conventional multiplex RT-PCR and real-time multiplex RT-PCR assays were developed using an L3-activated cuticlin transcript for L3 detection and a constitutively expressed transcript, tph-1, for ‘any-stage’ detection. Conclusions/Significance This assay can be used to simultaneously detect W. bancrofti infective stage larvae and ‘any-stage’ larvae in pooled vector mosquitoes. This test may be useful as a tool for assessing changes in transmission potential in the context of filariasis elimination programs. Lymphatic filariasis is a disabling and disfiguring disease caused by a parasite that is transmitted by a mosquito. The life cycle of the parasite requires two hosts: the mosquito vector and the human host. Part of the developmental life cycle of the parasite occurs in the mosquito and the other part in the human host. The parasite develops through four stages in the mosquito, only the last of which is infectious to humans. The third larval stage (L3) is the infective stage that initiates human infections when infective mosquitoes bite humans. There is currently a global program attempting to eliminate this disease by administering drugs to affected communities with the goal of interrupting transmission of the parasite. The new diagnostic tool described in this paper uses molecular techniques to specifically detect the infective stage of the parasite in mosquitoes. Many mosquitoes can be tested at one time to assess the risk of ongoing transmission of filariasis in communities. In addition, this new L3-detection assay can simultaneously detect whether the mosquitoes contain ‘any-stage’ of the parasite. This provides information on infection rates in humans in the community. Both pieces of information can be used in assessing the progress of disease elimination efforts.
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Affiliation(s)
- Sandra J Laney
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA.
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Coquillettidia (Culicidae, Diptera) mosquitoes are natural vectors of avian malaria in Africa. Malar J 2009; 8:193. [PMID: 19664282 PMCID: PMC3152766 DOI: 10.1186/1475-2875-8-193] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 08/10/2009] [Indexed: 11/15/2022] Open
Abstract
Background The mosquito vectors of Plasmodium spp. have largely been overlooked in studies of ecology and evolution of avian malaria and other vertebrates in wildlife. Methods Plasmodium DNA from wild-caught Coquillettidia spp. collected from lowland forests in Cameroon was isolated and sequenced using nested PCR. Female Coquillettidia aurites were also dissected and salivary glands were isolated and microscopically examined for the presence of sporozoites. Results In total, 33% (85/256) of mosquito pools tested positive for avian Plasmodium spp., harbouring at least eight distinct parasite lineages. Sporozoites of Plasmodium spp. were recorded in salivary glands of C. aurites supporting the PCR data that the parasites complete development in these mosquitoes. Results suggest C. aurites, Coquillettidia pseudoconopas and Coquillettidia metallica as new and important vectors of avian malaria in Africa. All parasite lineages recovered clustered with parasites formerly identified from several bird species and suggest the vectors capability of infecting birds from different families. Conclusion Identifying the major vectors of avian Plasmodium spp. will assist in understanding the epizootiology of avian malaria, including differences in this disease distribution between pristine and disturbed landscapes.
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Pedersen EM, Stolk WA, Laney SJ, Michael E. The role of monitoring mosquito infection in the Global Programme to Eliminate Lymphatic Filariasis. Trends Parasitol 2009; 25:319-27. [PMID: 19559649 DOI: 10.1016/j.pt.2009.03.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 03/09/2009] [Accepted: 03/27/2009] [Indexed: 11/26/2022]
Abstract
In addition to monitoring infection in the human host, there is also a need to assess larval infection in the vector mosquito population to evaluate the success of interventions for eliminating lymphatic filariasis transmission from endemic communities. Here, we review the current status of the available tools for quantifying vector infection and existing knowledge and evidence regarding potential infection thresholds for determining transmission interruption, to assess the potential for using vector infection monitoring as a tool for evaluating the success of filariasis treatment programmes.
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Affiliation(s)
- Erling M Pedersen
- DBL-Centre for Health Research and Development, Faculty of Life Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark.
