RESUMO
BACKGROUND: Malaria remains an important public health problem, particularly in sub-Saharan Africa. In Rwanda, where malaria ranks among the leading causes of mortality and morbidity, disease transmission is influenced by climatic factors. However, there is a paucity of studies investigating the link between climate change and malaria dynamics, which hinders the development of effective national malaria response strategies. Addressing this critical gap, this study analyses how climatic factors influence malaria transmission across Rwanda, thereby informing tailored interventions and enhancing disease management frameworks. METHODS: The study analysed the potential impact of temperature and cumulative rainfall on malaria incidence in Rwanda from 2012 to 2021 using meteorological data from the Rwanda Meteorological Agency and malaria case records from the Rwanda Health Management and Information System. The analysis was performed in two stages. First, district-specific generalized linear models with a quasi-Poisson distribution were applied, which were enhanced by distributed lag non-linear models to explore non-linear and lagged effects. Second, random effects multivariate meta-analysis was employed to pool the estimates and to refine them through best linear unbiased predictions. RESULTS: A 1-month lag with specific temperature and rainfall thresholds influenced malaria incidence across Rwanda. Average temperature of 18.5 °C was associated with higher malaria risk, while temperature above 23.9 °C reduced the risk. Rainfall demonstrated a dual effect on malaria risk: conditions of low (below 73 mm per month) and high (above 223 mm per month) precipitation correlated with lower risk, while moderate rainfall (87 to 223 mm per month) correlated with higher risk. Seasonal patterns showed increased malaria risk during the major rainy season, while the short dry season presented lower risk. CONCLUSION: The study underscores the influence of temperature and rainfall on malaria transmission in Rwanda and calls for tailored interventions that are specific to location and season. The findings are crucial for informing policy that enhance preparedness and contribute to malaria elimination efforts. Future research should explore additional ecological and socioeconomic factors and their differential contribution to malaria transmission.
Assuntos
Mudança Climática , Malária , Chuva , Temperatura , Ruanda/epidemiologia , Malária/epidemiologia , Malária/transmissão , Incidência , Humanos , Estações do Ano , ClimaRESUMO
BACKGROUND: Anopheles melas is an understudied malaria vector with a potential role in malaria transmission on the Bijagós Archipelago of Guinea-Bissau. This study presents the first whole-genome sequencing and population genetic analysis for this species from the Bijagós. To our knowledge, this also represents the largest population genetic analysis using WGS data from non-pooled An. melas mosquitoes. METHODS: WGS was conducted for 30 individual An. melas collected during the peak malaria transmission season in 2019 from six different islands on the Bijagós Archipelago. Bioinformatics tools were used to investigate the population structure and prevalence of insecticide resistance markers in this mosquito population. RESULTS: Insecticide resistance mutations associated with pyrethroid resistance in Anopheles gambiae s.s. from the Bijagós were absent in the An. melas population, and no signatures of selective sweeps were identified in insecticide resistance-associated genes. Analysis of structural variants identified a large duplication encompassing the cytochrome-P450 gene cyp9k1. Phylogenetic analysis using publicly available mitochondrial genomes indicated that An. melas from the Bijagós split into two phylogenetic groups because of differentiation on the mitochondrial genome attributed to the cytochrome C oxidase subunits COX I and COX II and the NADH dehydrogenase subunits 1, 4, 4L and 5. CONCLUSIONS: This study identified an absence of insecticide-resistant SNPs common to An. gambiae in the An. melas population, but did identify structural variation over insecticide resistance-associated genes. Furthermore, this study presents novel insights into the population structure of this malaria vector using WGS analysis. Additional studies are required to further understand the role of this vector in malaria transmission.
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Anopheles , Resistência a Inseticidas , Malária , Mosquitos Vetores , Filogenia , Sequenciamento Completo do Genoma , Animais , Resistência a Inseticidas/genética , Anopheles/genética , Anopheles/efeitos dos fármacos , Guiné-Bissau/epidemiologia , Mosquitos Vetores/genética , Mosquitos Vetores/efeitos dos fármacos , Malária/transmissão , Malária/epidemiologia , Inseticidas/farmacologia , Piretrinas/farmacologia , Genoma Mitocondrial/genética , FemininoRESUMO
The evolution of hematophagy involves a series of adaptations that allow blood-feeding insects to access and consume blood efficiently while managing and circumventing the host's hemostatic and immune responses. Mosquito, and other insects, utilize salivary proteins to regulate these responses at the bite site during and after blood feeding. We investigated the function of Anopheles gambiae salivary apyrase (AgApyrase) in regulating hemostasis in the mosquito blood meal and in Plasmodium transmission. Our results demonstrate that salivary apyrase, a known inhibitor of platelet aggregation, interacts with and activates tissue plasminogen activator, facilitating the conversion of plasminogen to plasmin, a human protease that degrades fibrin and facilitates Plasmodium transmission. We show that mosquitoes ingest a substantial amount of apyrase during blood feeding, which reduces coagulation in the blood meal by enhancing fibrin degradation and inhibiting platelet aggregation. AgApyrase significantly enhanced Plasmodium infection in the mosquito midgut, whereas AgApyrase immunization inhibited Plasmodium mosquito infection and sporozoite transmission. This study highlights a pivotal role for mosquito salivary apyrase for regulation of hemostasis in the mosquito blood meal and for Plasmodium transmission to mosquitoes and to the mammalian host, underscoring the potential for strategies to prevent malaria transmission.
