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1.
BMC Infect Dis ; 20(1): 757, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33059623

RESUMO

BACKGROUND: Individuals that work and sleep in remote forest and farm locations in the Greater Mekong Subregion continue to remain at high risk of both acquiring and transmitting malaria. These difficult-to-access population groups largely fall outside the reach of traditional village-centered interventions, presenting operational challenges for malaria programs. In Vietnam, over 60% of malaria cases are thought to be individuals who sleep in forests or on farms. New malaria elimination strategies are needed in countries where mobile and migrant workers frequently sleep outside of their homes. The aim of this study was to apply targeted surveillance-response based investigative approaches to gather location-specific data on confirmed malaria cases, with an objective to identify associated malaria prevention, treatment and risk behaviors of individuals sleeping in remote forest and farms sites in Vietnam. METHODS: A cross-sectional study using novel targeted reactive investigative approaches at remote area sleeping sites was conducted in three mountainous communes in Phu Yen province in 2016. Index cases were defined as individuals routinely sleeping in forests or farms who had tested positive for malaria. Index cases and non-infected neighbors from forest and farm huts within 500 m of the established sleeping locations of index cases were interviewed at their remote-area sleeping sites. RESULTS: A total of 307 participants, 110 index cases and 197 neighbors, were enrolled. Among 93 participants who slept in the forest, index cases were more likely to make > 5 trips to the forest per year (prevalence odds ratio (POR) 7.41, 95% confidence interval (CI) 2.66-20.63), sleep in huts without walls (POR 44.00, 95% CI 13.05-148.33), sleep without mosquito nets (POR 2.95, 95% CI 1.26-6.92), and work after dark (POR 5.48, 95% CI 1.84-16.35). Of the 204 farm-based respondents, a significantly higher proportion of index cases were involved in non-farming activities (logging) (POR 2.74, 95% CI 1.27-5.91). CONCLUSION: Investigative approaches employed in this study allowed for the effective recruitment and characterization of high-priority individuals frequently sleeping in remote forest and farm locations, providing relevant population and site-specific data that decision makers can use to design and implement targeted interventions to support malaria elimination.


Assuntos
Florestas , Malária/epidemiologia , Malária/transmissão , Adulto , Terapia Comportamental , Estudos Transversais , Fazendas , Feminino , Habitação , Humanos , Malária/tratamento farmacológico , Malária/prevenção & controle , Masculino , Pessoa de Meia-Idade , Mosquiteiros , Razão de Chances , Assunção de Riscos , Vietnã/epidemiologia , Vietnã/etnologia
3.
PLoS Pathog ; 16(9): e1008739, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32946522

RESUMO

Malaria-causing Plasmodium parasites traverse the mosquito midgut cells to establish infection at the basal side of the midgut. This dynamic process is a determinant of mosquito vector competence, yet the kinetics of the parasite migration is not well understood. Here we used transgenic mosquitoes of two Anopheles species and a Plasmodium berghei fluorescence reporter line to track parasite passage through the mosquito tissues at high spatial resolution. We provide new quantitative insight into malaria parasite invasion in African and Indian Anopheles species and propose that the mosquito complement-like system contributes to the species-specific dynamics of Plasmodium invasion.


Assuntos
Anopheles/parasitologia , Sistema Digestório/parasitologia , Interações Hospedeiro-Parasita , Malária/transmissão , Mosquitos Vetores/patogenicidade , Plasmodium berghei/fisiologia , Animais , Anopheles/crescimento & desenvolvimento , Feminino , Malária/parasitologia , Camundongos , Especificidade da Espécie
4.
PLoS Negl Trop Dis ; 14(9): e0008617, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32886679