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Weil GJ, Kastens W, Susapu M, Laney SJ, Williams SA, King CL, Kazura JW, Bockarie MJ. The impact of repeated rounds of mass drug administration with diethylcarbamazine plus albendazole on bancroftian filariasis in Papua New Guinea. PLoS Negl Trop Dis 2008; 2:e344. [PMID: 19065257 PMCID: PMC2586652 DOI: 10.1371/journal.pntd.0000344] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 11/11/2008] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND This study employed various monitoring methods to assess the impact of repeated rounds of mass drug administration (MDA) on bancroftian filariasis in Papua New Guinea, which has the largest filariasis problem in the Pacific region. METHODOLOGY/PRINCIPAL FINDINGS Residents of rural villages near Madang were studied prior to and one year after each of three rounds of MDA with diethylcarbamazine plus albendazole administered per World Health Organization (WHO) guidelines. The mean MDA compliance rate was 72.9%. Three rounds of MDA decreased microfilaremia rates (Mf, 1 ml night blood by filter) from 18.6% pre-MDA to 1.3% after the third MDA (a 94% decrease). Mf clearance rates in infected persons were 71%, 90.7%, and 98.1% after 1, 2, and 3 rounds of MDA. Rates of filarial antigenemia assessed by card test (a marker for adult worm infection) decreased from 47.5% to 17.1% (a 64% decrease) after 3 rounds of MDA. The filarial antibody rate (IgG(4) antibodies to Bm14, an indicator of filarial infection status and/or exposure to mosquito-borne infective larvae) decreased from 59.3% to 25.1% (a 54.6% decrease). Mf, antigen, and antibody rates decreased more rapidly in children <11 years of age (by 100%, 84.2%, and 76.8%, respectively) relative to older individuals, perhaps reflecting their lighter infections and shorter durations of exposure/infection prior to MDA. Incidence rates for microfilaremia, filarial antigenemia, and antifilarial antibodies also decreased significantly after MDA. Filarial DNA rates in Anopheles punctulatus mosquitoes that had recently taken a blood meal decreased from 15.1% to 1.0% (a 92.3% decrease). CONCLUSIONS/SIGNIFICANCE MDA had dramatic effects on all filariasis parameters in the study area and also reduced incidence rates. Follow-up studies will be needed to determine whether residual infection rates in residents of these villages are sufficient to support sustained transmission by the An. punctulatus vector. Lymphatic filariasis elimination should be feasible in Papua New Guinea if MDA can be effectively delivered to endemic populations.
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Affiliation(s)
- Gary J Weil
- Washington University School of Medicine, St. Louis, Missouri, USA.
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Ishtiaq F, Guillaumot L, Clegg SM, Phillimore AB, Black RA, Owens IPF, Mundy NI, Sheldon BC. Avian haematozoan parasites and their associations with mosquitoes across Southwest Pacific Islands. Mol Ecol 2008; 17:4545-55. [PMID: 18986499 DOI: 10.1111/j.1365-294x.2008.03935.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The degree to which haematozoan parasites can exploit a range of vectors and hosts has both ecological and evolutionary implications for their transmission and biogeography. Here we explore the extent to which closely related mosquito species share the same or closely related haematozoan parasites, and examine the overlap in parasite lineages with those isolated from avian hosts, Zosterops species, sampled across the same study sites. Mosquito samples were collected and analysed (14 species, n = 804) from four islands in Vanuatu and the main island of New Caledonia. Using polymerase chain reaction, 15.5% (14/90) of pooled mosquito (thoracic) samples showed positive amplifications. Subsequent phylogenetic analysis of the cytochrome b gene identified four genetically distinct Plasmodium and two Haemoproteus lineages from these samples, five of which were identical to parasite lineages (n = 21) retrieved from the avian hosts. We found that three Plasmodium lineages differing by a maximum of 0.9% sequence divergence were recovered from different species and genera of mosquitoes and two Haemoproteus lineages differing by 4.6% sequence divergence were carried by 10 distantly related (11-21% divergent) mosquito species. These data suggest a lack of both cospeciation and invertebrate host conservatism. Without experimental demonstration of the transmission cycle, it is not possible to establish whether these mosquitoes are the biological vectors of isolated parasite lineages, reflecting a limitation of a purely polymerase chain reaction-based approach. Nonetheless, our results raise the possibility of a new transmission pathway and highlight extensive invertebrate host shifts in an insular mosquito-parasite system.