Assuntos
Anopheles , Apirase , Hemostasia , Malária , Animais , Apirase/metabolismo , Anopheles/parasitologia , Hemostasia/efeitos dos fármacos , Malária/transmissão , Malária/parasitologia , Agregação Plaquetária/efeitos dos fármacos , Humanos , Ativador de Plasminogênio Tecidual/metabolismo , Proteínas de Insetos/metabolismo , Feminino , Camundongos , Fibrinolisina/metabolismo , Saliva/parasitologia , Fibrina/metabolismo , EsporozoítosRESUMO
BACKGROUND: The efficacy of vector control tools depends on the behavior of the vector species. Many studies have sought to determine the feeding behavior of Anopheles mosquitoes in different settings of Ethiopia. We have performed a systematic review aimed to generate pooled evidence on the overall and species-specific blood meal sources of Anopheles mosquitoes in Ethiopia. METHODS: A search for relevant articles was performed in two electronic databases (PubMed and Science Direct) and three search engines (Google Scholar, Research Gate and Google) between 11 March and 2 April 2024. Following the initial identification of articles, we used EndNote X8 software and removed duplicate articles and screened the remaining articles by careful reading of their titles and abstracts. The full text of articles that passed this screening phase was retrieved, read and evaluated against predetermined selection criteria. The final decision for inclusion in the systematic review was made after a methodological quality check using the JBI critical appraisal checklist. All relevant data were extracted from tables, figures and texts of the included articles using a premade template in Excel, and the data were analyzed using Stata version 14 software. RESULTS: Of the 2431 studies identified, 27 met the inclusion criteria; all were published between 1997 and 2024. At 215 data points (frequency of tests of each Anopheles species by location and method of mosquito collections), 18,771 Anopheles mosquitoes belonging to 23 species or species complexes were tested for blood meal sources. The commonest sources of blood meals for Anopheles mosquitoes were bovine (36.0%, n = 6758) and human (29.4%, n = 5520). Among the tested anophelines, Anopheles (An.) arabiensis accounted for 67.9% (n = 12,741), followed by An. pharoensis, An. demeilloni and An. stephensi at 10.0%, 5.6% and 4.4%, respectively. Overall, there was no difference in the mean proportion of An. arabiensis detected with domestic animal blood (33.4%, 95% confidence interval [CI] 32.4-34.4%) and those detected with human blood (31.8%, 95% CI 30.9-32.8%). However, a greater proportion of the outdoor collected An. arabiensis were found to feed on bovines (47.9%, 95% CI 35.3-60.6) compared to humans (12.9%, 95% CI 0.8-24.9, P < 0.01). The foraging ratio (FR), which accounts for host availability, was greater for bovines (FR = 0.7) than for humans (FR = 0.2) for An. arabiensis, indicating preferential feeding on bovine hosts. This host preference was supported by the host preference index (human:bovine = 0.4). Anopheles pharoensis was detected with a slightly higher human blood index (53.5%, n = 1005) compared to bovine blood index (45.2%, n = 849). In contrast, An. demeilloni, An. coustani and An. marshalli were detected with a higher bovine blood index. Recently invaded urban malaria vector, An. stephensi was found with a higher ovine blood index. CONCLUSIONS: Bovine and human hosts are common sources of a blood meal for Anopheles mosquitoes. In terms of host availability, An. arabiensis showed preferential feeding on bovines/cattle. Targeting domestic animals, bovines and ovines with endectocides could supplement current vector control interventions. STUDY REGISTRATION: The protocol of this study was registered on the International Prospective Register of Systematic Reviews, registration no. CRD42024515725.
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Anopheles , Comportamento Alimentar , Mosquitos Vetores , Animais , Anopheles/fisiologia , Etiópia , Mosquitos Vetores/fisiologia , Humanos , Bovinos , Malária/transmissão , Malária/prevenção & controleRESUMO
Urban areas in malaria-endemic countries in East Africa are experiencing a significant increase in malaria cases, with the establishment of an "exotic" urban malaria vector, Anopheles stephensi, increasing the risk of urban malaria. To this end, the present study aimed to investigate the emergence of this species in Arba Minch, Ethiopia. Following the detection of An. stephensi in other parts of Ethiopia, 76 artificial containers (55 discarded tyres, 18 concrete water storage, and three plastic containers) were sampled in 21 locations in Arba Minch town, for immature Anopheles mosquito stages, using the standard dipping technique. Larvae were reared into adults which were morphologically identified at the species level 2-3 days after emergence. Morphological identification results were confirmed by species-specific polymerase chain reaction. Of the examined containers, 67 (88%) had at least one Anopheles larva. Thirty-two of the adults emerged were morphologically identified as An. stephensi, with 26 (81%) confirmed by molecular analysis. This is the first study to report An. stephensi from Arba Minch, one of South Ethiopia's largest towns, highlighting the need for increased vigilance. The planned and ongoing study in and around Arba Minch will contribute to understanding the bionomics and role of An. stephensi in malaria parasite transmission, helping develop a strategy to address the impending risk of urban malaria in Ethiopia.
