Increasing the potential for malaria elimination by targeting zoophilic vectors.
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ABSTRACT:
SUBMITTER: Waite JL
PROVIDER: S-EPMC5238397 | biostudies-literature | 2017 Jan
REPOSITORIES: biostudies-literature
Publications
Increasing the potential for malaria elimination by targeting zoophilic vectors.
Waite Jessica L JL Swain Sunita S Lynch Penelope A PA Sharma S K SK Haque Mohammed Asrarul MA Montgomery Jacqui J Thomas Matthew B MB
Scientific reports 20170116
Countries in the Asia Pacific region aim to eliminate malaria by 2030. A cornerstone of malaria elimination is the effective management of Anopheles mosquito vectors. Current control tools such as insecticide treated nets or indoor residual sprays target mosquitoes in human dwellings. We find in a high transmission region in India, malaria vector populations show a high propensity to feed on livestock (cattle) and rest in outdoor structures such as cattle shelters. We also find evidence for a sh ...[more]
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Project description:BACKGROUND:Zanzibar provides a good case study for malaria elimination. The islands have experienced a dramatic reduction in malaria burden since the introduction of effective vector control interventions and case management. Malaria prevalence has now been maintained below 1% for the past decade and the islands can feasibly aim for elimination. METHODS:To better understand factors that may contribute to remaining low-level malaria transmission in Zanzibar, layered human behavioural and entomological research was conducted between December 2016 and December 2017 in 135 randomly selected households across six administrative wards. The study included: (1) household surveys, (2) structured household observations of nighttime activity and sleeping patterns, and (3) paired indoor and outdoor mosquito collections. Entomological and human behavioural data were integrated to provide weighted estimates of exposure to vector bites, accounting for proportions of people indoors or outdoors, and protected by insecticide-treated nets (ITNs) each hour of the night. RESULTS:Overall, 92% of female Anopheles mosquitoes were caught in the rainy season compared to 8% in the dry season and 72% were caught outdoors compared to 28% indoors. For individual ITN users, ITNs prevented an estimated two-thirds (66%) of exposure to vector bites and nearly three quarters (73%) of residual exposure was estimated to occur outdoors. Based on observed levels of ITN use in the study sites, the population-wide mean personal protection provided by ITNs was 42%. DISCUSSION/CONCLUSIONS:This study identified gaps in malaria prevention in Zanzibar with results directly applicable for improving ongoing programme activities. While overall biting risk was low, the most notable finding was that current levels of ITN use are estimated to prevent less than half of exposure to malaria vector bites. Variation in ITN use across sites and seasons suggests that additional gains could be made through targeted social and behaviour change interventions. However, even for ITN users, gaps in protection remain, with a majority of exposure to vector bites occurring outdoors before going to sleep. Supplemental interventions targeting outdoor exposure to malaria vectors, and groups that may be at increased risk of exposure to malaria vectors, should be explored.
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Project description:BackgroundIn 2012, the World Health Organization (WHO) released the Global Plan for Insecticide Resistance Management in malaria vectors to stress the need to address insecticide resistance. In a prospective multi-centric study commissioned by the Indian Council of Medical Research (ICMR), we assessed the insecticide susceptibility status of the primary malaria vectors in India from 2017 through 2019.MethodsThe insecticide susceptibility status of the prevalent primary malaria vectors - An. culicifacies, An. fluviatilis, An. stephensi, An. minimus and An. baimaii and secondary malaria vectors - An. aconitus, An. annularis and An. philippinensis/nivepes from 328 villages in 79 districts of 15 states of India were assessed following the WHO method mainly to insecticides used in vector control, organochlorine (DDT), organophosphate (malathion), and other pyrethroids (alpha-cypermethrin, cyfluthrin, lambda-cyhalothrin and permethrin). The study sites were selected as suggested by the National Vector Borne Disease Control Programme.ResultsThe primary malaria vector An. culicifacies showed resistance to DDT (50/50 districts including two districts of Northeastern India), malathion (27/44 districts), and deltamethrin (17/44 districts). This species was resistant to DDT alone in 19 districts, double resistant to DDT-malathion in 16 districts, double resistant to DDT-deltamethrin in 6 districts, and triple resistant to DDT-malathion-deltamethrin in 9 districts. An. minimus and An. baimaii were susceptible in Northeastern India while An. fluviatilis and the secondary malaria vector An. annularis was resistant to DDT in Jharkhand.ConclusionIn this study we report that among the primary vectors An. culicifacies is predominantly resistant to multiple insecticides. Our data suggest that periodic monitoring of insecticide susceptibility is vital. The national malaria program can take proactive steps for insecticide resistance management to continue its push toward malaria elimination in India.
