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Yi H, Devkota BR, Yu JS, Kim HJ. A research for an eco-friendly mosquito control by using a new mosquito trap (Mos-hole trap) in a cowshed in Yeoju of Korea. Anim Cells Syst (Seoul) 2014. [DOI: 10.1080/19768354.2014.938697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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102
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Dhimal M, Gautam I, Kreß A, Müller R, Kuch U. Spatio-temporal distribution of dengue and lymphatic filariasis vectors along an altitudinal transect in Central Nepal. PLoS Negl Trop Dis 2014; 8:e3035. [PMID: 25078276 PMCID: PMC4117448 DOI: 10.1371/journal.pntd.0003035] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 06/08/2014] [Indexed: 12/31/2022] Open
Abstract
Background Rapidly increasing temperatures in the mountain region of Nepal and recent reports of dengue fever and lymphatic filariasis cases from mountainous areas of central Nepal prompted us to study the spatio-temporal distribution of the vectors of these two diseases along an altitudinal transect in central Nepal. Methodology/Principal Findings We conducted a longitudinal study in four distinct physiographical regions of central Nepal from September 2011 to February 2012. We used BG-Sentinel and CDC light traps to capture adult mosquitoes. We found the geographical distribution of the dengue virus vectors Aedes aegypti and Aedes albopictus along our study transect to extend up to 1,310 m altitude in the Middle Mountain region (Kathmandu). The distribution of the lymphatic filariasis vector Culex quinquefasciatus extended up to at least 2,100 m in the High Mountain region (Dhunche). Statistical analysis showed a significant effect of the physiographical region and month of collection on the abundance of A. aegypti and C. quinquefasciatus only. BG-Sentinel traps captured significantly higher numbers of A. aegypti than CDC light traps. The meteorological factors temperature, rainfall and relative humidity had significant effects on the mean number of A. aegypti per BG-Sentinel trap. Temperature and relative humidity were significant predictors of the number of C. quinquefasciatus per CDC light trap. Dengue fever and lymphatic filariasis cases had previously been reported from all vector positive areas except Dhunche which was free of known lymphatic filariasis cases. Conclusions/Significance We conclude that dengue virus vectors have already established stable populations up to the Middle Mountains of Nepal, supporting previous studies, and report for the first time the distribution of lymphatic filariasis vectors up to the High Mountain region of this country. The findings of our study should contribute to a better planning and scaling-up of mosquito-borne disease control programmes in the mountainous areas of Nepal. Dengue fever, a viral disease transmitted by the bites of infected Aedes aegypti and Aedes albopictus mosquitoes, has been rapidly spreading in Nepal since it was first reported in this country in 2004. Similarly, lymphatic filariasis, a parasitic disease transmitted by Culex quinquefasciatus mosquitoes in Nepal, is a public health problem in terms of morbidity and impact on the social and economic status of poor people living in rural and slum areas. Evidence for more pronounced temperature rises in higher altitudes of Nepal and an increasing frequency of dengue fever and lymphatic filariasis cases reported from mountain areas, in the absence of recent data on the mosquito vectors of these diseases, prompted us to investigate their distribution and abundance in this country. In our study, we document the distribution of A. aegypti and A. albopictus from the lowlands up to 1,310 m altitude in Kathmandu, and the distribution of C. quinquefasciatus up to Dhunche (2,100 m altitude), the highest locality included in this study. The wide distribution of these important disease vectors in the mountains, previously considered non-endemic for dengue fever and lymphatic filariasis, calls for an extension and scaling-up of vector-borne disease surveillance and control programmes in Nepal.
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Affiliation(s)
- Meghnath Dhimal
- Nepal Health Research Council (NHRC), Ministry of Health and Population Complex, Kathmandu, Nepal
- Biodiversity and Climate Research Centre (BiK-F), Frankfurt am Main, Germany
- Institute for Atmospheric and Environmental Sciences (IAU), Goethe University, Frankfurt am Main, Germany
- * E-mail:
| | - Ishan Gautam
- Natural History Museum, Tribhuvan University, Swayambhu, Kathmandu, Nepal
| | - Aljoscha Kreß
- Biodiversity and Climate Research Centre (BiK-F), Frankfurt am Main, Germany
| | - Ruth Müller
- Biodiversity and Climate Research Centre (BiK-F), Frankfurt am Main, Germany
| | - Ulrich Kuch
- Biodiversity and Climate Research Centre (BiK-F), Frankfurt am Main, Germany
- Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe University, Frankfurt am Main, Germany
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103
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Hapairai LK, Marie J, Sinkins SP, Bossin HC. Effect of temperature and larval density on Aedes polynesiensis (Diptera: Culicidae) laboratory rearing productivity and male characteristics. Acta Trop 2014; 132 Suppl:S108-15. [PMID: 24316237 DOI: 10.1016/j.actatropica.2013.11.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 11/25/2013] [Accepted: 11/27/2013] [Indexed: 11/25/2022]
Abstract
Aedes polynesiensis Marks (Diptera: Culicidae) larvae were reared to adulthood in the laboratory under a range of temperatures and larval densities. We studied the effect of these variables on several life table parameters of relevance to male-release-based vector control strategies including: larval survivorship, developmental time to pupation, male to female ratio, male pupae yield, adult male size and survival. The range of tested rearing temperatures (20, 25, 27, and 30 °C) and larval densities (50, 100, 200, and 400 larvae/L) was selected within the conditions allowing larval growth and survival. Larval survivorship was the highest when larvae were reared at 200 larvae/L for all temperatures except 20 °C. Male to female ratio was male biased at all temperatures and densities. Time to pupation decreased with increasing temperatures. Larval density and temperature influenced the proportion of males pupating on first day of pupation with 43-47% of total male pupae produced at 25 °C. No significant differences in mean wing length were observed between male mosquitoes reared in the laboratory (except at 20 and 30 °C for some densities) and field collected males. Altogether, the study allowed the identification of rearing conditions delivering high male yield with essentially no female contamination, adequate adult male size and survival. Ae. polynesiensis thus appears particularly amenable to biological and mechanical sex separation offering good prospects for Ae. polynesiensis population suppression trials that rely on the production and release of large numbers of incompatible or sterile males.
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104
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Filaria zoogeography in Africa: ecology, competitive exclusion, and public health relevance. Trends Parasitol 2014; 30:163-9. [PMID: 24636357 DOI: 10.1016/j.pt.2014.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 02/04/2014] [Accepted: 02/09/2014] [Indexed: 11/20/2022]
Abstract
Six species of filariae infect humans in sub-Saharan Africa. We hypothesise that these nematodes are able to polyparasitise human hosts by having successfully, through competitive exclusion, adapted to distinct niches. Despite inhabiting the same host, adult stages reside in different tissue sites. Microfilariae of some species exhibit temporal separation by reaching peak levels in the blood at specific times of day. Spatial and temporal distributions in microfilaria location are exploited by the vector feeding-behaviour whereas adult survival is enhanced by occupying exclusive 'ecological' niches of the body. We present specific examples to demonstrate this concept, which is not only important from the biological aspect but important in the context of elimination programmes.
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105
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Rebollo MP, Bockarie MJ. Toward the elimination of lymphatic filariasis by 2020: treatment update and impact assessment for the endgame. Expert Rev Anti Infect Ther 2014; 11:723-31. [PMID: 23879610 DOI: 10.1586/14787210.2013.811841] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Lymphatic filariasis (LF) is an important public health problem endemic in 73 countries, where it is a major cause of acute and chronic morbidity and a significant impediment to socioeconomic development. It is targeted for elimination by 2020, through preventive chemotherapy using albendazole in combination with either ivermectin or diethylcarbamazine citrate. Preventive chemotherapy enables the regular and coordinated administration of safe, single-dose medications delivered through mass drug administration (MDA). Many countries are now scaling down MDA activities after achieving 100% geographic coverage and instituting monitoring and evaluation procedures to establish the impact of several consecutive rounds of MDA and determine if transmission has been interrupted. At the same time, countries yet to initiate MDA for elimination of LF will adopt improved mapping and coverage assessment protocols to accelerate the efforts for achieving global elimination by 2020. This review provides an update on treatment for LF and describes the current global status of the elimination efforts, transmission control processes and strategies for measuring impact and continuing surveillance after MDA has ceased.
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Affiliation(s)
- Maria P Rebollo
- Center for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
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106
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Hande S, Goswami K, Jena L, Reddy MVR. Exploring apposite therapeutic target for apoptosis in filarial parasite: a plausible hypothesis. Med Hypotheses 2014; 82:356-61. [PMID: 24472864 DOI: 10.1016/j.mehy.2013.12.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/27/2013] [Indexed: 10/25/2022]
Abstract
Human lymphatic filariasis is a parasitic disease with profound socioeconomic encumbrance owing to its associated disability, affecting predominantly but not limited to the developing nations of tropics and subtropics. There are several technical issues like poor therapeutic and preventive repertoire as well as administrative and infrastructural limitations which jeopardize the salvage measures and further complicate the plight. Therefore, considering the gravity of the problem, WHO has mandated (under tropical disease research scheme) for placing emphasis on validation of novel therapeutic targets against this disease with the unfortunate tag of 'neglected tropical disease'. However, dearth of knowledge of parasite biology viciously coupled with difficulty of access to parasitic material from suitable animal model along with growing cost burden of high end research poses formidable challenge. Based on the recent research evidences, here we propose a premise with targeted apoptotic impact as a novel rationale to be exploited towards anti-parasitic drug development. The new era of bioinformatics ushers in new optimism with a wide range of genomic and proteomic database in public domain. Such platform might offer wonders for drug research, but needs highly selective criterion specificity. In order to test our hypothesis presumptively, we deployed a scheme for identification of target proteins from filarial parasitic origin through wide database search with precise criteria of non-homology against the host along with functional essentiality for the parasite. Further screening for proteins with growth potential from such list of essential non-homologous proteins was undertaken to mine out suitable representative target for ensuing apoptotic impact though effective inhibitors. A unique protein enzyme, RNA dependent RNA polymerase, which besides its vital role in RNA virus is believed to have regulatory role in gene expression, emerged as a plausible target. This protein is rather unknown in human host and present in related nematode parasites including the pathogen of human lymphatic parasite. Further exploitation of bioinformatics approach with a proven inhibitor of this enzyme by molecular docking technique revealed the feasibility as valid antifilarial candidate. This strategy also underscored the significance of bioinformatics tools in circumventing the resource intensive research for drug development. This virtually verified paradigm need to be tested in real lab setting not only for therapeutic authentication of this novel rationale but also for development of insight into parasitic biology that may open up new outlook in host parasite relationship. If successful, this might ensure effective measure against this menace of such 'neglected tropical parasitic diseases'.
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Affiliation(s)
- Sneha Hande
- Department of Biochemistry, Mahatma Gandhi Institute of Medical Sciences, Sevagram 442 102, Maharashtra, India
| | - Kalyan Goswami
- Department of Biochemistry, Mahatma Gandhi Institute of Medical Sciences, Sevagram 442 102, Maharashtra, India.
| | - Lingaraj Jena
- Bioinformatics Center, Jamnalal Bajaj Tropical Disease Research Center, MGIMS, Sevagram 442 102, Maharashtra, India
| | - Maryada Venkata Rami Reddy
- Department of Biochemistry, Mahatma Gandhi Institute of Medical Sciences, Sevagram 442 102, Maharashtra, India
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107
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Bhattacharya K, Chandra G. Phagodeterrence, larvicidal and oviposition deterrence activity of Tragia involucrata L. (Euphorbiaceae) root extractives against vector of lymphatic filariasis Culex quinquefasciatus (Diptera: Culicidae). ASIAN PACIFIC JOURNAL OF TROPICAL DISEASE 2014. [DOI: 10.1016/s2222-1808(14)60444-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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108
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Al-Abd NM, Nor ZM, Al-Adhroey AH, Suhaimi A, Sivanandam S. Recent advances on the use of biochemical extracts as filaricidal agents. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2013; 2013:986573. [PMID: 24298292 PMCID: PMC3835708 DOI: 10.1155/2013/986573] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 09/05/2013] [Indexed: 02/01/2023]
Abstract
Lymphatic filariasis is a parasitic infection that causes a devastating public health and socioeconomic burden with an estimated infection of over 120 million individuals worldwide. The infection is caused by three closely related nematode parasites, namely, Wuchereria bancrofti, Brugia malayi, and B. timori, which are transmitted to human through mosquitoes of Anopheles, Culex, and Aedes genera. The species have many ecological variants and are diversified in terms of their genetic fingerprint. The rapid spread of the disease and the genetic diversification cause the lymphatic filarial parasites to respond differently to diagnostic and therapeutic interventions. This in turn prompts the current challenge encountered in its management. Furthermore, most of the chemical medications used are characterized by adverse side effects. These complications urgently warrant intense prospecting on bio-chemicals that have potent efficacy against either the filarial worms or thier vector. In lieu of this, we presented a review on recent literature that reported the efficacy of filaricidal biochemicals and those employed as vector control agents. In addition, methods used for biochemical extraction, screening procedures, and structure of the bioactive compounds were also presented.