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Anopheles , Larva , Malária , Mosquitos Vetores , Animais , Anopheles/parasitologia , Anopheles/classificação , Anopheles/fisiologia , Anopheles/crescimento & desenvolvimento , Etiópia , Malária/transmissão , Malária/epidemiologia , Mosquitos Vetores/parasitologia , Mosquitos Vetores/fisiologia , Mosquitos Vetores/crescimento & desenvolvimento , Mosquitos Vetores/classificação , Larva/crescimento & desenvolvimento , Reação em Cadeia da PolimeraseRESUMO
BACKGROUND: The emergence of insecticide resistance and its spread through populations of malaria vectors has decreased the number of insecticides available for control. Insecticide resistance has been observed in vector populations across sub-Saharan Africa in malaria endemic areas. Therefore, new compounds with different modes of action are needed that can be used in the management of resistance. The current study assessed the bioefficacy of the new indoor residual spray formulation, VECTRON™ T500 against Klypson 500 WG and water against laboratory reared and wild populations of Anopheles gambiae s.l.. The comparative experimental hut trial was implemented between June 2022 and December 2022 to determine the efficacy of VECTRON™ T500, containing the active ingredient (ai) broflanilide as a 50 % wettable powder (WP). The efficacy of VECTRON™ T500 was compared with a positive control, Klypson 500 WG, a wettable granule (WG) formulation that contains 50 % clothianidin. Cement and mud walls were sprayed with VECTRON™ T500, Klypson 500 WG with water sprayed as a negative control. The two insecticides and negative control were evaluated monthly for six months against laboratory and the field-derived An. gambiae s.l. using the standard WHO cone bioassays. Each wall had two cones on each day of testing. VECTRON™ T500 was sprayed on both surface types at a rate of 100mg ai/m2 whilst Klypson 500 WG was applied at a rate of 300 mg ai/m2. For both wall surface types, the vector from the laboratory-reared and the wild populations exhibited a low knockdown effect to both VECTRON™ T500 and Klypson 500 WG. A total of 3,840 mosquitoes were used of which 2,880 (75 %) were susceptible colony of An. gambiae s.s. and 960 (25 %) were wild An. gambiae s.l.. The VECTRON™ T500 induced a mortality of 97.8 %-98.1 % in the laboratory population and 83.2-95.0 % wild population mosquitoes on cement and mud-walled huts respectively while Klypson 500 WG ranged from 89.6-99.0 % for wild and 99.0-99.3 % for the laboratory population mosquitoes on cement and mud walls respectively. The knockdown due to VECTRON™ T500 was 7.08 % in the sixth month, while for Klypson 500 WG was 16.04-17.50 %. The monthly wall cone bioassay mortality with VECTRON™ T500 remained over 80 % for 6 months post-spraying for both laboratory and wild populations. The findings of this study have shown VECTRON™ T500 to have extended efficacy against malaria vector mosquitoes when applied to cement and mud walls. The evaluated new IRS formulation, VECTRON™ T500, performed equally with the positive control, Klypson 500 WG, regarding its impact on vector mortality.
Assuntos
Anopheles , Inseticidas , Controle de Mosquitos , Mosquitos Vetores , Animais , Anopheles/efeitos dos fármacos , Inseticidas/farmacologia , Inseticidas/administração & dosagem , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , Feminino , Malária/prevenção & controle , Malária/transmissão , Habitação , Resistência a InseticidasRESUMO
In recent decades, field and semi-field studies of malaria transmission have gathered geographic-specific information about mosquito ecology, behaviour and their sensitivity to interventions. Mathematical models of malaria transmission can incorporate such data to infer the likely impact of vector control interventions and hence guide malaria control strategies in various geographies. To facilitate this process and make model predictions of intervention impact available for different geographical regions, we developed AnophelesModel. AnophelesModel is an online, open-access R package that quantifies the impact of vector control interventions depending on mosquito species and location-specific characteristics. In addition, it includes a previously published, comprehensive, curated database of field entomological data from over 50 Anopheles species, field data on mosquito and human behaviour, and estimates of vector control effectiveness. Using the input data, the package parameterizes a discrete-time, state transition model of the mosquito oviposition cycle and infers species-specific impacts of various interventions on vectorial capacity. In addition, it offers formatted outputs ready to use in downstream analyses and by other models of malaria transmission for accurate representation of the vector-specific components. Using AnophelesModel, we show how the key implications for intervention impact change for various vectors and locations. The package facilitates quantitative comparisons of likely intervention impacts in different geographical settings varying in vector compositions, and can thus guide towards more robust and efficient malaria control recommendations. The AnophelesModel R package is available under a GPL-3.0 license at https://github.com/SwissTPH/AnophelesModel.