RESUMO

The zoonotic malaria parasite, Plasmodium knowlesi, is now a substantial public health problem in Malaysian Borneo. Current understanding of P. knowlesi vector bionomics and ecology in Sabah comes from a few studies near the epicentre of human cases in one district, Kudat. These have incriminated Anopheles balabacensis as the primary vector, and suggest that human exposure to vector biting is peri-domestic as well as in forest environments. To address the limited understanding of vector ecology and human exposure risk outside of Kudat, we performed wider scale surveillance across four districts in Sabah with confirmed transmission to investigate spatial heterogeneity in vector abundance, diversity and infection rate. Entomological surveillance was carried out six months after a cross-sectional survey of P. knowlesi prevalence in humans throughout the study area; providing an opportunity to investigate associations between entomological indicators and infection. Human-landing catches were performed in peri-domestic, farm and forest sites in 11 villages (3-4 per district) and paired with estimates of human P. knowlesi exposure based on sero-prevalence. Anopheles balabacensis was present in all districts but only 6/11 villages. The mean density of An. balabacensis was relatively low, but significantly higher in farm (0.094/night) and forest (0.082/night) than peri-domestic areas (0.007/night). Only one An. balabacensis (n = 32) was infected with P. knowlesi. Plasmodium knowlesi sero-positivity in people was not associated with An. balabacensis density at the village-level however post hoc analyses indicated the study had limited power to detect a statistical association due low vector density. Wider scale sampling revealed substantial heterogeneity in vector density and distribution between villages and districts. Vector-habitat associations predicted from this larger-scale surveillance differed from those inferred from smaller-scale studies in Kudat; highlighting the importance of local ecological context. Findings highlight potential trade-offs between maximizing temporal versus spatial breadth when designing entomological surveillance; and provide baseline entomological and epidemiological data to inform future studies of entomological risk factors for human P. knowlesi infection.


Assuntos
Anopheles/parasitologia , Malária/epidemiologia , Malária/transmissão , Mosquitos Vetores/parasitologia , Plasmodium knowlesi/isolamento & purificação , Animais , Bornéu/epidemiologia , Estudos Transversais , Fazendas , Florestas , Humanos , Malásia/epidemiologia , População Rural/estatística & dados numéricos , Soroconversão
5.
PLoS One ; 15(9): e0238323, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32898853

RESUMO

India, a persistently significant contributor to the global malaria burden, rolled out several anti-malaria interventions at the national and state level to control and recently, to eliminate the disease. Odisha, the eastern Indian state with the highest malaria burden experienced substantial gains shown by various anti-malaria initiatives implemented under the National Vector-borne Disease Control Programme (NVBDCP). However, recalcitrant high-transmission "pockets" of malaria persist in hard-to-reach stretches of the state, characterised by limited access to routine malaria surveillance and the forested hilly topography favouring unbridled vector breeding. The prevalence of asymptomatic malaria in such pockets serves as perpetual malaria reservoir, thus hindering its elimination. Therefore, a project with the acronym DAMaN was initiated since 2017 by state NVBDCP, targeting locally identified high endemic 'pockets' in 23 districts. DAMaN comprised biennial mass screening and treatment, provisioning of long-lasting insecticidal net (LLIN) and behavioural change communication. Subsequently, to inform policy, assessment of DAMaN was conceived that aims to estimate the coverage of the various components of the project; the prevalence of malaria, even at sub-patent level especially among pregnant/lactating women and children; and its impact on malaria incidence. A survey of DAMaN beneficiaries will measure coverage; and knowledge and practices related to LLIN; along with collection of blood specimens from a probability sample. A multi-stage stratified clustered sample of 2228 households (~33% having pregnant/lactating women) will be selected from 6 DAMaN districts. Routine DAMaN project data (2017-2018) and NVBDCP data (2013-2018) will be extracted. Rapid Diagnostic Test, Polymerase Chain Reaction and blood smear microscopy will be conducted to detect malarial parasitemia. In addition to measuring DAMaN's coverage and malarial prevalence in DAMaN pockets, its impact will be estimated using pre-post differences and Interrupted Time Series analysis using 2017 as the "inflection" point. The assessment may help to validate the unique strategies employed by DAMaN.


Assuntos
Antimaláricos/uso terapêutico , Mosquiteiros Tratados com Inseticida/estatística & dados numéricos , Malária/epidemiologia , Malária/prevenção & controle , Controle de Mosquitos/organização & administração , Controle de Mosquitos/normas , Plasmodium malariae/efeitos dos fármacos , Adolescente , Criança , Pré-Escolar , Feminino , Governo , Humanos , Incidência , Índia/epidemiologia , Lactente , Análise de Séries Temporais Interrompida , Malária/parasitologia , Malária/transmissão , Gravidez , Inquéritos e Questionários
6.
PLoS One ; 15(9): e0230984, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32946446