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Affiliation(s)
- Nazeh M. Al-Abd
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Zurainee Mohamed Nor
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Abdulelah H. Al-Adhroey
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Anwar Suhaimi
- Department of Rehabilitation Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - S. Sivanandam
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
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109
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Tediosi F, Steinmann P, de Savigny D, Tanner M. Developing eradication investment cases for onchocerciasis, lymphatic filariasis, and human African trypanosomiasis: rationale and main challenges. PLoS Negl Trop Dis 2013; 7:e2446. [PMID: 24244762 PMCID: PMC3820723 DOI: 10.1371/journal.pntd.0002446] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Fabrizio Tediosi
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Peter Steinmann
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Don de Savigny
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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110
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Long-lasting insecticidal nets are synergistic with mass drug administration for interruption of lymphatic filariasis transmission in Nigeria. PLoS Negl Trop Dis 2013; 7:e2508. [PMID: 24205421 PMCID: PMC3814337 DOI: 10.1371/journal.pntd.0002508] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 09/17/2013] [Indexed: 11/19/2022] Open
Abstract
In central Nigeria Anopheles mosquitoes transmit malaria and lymphatic filariasis (LF). The strategy used for interrupting LF transmission in this area is annual mass drug administration (MDA) with albendazole and ivermectin, but after 8 years of MDA, entomological evaluations in sentinel villages showed continued low-grade mosquito infection rates of 0.32%. After long-lasting insecticidal net (LLIN) distribution by the national malaria program in late 2010, however, we were no longer able to detect infected vectors over a 24-month period. This is evidence that LLINs are synergistic with MDA in interrupting LF transmission. In Plateau and Nasarawa states in central Nigeria, 4 million persons are threatened by a mosquito-transmitted parasitic disease called lymphatic filariasis (LF). LF can lead to elephantiasis, a crippling condition in which the limbs and genitals often are grotesquely swollen or enlarged. In communities afflicted by this disease, as many as 10% can be affected with swollen limbs, and 50% of men can suffer from swollen genitals. These conditions have a devastating effect on the quality of life of victims, impacting them not only physically but also emotionally and economically. Through health education and community-delivered mass drug administration (MDA) with donated medicines, the Nigerian Ministry of Health and its Carter Center partners have been trying to stop mosquitoes from transmitting LF. LF transmission, as measured by mosquito dissections, dropped dramatically after 8 years of annual MDA. However, it was not until the malaria program distributed long-lasting insecticidal nets in 2010 that the LF parasite no longer appeared in mosquito dissections. No LF infected mosquito was found over a 24-month long surveillance period following long-lasting insecticidal net distribution. The study concluded that MDA and long-lasting insecticidal nets work together to halt the transmission of LF.
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111
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Shawa ST, Mwase ET, Pedersen EM, Simonsen PE. Lymphatic filariasis in Luangwa District, South-East Zambia. Parasit Vectors 2013; 6:299. [PMID: 24499525 PMCID: PMC3853755 DOI: 10.1186/1756-3305-6-299] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 10/04/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Past case reports and recent data from LF mapping surveys indicate that LF occurs in Zambia, but no studies have been carried out to document its epidemiology and health implications. The present study assessed infection, disease, transmission and human perception aspects of LF in an endemic area of Luangwa District, South-East Zambia, as a background for planning and implementation of control. METHODS Two neighbouring rural communities were registered and a questionnaire survey undertaken. Clinical examination, and sampling of blood for circulating filarial antigens (CFA; marker of adult worm infection) and antibodies to Bm14 antigen (marker of exposure to transmission), were carried out during the daytime. Blood from CFA positive individuals was examined for microfilariae (mf) at night. Vector surveys were carried out in selected households, using light traps. RESULTS 985 individuals aged ≥ 1 year were registered. The CFA prevalence increased with age from 1.2% in age group 1-14 years to 20.6% in age group 50+ years (overall 8.6%). Wuchereria bancrofti mf were identified in 10.9% of CFA positive individuals (corresponding to a community prevalence of 0.9%). Prevalence and intensity of Bm14 antibodies were much higher in individuals ≥ 30 years than in younger individuals (57.2 vs. 19.3%; 0.594 vs. 0.241 OD-values). Elephantiasis and hydrocele were well known clinical manifestations in the area, but only one case of hydrocele was detected in the study population. Identified potential vectors were Anopheles funestus and An. gambiae. CONCLUSION The study confirmed that LF was endemic in the study communities, but infection and disease prevalence was low. Several indications, including a marked recent decline in CFA prevalence, suggest that transmission in the area is on the decrease, perhaps because of intensive application of malaria control measures targeting the Anopheles vectors. It is recommended that mass drug administration is initiated to accelerate this positive trend of decline in LF transmission in the area.
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Affiliation(s)
| | | | | | - Paul E Simonsen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Thorvaldsensvej 57, 1871 Frederiksberg C, Denmark.
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112
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Mosquito-parasite interactions can shape filariasis transmission dynamics and impact elimination programs. PLoS Negl Trop Dis 2013; 7:e2433. [PMID: 24069488 PMCID: PMC3772046 DOI: 10.1371/journal.pntd.0002433] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 08/06/2013] [Indexed: 11/19/2022] Open
Abstract
The relationship between mosquito vectors and lymphatic filariasis (LF) parasites can result in a range of transmission outcomes. Anophelines are generally characterized as poor vectors due to an inability to support development at low densities. However, it is important to understand the potential for transmission in natural vectors to maximize the success of elimination efforts. Primary vectors in Papua New Guinea (n = 1209) were dissected following exposure to microfilaremic blood (range 8-233 mf/20 µl). We examined density dependent and species-specific parasite prevalence, intensity and yield, barriers to parasite development as well as impacts on mosquito survival. We observed strikingly different parasite prevalence and yield among closely related species. Prevalence of infective stage larvae (L3s) ranged from 4.2% to 23.7% in An. punctulatus, 24.5% to 68.6% in An. farauti s.s. and 61.9% to 100% in An. hinesorum at low and high density exposures, respectively. Injection experiments revealed the greatest barrier to parasite development involved passage from the midgut into the hemocoel. The ratio of L3 to ingested mf at low densities was higher in An. hinesorum (yield = 1.0) and An. farauti s.s. (yield = 0.5) than has been reported in other anopheline vectors. There was a negative relationship between mosquito survival and bloodmeal mf density. In An. farauti s.s., increased parasite yield and survival at low densities suggest greater competence at low microfilaremias. In Papua New Guinea the likelihood of transmission will be strongly influenced by vector composition and changes in the mf reservoir as a result of elimination efforts. Global elimination efforts will be strengthened by the knowledge of transmission potential in the context of current control measures.
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113
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Fitness cost of Litomosoides sigmodontis filarial infection in mite vectors; implications of infected haematophagous arthropod excretory products in host-vector interactions. BIOMED RESEARCH INTERNATIONAL 2013; 2013:584105. [PMID: 24089685 PMCID: PMC3781844 DOI: 10.1155/2013/584105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 07/24/2013] [Accepted: 07/26/2013] [Indexed: 11/18/2022]
Abstract
Filariae are a leading cause of infections which are responsible for serious dermatological, ocular, and vascular lesions. Infective third stage larvae (L3) are transmitted through the bite of a haematophagous vector. Litomosoides sigmodontis is a well-established model of filariasis in the mouse, with the vector being the mite Ornithonyssus bacoti. The aim of the study was to analyse the filarial infection in mites to determine the consequences of filarial infection in the blood-feeding and the reproduction of mites as well as in the regulation of vector-induced inflammation in the mouse skin. Firstly, L3 are unevenly distributed throughout the host population and the majority of the population harbours a moderate infection (1 to 6 L3). Filarial infection does not significantly affect the probing delay for blood feeding. The number of released protonymphs is lower in infected mites but is not correlated with the L3 burden. Finally, induced excreted proteins from infected mites but not from uninfected mites stimulate TNF- α and the neutrophil-chemoattractant KC production by antigen-presenting cells (APCs). Altogether, these results describe the modification of the mite behavior under filarial infection and suggest that the immunomodulatory capacity of the mite may be modified by the presence of the parasite, hindering its defensive ability towards the vertebrate host.
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114
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Onyango SA, Kitron U, Mungai P, Muchiri EM, Kokwaro E, King CH, Mutuku FM. Monitoring malaria vector control interventions: effectiveness of five different adult mosquito sampling methods. JOURNAL OF MEDICAL ENTOMOLOGY 2013; 50:1140-51. [PMID: 24180120 PMCID: PMC3975164 DOI: 10.1603/me12206] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Long-term success of ongoing malaria control efforts based on mosquito bed nets (long-lasting insecticidal net) and indoor residual spraying is dependent on continuous monitoring of mosquito vectors, and thus on effective mosquito sampling tools. The objective of our study was to identify the most efficient mosquito sampling tool(s) for routine vector surveillance for malaria and lymphatic filariasis transmission in coastal Kenya. We evaluated relative efficacy of five collection methods--light traps associated with a person sleeping under a net, pyrethrum spray catches, Prokopack aspirator, clay pots, and urine-baited traps--in four villages representing three ecological settings along the south coast of Kenya. Of the five methods, light traps were the most efficient for collecting female Anopheles gambiae s.l. (Giles) (Diptera: Culicidae) and Anopheles funestus (Giles) (Diptera: Culicidae) mosquitoes, whereas the Prokopack aspirator was most efficient in collecting Culex quinquefasciatus (Say) (Diptera: Culicidae) and other culicines. With the low vector densities here, and across much of sub-Saharan Africa, wherever malaria interventions, long-lasting insecticidal nets, and/or indoor residual spraying are in place, the use of a single mosquito collection method will not be sufficient to achieve a representative sample of mosquito population structure. Light traps will remain a relevant tool for host-seeking mosquitoes, especially in the absence of human landing catches. For a fair representation of the indoor mosquito population, light traps will have to be supplemented with aspirator use, which has potential for routine monitoring of indoor resting mosquitoes, and can substitute the more labor-intensive and intrusive pyrethrum spray catches. There are still no sufficiently efficient mosquito collection methods for sampling outdoor mosquitoes, particularly those that are bloodfed.