Assuntos
Anopheles , Malária , Controle de Mosquitos , Mosquitos Vetores , Software , Animais , Humanos , Malária/transmissão , Malária/prevenção & controle , Anopheles/fisiologia , Mosquitos Vetores/fisiologia , Controle de Mosquitos/métodos , Biologia Computacional , Modelos BiológicosRESUMO
BACKGROUND: Anopheles stephensi is an invasive malaria vector in Africa that threatens to put an additional 126 million people at risk of malaria if it continues to spread. The island nation of Mauritius is highly connected to Asia and Africa and is at risk of introduction due to this connectivity. For early detection of An. stephensi, the Vector Biology and Control Division under the Ministry of Health in Mauritius, leveraged a well-established Aedes program, as An. stephensi is known to share Aedes habitats. These efforts triggered multisectoral coordination and cascading benefits of integrated vector and One Health approaches. METHODS: Beginning June 2021, entomological surveys were conducted at points of entry (seaport, airport) and on ships transporting livestock in collaboration with the Civil Aviation Department, the Mauritian Port Authority and National Veterinary Services. A total of 18, 39, 723 mosquito larval surveys were respectively conducted in the airport, seaport, and other localities in Mauritius while two, 20, and 26 adult mosquito surveys were respectively conducted in the airport, seaport, and twenty-six animal assembly points. Alongside adult mosquito surveys, surveillance of vectors of veterinary importance (e.g.- Culicoides spp.) was also carried out in collaboration with National Parks and Conservation Service and land owners. RESULTS: A total of 8,428 adult mosquitoes were collected and 1,844 larval habitats were positive for mosquitoes. All collected mosquitoes were morphologically identified and 151 Anopheles and 339 Aedes mosquitoes were also molecularly characterized. Mosquito species detected were Aedes albopictus, Anopheles arabiensis, An. coustani, An. merus, Culex quinquefasciatus, Cx. thalassius and Lutzia tigripes. Anopheles stephensi was not detected. The One Health approach was shared with the French Agricultural Research Centre for International Development (CIRAD), strengthening collaboration between Mauritius and Réunion Island on vector surveillance at entry points and insecticide resistance monitoring. The Indian Ocean Commission (IOC) was also alerted to the risk of An. stephensi, leading to regional efforts supporting trainings and development of a response strategy to An. stephensi bringing together stakeholders from Comoros, Madagascar, Mauritius, Réunion Island and Seychelles. CONCLUSIONS: Mauritius is a model system showing how existing public health entomology capabilities can be used to enhance vector surveillance and control and create multisectoral networks to respond to any emerging public and veterinary health vector-borne disease threat.
Assuntos
Anopheles , Malária , Controle de Mosquitos , Mosquitos Vetores , Saúde Única , Animais , Anopheles/fisiologia , Anopheles/classificação , Maurício , Mosquitos Vetores/fisiologia , Mosquitos Vetores/classificação , Malária/transmissão , Malária/prevenção & controle , Malária/epidemiologia , Controle de Mosquitos/métodos , Humanos , Aedes/fisiologia , Aedes/classificação , Ecossistema , Espécies Introduzidas , Larva/fisiologiaRESUMO
BACKGROUND: Intensive deployment of insecticide based malaria vector control tools resulted in the rapid evolution of phenotypes resistant to these chemicals. Understanding this process at the genomic level is important for the deployment of successful vector control interventions. Therefore, longitudinal sampling followed by whole genome sequencing (WGS) is necessary to understand how these evolutionary processes evolve over time. This study investigated the change in genetic structure and the evolution of the insecticide resistance variants in natural populations of Anopheles gambiae over time and space from 2012 to 2017 in Burkina Faso. METHODS: New genomic data have been generated from An. gambiae mosquitoes collected from three villages in the western part of Burkina Faso between 2012 and 2017. The samples were whole-genome sequenced and the data used in the An. gambiae 1000 genomes (Ag1000G) project as part of the Vector Observatory. Genomic data were analysed using the analysis pipeline previously designed by the Ag1000G project. RESULTS: The results showed similar and consistent nucleotide diversity and negative Tajima's D between An. gambiae sensu stricto (s.s.) and Anopheles coluzzii. Principal component analysis (PCA) and the fixation index (FST) showed a clear genetic structure in the An. gambiae sensu lato (s.l.) species. Genome-wide FST and H12 scans identified genomic regions under divergent selection that may have implications in the adaptation to ecological changes. Novel voltage-gated sodium channel pyrethroid resistance target-site alleles (V402L, I1527T) were identified at increasing frequencies alongside the established alleles (Vgsc-L995F, Vgsc-L995S and N1570Y) within the An. gambiae s.l. POPULATIONS: Organophosphate metabolic resistance markers were also identified, at increasing frequencies, within the An. gambiae s.s. populations from 2012 to 2017, including the SNP Ace1-G280S and its associated duplication. Variants simultaneously identified in the same vector populations raise concerns about the long-term efficacy of new generation bed nets and the recently organophosphate pirimiphos-methyl indoor residual spraying in Burkina Faso. CONCLUSION: These findings highlighted the benefit of genomic surveillance of malaria vectors for the detection of new insecticide resistance variants, the monitoring of the existing resistance variants, and also to get insights into the evolutionary processes driving insecticide resistance.