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Affiliation(s)
- F Ishtiaq
- Edward Grey Institute, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
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Laney SJ, Buttaro CJ, Visconti S, Pilotte N, Ramzy RMR, Weil GJ, Williams SA. A reverse transcriptase-PCR assay for detecting filarial infective larvae in mosquitoes. PLoS Negl Trop Dis 2008; 2:e251. [PMID: 18560545 PMCID: PMC2413423 DOI: 10.1371/journal.pntd.0000251] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Accepted: 05/20/2008] [Indexed: 11/19/2022] Open
Abstract
Background Existing molecular assays for filarial parasite DNA in mosquitoes cannot distinguish between infected mosquitoes that contain any stage of the parasite and infective mosquitoes that harbor third stage larvae (L3) capable of establishing new infections in humans. We now report development of a molecular L3-detection assay for Brugia malayi in vectors based on RT-PCR detection of an L3-activated gene transcript. Methodology/Principal Findings Candidate genes identified by bioinformatics analysis of EST datasets across the B. malayi life cycle were initially screened by PCR using cDNA libraries as templates. Stage-specificity was confirmed using RNA isolated from infected mosquitoes. Mosquitoes were collected daily for 14 days after feeding on microfilaremic cat blood. RT-PCR was performed with primer sets that were specific for individual candidate genes. Many promising candidates with strong expression in the L3 stage were excluded because of low-level transcription in less mature larvae. One transcript (TC8100, which encodes a particular form of collagen) was only detected in mosquitoes that contained L3 larvae. This assay detects a single L3 in a pool of 25 mosquitoes. Conclusions/Significance This L3-activated gene transcript, combined with a control transcript (tph-1, accession # U80971) that is constitutively expressed by all vector-stage filarial larvae, can be used to detect filarial infectivity in pools of mosquito vectors. This general approach (detection of stage-specific gene transcripts from eukaryotic pathogens) may also be useful for detecting infective stages of other vector-borne parasites. The Global Programme for the Elimination of Lymphatic Filariasis (GPELF) was launched in the year 1998 with the goal of eliminating lymphatic filariasis by 2020. As the success of mass drug administration (MDA) in the global program drives the rates of infection in endemic populations to very low levels, the development of new, highly sensitive methods are required for monitoring transmission by screening mosquitoes for the presence of L3 infective larvae. The current method of mosquito dissection to identify L3 larvae is laborious and insensitive and is not amenable to screening large numbers of mosquitoes. Existing molecular assays for the detection of filarial parasite DNA in mosquitoes are sensitive and can easily screen large numbers of vectors. However, current PCR-based methods cannot distinguish between infected mosquitoes that contain any stage of the parasite and infective mosquitoes that harbor third stage larvae (L3) capable of establishing new infections in humans. This paper reports the first development of a molecular L3-detection assay for a filarial parasite in mosquitoes based on RT-PCR detection of an L3-activated gene transcript. This strategy of detecting stage-specific messenger RNA from filarial parasites may also prove useful for detecting infective stages of other vector-borne pathogens.
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Affiliation(s)
- Sandra J Laney
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA.