RESUMO

Insecticide resistance genes are often associated with pleiotropic effects on various mosquito life-history traits. However, very little information is available on the impact of insecticide resistance on blood feeding process in mosquitoes. Here, using two recently detected DNA-based metabolic markers in the major malaria vector, An. funestus, we investigated how metabolic resistance genes could affect the blood meal intake. After allowing both the field F1 and lab F8 Anopheles funestus strains to feed on the human arm for 30 minutes, we assessed the association between key parameters of blood meal process including, probing time, feeding duration, blood feeding success, blood meal size, and markers of glutathione S-transferase (L119F-GSTe2) and cytochrome P450 (CYP6P9a_R)-mediated metabolic resistance. None of the parameters of blood meal process was associated with L119F-GSTe2 genotypes. By contrast, for CYP6P9a_R, homozygous resistant mosquitoes were significantly more able to blood-feed than homozygous susceptible (OR = 3.3; CI 95%: 1.4-7.7; P = 0.01) mosquitoes. Moreover, the volume of blood meal ingested by CYP6P9a-SS mosquitoes was lower than that of CYP6P9a-RS (P<0.004) and of CYP6P9a-RR (P<0.006). This suggests that CYP6P9a gene is inked with the feeding success and blood meal size of An. funestus. However, no correlation was found in the expression of CYP6P9a and that of genes encoding for salivary proteins involved in blood meal process. This study suggests that P450-based metabolic resistance may influence the blood feeding process of Anopheles funestus mosquito and consequently its ability to transmit malaria parasites.


Assuntos
Anopheles/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Glutationa Transferase/metabolismo , Proteínas de Insetos/metabolismo , Mosquitos Vetores/metabolismo , Animais , Anopheles/efeitos dos fármacos , Anopheles/genética , Anopheles/parasitologia , Sangue/metabolismo , Camarões , Sistema Enzimático do Citocromo P-450/genética , Comportamento Alimentar , Feminino , Glutationa Transferase/genética , Humanos , Proteínas de Insetos/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Malária/parasitologia , Malária/prevenção & controle , Malária/transmissão , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Mosquitos Vetores/parasitologia , Plasmodium/patogenicidade , Piretrinas/farmacologia , Proteínas e Peptídeos Salivares/metabolismo
8.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 32(4): 389-392, 2020 Aug 11.
Artigo em Chinês | MEDLINE | ID: mdl-32935514

RESUMO

OBJECTIVE: To understand the population distribution, density, seasonal fluctuation and nocturnal activity of malaria vectors in Anhui Province from 2016 to 2018, so as to provide a data support for formulating the control strategy for imported malaria during the malaria post-elimination stage. METHODS: The malaria vectors were monitored in 105 counties (cities or districts) of Anhui Province from 2016 to 2018, and the population density, seasonal fluctuation and nocturnal activity of the mosquitoes were observed using the lamp trapping and human bait trapping methods. The density of Anopheles mosquitoes was compared among different years, regions and mosquito-capturing sites. RESULTS: Anopheles mosquitoes were captured in 103 counties (cities or districts) of Anhui Province during the period from 2016 to 2018, and a total of 32 494 mosquitoes were captured using the lamp trapping method and 36 228 captured using the human bait trapping method. All captured mosquitoes were morphologically identified as Anopheles sinensis, and no An. anthropophagus was found. The density of An. sinensis peaked from June to August, and the peak nocturnal activity was found during the period between 19∶00 and 23∶00. Among all mosquito-capturing sites, the highest mosquito density was seen in the livestock and poultry sheds (H = 18.835, P < 0.05). The density of An. sinensis varied significantly in regions in 2016 and 2017 (H = 16.655 and 11.566, P < 0.01), and a low density was found in north of the Huai River. CONCLUSIONS: An. sinensis is widely distributed in Anhui Province, which is the currently predominant malaria vector in the province. During the malaria post-elimination stage, the malaria vector monitoring should be intensified and vector control interventions should be timely adopted in epidemic foci of Anhui Province to prevent the local re-transmission of overseas imported malaria.