Assuntos
Anopheles , Resistência a Inseticidas , Mosquitos Vetores , Sequenciamento Completo do Genoma , Resistência a Inseticidas/genética , Anopheles/genética , Anopheles/efeitos dos fármacos , Animais , Burkina Faso , Mosquitos Vetores/genética , Mosquitos Vetores/efeitos dos fármacos , Estudos Longitudinais , Evolução Molecular , Inseticidas/farmacologia , Malária/transmissãoRESUMO
BACKGROUND: The core vector control tools used to reduce malaria prevalence are currently long-lasting insecticidal nets (LLINs), and indoor residual spraying (IRS). These interventions are hindered by insecticide resistance and behavioural adaptation by malaria vectors. Thus, for effective interruption of malaria transmission, there is a need to develop novel vector control interventions and technologies to address the above challenges. Larviciding using drones was experimented as an innovative tool that could complement existing indoor interventions to control malaria. METHODS: A non-randomized larviciding trial was carried out in irrigated rice fields in sub-urban Kigali, Rwanda. Potential mosquito larval habitats in study sites were mapped and subsequently sprayed using multirotor drones. Application of Bacillus thuringiensis var. israelensis (Bti) (Vectobac® WDG) was followed by entomological surveys that were performed every two weeks over a ten-month period. Sampling of mosquito larvae was done with dippers while adult mosquitoes were collected using CDC miniature light traps (CDC-LT) and pyrethrum spraying collection (PSC) methods. Malaria cases were routinely monitored through community health workers in villages surrounding the study sites. RESULTS: The abundance of all-species mosquito larvae, Anopheles larvae and all-species pupae declined by 68.1%, 74.6% and 99.6%, respectively. Larval density was reduced by 93.3% for total larvae, 95.3% for the Anopheles larvae and 61.9% for pupae. The total adult mosquitoes and Anopheles gambiae sensu lato collected using CDC-Light trap declined by 60.6% and 80% respectively. Malaria incidence also declined significantly between intervention and control sites (U = 20, z = - 2.268, p = 0.023). CONCLUSIONS: The larviciding using drone technology implemented in Rwanda demonstrated a substantial reduction in abundance and density of mosquito larvae and, concomitant decline in adult mosquito populations and malaria incidences in villages contingent to the treatment sites. The scaling up of larval source management (LSM) has to be integrated in malaria programmes in targeted areas of malaria transmission in order to enhance the gains in malaria control.
Assuntos
Anopheles , Bacillus thuringiensis , Larva , Malária , Controle de Mosquitos , Mosquitos Vetores , Animais , Controle de Mosquitos/métodos , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Anopheles/efeitos dos fármacos , Malária/prevenção & controle , Malária/transmissão , Ruanda , Mosquitos Vetores/efeitos dos fármacos , Inseticidas/farmacologia , Humanos , Feminino , Oryza , Controle Biológico de Vetores/métodos , MasculinoRESUMO
BACKGROUND: Despite global efforts to reduce and eventually interrupt malaria transmission, the disease remains a pressing public health problem, especially in sub-Saharan Africa. This study presents a detailed spatio-temporal analysis of malaria transmission in Rwanda from 2012 to 2022. The main objective was to gain insights into the evolving patterns of malaria and to inform and tailor effective public health strategies. METHODS: The study used yearly aggregated data of malaria cases from the Rwanda health management information system. We employed a multifaceted analytical approach, including descriptive statistics and spatio-temporal analysis across three demographic groups: children under the age of 5 years, and males and females above 5 years. Bayesian spatially explicit models and spatio scan statistics were utilised to examine geographic and temporal patterns of relative risks and to identify clusters of malaria transmission. RESULTS: We observed a significant increase in malaria cases from 2014 to 2018, peaking in 2016 for males and females aged above 5 years with counts of 98,645 and 116,627, respectively and in 2018 for under 5-year-old children with 84,440 cases with notable geographic disparities. Districts like Kamonyi (Southern Province), Ngoma, Kayonza and Bugesera (Eastern Province) exhibited high burdens, possibly influenced by factors such as climate, vector control practices, and cross-border dynamics. Bayesian spatially explicit modeling revealed elevated relative risks in numerous districts, underscoring the heterogeneity of malaria transmission in these districts, and thus contributing to an overall rising trend in malaria cases until 2018, followed by a subsequent decline. Our findings emphasize that the heterogeneity of malaria transmission is potentially driven by ecologic, socioeconomic, and behavioural factors. CONCLUSIONS: The study underscores the complexity of malaria transmission in Rwanda and calls for climate adaptive, gender-, age- and district-specific strategies in the national malaria control program. The emergence of both artemisinin and pyrethoids resistance and persistent high transmission in some districts necessitates continuous monitoring and innovative, data-driven approaches for effective and sustainable malaria control.