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Affiliation(s)
- Shirley A. Onyango
- Department of Zoological Sciences, Kenyatta University, P.O. Box 43844, Nairobi 00100, Kenya
| | - Uriel Kitron
- Department of Environmental Studies, Math and Science Center, 400 Dowman Dr., Suite E511, Emory University, Atlanta, GA 30322
| | - Peter Mungai
- Center for Global Health and Diseases, CWRU School of Medicine, Wolstein 4126, 10900 Euclid Ave., Cleveland, OH, 44106-7286
| | - Eric M. Muchiri
- Division of Vector Borne Neglected and Tropical Diseases, Ministry of Public Health and Sanitation, P.O. Box 20750, Nairobi 00202, Kenya
| | - Elizabeth Kokwaro
- Department of Zoological Sciences, Kenyatta University, P.O. Box 43844, Nairobi 00100, Kenya
| | - Charles H. King
- Center for Global Health and Diseases, CWRU School of Medicine, Wolstein 4126, 10900 Euclid Ave., Cleveland, OH, 44106-7286
| | - Francis M. Mutuku
- Department of Environmental Studies, Math and Science Center, 400 Dowman Dr., Suite E511, Emory University, Atlanta, GA 30322
- Corresponding author,
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115
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Richards FO, Emukah E, Graves PM, Nkwocha O, Nwankwo L, Rakers L, Mosher A, Patterson A, Ozaki M, Nwoke BEB, Ukaga CN, Njoku C, Nwodu K, Obasi A, Miri ES. Community-wide distribution of long-lasting insecticidal nets can halt transmission of lymphatic filariasis in southeastern Nigeria. Am J Trop Med Hyg 2013; 89:578-87. [PMID: 23939708 PMCID: PMC3771303 DOI: 10.4269/ajtmh.12-0775] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 05/17/2013] [Indexed: 11/07/2022] Open
Abstract
Lymphatic filariasis (LF) in rural southeastern Nigeria is transmitted mainly by Anopheles spp. mosquitoes. Potential coinfection with Loa loa in this area has prevented use of ivermectin in the mass drug administration (MDA) strategy for LF elimination because of potential severe adverse L. loa-related reactions. This study determined if long-lasting insecticidal net (LLIN) distribution programs for malaria would interrupt LF transmission in such areas, without need for MDA. Monthly entomologic monitoring was conducted in sentinel villages before and after LLIN distribution to all households and all age groups (full coverage) in two districts, and to pregnant women and children less than five years of age in the other two districts. No change in human LF microfilaremia prevalence was observed, but mosquito studies showed a statistically significant decrease in LF infection and infectivity with full-coverage LLIN distribution. We conclude that LF transmission can be halted in southeastern Nigeria by full-coverage LLIN distribution, without MDA.
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Affiliation(s)
- Frank O Richards
- Malaria, River Blindness, Lymphatic Filariasis, and Schistosomiasis Programs, The Carter Center, 453 Freedom Parkway, Atlanta, GA 30307, USA.
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Hapairai LK, Sang MAC, Sinkins SP, Bossin HC. Population studies of the filarial vector Aedes polynesiensis (Diptera: Culicidae) in two island settings of French Polynesia. JOURNAL OF MEDICAL ENTOMOLOGY 2013; 50:965-976. [PMID: 24180100 DOI: 10.1603/me12246] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A mark-release-recapture study was conducted to estimate the adult population size, migration, and dispersal patterns of male and female Aedes (Stegomyia) polynesiensis (Marks) in a valley of Moorea, a volcanic island, and a motu (islet) on the atoll of Tetiaroa, two settings typical of the Society Islands. Aedes polynesiensis recapture rate was high for females and low for males. The distribution of Aedes species in the valley was heterogeneous. Marked individuals dispersed to most parts of the motu and over great distances in the valley for some females. The study provides insights into the field dynamics of Ae. polynesiensis populations and confirms that more efficient sampling methods are warranted. There was no evidence of active migration between motus on the atoll, suggesting that Tetiaroa is a suitable site for small-scale initial open releases of Wolbachia incompatible insect technique and other sterile insect technique-like suppression or replacement strategies.
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Affiliation(s)
- Limb K Hapairai
- Unit of Emerging Infectious Diseases, Institut Louis Malardé, Papeete, Tahiti 98713, French Polynesia
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Reimer LJ, Thomsen EK, Tisch DJ, Henry-Halldin CN, Zimmerman PA, Baea ME, Dagoro H, Susapu M, Hetzel MW, Bockarie MJ, Michael E, Siba PM, Kazura JW. Insecticidal bed nets and filariasis transmission in Papua New Guinea. N Engl J Med 2013; 369:745-53. [PMID: 23964936 PMCID: PMC3835352 DOI: 10.1056/nejmoa1207594] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Global efforts to eliminate lymphatic filariasis are based on the annual mass administration of antifilarial drugs to reduce the microfilaria reservoir available to the mosquito vector. Insecticide-treated bed nets are being widely used in areas in which filariasis and malaria are coendemic. METHODS We studied five villages in which five annual mass administrations of antifilarial drugs, which were completed in 1998, reduced the transmission of Wuchereria bancrofti, one of the nematodes that cause lymphatic filariasis. A total of 21,899 anopheles mosquitoes were collected for 26 months before and 11 to 36 months after bed nets treated with long-lasting insecticide were distributed in 2009. We evaluated the status of filarial infection and the presence of W. bancrofti DNA in anopheline mosquitoes before and after the introduction of insecticide-treated bed nets. We then used a model of population dynamics to estimate the probabilities of transmission cessation. RESULTS Village-specific rates of bites from anopheline mosquitoes ranged from 6.4 to 61.3 bites per person per day before the bed-net distribution and from 1.1 to 9.4 bites for 11 months after distribution (P<0.001). During the same period, the rate of detection of W. bancrofti in anopheline mosquitoes decreased from 1.8% to 0.4% (P=0.005), and the rate of detection of filarial DNA decreased from 19.4% to 14.9% (P=0.13). The annual transmission potential was 5 to 325 infective larvae inoculated per person per year before the bed-net distribution and 0 after the distribution. Among all five villages with a prevalence of microfilariae of 2 to 38%, the probability of transmission cessation increased from less than 1.0% before the bed-net distribution to a range of 4.9 to 95% in the 11 months after distribution. CONCLUSIONS Vector control with insecticide-treated bed nets is a valuable tool for W. bancrofti elimination in areas in which anopheline mosquitoes transmit the parasite. (Funded by the U.S. Public Health Service and the National Institutes of Health.).
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Affiliation(s)
- Lisa J Reimer
- Papua New Guinea Institute of Medical Research, Goroka and Madang, Papua New Guinea
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Singh BK, Bockarie MJ, Gambhir M, Siba PM, Tisch DJ, Kazura J, Michael E. Sequential modelling of the effects of mass drug treatments on anopheline-mediated lymphatic filariasis infection in Papua New Guinea. PLoS One 2013; 8:e67004. [PMID: 23826185 PMCID: PMC3691263 DOI: 10.1371/journal.pone.0067004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 05/16/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Lymphatic filariasis (LF) has been targeted by the WHO for global eradication leading to the implementation of large scale intervention programs based on annual mass drug administrations (MDA) worldwide. Recent work has indicated that locality-specific bio-ecological complexities affecting parasite transmission may complicate the prediction of LF extinction endpoints, casting uncertainty on the achievement of this initiative. One source of difficulty is the limited quantity and quality of data used to parameterize models of parasite transmission, implying the important need to update initially-derived parameter values. Sequential analysis of longitudinal data following annual MDAs will also be important to gaining new understanding of the persistence dynamics of LF. Here, we apply a Bayesian statistical-dynamical modelling framework that enables assimilation of information in human infection data recorded from communities in Papua New Guinea that underwent annual MDAs, into our previously developed model of parasite transmission, in order to examine these questions in LF ecology and control. RESULTS Biological parameters underlying transmission obtained by fitting the model to longitudinal data remained stable throughout the study period. This enabled us to reliably reconstruct the observed baseline data in each community. Endpoint estimates also showed little variation. However, the updating procedure showed a shift towards higher and less variable values for worm kill but not for any other drug-related parameters. An intriguing finding is that the stability in key biological parameters could be disrupted by a significant reduction in the vector biting rate prevailing in a locality. CONCLUSIONS Temporal invariance of biological parameters in the face of intervention perturbations indicates a robust adaptation of LF transmission to local ecological conditions. The results imply that understanding the mechanisms that underlie locally adapted transmission dynamics will be integral to identifying points of system fragility, and thus countermeasures to reliably facilitate LF extinction both locally and globally.
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Affiliation(s)
- Brajendra K Singh
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America.
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Bockarie MJ, Kelly-Hope LA, Rebollo M, Molyneux DH. Preventive chemotherapy as a strategy for elimination of neglected tropical parasitic diseases: endgame challenges. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120144. [PMID: 23798692 PMCID: PMC3720042 DOI: 10.1098/rstb.2012.0144] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Global efforts to address neglected tropical diseases (NTDs) were stimulated in January 2012 by the London declaration at which 22 partners, including the Bill & Melinda Gates Foundation, World Bank, World Health Organization (WHO) and major pharmaceutical companies committed to sustaining and expanding NTD programmes to eliminate or eradicate 11 NTDs by 2020 to achieve the goals outlined in the recently published WHO road map. Here, we present the current context of preventive chemotherapy for some NTDs, and discuss the problems faced by programmes as they consider the 'endgame', such as difficulties of access to populations in post-conflict settings, limited human and financial resources, and the need to expand access to clean water and improved sanitation for schistosomiasis and soil-transmitted helminthiasis. In the case of onchocerciasis and lymphatic filariasis, ivermectin treatment carries a significant risk owing to serious adverse effects in some patients co-infected with the tropical eye worm Loa loa filariasis. We discuss the challenges of managing complex partnerships, and maintain advocacy messages for the continued support for elimination of these preventable diseases.
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Affiliation(s)
- Moses J Bockarie
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.
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Can malaria vector control accelerate the interruption of lymphatic filariasis transmission in Africa; capturing a window of opportunity? Parasit Vectors 2013; 6:39. [PMID: 23433078 PMCID: PMC3599698 DOI: 10.1186/1756-3305-6-39] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Accepted: 02/05/2013] [Indexed: 11/23/2022] Open
Abstract
Background The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was launched in 2000, and nearly all endemic countries in the Americas, Eastern Mediterranean and Asia-Pacific regions have now initiated the WHO recommended mass drug administration (MDA) campaign to interrupt transmission of the parasite. However, nearly 50% of the LF endemic countries in Africa are yet to implement the GPELF MDA strategy, which does not include vector control. Nevertheless, the recent scale up in insecticide treated /long lasting nets (ITNs/LLINs) and indoor residual spraying (IRS) for malaria control in Africa may significantly impact LF transmission because the parasite is transmitted mainly by Anopheles mosquitoes. This study examined the magnitude, geographical extent and potential impact of vector control in the 17 African countries that are yet to or have only recently started MDA. Methods National data on mosquito bed nets, ITNs/LLINs and IRS were obtained from published literature, national reports, surveys and datasets from public sources such as Demographic Health Surveys, Malaria Indicator Surveys, Multiple Indicator Cluster Surveys, Malaria Report, Roll Back Malaria and President’s Malaria Initiative websites. The type, number and distribution of interventions were summarised and mapped at sub-national level. and compared with known or potential LF distributions, and those which may be co-endemic with Loa loa and MDA is contraindicated. Results Analyses found that vector control activities had increased significantly since 2005, with a three-fold increase in ITN ownership and IRS coverage. However, coverage varied dramatically across the 17 countries; some regions reported >70% ITNs ownership and regular IRS activity, while others had no coverage in remote rural populations where the risk of LF was potentially high and co-endemic with high risk L.loa. Conclusions Despite many African countries being slow to initiate MDA for LF, the continued commitment and global financial support for NTDs, and the concurrent expansion of vector control activities for malaria, is promising. It is not beyond the capacity of GPELF to reach its target of global LF elimination by 2020, but monitoring and evaluating the impact of these activities over the next decade will be critical to its success.