Assuntos
Anopheles , Malária , Mosquitos Vetores , Distribuição Animal , Animais , Anopheles/parasitologia , China , Malária/parasitologia , Malária/transmissão , Mosquitos Vetores/parasitologia , Densidade Demográfica , Estações do Ano
9.
PLoS One ; 15(8): e0234098, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817616

RESUMO

In French Guiana, the malaria, a parasitic infection transmitted by Anopheline mosquitoes, remains a disease of public health importance. To prevent malaria transmission, the main effective way remains Anopheles control. For an effective control, accurate Anopheles species identification is indispensable to distinguish malaria vectors from non-vectors. Although, morphological and molecular methods are largely used, an innovative tool, based on protein pattern comparisons, the Matrix Assisted Laser Desorption / Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) profiling, emerged this last decade for arthropod identification. However, the limited mosquito fauna diversity of reference MS spectra remains one of the main drawback for its large usage. The aim of the present study was then to create and to share reference MS spectra for the identification of French Guiana Anopheline species. A total of eight distinct Anopheles species, among which four are malaria vectors, were collected in 6 areas. To improve Anopheles identification, two body parts, legs and thoraxes, were independently submitted to MS for the creation of respective reference MS spectra database (DB). This study underlined that double checking by MS enhanced the Anopheles identification confidence and rate of reliable classification. The sharing of this reference MS spectra DB should make easier Anopheles species monitoring in endemic malaria area to help malaria vector control or elimination programs.


Assuntos
Anopheles/classificação , Mosquitos Vetores/classificação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Animais , Anopheles/química , Guiana Francesa , Malária/classificação , Malária/transmissão , Especificidade da Espécie , Tórax
10.
PLoS Negl Trop Dis ; 14(8): e0008605, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797109

RESUMO

In human communities inhabiting areas-such as West Bengal- India-where perpetuate the pre-imago & adult developmental stages of mosquitoes; many infectious diseases are still diagnosed such as Dengue, Malaria and Acute Encephalitis Syndrome. The control of the aquatic developmental stages is one of the easiest way to prevent the emergence of adults-the blood feeding adult females being thus prevented to sample their blood meal and to lay their eggs in the aquatic milieu where develop the aquatic pre-imaginal developmental stages. Moreover, reducing the adult population size also the probability of for the blood feeding adult female mosquitoes to act as hosts and vectors of the arboviruses such as dengue virus & Japanese encephalitis virus as well as of Plasmodium. Several environmental factors including water quality parameters are responsible for the selection of oviposition sites by the female mosquitoes. In our study, larval densities of three important mosquitoes (Aedes/A. albopictus, Anopheles/An. stephensi and Culex/C. vishnui) were measured and water qualities of their habitat i.e. pH, Specific Conductance, Dissolved Oxygen, Chemical Oxygen Demand, Total alkalinity (Talk), Hardness, Nitrate nitrogen and Ammonia nitrogen were analyzed in 2017 and 2018 in many districts of West Bengal where humans beings are suffering from arboviruses and /or malaria. Whereas we have found positive correlation of density of C. vishnui and A. albopictus with the water factors except Chemical Oxygen Demand (COD) and Talk, for An. stephensi all these factors except pH, COD and Talk have positive correlation. Hardness of the water shows positive correlation with the density of An. stephensi and C. vishnui but negative correlation with density of A. albopictus. Contour plot analysis demonstrates that occurrence of each mosquito species lies in between specific range of water factors. Inter- correlation analysis revealed that mosquitoes were negatively correlated with each other. A positive correlation of the water quality parameters and larval density, over two successive years, was also noticed. In conclusion, the increasing level of pollution due to industrial and other irresponsible waste management system which changes the water quality parameters may also influence mosquito population.


Assuntos
Ecossistema , Controle de Mosquitos , Mosquitos Vetores/fisiologia , Aedes/fisiologia , Animais , Anopheles/fisiologia , Arbovirus , Culex/fisiologia , Dengue/transmissão , Vírus da Encefalite Japonesa (Espécie) , Encefalite Japonesa/transmissão , Feminino , Humanos , Concentração de Íons de Hidrogênio , Índia , Larva , Modelos Logísticos , Malária/transmissão , Mosquitos Vetores/parasitologia , Mosquitos Vetores/virologia , Análise Multivariada , Densidade Demográfica , Água
11.
Science ; 369(6507): 1128-1132, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32855340

RESUMO

Hemocytes limit the capacity of mosquitoes to transmit human pathogens. Here we profile the transcriptomes of 8506 hemocytes of Anopheles gambiae and Aedes aegypti mosquito vectors. Our data reveal the functional diversity of hemocytes, with different subtypes of granulocytes expressing distinct and evolutionarily conserved subsets of effector genes. A previously unidentified cell type in An. gambiae, which we term "megacyte," is defined by a specific transmembrane protein marker (TM7318) and high expression of lipopolysaccharide-induced tumor necrosis factor-α transcription factor 3 (LL3). Knockdown experiments indicate that LL3 mediates hemocyte differentiation during immune priming. We identify and validate two main hemocyte lineages and find evidence of proliferating granulocyte populations. This atlas of medically relevant invertebrate immune cells at single-cell resolution identifies cellular events that underpin mosquito immunity to malaria infection.