Assuntos
Teorema de Bayes , Malária , Análise Espaço-Temporal , Ruanda/epidemiologia , Humanos , Pré-Escolar , Feminino , Masculino , Malária/epidemiologia , Malária/transmissão , Criança , Lactente , Demografia , Adolescente , Recém-NascidoRESUMO
Improved understanding of mosquito-plant feeding interactions can reveal insights into the ecological dynamics of pathogen transmission. In wild malaria vectors Anopheles gambiae s.l. and An. funestus group surveyed in selected dryland ecosystems of Kenya, we found a low level of plant feeding (2.8%) using biochemical cold anthrone test but uncovered 14-fold (41%) higher rate via DNA barcoding targeting the chloroplast rbcL gene. Plasmodium falciparum positivity was associated with either reduced or increased total sugar levels and varied by mosquito species. Gut analysis revealed the mosquitoes to frequently feed on acacia plants (~ 89%) (mainly Vachellia tortilis) in the family Fabaceae. Chemical analysis revealed 1-octen-3-ol (29.9%) as the dominant mosquito attractant, and the sugars glucose, sucrose, fructose, talose and inositol enriched in the vegetative parts, of acacia plants. Nutritional analysis of An. longipalpis C with high plant feeding rates detected fewer sugars (glucose, talose, fructose) compared to acacia plants. These results demonstrate (i) the sensitivity of DNA barcoding to detect plant feeding in malaria vectors, (ii) Plasmodium infection status affects energetic reserves of wild anopheline vectors and (iii) nutrient content and olfactory cues likely represent potent correlates of acacia preferred as a host plant by diverse malaria vectors. The results have relevance in the development of odor-bait control strategies including attractive targeted sugar-baits.
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Anopheles , Código de Barras de DNA Taxonômico , Ecossistema , Mosquitos Vetores , Plasmodium falciparum , Animais , Mosquitos Vetores/parasitologia , Mosquitos Vetores/genética , Anopheles/parasitologia , Anopheles/genética , Anopheles/metabolismo , Quênia , Plasmodium falciparum/genética , Plasmodium falciparum/metabolismo , Malária/transmissão , Malária/parasitologia , Acacia/metabolismo , Acacia/parasitologia , Acacia/genética , Comportamento Alimentar/fisiologia , Ribulose-Bifosfato Carboxilase/metabolismo , Ribulose-Bifosfato Carboxilase/genéticaRESUMO
BACKGROUND: Endemic African malaria vectors are poorly adapted to typical urban ecologies. However, Anopheles stephensi, an urban malaria vector formerly confined to South Asia and the Persian Gulf, was recently detected in Africa and may change the epidemiology of malaria across the continent. Little is known about the public health implications of An. stephensi in Africa. This study is designed to assess the relative importance of household exposure to An. stephensi and endemic malaria vectors for malaria risk in urban Sudan and Ethiopia. METHODS: Case-control studies will be conducted in 3 urban settings (2 in Sudan, 1 in Ethiopia) to assess the association between presence of An. stephensi in and around households and malaria. Cases, defined as individuals positive for Plasmodium falciparum and/or P. vivax by microscopy/rapid diagnostic test (RDT), and controls, defined as age-matched individuals negative for P. falciparum and/or P. vivax by microscopy/RDT, will be recruited from public health facilities. Both household surveys and entomological surveillance for adult and immature mosquitoes will be conducted at participant homes within 48 hours of enrolment. Adult and immature mosquitoes will be identified by polymerase chain reaction (PCR). Conditional logistic regression will be used to estimate the association between presence of An. stephensi and malaria status, adjusted for co-occurrence of other malaria vectors and participant gender. CONCLUSIONS: Findings from this study will provide evidence of the relative importance of An. stephensi for malaria burden in urban African settings, shedding light on the need for future intervention planning and policy development.
Assuntos
Anopheles , Mosquitos Vetores , Anopheles/parasitologia , Etiópia/epidemiologia , Sudão/epidemiologia , Animais , Humanos , Estudos de Casos e Controles , Mosquitos Vetores/parasitologia , Características da Família , Malária/epidemiologia , Malária/transmissão , Malária Falciparum/epidemiologia , Malária Falciparum/transmissão , Plasmodium falciparum/isolamento & purificação , Feminino , MasculinoRESUMO
The two main Afrotropical malaria vectors - Anopheles coluzzii and An. gambiae - are genetically distinct and reproductively isolated across West Africa. However, populations at the western extreme of their range are assigned as "intermediate" between the two species by whole genome sequence (WGS) data, and as hybrid forms by conventional molecular diagnostics. By exploiting WGS data from 1190 specimens collected across west Africa via the Anopheles gambiae 1000 Genomes network, we identified a putative taxon in the far-west (provisionally named Bissau molecular form), which did not arise by admixture but rather may have originated at the same time as the split between An. coluzzii and An. gambiae. Intriguingly, this taxon lacks insecticide resistance mechanisms commonly observed in the two main species. These findings lead to a change of perspective on malaria vector species in the far-west region with potential for epidemiological implications, and a new challenge for genetic-based mosquito control approaches.