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Correia JC, Barbosa RMR, Oliveira CMFD, Albuquerque CMRD. Residential characteristics aggravating infestation by Culex quinquefasciatus in a region of Northeastern Brazil. Rev Saude Publica 2013; 46:935-41. [PMID: 23380836 DOI: 10.1590/s0034-89102013005000010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE Analyse how basic sanitation conditions, water supply and housing conditions affect the concentration of Culex quinquefasciatus METHODS Populations of C. quinquefasciatus in 61 houses in the municipality of Olinda, PE, were monitored between October 2009 and October 2010. Observations were carried out in homes without the presence of preferred breeding sites in order to identify characteristics that may be aggravating factors for the development of the mosquito. Five aggravating factors were analysed: vegetation cover surrounding the home, number of residents/home, water storage, sewage drainage and water drainage. These characteristics were analysed in terms of presence or absence and as indicators of the degree of infestation, which was estimated through monitoring the concentration of eggs (oviposition traps - BR-OVT) and adults (CDC light traps). RESULTS Sewage drainage to a rudimentary septic tank or to the open air was the most frequent aggravating factor in the homes (91.8%), although the presence of vegetation was the only characteristic that significantly influenced the increase in the number of egg rafts (p = 0.02). The BR-OVT achieved positive results in 95.1% of the evaluations, with the presence of at least one egg raft per month. A total of 2,366 adults were caught, with a mosquito/room/night ratio of 32.9. No significant difference was found in the number of mosquitoes caught in the homes. CONCLUSIONS Although the sanitation and water supply influence the population density of C. quinquefasciatus, residence features that are not usually considered in control measures can be aggravating factors in sustaining the mosquito population.
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Affiliation(s)
- Juliana Cavalcanti Correia
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, 52011-330 Recife, PE, Brasil.
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Graves PM, Makita L, Susapu M, Brady MA, Melrose W, Capuano C, Zhang Z, Dapeng L, Ozaki M, Reeve D, Ichimori K, Kazadi WM, Michna F, Bockarie MJ, Kelly-Hope LA. Lymphatic filariasis in Papua New Guinea: distribution at district level and impact of mass drug administration, 1980 to 2011. Parasit Vectors 2013; 6:7. [PMID: 23311302 PMCID: PMC3606332 DOI: 10.1186/1756-3305-6-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 12/23/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Lymphatic filariasis (LF) caused by Wuchereria bancrofti is present at high prevalence in some parts of Papua New Guinea. However, there has been no rigorous data-based representative assessment of nationwide prevalence of LF. The LF programme has been daunted by the scope of the problem, and progress on mass drug administration (MDA) has been slow and lacking in resources. METHODS A systematic literature review identified LF surveys in Papua New Guinea between 1980 and 2011. Results were extracted by location, time period and test used (blood slide, immunochromatographic test (ICT) or Og4C3 ELISA) and combined by district. Three criteria schemes based on the Global Programme to Eliminate Lymphatic Filariasis guidelines, with modifications, were developed to classify and prioritize districts by prevalence level. Results of repeated surveys in the same sites were used to investigate the impact of MDA on LF prevalence over the time period. RESULTS There were 312 distinct survey sites identified in 80 of the 89 districts over the 31-year period. The overall LF prevalence in the sites tested was estimated at 18.5 to 27.5% by blood slide for microfilariae (Mf), 10.1% to 12.9% by ICT and 45.4% to 48.8% by Og4C3. Biases in site selection towards areas with LF, and change in type of assay used, affected the prevalence estimates, but overall decline in prevalence over the time period was observed. Depending on the criteria used, 34 to 36 districts (population 2.7 to 2.9 million) were classed as high endemic (≥5% prevalence), 15 to 25 districts (1.7 to 1.9 million) as low endemic (<5%) and 20 to 31 (1.3 to 2.2 million) as non-endemic. Nine districts (0.7 million) had no information. The strong impact of MDA, especially on microfilaria (Mf) prevalence, was noted in sites with repeat surveys. CONCLUSIONS This analytical review of past surveys of LF in Papua New Guinea enables better estimation of the national burden, identifies gaps in knowledge, quantifies and locates the population at risk, and can be used to predict the likely impact of MDA and/or vector control. Better targeting of districts by level of prevalence will strengthen the control programme, facilitate monitoring of the disease trend and increase the likelihood of reaching the target of LF elimination by 2020.
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Affiliation(s)
- Patricia M Graves
- Department of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Cairns and Townsville, Queensland, Australia
- James Cook University, PO Box 6811, Cairns, Queensland, 4870, Australia
| | - Leo Makita
- Department of Health, Port Moresby, Papua New Guinea
| | - Melinda Susapu
- Department of Health, Port Moresby, Papua New Guinea
- WHO, Port Moresby, Papua New Guinea
| | - Molly A Brady
- Current address: WHO, Regional Office for the Western Pacific, Manila, Philippines
| | - Wayne Melrose
- Department of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Cairns and Townsville, Queensland, Australia
| | - Corinne Capuano
- Current address: WHO, Regional Office for the Western Pacific, Manila, Philippines
| | | | | | - Masayo Ozaki
- WHO, Pacific Programme to Eliminate Lymphatic Filariasis (PacELF), Suva, Republic of Fiji
- Current address: University of Alabama School of Medicine, Birmingham, Alabama, USA
| | - David Reeve
- Department of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Cairns and Townsville, Queensland, Australia
| | | | | | - Frederick Michna
- Department of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Cairns and Townsville, Queensland, Australia
| | - Moses J Bockarie
- Liverpool School of Tropical Medicine (LSTM), Centre for Neglected Tropical Diseases, Liverpool, United Kingdom of Great Britain and Northern Ireland
| | - Louise A Kelly-Hope
- Liverpool School of Tropical Medicine (LSTM), Centre for Neglected Tropical Diseases, Liverpool, United Kingdom of Great Britain and Northern Ireland
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McNulty SN, Mitreva M, Weil GJ, Fischer PU. Inter and intra-specific diversity of parasites that cause lymphatic filariasis. INFECTION GENETICS AND EVOLUTION 2012. [PMID: 23201850 DOI: 10.1016/j.meegid.2012.11.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Lymphatic filariasis is caused by three closely related nematode parasites: Wuchereria bancrofti, Brugia malayi and Brugia timori. These species have many ecological variants that differ in several aspects of their biology such as mosquito vector species, host range, periodicity, and morphology. Although the genome of B. malayi (the first genome sequenced from a parasitic nematode) has been available for more than five years, very little is known about genetic variability among the lymphatic dwelling filariae. The genetic diversity among these worms is not only interesting from a biological perspective, but it may have important practical implications for the Global Program to Eliminate Lymphatic Filariasis, as the parasites may respond differently to diagnostic tests and/or medical interventions. Therefore, better information on their genetic variability is urgently needed. With improved methods for nucleic acid extraction and recent advances in sequencing chemistry and instrumentation, this gap can be filled relatively inexpensively. Improved information on filarial genetic diversity may increase the chances of success for lymphatic filariasis elimination programs.
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Affiliation(s)
- Samantha N McNulty
- Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States
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Fontes G, Leite AB, Vasconcelos de Lima AR, Freitas H, Ehrenberg JP, da Rocha EMM. Lymphatic filariasis in Brazil: epidemiological situation and outlook for elimination. Parasit Vectors 2012; 5:272. [PMID: 23181663 PMCID: PMC3545725 DOI: 10.1186/1756-3305-5-272] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Accepted: 11/01/2012] [Indexed: 11/10/2022] Open
Abstract
Since the World Health Assembly's (Resolution WHA 50.29, 1997) call for the elimination of lymphatic filariasis by the year 2020, most of the endemic countries identified have established programmes to meet this objective. In 1997, a National Lymphatic Filariasis Elimination Plan was drawn up by the Ministry of Health of Brazil, creating local programs for the elimination of Bancroftian filariasis in areas with active transmission. Based on a comprehensive bibliographic search for available studies and reports of filariasis epidemiology in Brazil, current status of this parasitic infection and the outlook for its elimination in the country were analysed. From 1951 to 1958 a nationwide epidemiological study conducted in Brazil confirmed autochthonous transmission of Bancroftian filariasis in 11 cities of the country. Control measures led to a decline in parasite rates, and in the 1980s only the cities of Belém in the Amazonian region (Northern region) and Recife (Northeastern region) were considered to be endemic. In the 1990s, foci of active transmission of LF were also described in the cities of Maceió, Olinda, Jaboatão dos Guararapes, and Paulista, all in the Northeastern coast of Brazil. Data provide evidence for the absence of microfilaremic subjects and infected mosquitoes in Belém, Salvador and Maceió in the past few years, attesting to the effectiveness of the measures adopted in these cities. Currently, lymphatic filariasis is a public health problem in Brazil only in four cities of the metropolitan Recife region (Northeastern coast). Efforts are being concentrated in these areas, with a view to eliminating the disease in the country.
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Affiliation(s)
- Gilberto Fontes
- Universidade Federal de Alagoas, Maceió, Alagoas, Brazil
- Universidade Federal de São João del Rei, Campus Centro Oeste, Rua Sebastião Gonçalves Coelho, 400, Divinópolis, Minas Gerais, 35501-296, Brazil
| | | | | | - Helen Freitas
- Secretaria de Vigilância em Saúde do Ministério da Saúde, Brasilia, Brazil
| | - John Patrick Ehrenberg
- World Health Organization (WHO – WPRO), Western Pacific Regional Office, Manila, Philippines
| | - Eliana Maria Mauricio da Rocha
- Universidade Federal de Alagoas, Maceió, Alagoas, Brazil
- Universidade Federal de São João del Rei, Campus Centro Oeste, Rua Sebastião Gonçalves Coelho, 400, Divinópolis, Minas Gerais, 35501-296, Brazil
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O'Connor L, Plichart C, Sang AC, Brelsfoard CL, Bossin HC, Dobson SL. Open release of male mosquitoes infected with a wolbachia biopesticide: field performance and infection containment. PLoS Negl Trop Dis 2012; 6:e1797. [PMID: 23166845 PMCID: PMC3499408 DOI: 10.1371/journal.pntd.0001797] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 07/13/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Lymphatic filariasis (LF) is a globally significant disease, with 1.3 billion persons in 83 countries at risk. A coordinated effort of administering annual macrofilaricidal prophylactics to the entire at-risk population has succeeded in impacting and eliminating LF transmission in multiple regions. However, some areas in the South Pacific are predicted to persist as transmission sites, due in part to the biology of the mosquito vector, which has led to a call for additional tools to augment drug treatments. Autocidal strategies against mosquitoes are resurging in the effort against invasive mosquitoes and vector borne disease, with examples that include field trials of genetically modified mosquitoes and Wolbachia population replacement. However, critical questions must be addressed in anticipation of full field trials, including assessments of field competitiveness of transfected males and the risk of unintended population replacement. METHODOLOGY/PRINCIPAL FINDINGS We report the outcome of field experiments testing a strategy that employs Wolbachia as a biopesticide. The strategy is based upon Wolbachia-induced conditional sterility, known as cytoplasmic incompatibility, and the repeated release of incompatible males to suppress a population. A criticism of the Wolbachia biopesticide approach is that unintended female release or horizontal Wolbachia transmission can result in population replacement instead of suppression. We present the outcome of laboratory and field experiments assessing the competitiveness of transfected males and their ability to transmit Wolbachia via horizontal transmission. CONCLUSIONS/SIGNIFICANCE The results demonstrate that Wolbachia-transfected Aedes polynesiensis males are competitive under field conditions during a thirty-week open release period, as indicated by mark, release, recapture and brood-hatch failure among females at the release site. Experiments demonstrate the males to be 'dead end hosts' for Wolbachia and that methods were adequate to prevent population replacement at the field site. The findings encourage the continued development and extension of a Wolbachia autocidal approach to additional medically important mosquito species.