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| S-EPMC10589990 | biostudies-literature
Project description:Novel insecticides were recently introduced to counter pyrethroid resistance threats in African malaria vectors. To prolong their effectiveness, potential cross-resistance from promiscuous pyrethroid metabolic resistance mechanisms must be elucidated. Here, we demonstrate that the duplicated P450s CYP6P9a/-b, proficient pyrethroid metabolizers, reduce neonicotinoid efficacy in Anopheles funestus while enhancing the potency of chlorfenapyr. Transgenic expression of CYP6P9a/-b in Drosophila confirmed that flies expressing both genes were significantly more resistant to neonicotinoids than controls, whereas the contrasting pattern was observed for chlorfenapyr. This result was also confirmed by RNAi knockdown experiments. In vitro expression of recombinant CYP6P9a and metabolism assays established that it significantly depletes both clothianidin and chlorfenapyr, with metabolism of chlorfenapyr producing the insecticidally active intermediate metabolite tralopyril. This study highlights the risk of cross-resistance between pyrethroid and neonicotinoid and reveals that chlorfenapyr-based control interventions such as Interceptor G2 could remain efficient against some P450-based resistant mosquitoes.
| S-EPMC11372441 | biostudies-literature
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| S-EPMC10711498 | biostudies-literature
Project description:BackgroundSchoolchildren with asymptomatic malaria infections often go undiagnosed and untreated, serving as reservoirs for infection that hamper malaria control and elimination efforts. In this context, little is known about the magnitude of asymptomatic malaria infections in apparently healthy schoolchildren in Ethiopia. This study was aimed at determining the prevalence of asymptomatic malaria infection and its associated factors in apparently healthy schoolchildren in Ethiopia.MethodsFrom September 2021 to January 2022, a school-based cross-sectional study was conducted on 994 apparently healthy schoolchildren (aged 6-15 years) selected from 21 primary schools in the Gomma district, of Jimma zone, southwestern Oromia, Ethiopia. A multi-stage sampling technique was used to select schools and participants. After allocating the total sample proportionally to each school and then to each grade, participants were selected using the lottery method from a list of student records (rosters). Finger-pricked blood samples were collected for microscopy blood film preparation and malaria rapid diagnostic test (RDT) (SD Bioline Malaria Ag Pf/Pv). Moreover, dry blood spots (DBSs) were prepared onto filter papers for quantitative real time polymerase chain reaction (qPCR) analysis.ResultsAs determined by RDT and microscopy, the prevalence of asymptomatic malaria was 2.20% and 1.51%, respectively. Using qPCR, the overall prevalence was 5.03% (50/994). Of this, Plasmodium falciparum, Plasmodium vivax and mixed infections accounted for 90%, 6% and 4%, respectively. Submicroscopic asymptomatic malaria infection was also accounted for 70% (35/50) of the overall prevalence. Household head age, nighttime outdoor activities of household heads, family history of malaria, absence of insecticide-treated nets (ITN), and presence of stagnant water around the houses are all significantly associated with asymptomatic malaria infections among schoolchildren.ConclusionsThis study found that both RDT and microscopy underestimated the prevalence of asymptomatic malaria in schoolchildren. However, qPCR was able to detect even low levels of parasitaemia and revealed a higher prevalence of asymptomatic submicroscopic malaria infections. The findings imply that schoolchildren with asymptomatic malaria infection are potential hotspot for malaria reservoir that fuels ongoing transmission. Therefore, it is imperative to include schoolchildren and schools in malaria intervention package and equally important is the adoption of more advanced and sensitive diagnostic tools, which would be crucial for successful malaria control and elimination efforts. Targeted interventions for asymptomatic malaria-infected schoolchildren can provide invaluable support to the National Malaria Control Programme in controlling and eventually eliminating the disease.
