51
|
Malima RC, Oxborough RM, Tungu PK, Maxwell C, Lyimo I, Mwingira V, Mosha FW, Matowo J, Magesa SM, Rowland MW. Behavioural and insecticidal effects of organophosphate-, carbamate- and pyrethroid-treated mosquito nets against African malaria vectors. MEDICAL AND VETERINARY ENTOMOLOGY 2009; 23:317-325. [PMID: 19941597 DOI: 10.1111/j.1365-2915.2009.00837.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Three insecticides - the pyrethroid deltamethrin, the carbamate carbosulfan and the organophosphate chlorpyrifos-methyl - were tested on mosquito nets in experimental huts to determine their potential for introduction as malaria control measures. Their behavioural effects and efficacy were examined in Anopheles gambiae Giles s.s. (Diptera: Culicidae) and Anopheles funestus Giles s.s. in Muheza, Tanzania, and in Anopheles arabiensis Patton and Culex quinquefasciatus Say in Moshi, Tanzania. A standardized dosage of 25 mg/m(2) plus high dosages of carbosulfan (50 mg/m(2), 100 mg/m(2) and 200 mg/m(2)) and chlorpyrifos-methyl (100 mg/m(2)) were used to compare the three types of insecticide. At 25 mg/m(2), the rank order of the insecticides for insecticide-induced mortality in wild An. gambiae and An. funestus was, respectively, carbosulfan (88%, 86%) > deltamethrin (79%, 78%) > chlorpyrifos-methyl (35%, 53%). The rank order of the insecticides for blood-feeding inhibition (reduction in the number of blood-fed mosquitoes compared with control) in wild An. gambiae and An. funestus was deltamethrin > chlorpyrifos-methyl > carbosulfan. Carbosulfan was particularly toxic to endophilic anophelines at 200 mg/m(2), killing 100% of An. gambiae and 98% of An. funestus that entered the huts. It was less effective against the more exophilic An. arabiensis (67% mortality) and carbamate-resistant Cx quinquefasciatus (36% mortality). Carbosulfan deterred anophelines from entering huts, but did not deter carbamate-resistant Cx quinquefasciatus. Deltamethrin reduced the proportion of insects engaged in blood-feeding, probably as a consequence of contact irritancy, whereas carbosulfan seemed to provide personal protection through deterred entry or perhaps a spatial repellent action. Any deployment of carbosulfan as an individual treatment on nets should be carried out on a large scale to reduce the risk of diverting mosquitoes to unprotected individuals. Chlorpyrifos-methyl was inferior to deltamethrin in terms of mortality and blood-feeding inhibition and would be better deployed on a net in combination with a pyrethroid to control insecticide-resistant mosquitoes.
Collapse
Affiliation(s)
- R C Malima
- Amani Centre, National Institute for Medical Research, Muheza, Tanzania
| | | | | | | | | | | | | | | | | | | |
Collapse
|
52
|
Smith DL, Hay SI, Noor AM, Snow RW. Predicting changing malaria risk after expanded insecticide-treated net coverage in Africa. Trends Parasitol 2009; 25:511-6. [PMID: 19744887 PMCID: PMC2768685 DOI: 10.1016/j.pt.2009.08.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 07/14/2009] [Accepted: 08/07/2009] [Indexed: 11/01/2022]
Abstract
The Roll Back Malaria (RBM) partnership has established goals for protecting vulnerable populations with locally appropriate vector control. In many places, these goals will be achieved by the mass distribution of insecticide treated bednets (ITNs). Mathematical models can forecast an ITN-driven realignment of malaria endemicity, defined by the Plasmodium falciparum parasite rate (PfPR) in children, to predict PfPR endpoints and appropriate program timelines for this change in Africa. The relative ease of measuring PfPR and its widespread use make it particularly suitable for monitoring and evaluation. This theory provides a method for context-dependent evaluation of ITN programs and a basis for setting rational ITN coverage targets over the next decade.