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Affiliation(s)
- Linda O'Connor
- Department of Entomology, University of Kentucky, Lexington, Kentucky, United States of America
| | | | | | - Corey L. Brelsfoard
- Department of Entomology, University of Kentucky, Lexington, Kentucky, United States of America
| | | | - Stephen L. Dobson
- Department of Entomology, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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de Souza DK, Koudou B, Kelly-Hope LA, Wilson MD, Bockarie MJ, Boakye DA. Diversity and transmission competence in lymphatic filariasis vectors in West Africa, and the implications for accelerated elimination of Anopheles-transmitted filariasis. Parasit Vectors 2012; 5:259. [PMID: 23151383 PMCID: PMC3533928 DOI: 10.1186/1756-3305-5-259] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 11/04/2012] [Indexed: 11/10/2022] Open
Abstract
Lymphatic Filariasis (LF) is targeted for elimination by the Global Programme for the Elimination of Lymphatic Filariasis (GPELF). The strategy adopted is based on the density dependent phenomenon of Facilitation, which hypothesizes that in an area where the vector species transmitting Wuchereria bancrofti are Anopheles mosquitoes, it is feasible to eliminate LF using Mass Drug Administration (MDA) because of the inability of Anopheles species to transmit low-density microfilaraemia. Even though earlier studies have shown Anopheles species can exhibit the process of Facilitation in West Africa, observations point towards the process of Limitation in certain areas, in which case vector control is recommended. Studies on Anopheles species in West Africa have also shown genetic differentiation, cryptic taxa and speciation, insecticide resistance and the existence of molecular and chromosomal forms, all of which could influence the vectorial capacity of the mosquitoes and ultimately the elimination goal. This paper outlines the uniqueness of LF vectors in West Africa and the challenges it poses to the 2020 elimination goal, based on the current MDA strategies.
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Affiliation(s)
- Dziedzom K de Souza
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon-Accra, Ghana
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van den Berg H, Kelly-Hope LA, Lindsay SW. Malaria and lymphatic filariasis: the case for integrated vector management. THE LANCET. INFECTIOUS DISEASES 2012; 13:89-94. [PMID: 23084831 DOI: 10.1016/s1473-3099(12)70148-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The global programmes to eliminate both malaria and lymphatic filariasis are facing operational and technical challenges. Available data show that the use of treated or untreated bednets and indoor residual spraying for malaria control concomitantly reduced filarial rates. In turn, mass drug administration campaigns against lymphatic filariasis can be combined with the distribution of insecticide-treated bednets. Combining these disease control efforts could lead to more efficient use of resources, more accurate attribution of effects, and more effective control of both diseases. Systematic integration requires coordination at all levels, mapping of coendemic areas, and comprehensive monitoring and evaluation.
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Affiliation(s)
- Henk van den Berg
- Laboratory of Entomology, Wageningen University, Wageningen, Netherlands.
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van den Berg H, Velayudhan R, Ebol A, Catbagan BHG, Turingan R, Tuso M, Hii J. Operational efficiency and sustainability of vector control of malaria and dengue: descriptive case studies from the Philippines. Malar J 2012; 11:269. [PMID: 22873707 PMCID: PMC3425236 DOI: 10.1186/1475-2875-11-269] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 08/08/2012] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Analysis is lacking on the management of vector control systems in disease-endemic countries with respect to the efficiency and sustainability of operations. METHODS Three locations were selected, at the scale of province, municipality and barangay (i.e. village). Data on disease incidence, programme activities, and programme management were collected on-site through meetings and focus group discussions. RESULTS Adaptation of disease control strategies to the epidemiological situation per barangay, through micro-stratification, brings gains in efficiency, but should be accompanied by further capacity building on local situational analysis for better selection and targeting of vector control interventions within the barangay. An integrated approach to vector control, aiming to improve the rational use of resources, was evident with a multi-disease strategy for detection and response, and by the use of combinations of vector control methods. Collaboration within the health sector was apparent from the involvement of barangay health workers, re-orientation of job descriptions and the creation of a disease surveillance unit. The engagement of barangay leaders and use of existing community structures helped mobilize local resources and voluntary services for vector control. In one location, local authorities and the community were involved in the planning, implementation and evaluation of malaria control, which triggered local programme ownership. CONCLUSIONS Strategies that contributed to an improved efficiency and sustainability of vector control operations were: micro-stratification, integration of vector control within the health sector, a multi-disease approach, involvement of local authorities, and empowerment of communities. Capacity building on situational analysis and vector surveillance should be addressed through national policy and guidelines.
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Nandha B, Krishnamoorthy K. Impact of education campaign on community-based vector control in hastening the process of elimination of lymphatic filariasis in Tamil Nadu, South India. HEALTH EDUCATION RESEARCH 2012; 27:585-594. [PMID: 21724963 DOI: 10.1093/her/cyr045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Globally mosquito-borne lymphatic filariasis (LF) is targeted for elimination by 2020. Towards this goal, the scope of community-based vector control as a supplementary strategy to mass drug administration (MDA) was assessed through an intensive education campaign and evaluated using pre- and post-educational surveys in an intervention and comparison village in Tamil Nadu, South India. Environmental and entomological indicators for breeding sites and mosquito density were examined before and after the intervention. Significant (P < 0.05) increase in knowledge was observed in intervention area with regard to transmission and control of LF. Relative change between intervention and comparison villages before and after intervention was also significant (z = >1.96). Multiple mosquito control and personal protection methods were in use during the post-intervention assessment and was evident from the significantly (P < 0.05) higher average score. Breeding sources declined significantly (P < 0.05) in the intervention village with a significant relative change (z = 4.32). Significant reduction in per man-hour indoor resting density of mosquitoes was observed in the intervention area compared to baseline. The per capita cost for reducing 87% of the mosquito density was $ 0.32 indicating the effectiveness of community-based approach. The usefulness of this strategy in the elimination of LF is discussed.
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Affiliation(s)
- B Nandha
- Department of Health Economics, Vector Control Research Centre, Indira Nagar, Pondicherry 605 006, India.
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Díaz-Menéndez M, Norman F, Monge-Maillo B, Pérez-Molina JA, López-Vélez R. [Filariasis in clinical practice]. Enferm Infecc Microbiol Clin 2012; 29 Suppl 5:27-37. [PMID: 22305667 DOI: 10.1016/s0213-005x(11)70041-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Filariases are infections caused by distinct species of nematodes. These infections are transmitted through insect bites and primarily affect lymph nodes and skin. Filariases are classified as neglected diseases and affect millions, producing severe disability and social stigma. This type of infection is rarely diagnosed in travellers, as prolonged stays in endemic areas are usually required acquire infection. Infections may be asymptomatic, and clinical manifestations depend on the host immune response to the infection and the parasite burden. Diagnosis is based on the demonstration of microfilariae in blood or skin, but there are other methods that support the diagnosis. Individual treatment is effective, but community interventions, mostly mass drug administration, have helped to diminish the incidence of filariases.
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Affiliation(s)
- Marta Díaz-Menéndez
- Unidad de Medicina Tropical, Servicio de Enfermedades Infecciosas, Hospital Ramón y Cajal, Madrid, España
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Lalrotluanga, Ngente L, Nachimuthu SK, Guruswami G. Insecticidal and repellent activity of Hiptage benghalensis L. Kruz (Malpighiaceae) against mosquito vectors. Parasitol Res 2012; 111:1007-17. [PMID: 22565399 DOI: 10.1007/s00436-012-2925-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 04/10/2012] [Indexed: 10/28/2022]
Abstract
Plant-based insecticides for vector control are urgently needed for Anopheles barbirostris, Culex quinquefasciatus, and Aedes albopictus which are the primary vectors of malaria, lymphatic filariasis, and dengue, respectively, in India and other South East Asian countries. In the present study, larvicidal, adulticidal, and repellent activities of acetone root bark extract of Hiptage benghalensis were tested against the larvae and adults of the three mosquito vectors. The acetone root bark extracts of H. benghalensis was more effective as larvicides with low LC(50) (11.15-16.78 ppm) and LT50 (1.25-4.84 h at 200 and 400 ppm) values. Results of log probit analysis (at 95 % confidence level) and regression analysis of crude acetone root bark extract of H. benghalensis revealed that lethal concentration (LC(50)) values gradually decreased with the exposure periods; lethal time (LT(50)) decreased with the concentration, and the mortality is positively correlated with the concentration. The order of susceptibility of the three mosquito species was as follows: A. albopictus > A. barbirostris > C. quinquefascitus. Biochemical changes were also evidenced in third instar larvae of three mosquito species following a sublethal exposure for 24 h. The level of sugar, glycogen, lipids, and proteins was significantly (P < 0.05) reduced in larvae treated with H. benghalensis. The acetone root bark extracts of H. benghalensis is less toxic to adults and repelled laboratory-reared female A. barbirostris, A. albopictus, and C. quinquefascitus with the short median protection times of 57.66-135, 72.41-134.16, and 47.66-93 min, respectively. The present investigation proves it as a potent larvicide against A. albopictus, A. barbirostris, and C. quinquefascitus, which can be recommended to control these mosquito species on its breeding site. However, further investigations are needed to confirm the lethal effects of H. benghalensis in field conditions and its impact on the nontarget organisms.
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Affiliation(s)
- Lalrotluanga
- Department of Zoology, Mizoram University, Aizawl, 796 004, Mizoram, India.
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Boatin BA, Basáñez MG, Prichard RK, Awadzi K, Barakat RM, García HH, Gazzinelli A, Grant WN, McCarthy JS, N'Goran EK, Osei-Atweneboana MY, Sripa B, Yang GJ, Lustigman S. A research agenda for helminth diseases of humans: towards control and elimination. PLoS Negl Trop Dis 2012; 6:e1547. [PMID: 22545161 PMCID: PMC3335858 DOI: 10.1371/journal.pntd.0001547] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human helminthiases are of considerable public health importance in sub-Saharan Africa, Asia, and Latin America. The acknowledgement of the disease burden due to helminth infections, the availability of donated or affordable drugs that are mostly safe and moderately efficacious, and the implementation of viable mass drug administration (MDA) interventions have prompted the establishment of various large-scale control and elimination programmes. These programmes have benefited from improved epidemiological mapping of the infections, better understanding of the scope and limitations of currently available diagnostics and of the relationship between infection and morbidity, feasibility of community-directed or school-based interventions, and advances in the design of monitoring and evaluation (M&E) protocols. Considerable success has been achieved in reducing morbidity or suppressing transmission in a number of settings, whilst challenges remain in many others. Some of the obstacles include the lack of diagnostic tools appropriate to the changing requirements of ongoing interventions and elimination settings; the reliance on a handful of drugs about which not enough is known regarding modes of action, modes of resistance, and optimal dosage singly or in combination; the difficulties in sustaining adequate coverage and compliance in prolonged and/or integrated programmes; an incomplete understanding of the social, behavioural, and environmental determinants of infection; and last, but not least, very little investment in research and development (R&D). The Disease Reference Group on Helminth Infections (DRG4), established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR), was given the mandate to undertake a comprehensive review of recent advances in helminthiases research, identify research gaps, and rank priorities for an R&D agenda for the control and elimination of these infections. This review presents the processes undertaken to identify and rank ten top research priorities; discusses the implications of realising these priorities in terms of their potential for improving global health and achieving the Millennium Development Goals (MDGs); outlines salient research funding needs; and introduces the series of reviews that follow in this PLoS Neglected Tropical Diseases collection, "A Research Agenda for Helminth Diseases of Humans."