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| S-EPMC9250186 | biostudies-literature
Project description:BackgroundTremendous progress has been made in the last ten years in reducing morbidity and mortality caused by malaria, in part because of increases in global funding for malaria control and elimination. Today, many countries are striving for malaria elimination. However, a major challenge is the neglect of cross-border and regional initiatives in malaria control and elimination. This paper seeks to better understand Global Fund support for multi-country initiatives.MethodsDocuments and proposals were extracted and reviewed from two main sources, the Global Fund website and Aidspan.org. Documents and reports from the Global Fund Technical Review Panel, Board, and Secretariat documents such as guidelines and proposal templates were reviewed to establish the type of policies enacted and guidance provided from the Global Fund on multi-country initiatives and applications. From reviewing this information, the researchers created 29 variables according to eight dimensions to use in a review of Round 10 applications. All Round 10 multi-country applications (for HIV, malaria and tuberculosis) and all malaria multi-country applications (6) from Rounds 1 - 10 were extracted from the Global Fund website. A blind review was conducted of Round 10 applications using the 29 variables as a framework, followed by a review of four of the six successful malaria multi-country grant applications from Rounds 1 - 10.FindingsDuring Rounds 3 - 10 of the Global Fund, only 5.8% of grants submitted were for multi-country initiatives. Out of 83 multi-country proposals submitted, 25.3% were approved by the Technical Review Panel (TRP) for funding, compared to 44.9% of single-country applications. The majority of approved multi-country applications were for HIV (76.2%), followed by malaria (19.0%), then tuberculosis (4.8%). TRP recommendations resulted in improvements to application forms, although guidance was generally vague. The in-depth review of Round 10 multi-country proposals showed that applicants described their projects in one of two ways: a regional 'network approach' by which benefits are derived from economies of scale or from enhanced opportunities for mutual support and learning or the development of common policies and approaches; or a 'cross-border' approach for enabling activities to be more effectively delivered towards border-crossing populations or vectors. In Round 10, only those with a 'network approach' were recommended for funding. The Global Fund has only ever approved six malaria multi-country applications. Four approved applications stated strong arguments for a multi-country initiative, combining both 'cross-border' and 'network' approaches.ConclusionWith the cancellation of Round 11 and the proposal that the Global Fund adopt a more targeted and strategic approach to funding, the time is opportune for the Global Fund to develop a clear consensus about the key factors and criteria for funding malaria specific multi-country initiatives. This study found that currently there was a lack of guidance on the key features that a successful multi-country proposal needs to be approved and that applications directed towards the 'network' approach were most successful in Round 10. This type of multi-country proposal may favour other diseases such as HIV, whereas the need for malaria control and elimination is different, focusing on cross-border coordination and delivery of interventions to specific groups. The Global Fund should seek to address these issues and give better guidance to countries and regions and investigate disease-specific calls for multi-country and regional applications.
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Project description:BackgroundPlasmodium knowlesi, a simian malaria parasite infection, increases as Plasmodium falciparum and Plasmodium vivax infections decrease in Johor, Malaysia. Therefore, this study aimed to identify the distribution of vectors involved in knowlesi malaria transmission in Johor. This finding is vital in estimating hotspot areas for targeted control strategies.MethodsAnopheles mosquitoes were collected from the location where P. knowlesi cases were reported. Cases of knowlesi malaria from 2011 to 2019 in Johor were analyzed. Internal transcribed spacers 2 (ITS2) and cytochrome c oxidase subunit I (COI) genes were used to identify the Leucosphyrus Group of Anopheles mosquitoes. In addition, spatial analysis was carried out on the knowlesi cases and vectors in Johor.ResultsOne hundred and eighty-nine cases of P. knowlesi were reported in Johor over 10 years. Young adults between the ages of 20-39 years comprised 65% of the cases. Most infected individuals were involved in agriculture and army-related occupations (22% and 32%, respectively). Four hundred and eighteen Leucosphyrus Group Anopheles mosquitoes were captured during the study. Anopheles introlatus was the predominant species, followed by Anopheles latens. Spatial analysis by Kriging interpolation found that hotspot regions of P. knowlesi overlapped or were close to the areas where An. introlatus and An. latens were found. A significantly high number of vectors and P. knowlesi cases were found near the road within 0-5 km.ConclusionsThis study describes the distribution of P. knowlesi cases and Anopheles species in malaria-endemic transmission areas in Johor. Geospatial analysis is a valuable tool for studying the relationship between vectors and P. knowlesi cases. This study further supports that the Leucosphyrus Group of mosquitoes might be involved in transmitting knowlesi malaria cases in Johor. These findings may provide initial evidence to prioritize diseases and vector surveillance.
| S-EPMC8555301 | biostudies-literature
Project description:BackgroundEurope and Italy were declared malaria free since the 1970s although the presence of competent vectors and the high number of yearly imported malaria cases make this disease a potential rising health issue. In September 2017, a cryptic fatal case of Plasmodium falciparum malaria in the Province of Trento, Italy, raised the concern of health authorities on the possible resurgence of this disease in the Mediterranean Basin.MethodsAn entomological surveillance by means of BG traps, CDC light traps and larval search was performed. Sites were chosen among urban and suburban environments (e.g. private houses, public parks, schools, cemeteries, ecotone urban/forest, farms), ranging from an altitude of 91 to 1332 m above sea level. All the mosquitoes collected were morphologically identified and about half of them (103; 49%) were confirmed with the sequencing analysis of the rRNA internal transcribed spacer 2 (ITS-2).ResultsIn the present study 287 sites were screened for the presence of Anopheles spp. and 211 specimens were collected and identified. Hundred-eighteen individuals (56%) belonged to Anopheles plumbeus, 56 (26.5%) to Anopheles maculipennis complex, 10 (4.7%) to Anopheles claviger and 27 were identified only at genus level. This is the first record for the presence of An. plumbeus in the study area.ConclusionsThe presence of Anopheles spp. mosquitoes in the Province of Trento, Italy, has been updated with the occurrence of An. plumbeus. The risk of malaria endemicity in the area is to be considered very low, but urban and peri-urban habitat may act as potential breeding sites for the presence of mosquito vectors and should be constantly monitored.
| S-EPMC6489321 | biostudies-literature