Collapse
Affiliation(s)
- David L Smith
- Department of Biology and Emerging Pathogens Institute, University of Florida, P.O. Box 100009, Gainesville, Florida 32610, USA.
| | | | | | | |
Collapse
|
53
|
Dialynas E, Topalis P, Vontas J, Louis C. MIRO and IRbase: IT tools for the epidemiological monitoring of insecticide resistance in mosquito disease vectors. PLoS Negl Trop Dis 2009; 3:e465. [PMID: 19547750 PMCID: PMC2694272 DOI: 10.1371/journal.pntd.0000465] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 05/22/2009] [Indexed: 12/03/2022] Open
Abstract
Background Monitoring of insect vector populations with respect to their susceptibility to one or more insecticides is a crucial element of the strategies used for the control of arthropod-borne diseases. This management task can nowadays be achieved more efficiently when assisted by IT (Information Technology) tools, ranging from modern integrated databases to GIS (Geographic Information System). Here we describe an application ontology that we developed de novo, and a specially designed database that, based on this ontology, can be used for the purpose of controlling mosquitoes and, thus, the diseases that they transmit. Methodology/Principal Findings The ontology, named MIRO for Mosquito Insecticide Resistance Ontology, developed using the OBO-Edit software, describes all pertinent aspects of insecticide resistance, including specific methodology and mode of action. MIRO, then, forms the basis for the design and development of a dedicated database, IRbase, constructed using open source software, which can be used to retrieve data on mosquito populations in a temporally and spatially separate way, as well as to map the output using a Google Earth interface. The dependency of the database on the MIRO allows for a rational and efficient hierarchical search possibility. Conclusions/Significance The fact that the MIRO complies with the rules set forward by the OBO (Open Biomedical Ontologies) Foundry introduces cross-referencing with other biomedical ontologies and, thus, both MIRO and IRbase are suitable as parts of future comprehensive surveillance tools and decision support systems that will be used for the control of vector-borne diseases. MIRO is downloadable from and IRbase is accessible at VectorBase, the NIAID-sponsored open access database for arthropod vectors of disease. It is a historical fact that a successful campaign against vector populations is one of the prerequisites for effectively fighting and eventually eradicating arthropod-borne diseases, be that in an epidemic or, even more so, in endemic cases. Based mostly on the use of insecticides and environmental management, vector control is now increasingly hampered by the occurrence of insecticide resistance that manifests itself, and spreads rapidly, briefly after the introduction of a (novel) chemical substance. We make use here of a specially built ontology, MIRO, to drive a new database, IRbase, dedicated to storing data on the occurrence of insecticide resistance in mosquito populations worldwide. The ontological approach to the design of databases offers the great advantage that these can be searched in an efficient way. Moreover, it also provides for an increased interoperability of present and future epidemiological tools. IRbase is now being populated by both older data from the literature and data recently collected from field.
Collapse
Affiliation(s)
- Emmanuel Dialynas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
| | - Pantelis Topalis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
| | - John Vontas
- Laboratory of Pesticide Science, Agricultural University of Athens, Athens, Greece
- Vector Research, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Department of Biology, University of Crete, Heraklion, Crete, Greece
| | - Christos Louis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
- Department of Biology, University of Crete, Heraklion, Crete, Greece
- * E-mail:
| |
Collapse
|
54
|
Britch SC, Linthicum KJ, Wynn WW, Walker TW, Farooq M, Smith VL, Robinson CA, Lothrop BB, Snelling M, Gutierrez A, Lothrop HD. Evaluation of barrier treatments on native vegetation in a southern California desert habitat. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2009; 25:184-193. [PMID: 19653501 DOI: 10.2987/08-5830.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Treating perimeters with residual insecticides for protection from mosquito vectors has shown promise. These barrier treatments are typically evaluated in temperate or tropical areas using abundant vegetation as a substrate. However, there is an emerging interest to develop this technology to protect deployed US troops in extreme desert environments with sparse vegetation. We used a remote desert area in the Coachella Valley, California, to 1) evaluate bifenthrin barrier treatments on native xeric vegetation and 2) compare treatments applied with electrostatic and conventional spray technologies. Through a combination of laboratory bioassays on treated and control vegetation sampled at specific intervals over 63 days, synchronized with field surveillance of mosquitoes, we measured the temporal pattern of bioactivity of bifenthrin barriers under natural hot, dry, and dusty desert conditions. Regardless of spray technology, mosquito catch in treated plots was about 80% lower than the catch in control plots 1 day after treatment. This reduction in mosquito numbers in treated plots declined each week after treatment but remained at about 40% lower than control plots after 28 days. Field data were corroborated by results from bioassays that showed significantly higher mosquito mortality on treated vegetation over controls out to 28 days postspray. We concluded that barrier treatments in desert environments, when implemented as part of a suite of integrated control measures, may offer a significant level of protection from mosquitoes for deployed troops. Given the comparable performance of the tested spray technologies, we discuss considerations for choosing a barrier treatment sprayer for military scenarios.