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Affiliation(s)
- Boakye A. Boatin
- Lymphatic Filariasis Support Centre, Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
- Institute of Parasitology, McGill University, Montreal, Canada
| | - María-Gloria Basáñez
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, United Kingdom
| | | | - Kwablah Awadzi
- Onchocerciasis Chemotherapy Research Centre, Hohoe Hospital, Hohoe, Ghana
| | - Rashida M. Barakat
- High Institute of Public Health, Alexandria University, Alexandria, Egypt
| | - Héctor H. García
- Department of Microbiology, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Andrea Gazzinelli
- Department of Maternal and Child Nursing and Public Health, School of Nursing, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Warwick N. Grant
- The Nematode Functional Genomics Laboratory, La Trobe University, Victoria, Australia
| | - James S. McCarthy
- Queensland Institute of Medical Research, University of Queensland, Herston, Australia
| | - Eliézer K. N'Goran
- Laboratoire de Zoologie et de Biologie Animale, Université de Cocody, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Mike Y. Osei-Atweneboana
- Council for Scientific and Industrial Research (CSIR), Department of Environmental Biology and Health, Water Research Institute, Accra, Ghana
| | - Banchob Sripa
- Tropical Disease Research Laboratory, Division of Experimental Pathology, Department of Pathology, Khon Kaen University, Khon Kaen, Thailand
| | - Guo-Jing Yang
- Department of Schistosomiasis Control, Jiangsu Institute of Parasitic Diseases, Meiyuan Yangxiang, Wuxi, People's Republic of China
| | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
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Jones CM, Machin C, Mohammed K, Majambere S, Ali AS, Khatib BO, McHa J, Ranson H, Kelly-Hope LA. Insecticide resistance in Culex quinquefasciatus from Zanzibar: implications for vector control programmes. Parasit Vectors 2012; 5:78. [PMID: 22520274 PMCID: PMC3349604 DOI: 10.1186/1756-3305-5-78] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Accepted: 04/21/2012] [Indexed: 11/10/2022] Open
Abstract
Background Zanzibar has a long history of lymphatic filariasis (LF) caused by the filarial parasite Wuchereria bancrofti, and transmitted by the mosquito Culex quinquefasciatus Say. The LF Programme in Zanzibar has successfully implemented mass drug administration (MDA) to interrupt transmission, and is now in the elimination phase. Monitoring infections in mosquitoes, and assessing the potential role of interventions such as vector control, is important in case the disease re-emerges as a public health problem. Here, we examine Culex mosquito species from the two main islands to detect W. bancrofti infection and to determine levels of susceptibility to the insecticides used for vector control. Methods Culex mosquitoes collected during routine catches in Vitongoji, Pemba Island, and Makadara, Unguja Island were tested for W. bancrofti infection using PCR. Insecticide bioassays on Culex mosquitoes were performed to determine susceptibility to permethrin, deltamethrin, lambda-cyhalothrin, DDT and bendiocarb. Additional synergism assays with piperonyl butoxide (PBO) were used for lambda-cyhalothrin. Pyrosequencing was used to determine the kdr genotype and sequencing of the mitochondrial cytochrome oxidase I (mtCOI) subunit performed to identify ambiguous Culex species. Results None of the wild-caught Culex mosquitoes analysed were found to be positive for W. bancrofti. High frequencies of resistance to all insecticides were found in Wete, Pemba Island, whereas Culex from the nearby site of Tibirinzi (Pemba) and in Kilimani, Unguja Island remained relatively susceptible. Species identification confirmed that mosquitoes from Wete were Culex quinquefasciatus. The majority of the Culex collected from Tibirinzi and all from Kilimani could not be identified to species by molecular assays. Two alternative kdr alleles, both resulting in a L1014F substitution were detected in Cx. quinquefasciatus from Wete with no homozygote susceptible detected. Metabolic resistance to pyrethroids was also implicated by PBO synergism assays. Conclusions Results from the xenomonitoring are encouraging for the LF programme in Zanzibar. However, the high levels of pyrethroid resistance found in the principle LF vector in Pemba Island will need to be taken into consideration if vector control is to be implemented as part of the elimination programme.
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Shiferaw W, Kebede T, Graves PM, Golasa L, Gebre T, Mosher AW, Tadesse A, Sime H, Lambiyo T, Panicker KN, Richards FO, Hailu A. Lymphatic filariasis in western Ethiopia with special emphasis on prevalence of Wuchereria bancrofti antigenaemia in and around onchocerciasis endemic areas. Trans R Soc Trop Med Hyg 2011; 106:117-27. [PMID: 22154976 DOI: 10.1016/j.trstmh.2011.10.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 10/06/2011] [Accepted: 10/06/2011] [Indexed: 10/14/2022] Open
Abstract
Lymphatic filariasis is known to be endemic in Gambella Region, western Ethiopia, but the full extent of its endemicity in other regions is unknown. A national mapping program for Ethiopia was initiated in 2008. This report summarizes initial data on the prevalence of Wuchereria bancrofti antigenaemia based on surveys carried out in a sampled population of 11685 individuals living in 125 villages (112 districts) of western Ethiopia. The overall prevalence rate was 3.7%, but high geographical clustering and variation in prevalence (ranging from 0% to more than 50%) was found. The prevalence of hydrocele (in males) and lymphoedema of limbs was 0.8% and 3.6% respectively. Significantly higher (χ(2)=49.6; P<0.01) prevalence of antigenaemia was noted in known onchocerciasis endemic districts (4.7%) compared to non-onchocerciasis endemic districts (2.3%). Thirty-four of the 112 districts, with a population of 1547685 in 2007, were found to be endemic. Of these, the numbers of districts with prevalence rates of >20%, 10-20% and 5-9% were nine, 14 and 20 respectively. Twenty-nine of these 34 endemic districts were found in three regions: Gambella Region (seven districts), Beneshangul-Gumuz Region (13 districts), and Southern Nations, Nationalities and Peoples' Region (SNNPR) (nine districts). The other five were from Amhara (two districts) and Oromia (three districts) regions. A tentative distribution map has been drawn to facilitate the launching of the Ethiopia LF elimination program.
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Affiliation(s)
- Welelta Shiferaw
- Department of Microbiology, Immunology and Parasitology (DMIP); Faculty of Medicine, Addis Ababa University, Addis Ababa, Ethiopia
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Richards FO, Eigege A, Miri ES, Kal A, Umaru J, Pam D, Rakers LJ, Sambo Y, Danboyi J, Ibrahim B, Adelamo SE, Ogah G, Goshit D, Oyenekan OK, Mathieu E, Withers PC, Saka YA, Jiya J, Hopkins DR. Epidemiological and entomological evaluations after six years or more of mass drug administration for lymphatic filariasis elimination in Nigeria. PLoS Negl Trop Dis 2011; 5:e1346. [PMID: 22022627 PMCID: PMC3191131 DOI: 10.1371/journal.pntd.0001346] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 08/22/2011] [Indexed: 11/18/2022] Open
Abstract
The current strategy for interrupting transmission of lymphatic filariasis (LF) is annual mass drug administration (MDA), at good coverage, for 6 or more years. We describe our programmatic experience delivering the MDA combination of ivermectin and albendazole in Plateau and Nasarawa states in central Nigeria, where LF is caused by anopheline transmitted Wuchereria bancrofti. Baseline LF mapping using rapid blood antigen detection tests showed mean local government area (LGA) prevalence of 23% (range 4–62%). MDA was launched in 2000 and by 2003 had been scaled up to full geographic coverage in all 30 LGAs in the two states; over 26 million cumulative directly observed treatments were provided by community drug distributors over the intervention period. Reported treatment coverage for each round was ≥85% of the treatment eligible population of 3.7 million, although a population-based coverage survey in 2003 showed lower coverage (72.2%; 95% CI 65.5–79.0%). To determine impact on transmission, we monitored three LF infection parameters (microfilaremia, antigenemia, and mosquito infection) in 10 sentinel villages (SVs) serially. The last monitoring was done in 2009, when SVs had been treated for 7–10 years. Microfilaremia in 2009 decreased by 83% from baseline (from 4.9% to 0.8%); antigenemia by 67% (from 21.6% to 7.2%); mosquito infection rate (all larval stages) by 86% (from 3.1% to 0.4%); and mosquito infectivity rate (L3 stages) by 76% (from 1.3% to 0.3%). All changes were statistically significant. Results suggest that LF transmission has been interrupted in 5 of the 10 SVs, based on 2009 finding of microfilaremia ≥1% and/or L3 stages in mosquitoes. Four of the five SVs where transmission persists had baseline antigenemia prevalence of >25%. Longer or additional interventions (e.g., more frequent MDA treatments, insecticidal bed nets) should be considered for ‘hot spots’ where transmission is ongoing. Lymphatic filariasis is a mosquito transmitted disease that is best known for causing elephantiasis (grossly swollen legs and genitals). The current strategy for halting lymphatic filariasis in sub Saharan Africa is to establish programs that deliver 6 or more years of annual doses of tablets in community wide treatment programs (called mass drug administration). The tablets are safe, and donated by Merck & Co. and GlaxoSmithKline. We describe a mass drug administration program in central Nigeria that has, since 2000, provided over 23 million cumulative annual treatments to a population of 3.7 million persons. To assess what should be happening generally throughout the program area, lymphatic filariasis infection was monitored in ten ‘sentinel villages.’ In 2009, sentinel village monitoring showed that lymphatic filariasis infection had been reduced between 67–86% compared to levels present when the program began. However, these results were not as good as desired, and suggest that longer or increased efforts are needed beyond 6 years if lymphatic filariasis elimination is to be achieved.
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Affiliation(s)
| | | | | | | | | | - Davou Pam
- University of Jos, Plateau State, Jos, Nigeria
| | - Lindsay J. Rakers
- The Carter Center, Atlanta, Georgia, United States of America
- * E-mail:
| | | | | | | | | | - Gladys Ogah
- Nasarawa State Ministry of Health, Lafia, Nigeria
| | | | | | - Els Mathieu
- Centers for Disease Control, Atlanta, Georgia, United States of America
| | | | - Yisa A. Saka
- Nigeria Federal Ministry of Health, Abuja, Nigeria
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Insect immune responses to nematode parasites. Trends Parasitol 2011; 27:537-47. [PMID: 21982477 DOI: 10.1016/j.pt.2011.09.001] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 09/01/2011] [Accepted: 09/08/2011] [Indexed: 12/16/2022]
Abstract
Host innate immunity plays a central role in detecting and eliminating microbial pathogenic infections in both vertebrate and invertebrate animals. Entomopathogenic or insect pathogenic nematodes are of particular importance for the control of insect pests and vectors of pathogens, while insect-borne nematodes cause serious diseases in humans. Recent work has begun to use the power of insect models to investigate host-nematode interactions and uncover host antiparasitic immune reactions. This review describes recent findings on innate immune evasion strategies of parasitic nematodes and host cellular and humoral responses to the infection. Such information can be used to model diseases caused by human parasitic nematodes and provide clues indicating directions for research into the interplay between vector insects and their invading tropical parasites.
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Farajollahi A, Fonseca DM, Kramer LD, Kilpatrick AM. "Bird biting" mosquitoes and human disease: a review of the role of Culex pipiens complex mosquitoes in epidemiology. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2011; 11:1577-85. [PMID: 21875691 PMCID: PMC3190018 DOI: 10.1016/j.meegid.2011.08.013] [Citation(s) in RCA: 371] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 08/15/2011] [Accepted: 08/16/2011] [Indexed: 11/27/2022]
Abstract
The transmission of vector-borne pathogens is greatly influenced by the ecology of their vector, which is in turn shaped by genetic ancestry, the environment, and the hosts that are fed on. One group of vectors, the mosquitoes in the Culex pipiens complex, play key roles in the transmission of a range of pathogens including several viruses such as West Nile and St. Louis encephalitis viruses, avian malaria (Plasmodium spp.), and filarial worms. The Cx. pipiens complex includes Culex pipiens pipiens with two forms, pipiens and molestus, Culex pipiens pallens, Culex quinquefasciatus, Culex australicus, and Culex globocoxitus. While several members of the complex have limited geographic distributions, Cx. pipienspipiens and Cx. quinquefasciatus are found in all known urban and sub-urban temperate and tropical regions, respectively, across the world, where they are often principal disease vectors. In addition, hybrids are common in areas of overlap. Although gaps in our knowledge still remain, the advent of genetic tools has greatly enhanced our understanding of the history of speciation, domestication, dispersal, and hybridization. We review the taxonomy, genetics, evolution, behavior, and ecology of members of the Cx. pipiens complex and their role in the transmission of medically important pathogens. The adaptation of Cx. pipiens complex mosquitoes to human-altered environments led to their global distribution through dispersal via humans and, combined with their mixed feeding patterns on birds and mammals (including humans), increased the transmission of several avian pathogens to humans. We highlight several unanswered questions that will increase our ability to control diseases transmitted by these mosquitoes.