Assuntos
Aedes/imunologia , Anopheles/imunologia , Hemócitos/imunologia , Imunidade Celular , Malária/transmissão , Mosquitos Vetores/imunologia , Aedes/genética , Animais , Anopheles/genética , Feminino , Perfilação da Expressão Gênica , Técnicas de Silenciamento de Genes , Granulócitos/imunologia , Hemócitos/metabolismo , Malária/imunologia , Malária/parasitologia , Camundongos , Mosquitos Vetores/genética , RNA-Seq , Análise de Célula Única
12.
PLoS Comput Biol ; 16(8): e1008121, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797077

RESUMO

Vector control has been a key component in the fight against malaria for decades, and chemical insecticides are critical to the success of vector control programs worldwide. However, increasing resistance to insecticides threatens to undermine these efforts. Understanding the evolution and propagation of resistance is thus imperative to mitigating loss of intervention effectiveness. Additionally, accelerated research and development of new tools that can be deployed alongside existing vector control strategies is key to eradicating malaria in the near future. Methods such as gene drives that aim to genetically modify large mosquito populations in the wild to either render them refractory to malaria or impair their reproduction may prove invaluable tools. Mathematical models of gene flow in populations, which is the transfer of genetic information from one population to another through migration, can offer invaluable insight into the behavior and potential impact of gene drives as well as the spread of insecticide resistance in the wild. Here, we present the first multi-locus, agent-based model of vector genetics that accounts for mutations and a many-to-many mapping cardinality of genotypes to phenotypes to investigate gene flow, and the propagation of gene drives in Anopheline populations. This model is embedded within a large scale individual-based model of malaria transmission representative of a high burden, high transmission setting characteristic of the Sahel. Results are presented for the selection of insecticide-resistant vectors and the spread of resistance through repeated deployment of insecticide treated nets (ITNs), in addition to scenarios where gene drives act in concert with existing vector control tools such as ITNs. The roles of seasonality, spatial distribution of vector habitat and feed sites, and existing vector control in propagating alleles that confer phenotypic traits via gene drives that result in reduced transmission are explored. The ability to model a spectrum of vector species with different genotypes and phenotypes in the context of malaria transmission allows us to test deployment strategies for existing interventions that reduce the deleterious effects of resistance and allows exploration of the impact of new tools being proposed or developed.


Assuntos
Anopheles/genética , Tecnologia de Impulso Genético/métodos , Resistência a Inseticidas/genética , Malária , Mosquitos Vetores/genética , Animais , Aptidão Genética , Humanos , Malária/prevenção & controle , Malária/transmissão , Análise de Sistemas
13.
Nat Commun ; 11(1): 4353, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32859908

RESUMO

Continental-scale models of malaria climate suitability typically couple well-established temperature-response models with basic estimates of vector habitat availability using rainfall as a proxy. Here we show that across continental Africa, the estimated geographic range of climatic suitability for malaria transmission is more sensitive to the precipitation threshold than the thermal response curve applied. To address this problem we use downscaled daily climate predictions from seven GCMs to run a continental-scale hydrological model for a process-based representation of mosquito breeding habitat availability. A more complex pattern of malaria suitability emerges as water is routed through drainage networks and river corridors serve as year-round transmission foci. The estimated hydro-climatically suitable area for stable malaria transmission is smaller than previous models suggest and shows only a very small increase in state-of-the-art future climate scenarios. However, bigger geographical shifts are observed than with most rainfall threshold models and the pattern of that shift is very different when using a hydrological model to estimate surface water availability for vector breeding.