Collapse
Affiliation(s)
- Seth C Britch
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, 1600 SW 23rd Drive, Gainesville, FL 32608, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
55
|
Oxborough RM, Mosha FW, Matowo J, Mndeme R, Feston E, Hemingway J, Rowland M. Mosquitoes and bednets: testing the spatial positioning of insecticide on nets and the rationale behind combination insecticide treatments. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2009; 102:717-27. [PMID: 19000389 DOI: 10.1179/136485908x337553] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The recent development of pyrethroid resistance of operational significance in Anopheles gambiae s.l. is a major threat to the control of malaria in West Africa. The so-called '2-in-1' bednet, in which the top of the net is treated with a non-pyrethroid insecticide and the sides with pyrethroid, has been proposed as a way of maintaining efficacy in the wake of such resistance. A host-seeking female Anopheles mosquito must contact both the top and sides of a '2-in-1' net, however, for such nets to be useful in resistance management. In the present study, the interaction between mosquitoes and insecticide-treated bednets (ITN) was explored by restricting the insecticide to particular surfaces of the nets (top only or sides only) and then testing these nets, untreated nets and nets treated on all their surfaces in experimental huts, under simulated field conditions. Over the 6-week trial, there was no significant difference in An. arabiensis mortality between nets treated with pyrethroid on the top only (39.2%), sides only (39.6%) and all surfaces (39.7%), thus indicating that a female An. arabiensis usually contacts both the top and sides of a bednet during its host-seeking behaviour. The data on blood-feeding indicated, however, that the insecticide used on the sides of the net may be more important in preventing mosquito biting than that on the top. These results support the rationale behind the '2-in-1' nets. Such nets may have advantages over the use of nets treated on all surfaces with a mixture of insecticides that includes a non-pyrethroid component. With the '2-in-1', the more toxic component can be deployed on the top of the net, away from human contact, while the more repellent pyrethroid can be restricted to the sides, to prevent blood-feeding. With the scaling-up of ITN coverage and the need to preserve pyrethroid efficacy, more consideration should be given to switching from pyrethroid-only nets to 'combination' nets that have been treated with a pyrethroid and another insecticide. Since the mosquitoes that act as malarial vectors may contact all surfaces of a bednet during their host-seeking, spatial heterogeneity in insecticide levels over the surface of a net may not reduce that net's overall efficacy. Nets with a rather uneven distribution of insecticide (such as those that might be produced using home-treatment insecticide kits) may therefore be no less effective, prior to washing, than nets with a more even distribution of insecticide (such as long-lasting insecticidal nets produced under factory conditions).