Assuntos
Anopheles , Mosquitos Vetores , Anopheles/genética , Anopheles/classificação , Animais , Mosquitos Vetores/genética , Mosquitos Vetores/classificação , África Ocidental , Resistência a Inseticidas/genética , Malária/transmissão , Genoma de Inseto , Sequenciamento Completo do Genoma , FilogeniaRESUMO
The Democratic Republic of Congo (DRC) suffers from one of the highest malaria burdens worldwide, but information on its Anopheles vector populations is relatively limited. Preventative malaria control in DRC is reliant on pyrethroid-treated nets, raising concerns over the potential impacts of insecticide resistance. We sampled Anopheles gambiae from three geographically distinct populations (Kimpese, Kapolowe and Mikalayi) in southern DRC, collecting from three sub-sites per population and characterising mosquito collections from each for resistance to pyrethroids using WHO tube bioassays. Resistance to each of three different pyrethroids was generally high in An. gambiae with < 92% mortality in all tests, but varied between collections, with mosquitoes from Kimpese being the most resistant. Whole genome sequencing of 165 An. gambiae revealed evidence for genetic differentiation between Kimpese and Kapolowe/Mikalayi, but not between the latter two sample sites despite separation of approximately 800 km. Surprisingly, there was evidence of population structure at a small spatial scale between collection subsites in Kimpese, despite separation of just tens of kilometres. Intra-population (H12) and inter-population (FST) genome scans identified multiple peaks corresponding to genes associated with insecticide resistance such as the voltage gated sodium channel (Vgsc) target site on chromosome 2L, a Cyp6 cytochrome P450 cluster on chromosome arm 2R, and the Cyp9k1 P450 gene on chromosome X. In addition, in the Kimpese subsites, the P450 redox partner gene Cpr showed evidence for contemporary selection (H12) and population differentiation (FST) meriting further exploration as a potential resistance associated marker.
Assuntos
Anopheles , Resistência a Inseticidas , Inseticidas , Mosquitos Vetores , Piretrinas , Animais , Anopheles/genética , Anopheles/efeitos dos fármacos , Resistência a Inseticidas/genética , República Democrática do Congo , Piretrinas/farmacologia , Inseticidas/farmacologia , Mosquitos Vetores/genética , Mosquitos Vetores/efeitos dos fármacos , Malária/transmissãoRESUMO
BACKGROUND: The community involvement and the people's knowledge allow detailed information about the distribution, location, and identification of mosquito breeding-sites. Information which is fundamental for their efficient management and elimination. Since participatory mapping has proven to be an effective tool to identify health determinants, the study aimed to apply the methodology to identify and map potential mosquito breeding-sites in Tambai, Nhamatanda, Mozambique. METHODS: A study was conducted using an open-question guide. Discussions were held with 94 participants within ten focus groups, selected in collaboration with local community leaders. A thematic content analysis was performed. Descriptive statistics were used to characterize sociodemographic data. Geographic Positioning System (GPS) was used to compare and map potential breeding-sites. Children under 5 years of age who tested positive for malaria, were georeferenced to the maps. RESULTS: Participants were aware of causes and transmission of malaria, no major differences between groups were observed regarding knowledge and identification of principal potential breeding sites. Gender and age determined specific information, number, and diversity of identified potential breeding sites. A total of 125 potential breeding-sites (36 permanent and 89 temporary) were mapped. CONCLUSIONS: Several potential mosquito breeding-sites were identified, located throughout the community, often near house conglomerates and malaria cases. Community participatory mapping could be used to identify potential mosquito breeding-sites by the national malaria control programmes to establish an efficient larval surveillance system, while improving community engagement and control strategies. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT04419766.
Assuntos
Malária , Adolescente , Adulto , Animais , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem , Anopheles/parasitologia , Anopheles/fisiologia , Pesquisa Participativa Baseada na Comunidade , Mapeamento Geográfico , Malária/diagnóstico , Malária/prevenção & controle , Malária/transmissão , Mosquitos Vetores/parasitologia , Mosquitos Vetores/fisiologia , Moçambique , Estudos Prospectivos , CriançaRESUMO
Malaria is an infectious disease caused by several species of the genus Plasmodium. It is usually transmitted by female Anopheles mosquitoes. Other routes of transmission include mother-to-child transmission, shared use of needles, blood transfusion and solid organ transplantation. In non-endemic countries, malaria is often diagnosed on the basis of a history of journeys or migration from endemic areas. Transplant-transmitted malaria might represent a diagnostic challenge for clinicians. Here, we report the casual diagnosis of possible transplant-transmitted malaria in a Spanish patient with no previous visits to endemic areas. He developed symptoms one month after receiving a liver transplant from a deceased donor immigrated from Ghana. After being admitted to the Emergency Room, a complete blood count revealed an abnormal cell population which activated an 'infested red blood cells' flag (iRBC). This finding led to perform a blood smear and further tests which confirmed the diagnosis of malaria. Given that automated complete blood counts are usually performed for any patient with fever, they represent a useful tool to detect malaria in unsuspected patients. In particular, the iRBC flag implemented in Sysmex XN-Series™ hematology analyzers is a useful screening tool for malaria in clinical laboratories.