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Affiliation(s)
- Ary Farajollahi
- Rutgers University, Center for Vector Biology, New Brunswick, New Jersey
| | - Dina M. Fonseca
- Rutgers University, Center for Vector Biology, New Brunswick, New Jersey
| | - Laura D. Kramer
- Wadsworth Center, New York State Department of Health, Slingerlands, New York, and State University of New York at Albany, Albany, New York
| | - A. Marm Kilpatrick
- Dept. Ecology and Evolutionary Biology, University of California, Santa Cruz, California
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Kelly-Hope LA, Thomas BC, Bockarie MJ, Molyneux DH. Lymphatic filariasis in the Democratic Republic of Congo; micro-stratification overlap mapping (MOM) as a prerequisite for control and surveillance. Parasit Vectors 2011; 4:178. [PMID: 21923949 PMCID: PMC3183006 DOI: 10.1186/1756-3305-4-178] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 09/18/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Democratic Republic of Congo (DRC) has a significant burden of lymphatic filariasis (LF) caused by the parasite Wuchereria bancrofti. A major impediment to the expansion of the LF elimination programme is the risk of serious adverse events (SAEs) associated with the use of ivermectin in areas co-endemic for onchocerciasis and loiasis. It is important to analyse these and other factors, such as soil transmitted helminths (STH) and malaria co-endemicity, which will impact on LF elimination. RESULTS We analysed maps of onchocerciasis community-directed treatment with ivermectin (CDTi) from the African Programme for Onchocerciasis Control (APOC); maps of predicted prevalence of Loa loa; planned STH control maps of albendazole (and mebendazole) from the Global Atlas of Helminth Infections (GAHI); and bed nets and insecticide treated nets (ITNs) distribution from Demographic and Health Surveys (DHS) as well as published historic data which were incorporated into overlay maps. We developed an approach we designate as micro-stratification overlap mapping (MOM) to identify areas that will assist the implementation of LF elimination in the DRC. The historic data on LF was found through an extensive review of the literature as no recently published information was available. CONCLUSIONS This paper identifies an approach that takes account of the various factors that will influence not only country strategies, but suggests that country plans will require a finer resolution mapping than usual, before implementation of LF activities can be efficiently deployed. This is because 1) distribution of ivermectin through APOC projects will already have had an impact of LF intensity and prevalence 2) DRC has been up scaling bed net distribution which will impact over time on transmission of W. bancrofti and 3) recently available predictive maps of L. loa allow higher risk areas to be identified, which allow LF implementation to be initiated with reduced risk where L. loa is considered non-endemic. We believe that using the proposed MOM approach is essential for planning the expanded distribution of drugs for LF programmes in countries co-endemic for filarial infections.
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Affiliation(s)
- Louise A Kelly-Hope
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Brent C Thomas
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Moses J Bockarie
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - David H Molyneux
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
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Hickner PV, deBruyn B, Lovin DD, Mori A, Saski CA, Severson DW. Enhancing genome investigations in the mosquito Culex quinquefasciatus via BAC library construction and characterization. BMC Res Notes 2011; 4:358. [PMID: 21914202 PMCID: PMC3180476 DOI: 10.1186/1756-0500-4-358] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 09/13/2011] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Culex quinquefasciatus (Say) is a major species in the Culex pipiens complex and an important vector for several human pathogens including West Nile virus and parasitic filarial nematodes causing lymphatic filariasis. It is common throughout tropical and subtropical regions and is among the most geographically widespread mosquito species. Although the complete genome sequence is now available, additional genomic tools are needed to improve the sequence assembly. FINDINGS We constructed a bacterial artificial chromosome (BAC) library using the pIndigoBAC536 vector and HindIII partially digested DNA isolated from Cx. quinquefasciatus pupae, Johannesburg strain (NDJ). Insert size was estimated by NotI digestion and pulsed-field gel electrophoresis of 82 randomly selected clones. To estimate genome coverage, each 384-well plate was pooled for screening with 29 simple sequence repeat (SSR) and five gene markers. The NDJ library consists of 55,296 clones arrayed in 144 384-well microplates. Fragment insert size ranged from 50 to 190 kb in length (mean = 106 kb). Based on a mean insert size of 106 kb and a genome size of 579 Mbp, the BAC library provides ~10.1-fold coverage of the Cx. quinquefasciatus genome. PCR screening of BAC DNA plate pools for SSR loci from the genetic linkage map and for four genes associated with reproductive diapause in Culex pipiens resulted in a mean of 9.0 positive plate pools per locus. CONCLUSION The NDJ library represents an excellent resource for genome assembly enhancement and characterization in Culex pipiens complex mosquitoes.
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Affiliation(s)
- Paul V Hickner
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Becky deBruyn
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Diane D Lovin
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Akio Mori
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | | | - David W Severson
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
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Cartaxo MF, Ayres CF, Weetman D. Loss of genetic diversity in Culex quinquefasciatus targeted by a lymphatic filariasis vector control program in Recife, Brazil. Trans R Soc Trop Med Hyg 2011; 105:491-9. [DOI: 10.1016/j.trstmh.2011.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 05/09/2011] [Accepted: 05/09/2011] [Indexed: 10/18/2022] Open
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First evidence of spatial clustering of lymphatic filariasis in an Aedes polynesiensis endemic area. Acta Trop 2011; 120 Suppl 1:S39-47. [PMID: 21172296 DOI: 10.1016/j.actatropica.2010.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 11/30/2010] [Accepted: 12/01/2010] [Indexed: 11/24/2022]
Abstract
Successful elimination of lymphatic filariasis (LF) requires accurate identification of residual foci of transmission and stringent surveillance strategies to combat potential resurgence. This is challenging in areas where the day-biting Aedes polynesiensis is endemic, such as Samoa, since in previous studies no geographical clustering of infection has been demonstrated. Another challenge for this low prevalence phase is the choice of diagnostic assay as testing for circulating filarial antigen (CFA) or microfilariae (Mf) alone may not have adequate sensitivity. This could be solved by using the commercially available filariasis Cellabs enzyme linked immunosorbent assay (CELISA) to measure antibody. In the current study five Samoan villages were chosen based on previous epidemiological assessments to represent a range of infection prevalences. CFA, Mf, and antibody levels in children ≤ 10 years had been recorded and results linked to household of residence and/or primary school of attendance. To ascertain the location of exposure, two scenarios based on potential foci of transmission around communities and schools were explored. Both scenarios revealed significant spatial clusters of households with infected individuals and a relationship to antibody positive children when they were included in the spatial analysis. Fasitoo-Tai had the highest LF prevalence and largest geographical spatial clusters for both scenarios. In Falefa, spatial clusters were detected only for the primary school scenario. In Tafua, which spanned an area of 19.5 km(2), no spatial clusters were detected. Lastly, in Siufaga, the village with the lowest LF prevalence, significant clustering of infected individuals was observed and, for the primary school scenario, this was geographically related to exposure. These promising findings are the first published evidence of spatial clustering of LF in a day-biting Ae. polynesiensis endemic area.
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142
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Lymphatic filariasis in children: clinical features, infection burdens and future prospects for elimination. Parasitology 2011; 138:1559-68. [PMID: 21810306 DOI: 10.1017/s003118201100117x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Lymphatic filariasis (LF), a common parasitic infection in tropical countries, causes lymphoedema of limbs, hydrocele and acute attacks of dermato-lymphangio-adenitis. Recent advances in diagnosis have helped to recognize that LF infection is often acquired in childhood. Newly available diagnostic techniques like sensitive antigen and antibody assays, Doppler ultrasonography and lymphoscintigraphy have helped to understand the subclinical pathology caused by this infection, which was hitherto generally believed to be irreversible. Recent studies indicate that drugs used in the mass drug administration (MDA) programme under GPELF are capable of reversing the sub-clinical lymphatic damage in children and provide benefits other than interruption of transmission. Albendazole and ivermectin used in MDA are effective against soil-transmitted helminthic infections common in children in LF endemic areas. Thus MDA had other 'beyond LF' benefits in treated children including increased appetite, weight gain, greater learning ability and concentration, better school attendance and prevention of anaemia. MDA should no longer be viewed as a measure for interrupting transmission alone. Recent findings of reversibility of early lymphatic pathology in treated children indicate that both MDA and 'foot-hygiene' measures are effective strategies in preventing and managing morbidity. Programme managers should effectively utilize this information to strengthen their advocacy efforts to achieve high and sustainable coverage in MDA.
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143
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Ashton RA, Kyabayinze DJ, Opio T, Auma A, Edwards T, Matwale G, Onapa A, Brooker S, Kolaczinski JH. The impact of mass drug administration and long-lasting insecticidal net distribution on Wuchereria bancrofti infection in humans and mosquitoes: an observational study in northern Uganda. Parasit Vectors 2011; 4:134. [PMID: 21756371 PMCID: PMC3158553 DOI: 10.1186/1756-3305-4-134] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 07/15/2011] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Lymphatic filariasis (LF) in Uganda is caused by Wuchereria bancrofti and transmitted by anopheline mosquitoes. The mainstay of elimination has been annual mass drug administration (MDA) with ivermectin and albendazole, targeted to endemic districts, but has been sporadic and incomplete in coverage. Vector control could potentially contribute to reducing W. bancrofti transmission, speeding up progress towards elimination. To establish whether the use of long-lasting insecticidal nets (LLINs) can contribute towards reducing transmission of W. bancrofti in a setting with ongoing MDA, a study was conducted in an area of Uganda highly endemic for both LF and malaria. Baseline parasitological and entomological assessments were conducted in 2007, followed by high-coverage LLIN distribution. Net use and entomological surveys were carried out after one year, and final parasitological and entomological evaluations were conducted in 2010. Three rounds of MDA had taken place before the study commenced, with a further three rounds completed during the course of the study. RESULTS In 2007, rapid mapping indicated 22.3% of schoolchildren were W. bancrofti antigen positive, and a baseline survey during the same year found age-adjusted microfilaraemia prevalence was 3.7% (95% confidence interval (CI): 2.6-5.3%). In 2010, age-adjusted microfilaraemia prevalence had fallen to 0.4%, while antigenaemia rates were 0.2% in children < 5 years and 6.0% in ≥ 5 years. In 2010, universal coverage of mosquito nets in a household was found to be protective against W. bancrofti antigen (odds ratio = 0.44, 95% CI: 0.22-0.89). Prevalence of W. bancrofti larvae in anopheline mosquitoes had decreased significantly between the 2007 and 2010 surveys, but there was an apparent increase in vector densities. CONCLUSION A marked reduction in W. bancrofti infection and infectivity in humans was observed in the study area, where both MDA and LLINs were used to reduce transmission. The extent to which LLINs contributed to this decline is equivocal, however. Further work investigating the impact of vector control on anopheline-transmitted LF in an endemic area not benefitting from MDA would be valuable to determine the effect of such interventions on their own.
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Affiliation(s)
- Ruth A Ashton
- Malaria Consortium Africa, Kampala, Uganda
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | | | - Tom Opio
- District Health Office, Dokolo, Uganda
| | - Anna Auma
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Tansy Edwards
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Gabriel Matwale
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | | | - Simon Brooker
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
- Malaria Public Health & Epidemiology Group, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Jan H Kolaczinski
- Malaria Consortium Africa, Kampala, Uganda
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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Njenga SM, Mwandawiro CS, Wamae CN, Mukoko DA, Omar AA, Shimada M, Bockarie MJ, Molyneux DH. Sustained reduction in prevalence of lymphatic filariasis infection in spite of missed rounds of mass drug administration in an area under mosquito nets for malaria control. Parasit Vectors 2011; 4:90. [PMID: 21612649 PMCID: PMC3125382 DOI: 10.1186/1756-3305-4-90] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 05/25/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was established by the World Health Organisation (WHO) in 2000 with the goal of eliminating lymphatic filariasis (LF) as a public health problem globally by 2020. Mass drug administration (MDA) of antifilarial drugs is the principal strategy recommended for global elimination. Kenya launched a National Programme for Elimination of Lymphatic Filariasis (NPELF) in Coast Region in 2002. During the same year a longitudinal research project to monitor trends of LF infection during MDA started in a highly endemic area in Malindi District. High coverage of insecticide treated nets (ITNs) in the coastal region has been associated with dramatic decline in hospital admissions due to malaria; high usage of ITNs is also expected to have an impact on LF infection, also transmitted by mosquitoes. RESULTS Four rounds of MDA with diethylcarbamazine citrate (DEC) and albendazole were given to 8 study villages over an 8-year period. Although annual MDA was not administered for several years the overall prevalence of microfilariae declined significantly from 20.9% in 2002 to 0.9% in 2009. Similarly, the prevalence of filarial antigenaemia declined from 34.6% in 2002 to 10.8% in 2009. All the examined children born since the start of the programme were negative for filarial antigen in 2009. CONCLUSIONS Despite the fact that the study villages missed MDA in some of the years, significant reductions in infection prevalence and intensity were observed at each survey. More importantly, there were no rebounds in infection prevalence between treatment rounds. However, because of confounding variables such as insecticide-treated bed nets (ITNs), it is difficult to attribute the reduction to MDA alone as ITNs can lead to a significant reduction in exposure to filariasis vectors. The results indicate that national LF elimination programmes should be encouraged to continue provision of MDA albeit constraints that may lead to missing of MDA in some years.