Collapse
Affiliation(s)
- R M Oxborough
- Kilimanjaro Christian Medical Centre, PO Box 3010, Moshi, Tanzania.
| | | | | | | | | | | | | |
Collapse
|
56
|
Fernando S, Abeyasinghe R, Galappaththy G, Gunawardena N, Rajapakse L. Community factors affecting long-lasting impregnated mosquito net use for malaria control in Sri Lanka. Trans R Soc Trop Med Hyg 2008; 102:1081-8. [DOI: 10.1016/j.trstmh.2008.06.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 06/11/2008] [Accepted: 06/11/2008] [Indexed: 11/16/2022] Open
|
57
|
Faber BW, Remarque EJ, Kocken CHM, Cheront P, Cingolani D, Xhonneux F, Jurado M, Haumont M, Jepsen S, Leroy O, Thomas AW. Production, quality control, stability and pharmacotoxicity of cGMP-produced Plasmodium falciparum AMA1 FVO strain ectodomain expressed in Pichia pastoris. Vaccine 2008; 26:6143-50. [PMID: 18804135 DOI: 10.1016/j.vaccine.2008.08.055] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 08/06/2008] [Accepted: 08/31/2008] [Indexed: 10/21/2022]
Abstract
Plasmodium falciparum apical membrane antigen 1 (PfAMA1) is a leading asexual blood stage vaccine candidate for malaria. In preparation for clinical trials, PfAMA1 ectodomain (amino acid 25-545, FVO strain) was produced in Pichia pastoris by 35L scale fed batch fermentation under current Good Manufacturing Practice (cGMP). Fermentation was followed by a three-step chromatographic purification procedure resulting in a yield of 5.8g of purified protein. As judged by size exclusion chromatography, the cGMP-product comprised >95% PfAMA1 monomer, the remainder being predominantly PfAMA1 dimer. In SDS-PAGE two main bands of 68 and 70kDa and some minor bands were evident. Under reducing conditions a site of limited proteolytic cleavage within a disulphide bonded region became evident; less than 15% of the protein had this internal cleavage. By mass-spectrometric analysis, all bands analyzed in overloaded SDS-PAGE gels comprised PfAMA1 derived products. The protein was quantitatively bound by immobilized 4G2, a monoclonal antibody reactive with a reduction sensitive conformational determinant. The lyophilized product was stable for over 1 year. Immunopotency did not diminish, and storage did not lead to alterations in the behaviour of the protein upon formulation with adjuvants selected for Phase I clinical evaluation. These formulations also showed no pharmacotoxicity in rabbits. The final product conformed to preset criteria and was judged suitable for use in human clinical trials.
Collapse
Affiliation(s)
- Bart W Faber
- Department of Parasitology, Biomedical Primate Research Center, Lange Kleiweg 139, 2288 GJ Rijswijk, The Netherlands
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
58
|
Kolaczinski JH, Hope A, Ruiz JA, Rumunu J, Richer M, Seaman J. Kala-azar epidemiology and control, southern Sudan. Emerg Infect Dis 2008; 14:664-6. [PMID: 18394290 PMCID: PMC2570907 DOI: 10.3201/eid1404.071099] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Southern Sudan is one of the areas in eastern Africa most affected by visceral leishmaniasis (kala-azar), but lack of security and funds has hampered control. Since 2005, the return of stability has opened up new opportunities to expand existing interventions and introduce new ones.