Assuntos
Transplante de Fígado , Malária , Plasmodium malariae , Humanos , Malária/diagnóstico , Malária/transmissão , Plasmodium malariae/isolamento & purificação , Masculino , Gana , Pessoa de Meia-Idade , EspanhaRESUMO
OBJECTIVES: This study assesses exposure to malaria vector mosquitos that is nonpreventable through use of nets, the contribution of outdoor and indoor biting towards residual vector exposure, and the risk factors for being bitten and for being infected with malaria parasites on Bioko Island, Equatorial Guinea. METHODS: Human behavior and malaria infection data were collected from 13,735 randomly selected residents during cross-sectional surveys, concomitantly with entomological human landing catches, indoors and outdoors, in 20 locations on the Island. Self-reported time of going indoors, going to bed and whether using a net were analyzed to impute for each respondent the number of bites received outdoors and indoors during the night before the survey. RESULTS: On average, each person received 2.7 (95% CI: 2.6-2.8) bites per night outdoors, 8.5 (8.3 to 8.7) bites indoors if not using a net, and 4.7 (4.5 to 4.8) bites indoors if using a net. Malaria infection was associated with more bites, regardless of whether received indoors or outdoors. Older age, male gender, not using a net, rural location, and going indoors later increased the risk of being bitten. The proportion of bites not averted by using a net was estimated as 66% (61 to 71). CONCLUSIONS: A large proportion of biting, mostly indoors, may not be preventable by bednets. Tools targeting indoor biting should be prioritized in Bioko. Novel vector control tools are urgently needed to reduce overall exposure to mosquito bites.
Assuntos
Mordeduras e Picadas de Insetos , Malária , Controle de Mosquitos , Mosquitos Vetores , Humanos , Guiné Equatorial/epidemiologia , Mordeduras e Picadas de Insetos/prevenção & controle , Mordeduras e Picadas de Insetos/epidemiologia , Masculino , Feminino , Adulto , Animais , Malária/transmissão , Malária/prevenção & controle , Malária/epidemiologia , Estudos Transversais , Controle de Mosquitos/métodos , Adolescente , Pessoa de Meia-Idade , Adulto Jovem , Criança , Mosquitos Vetores/parasitologia , Pré-Escolar , Fatores de Risco , Lactente , IdosoRESUMO
Climate change is a significant risk multiplier and profoundly influences the transmission dynamics, geographical distribution, and resurgence of vector-borne diseases (VBDs). Bangladesh has a noticeable rise in VBDs attributed to climate change. Despite the severity of this issue, the interconnections between climate change and VBDs in Bangladesh have yet to be thoroughly explored. To address this research gap, our review meticulously examined existing literature on the relationship between climate change and VBDs in Bangladesh. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach, we identified 3849 records from SCOPUS, Web of Science, and Google Scholar databases. Ultimately, 22 research articles meeting specific criteria were included. We identified that the literature on the subject matter of this study is non-contemporaneous, with 68% of studies investing datasets before 2014, despite studies on climate change and dengue nexus having increased recently. We pinpointed Dhaka and Chittagong Hill Tracts as the dengue and malaria research hotspots, respectively. We highlighted that the 2023 dengue outbreak illustrates a possible shift in dengue-endemic areas in Bangladesh. Moreover, dengue cases surged by 317% in 2023 compared to 2019 records, with a corresponding 607% increase in mortality compared to 2022. A weak connection was observed between dengue incidents and climate drivers, including the El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). However, no compelling evidence supported an association between malaria cases, and Sea Surface Temperature (SST) in the Bay of Bengal, along with the NINO3 phenomenon. We observed minimal microclimatic and non-climatic data inclusion in selected studies. Our review holds implications for policymakers, urging the prioritization of mitigation measures such as year-round surveillance and early warning systems. Ultimately, it calls for resource allocation to empower researchers in advancing the understanding of VBD dynamics amidst changing climates.
Assuntos
Mudança Climática , Dengue , Doenças Transmitidas por Vetores , Bangladesh/epidemiologia , Humanos , Doenças Transmitidas por Vetores/epidemiologia , Dengue/epidemiologia , Dengue/transmissão , Animais , Malária/epidemiologia , Malária/transmissão , Surtos de DoençasRESUMO
Malaria is initiated as Plasmodium sporozoites are injected into the dermis when an infected mosquito probes on a vertebrate host for a blood meal. Factors in the mosquito saliva, such as AgTRIO, can alter the ability of Anopheles gambiae to transmit Plasmodium. We therefore used CRISPR-Cas9-mediated genome editing to generate AgTRIO knockout (KO) A. gambiae and examined the ability of these mosquitoes to probe on a vertebrate host. AgTRIO KO mosquitoes showed a diminished host probing capacity and required repetitive probing to locate a blood resource to complete a blood meal. This increased probing resulted in enhanced Plasmodium transmission to the vertebrate host. Our data demonstrate the importance of the A. gambiae saliva protein AgTRIO in probing and its influence on the ability of mosquitoes to transmit malaria.