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Affiliation(s)
- Sammy M Njenga
- Kenya Medical Research Institute (KEMRI), Mbagathi Road, Nairobi, Kenya
| | | | - C Njeri Wamae
- Kenya Medical Research Institute (KEMRI), Mbagathi Road, Nairobi, Kenya
- Kenya Methodist University, Meru, Kenya
| | | | - Anisa A Omar
- Ministry of Public Health and Sanitation, Nairobi, Kenya
| | - Masaaki Shimada
- Kenya Medical Research Institute (KEMRI), Mbagathi Road, Nairobi, Kenya
- Nagasaki University Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Moses J Bockarie
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Liverpool, UK
| | - David H Molyneux
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Liverpool, UK
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García-Rejón JE, Loroño-Pino MA, Farfán-Ale JA, Flores-Flores LF, López-Uribe MP, Najera-Vazquez MDR, Nuñez-Ayala G, Beaty BJ, Eisen L. Mosquito infestation and dengue virus infection in Aedes aegypti females in schools in Merida, Mexico. Am J Trop Med Hyg 2011; 84:489-96. [PMID: 21363990 DOI: 10.4269/ajtmh.2011.10-0654] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We determined abundance of Aedes aegypti mosquitoes and presence of dengue virus (DENV) in females collected from schools in Mérida, México, during 2008 and 2009. Backpack aspiration from 24 schools produced 468 females of Ae. aegypti and 1,676 females of another human biter, Culex quinquefasciatus. Ae. aegypti females were collected most commonly from classrooms followed by offices and bathrooms. Of these females, 24.7% were freshly fed. Examination of 118 pools of Ae. aegypti females (total of 415 females) for presence of DENV RNA produced 19 positive pools (16.1%). DENV-infected pools were detected from 11 (45.8%) of 24 schools and came from different room types, including classrooms, offices, and bathrooms. The overall rate of DENV infection per 100 Ae. aegypti females was 4.8. We conclude that schools in Mérida present a risk environment for students, teachers, and other personnel to be exposed to mosquitoes and bites of DENV-infected Ae. aegypti females.
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Affiliation(s)
- Julián E García-Rejón
- Laboratorio de Arbovirología, Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad Autónoma de Yucatán, Centro, Mérida, Yucatán, México.
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146
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Mahmoud A, Zerhouni E. Neglected tropical diseases: moving beyond mass drug treatment to understanding the science. Health Aff (Millwood) 2011; 28:1726-33. [PMID: 19887413 DOI: 10.1377/hlthaff.28.6.1726] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Neglected tropical diseases (NTDs) represent a major health burden in many developing countries. To date, global efforts to control thirteen parasitic and bacterial infections that affect more than 1.4 billion people have relied on mass drug administration. This singular approach should now be expanded to a more comprehensive suite of tools including coordinated community-based programs, vector control, local training, education, and environmental change. In addition, an intensive basic research agenda is urgently needed to develop effective diagnostic, preventive, and therapeutic interventions to stay one step ahead of the evolutionary adaptation tactics of disease-causing microbes and parasites.
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Affiliation(s)
- Adel Mahmoud
- Department of Molecular Biology and Woodrow Wilson School, Princeton University
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Monitoring mosquitoes in urban Dar es Salaam: evaluation of resting boxes, window exit traps, CDC light traps, Ifakara tent traps and human landing catches. Parasit Vectors 2011; 4:40. [PMID: 21418622 PMCID: PMC3069960 DOI: 10.1186/1756-3305-4-40] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 03/21/2011] [Indexed: 11/17/2022] Open
Abstract
Background Ifakara tent traps (ITT) are currently the only sufficiently sensitive, safe, affordable and practical method for routine monitoring host-seeking mosquito densities in Dar es Salaam. However, it is not clear whether ITT catches represent indoors or outdoors biting densities. ITT do not yield samples of resting, fed mosquitoes for blood meal analysis. Methods Outdoors mosquito sampling methods, namely human landing catch (HLC), ITT (Design B) and resting boxes (RB) were conducted in parallel with indoors sampling using HLC, Centers for Disease Control and Prevention miniature light traps (LT) and RB as well as window exit traps (WET) in urban Dar es Salaam, rotating them thirteen times through a 3 × 3 Latin Square experimental design replicated in four blocks of three houses. This study was conducted between 6th May and 2rd July 2008, during the main rainy season when mosquito biting densities reach their annual peak. Results The mean sensitivities of indoor RB, outdoor RB, WET, LT, ITT (Design B) and HLC placed outdoor relative to HLC placed indoor were 0.01, 0.005, 0.036, 0.052, 0.374, and 1.294 for Anopheles gambiae sensu lato (96% An. gambiae s.s and 4% An. arabiensis), respectively, and 0.017, 0.053, 0.125, 0.423, 0.372 and 1.140 for Culex spp, respectively. The ITT (Design B) catches correlated slightly better to indoor HLC (r2 = 0.619, P < 0.001, r2 = 0.231, P = 0.001) than outdoor HLC (r2 = 0.423, P < 0.001, r2 = 0.228, P = 0.001) for An. gambiae s.l. and Culex spp respectively but the taxonomic composition of mosquitoes caught by ITT does not match those of the indoor HLC (χ2 = 607.408, degrees of freedom = 18, P < 0.001). The proportion of An. gambiae caught indoors was unaffected by the use of an LLIN in that house. Conclusion The RB, WET and LT are poor methods for surveillance of malaria vector densities in urban Dar es Salaam compared to ITT and HLC but there is still uncertainty over whether the ITT best reflects indoor or outdoor biting densities. The particular LLIN evaluated here failed to significantly reduce house entry by An. gambiae s.l. suggesting a negligible repellence effect.
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Morais SAD, Moratore C, Suesdek L, Marrelli MT. Genetic-morphometric variation in Culex quinquefasciatus from Brazil and La Plata, Argentina. Mem Inst Oswaldo Cruz 2011; 105:672-6. [PMID: 20835615 DOI: 10.1590/s0074-02762010000500012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 04/29/2010] [Indexed: 11/22/2022] Open
Abstract
Variation among natural populations of Culex (Culex) quinquefasciatus Say is associated with different vectorial capacities. The species Cx. quinquefasciatus is present in the equatorial, tropical and subtropical zones in the Brazilian territory, with intermediate forms between Cx. quinquefasciatus and Culex pipiens occurring in regions of latitudes around 33°-35° S. Herein, we studied geographically distinct populations of Cx. quinquefasciatus by genetic characterization and analysis of intra-specific wing morphometrics. After morphological analysis, molecular characterization of Cx. quinquefasciatus and intermediate forms was performed by polymerase chain reaction of the polymorphic nuclear region of the second intron of the acetylcholinesterase locus. Additionally, the morphology of adult female wings collected from six locations was analyzed. Wing centroid sizes were significantly different between some geographical pairs. Mean values of R2/R2+3 differed significantly after pairwise comparisons. The overall wing shape represented by morphometric characters could be divided into two main groupings. Our data suggest that Brazilian samples are morphologically and genetically distinct from the Argentinean samples and also indicated a morphological distinction between northern and southern populations of Brazilian Cx. quinquefasciatus. We suggest that wing morphology may be used for preliminary assessment of population structure of Cx. quinquefasciatusin Brazil.
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Affiliation(s)
- Sirlei Antunes de Morais
- Departamento de Epidemiologia, Faculdade de Saúde Pública, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brasil
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Aliota MT, Chen CC, Dagoro H, Fuchs JF, Christensen BM. Filarial worms reduce Plasmodium infectivity in mosquitoes. PLoS Negl Trop Dis 2011; 5:e963. [PMID: 21347449 PMCID: PMC3035669 DOI: 10.1371/journal.pntd.0000963] [Citation(s) in RCA: 24] [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: 08/30/2010] [Accepted: 01/10/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Co-occurrence of malaria and filarial worm parasites has been reported, but little is known about the interaction between filarial worm and malaria parasites with the same Anopheles vector. Herein, we present data evaluating the interaction between Wuchereria bancrofti and Anopheles punctulatus in Papua New Guinea (PNG). Our field studies in PNG demonstrated that An. punctulatus utilizes the melanization immune response as a natural mechanism of filarial worm resistance against invading W. bancrofti microfilariae. We then conducted laboratory studies utilizing the mosquitoes Armigeres subalbatus and Aedes aegypti and the parasites Brugia malayi, Brugia pahangi, Dirofilaria immitis, and Plasmodium gallinaceum to evaluate the hypothesis that immune activation and/or development by filarial worms negatively impact Plasmodium development in co-infected mosquitoes. Ar. subalbatus used in this study are natural vectors of P. gallinaceum and B. pahangi and they are naturally refractory to B. malayi (melanization-based refractoriness). METHODOLOGY/PRINCIPAL FINDINGS Mosquitoes were dissected and Plasmodium development was analyzed six days after blood feeding on either P. gallinaceum alone or after taking a bloodmeal containing both P. gallinaceum and B. malayi or a bloodmeal containing both P. gallinaceum and B. pahangi. There was a significant reduction in the prevalence and mean intensity of Plasmodium infections in two species of mosquito that had dual infections as compared to those mosquitoes that were infected with Plasmodium alone, and was independent of whether the mosquito had a melanization immune response to the filarial worm or not. However, there was no reduction in Plasmodium development when filarial worms were present in the bloodmeal (D. immitis) but midgut penetration was absent, suggesting that factors associated with penetration of the midgut by filarial worms likely are responsible for the observed reduction in malaria parasite infections. CONCLUSIONS/SIGNIFICANCE These results could have an impact on vector infection and transmission dynamics in areas where Anopheles transmit both parasites, i.e., the elimination of filarial worms in a co-endemic locale could enhance malaria transmission.
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Affiliation(s)
- Matthew T. Aliota
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Cheng-Chen Chen
- Department of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Henry Dagoro
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Jeremy F. Fuchs
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Bruce M. Christensen
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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150
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Abstract
Different challenges are presented by the variety of malaria transmission environments present in the world today. In each setting, improved control for reduction of morbidity is a necessary first step towards the long-range goal of malaria eradication and a priority for regions where the disease burden is high. For many geographic areas where transmission rates are low to moderate, sustained and well-managed application of currently available tools may be sufficient to achieve local elimination. The research needs for these areas will be to sustain and perhaps improve the effectiveness of currently available tools. For other low-to-moderate transmission regions, notably areas where the vectors exhibit behaviours such as outdoor feeding and resting that are not well targeted by current strategies, new interventions that target predictable features of the biology/ecologies of the local vectors will be required. To achieve elimination in areas where high levels of transmission are sustained by very efficient vector species, radically new interventions that significantly reduce the vectorial capacity of wild populations will be needed. Ideally, such interventions should be implemented with a one-time application with a long-lasting impact, such as genetic modification of the vectorial capacity of the wild vector population.
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