Collapse
|
59
|
Dicko A, Sagara I, Sissoko MS, Guindo O, Diallo AI, Kone M, Toure OB, Sacko M, Doumbo OK. Impact of intermittent preventive treatment with sulphadoxine-pyrimethamine targeting the transmission season on the incidence of clinical malaria in children in Mali. Malar J 2008; 7:123. [PMID: 18611271 PMCID: PMC2500037 DOI: 10.1186/1475-2875-7-123] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Accepted: 07/08/2008] [Indexed: 11/28/2022] Open
Abstract
Background Recent studies have shown that intermittent preventive malaria treatment (IPT) in infants in areas of stable malaria transmission reduces malaria and severe anaemia incidence. However in most areas malaria morbidity and mortality remain high in older children. Methods To evaluate the effect of seasonal IPT with sulphadoxine pyrimethamine (SP) on incidence of malaria disease in area of seasonal transmission, 262 children 6 months-10 years in Kambila, Mali were randomized to receive either IPT with SP twice at eight weeks interval or no IPT during the transmission season of 2002 and were followed up for 12 months. Subjects were also followed during the subsequent transmission season in 2003 to assess possible rebound effect. Clinical malaria cases were treated with SP and followed to assess the in vivo response during both periods. Results The incidence rate of malaria disease per 1,000 person-months during the first 12 months was 3.2 episodes in the treatment group vs. 5.8 episodes in the control group with age-adjusted Protective Efficacy (PE) of 42.5%; [95% CI 28.6%–53.8%]. When the first 16 weeks of follow up is considered age-adjusted PE was 67.5% [95% CI 55.3% – 76.6%]. During the subsequent transmission season, the incidence of clinical malaria per 1000 persons-days was similar between the two groups (23.0 vs 21.5 episodes, age-adjusted IRR = 1.07 [95% CI, 0.90–1.27]). No significant difference was detected in in vivo response between the groups during both periods. Conclusion Two malaria intermittent treatments targeting the peak transmission season reduced the annual incidence rate of clinical malaria by 42.5% in an area with intense seasonal transmission. This simple strategy is likely to be one of the most effectives in reducing malaria burden in such areas. Trial Registration Clinicaltrials.gov NCT00623155
Collapse
Affiliation(s)
- Alassane Dicko
- Malaria Research and Training Center, Departments of Epidemiology of Parasitic Diseases, Faculty of Medicine Pharmacy and Dentistry, University of Bamako, P.O. Box 1805, Bamako, Mali.
| | | | | | | | | | | | | | | | | |
Collapse
|
60
|
Irish S, N'guessan R, Boko P, Metonnou C, Odjo A, Akogbeto M, Rowland M. Loss of protection with insecticide-treated nets against pyrethroid-resistant Culex quinquefasciatus mosquitoes once nets become holed: an experimental hut study. Parasit Vectors 2008; 1:17. [PMID: 18564409 PMCID: PMC2459145 DOI: 10.1186/1756-3305-1-17] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 06/18/2008] [Indexed: 11/30/2022] Open
Abstract
Background An important advantage of pyrethroid-treated nets over untreated nets is that once nets become worn or holed a pyrethroid treatment will normally restore protection. The capacity of pyrethroids to kill or irritate any mosquito that comes into contact with the net and prevent penetration of holes or feeding through the sides are the main reasons why treated nets continue to provide protection despite their condition deteriorating over time. Pyrethroid resistance is a growing problem among Anopheline and Culicine mosquitoes in many parts of Africa. When mosquitoes become resistant the capacity of treated nets to provide protection might be diminished, particularly when holed. An experimental hut trial against pyrethroid-resistant Culex quinquefasciatus was therefore undertaken in southern Benin using a series of intact and holed nets, both untreated and treated, to assess any loss of protection as nets deteriorate with use and time. Results There was loss of protection when untreated nets became holed; the proportion of mosquitoes blood feeding increased from 36.2% when nets were intact to between 59.7% and 68.5% when nets were holed to differing extents. The proportion of mosquitoes blood feeding when treated nets were intact was 29.4% which increased to 43.6–57.4% when nets were holed. The greater the number of holes the greater the loss of protection regardless of whether nets were untreated or treated. Mosquito mortality in huts with untreated nets was 12.9–13.6%; treatment induced mortality was less than 12%. The exiting rate of mosquitoes into the verandas was higher in huts with intact nets. Conclusion As nets deteriorate with use and become increasingly holed the capacity of pyrethroid treatments to restore protection is greatly diminished against resistant Culex quinquefasciatus mosquitoes.
Collapse
Affiliation(s)
- S Irish
- London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK.
| | | | | | | | | | | | | |
Collapse
|
61
|
Hay SI, Smith DL, Snow RW. Measuring malaria endemicity from intense to interrupted transmission. THE LANCET. INFECTIOUS DISEASES 2008; 8:369-78. [PMID: 18387849 PMCID: PMC2653619 DOI: 10.1016/s1473-3099(08)70069-0] [Citation(s) in RCA: 242] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
The quantification of malaria transmission for the classification of malaria risk has long been a concern for epidemiologists. During the era of the Global Malaria Eradication Programme, measurements of malaria endemicity were institutionalised by their incorporation into rules outlining defined action points for malaria control programmes. We review the historical development of these indices and their contemporary relevance. This is at a time when many malaria-endemic countries are scaling-up their malaria control activities and reconsidering their prospects for elimination. These considerations are also important to an international community that has recently been challenged to revaluate the prospects for malaria eradication.