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Boakye DA, Baidoo HA, Glah E, Brown C, Appawu M, Wilson MD. Monitoring lymphatic filariasis interventions: Adult mosquito sampling, and improved PCR - based pool screening method for Wuchereria bancrofti infection in Anopheles mosquitoes. FILARIA JOURNAL 2007; 6:13. [PMID: 18047647 PMCID: PMC2235849 DOI: 10.1186/1475-2883-6-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Accepted: 11/29/2007] [Indexed: 12/01/2022]
Abstract
Background Monitoring and evaluation are essential to the successful implementation of mass drug administration programmes for LF elimination. Monitoring transmission when it is low requires both large numbers of mosquito vectors and sensitive methods for detecting Wuchereria bancrofti infections in them. PCR-based methods are preferred over classical dissections but the best protocol so far achieved detection of one L3 Wuchereria bancrofti larva in a pool of 35–50 Anopheles mosquitoes. It also lacks consistency and remains still a costly tool. Hence we decided to improve upon this to achieve detection in a pool of 100 or more by enhancing the quality of the template DNA. Prior to this we also evaluated three vector sampling methods in the context of numbers for monitoring. Methods Human landing, pyrethrium spray and light traps catches were conducted concurrently at sites in an LF endemic district in Ghana and the numbers obtained compared. Two DNA extraction methods; Bender buffer and phenol/chloroform purification, and DNAeasy Tissue kit (Quaigen Inc) were used on pools of 25, 50, 75 100 and 150 mosquitoes each seeded with one L3 or its quivalent amount of DNA. Then another set of extracted DNA by the two methods was subjected to Dynal bead purification method (using capture oligonucleotide primers). These were used as template DNA in PCR to amplify W. bancrofti sequences. The best PCR result was then evaluated in the field at five sites by comparing its results (infections per 1000 mosquitoes) with that of dissection of roughly equal samples sizes. Results The largest numbers of mosquitoes were obtained with the human landing catches at all the sites sampled. Although PCR detection of one L3 in pools of 25, 50 and 75 mosquitoes was consistent irrespective of the extraction method, that of one L3 in 100 was only achieved with the kit-extracted DNA/Dynal bead purification method. Infections were found at only two sites by both dissection and pool-screening being 14.3 and 19 versus 13.4 and 20.1 per 1000 Anopheles mosquitoes respectively, which were not statistically significant Discussion and conclusion HLC still remains the best option for sampling for the large numbers of mosquitoes required for monitoring transmission during MDA programmes, when vector population densities are high and classical indices of transmission are required. One – in – 100 detection is an improvement on previous PCR pool-screening methods, which in our opinion was a result of the introduction of the extra step of parasite DNA capture using Dynal/beads. As pool sizes increase the insects DNA will swamp parasite DNA making the latter less available for an efficient PCR, therefore we propose either additional steps of parasite DNA capture or real-time PCR to improve further the pool screening method. The study also attests also to the applicability of Katholi et al's algorithm developed for determining onchocerciasis prevalence in LF studies.
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Affiliation(s)
- Daniel A Boakye
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, P,O, Box LG 581, Legon, Accra, Ghana.
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Plichart C, Laney SJ, Sechan Y, Davies N, Legrand AM. Erratum to: PCR and dissection as tools to monitor filarial infection of Aedes polynesiensismosquitoes in French Polynesia. FILARIA JOURNAL 2007. [PMCID: PMC1847676 DOI: 10.1186/1475-2883-6-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Fischer P, Erickson SM, Fischer K, Fuchs JF, Rao RU, Christensen BM, Weil GJ. Persistence of Brugia malayi DNA in vector and non-vector mosquitoes: implications for xenomonitoring and transmission monitoring of lymphatic filariasis. Am J Trop Med Hyg 2007; 76:502-7. [PMID: 17360875 PMCID: PMC2196403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023] Open
Abstract
Xenomonitoring (detection of filarial larvae or their DNA in mosquitoes) is a sensitive marker for assessing the endemicity of filariasis and a useful tool for evaluating elimination programs. To examine the fate of microfilariae (mf) and filarial DNA in vector competent and non-competent mosquito strains, we compared the detection of Brugia malayi parasites by dissection and by quantitative real-time polymerase chain reaction (PCR) in three different mosquito strains. We conclude that PCR is much more sensitive than dissection for detecting filarial larvae, especially their remnants in mosquitoes. However, parasite DNA can be detected in both vector and non-vector mosquitoes for two weeks or longer after they ingest mf-positive blood. Thus, although xenomonitoring with vector and non-vector mosquito species may be a sensitive method for indirectly detecting filarial parasites in human populations, positive test results for parasite DNA in mosquitoes do not necessarily prove that transmission is ongoing in the study area.
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Affiliation(s)
- Peter Fischer
- Department of Internal Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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