Collapse
Affiliation(s)
- Simon I Hay
- Malaria Public Health and Epidemiology Group, Centre for Geographic Medicine, Kenya Medical Research Institute/University of Oxford/Wellcome Trust Collaborative Programme, Nairobi, Kenya.
| | | | | |
Collapse
|
62
|
Goesch JN, Schwarz NG, Decker ML, Oyakhirome S, Borchert LB, Kombila UD, Poetschke M, Lell B, Issifou S, Kremsner PG, Grobusch MP. Socio-economic status is inversely related to bed net use in Gabon. Malar J 2008; 7:60. [PMID: 18423025 PMCID: PMC2358918 DOI: 10.1186/1475-2875-7-60] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 04/18/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-treated bed nets (ITNs) range among the most effective measures of malaria prophylaxis, yet their implementation level in sub-Saharan Africa is still low. The goal of this study was to investigate the influence of socio-economic factors on the use of bed nets by mothers in Gabon. METHODS A cross-sectional study was conducted completing pre-tested, interviewer-administered questionnaires exploring socioeconomic proxy measures with 397 mothers or guardians of young children. Respondents were grouped according to their socio-economic situation, using scores. The condition of the bed nets was evaluated during a home visit. RESULTS Socio-economic factors of wellbeing were negatively associated with bed net use, such as living in a stone house (OR 0.26, 95% CI 0.14-0.48), running water in the house (OR 0.44, 95% CI 0.21-0.92), shower/flush toilet in the house (OR 0.39/0.34, 95% CI 0.21-0.75/0.16-0.73), ownership of a freezer (OR 0.50, 95% CI 0.26-0.96) and belonging to the highest group in the economic score (OR 0.32, 95% CI 0.15-0.67). In contrast, similar factors were positively associated with a good maintenance condition of the bed nets: higher monthly income (OR 5.64, 95% CI 2.41-13.19) and belonging to the highest group in the economic score (OR 2.55, 95% CI 1.19 - 5.45). CONCLUSION Among the poorest families in Lambaréné the coverage with untreated nets (UTNs) is the highest, but the condition of these UTNs is the worst. To achieve a broad implementation of ITNs in Lambaréné, there is an urgent need for educational programmes as well as need-tailored marketing strategies for ITNs.
Collapse
Affiliation(s)
- Julia N Goesch
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
63
|
Abstract
PURPOSE OF REVIEW This review summarizes recent evidence regarding the efficacy of intermittent preventive treatment with focus on infancy (IPTi) and the rationale behind such a control strategy. RECENT FINDINGS Pooled safety and efficacy analyses of all six trials of IPTi with sulfadoxine-pyrimethamine conducted between 1999 and 2007 have demonstrated a 30% protective efficacy against clinical malaria, a 24% protective efficacy against all-cause hospital admissions, a 37% protective efficacy against malaria-related hospital admissions, and a 15% protective efficacy against anemia, all in the first year of life. Rebound in malaria following discontinuation of the intervention has not been noted in pooled analyses of the IPTi trials. SUMMARY Given the efficacy, excellent safety and tolerability of the intervention and the fact that it is inexpensive and easily deliverable if linked to the Expanded Programme on Immunization, IPTi-sulfadoxine-pyrimethamine appears to add a valuable tool to the malaria-control armamentarium in endemic areas of Africa. Routine monitoring of sulfadoxine-pyrimethamine efficacy will be required to guide future IPTi programme implementation. Variations of IPTi that target older children may be required for areas of Africa with highly seasonal malaria transmission.
Collapse
|
64
|
Crawley J, Hill J, Yartey J, Robalo M, Serufilira A, Ba-Nguz A, Roman E, Palmer A, Asamoa K, Steketee R. From evidence to action? Challenges to policy change and programme delivery for malaria in pregnancy. THE LANCET. INFECTIOUS DISEASES 2007; 7:145-55. [PMID: 17251085 DOI: 10.1016/s1473-3099(07)70026-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper discusses the factors that influence whether strategies for preventing and treating malaria in pregnancy are successfully translated into national policy and programme implementation, and identifies key operational research issues. Countries require guidance on how to assess the effectiveness of intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine in the context of increasing sulfadoxine-pyrimethamine resistance. At the same time, data on the safety and efficacy of alternatives to sulfadoxine-pyrimethamine for prevention and treatment are urgently needed. Systematic examination of the cultural and operational constraints to delivery and uptake of IPTp with sulfadoxine-pyrimethamine and use of insecticide-treated nets would provide a rational basis for strategies aimed at improving coverage. Standardised methodology must be used to monitor IPTp coverage and to compare different approaches for scaling-up the delivery of insecticide-treated nets to pregnant women. Adequate budgetary provision for the implementation of policy and for operational research to improve programme delivery should be included in national applications to the Global Fund to Fight AIDS, Tuberculosis and Malaria. The provision of clear policy guidance on malaria in pregnancy and its translation into evidence-based guidelines that are made widely available at a country level are central to improving malaria control in this particularly vulnerable group.
Collapse
Affiliation(s)
- Jane Crawley
- Global Malaria Programme, World Health Organization, Geneva, Switzerland.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
65
|
Broen K, Brustoski K, Engelmann I, Luty AJF. Placental Plasmodium falciparum infection: causes and consequences of in utero sensitization to parasite antigens. Mol Biochem Parasitol 2006; 151:1-8. [PMID: 17081634 DOI: 10.1016/j.molbiopara.2006.10.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Accepted: 10/02/2006] [Indexed: 11/26/2022]
Abstract
Available evidence suggests that, in African populations, systemic blood-dwelling parasitoses of mothers are associated with enhanced susceptibility to infection of their offspring. Thus, children born to mothers with filariasis or schistosomiasis are infected earlier, and offspring of mothers with placental Plasmodium falciparum at delivery, commonly referred to as pregnancy-associated malaria or PAM, are themselves at higher risk of developing parasitaemia during infancy. Since foetal/neonatal antigen-presenting cells (APC) are either immature or provide insufficient costimulatory signals to T cells, thus favouring tolerance induction, it is commonly assumed that soluble parasite components [protein antigens], transferred transplacentally and inducing foetal immune tolerance, are largely, if not exclusively, responsible for these outcomes. Plasmodial asexual blood stage antigen-specific T cells are detectable in as many as two-thirds of all cord blood samples in malaria-endemic countries of sub-Saharan Africa, indicating that in utero sensitization may be a common phenomenon during pregnancy in these populations. Parasite antigen-specific T cell responses of neonates born to helminth-infected mothers display a highly skewed Th2-type cytokine pattern, with a prominent role for the regulatory cytokine interleukin (IL)-10. Similarly, the cord blood immune response of those born to mothers identified with on-going PAM is characterised by inducible parasite antigen-specific IL-10-producing regulatory T cells that can inhibit both APC HLA expression and Th1-type T cell responses. In contrast, plasmodial antigen-specific Th1-type responses, characterised by IFN-gamma production, predominate in cord blood of those born to mothers successfully treated for Pf malaria during gestation, suggesting that the duration and/or the nature of antigen exposure in utero governs the outcome with respect to neonatal immune responses. Aspects of APC function in the context of these differentially modulated responses, whether and how the latter translate into altered susceptibility to Pf infection during infancy, as well as the possible implications for vaccination in early life, are aspects that are discussed in this review.
Collapse
Affiliation(s)
- Kelly Broen
- Department of Medical Microbiology 268, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | | | | | | |
Collapse
|