Assuntos
Mudança Climática , Hidrologia/métodos , Malária/transmissão , África/epidemiologia , Animais , Anopheles/fisiologia , Ecologia , Ecossistema , Mapeamento Geográfico , Geografia , Malária/epidemiologia , Mosquitos Vetores/fisiologia , Rios , Estações do Ano , Temperatura
14.
PLoS One ; 15(8): e0235697, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32750051

RESUMO

In an era of big data, the availability of satellite-derived global climate, terrain, and land cover imagery presents an opportunity for modeling the suitability of malaria disease vectors at fine spatial resolutions, across temporal scales, and over vast geographic extents. Leveraging cloud-based geospatial analytical tools, we present an environmental suitability model that considers water resources, flow accumulation areas, precipitation, temperature, vegetation, and land cover. In contrast to predictive models generated using spatially and temporally discontinuous mosquito presence information, this model provides continuous fine-spatial resolution information on the biophysical drivers of suitability. For the purposes of this study the model is parameterized for Anopheles gambiae s.s. in Malawi for the rainy (December-March) and dry seasons (April-November) in 2017; however, the model may be repurposed to accommodate different mosquito species, temporal periods, or geographical boundaries. Final products elucidate the drivers and potential habitat of Anopheles gambiae s.s. Rainy season results are presented by quartile of precipitation; Quartile four (Q4) identifies areas most likely to become inundated and shows 7.25% of Malawi exhibits suitable water conditions (water only) for Anopheles gambiae s.s., approximately 16% for water plus another factor, and 8.60% is maximally suitable, meeting suitability thresholds for water presence, terrain characteristics, and climatic conditions. Nearly 21% of Malawi is suitable for breeding based on land characteristics alone and 28.24% is suitable according to climate and land characteristics. Only 6.14% of the total land area is suboptimal. Dry season results show 25.07% of the total land area is suboptimal or unsuitable. Approximately 42% of Malawi is suitable based on land characteristics alone during the dry season, and 13.11% is suitable based on land plus another factor. Less than 2% meets suitability criteria for climate, water, and land criteria. Findings illustrate environmental drivers of suitability for malaria vectors, providing an opportunity for a more comprehensive approach to malaria control that includes not only modeled species distributions, but also the underlying drivers of suitability for a more effective approach to environmental management.


Assuntos
Big Data , Malária/epidemiologia , Saúde Pública , Animais , Anopheles/fisiologia , Cruzamento , Clima , Humanos , Malária/transmissão , Malaui/epidemiologia , Mosquitos Vetores/fisiologia , Ferramenta de Busca , Estações do Ano
15.
Proc Natl Acad Sci U S A ; 117(36): 22042-22050, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32843339

RESUMO

Malaria vector control may be compromised by resistance to insecticides in vector populations. Actions to mitigate against resistance rely on surveillance using standard susceptibility tests, but there are large gaps in the monitoring data across Africa. Using a published geostatistical ensemble model, we have generated maps that bridge these gaps and consider the likelihood that resistance exceeds recommended thresholds. Our results show that this model provides more accurate next-year predictions than two simpler approaches. We have used the model to generate district-level maps for the probability that pyrethroid resistance in Anopheles gambiae s.l. exceeds the World Health Organization thresholds for susceptibility and confirmed resistance. In addition, we have mapped the three criteria for the deployment of piperonyl butoxide-treated nets that mitigate against the effects of metabolic resistance to pyrethroids. This includes a critical review of the evidence for presence of cytochrome P450-mediated metabolic resistance mechanisms across Africa. The maps for pyrethroid resistance are available on the IR Mapper website, where they can be viewed alongside the latest survey data.


Assuntos
Anopheles/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Malária/transmissão , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , África , Animais , Anopheles/fisiologia , Humanos , Mosquiteiros Tratados com Inseticida , Mosquitos Vetores/fisiologia , Piretrinas/farmacologia
17.
Proc Biol Sci ; 287(1931): 20201093, 2020 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-32693720

RESUMO

Models predicting disease transmission are vital tools for long-term planning of malaria reduction efforts, particularly for mitigating impacts of climate change. We compared temperature-dependent malaria transmission models when mosquito life-history traits were estimated from a truncated portion of the lifespan (a common practice) versus traits measured across the full lifespan. We conducted an experiment on adult female Anopheles stephensi, the Asian urban malaria mosquito, to generate daily per capita values for mortality, egg production and biting rate at six constant temperatures. Both temperature and age significantly affected trait values. Further, we found quantitative and qualitative differences between temperature-trait relationships estimated from truncated data versus observed lifetime values. Incorporating these temperature-trait relationships into an expression governing the thermal suitability of transmission, relative R0(T), resulted in minor differences in the breadth of suitable temperatures for Plasmodium falciparum transmission between the two models constructed from only An. stephensi trait data. However, we found a substantial increase in thermal niche breadth compared with a previously published model consisting of trait data from multiple Anopheles mosquito species. Overall, this work highlights the importance of considering how mosquito trait values vary with mosquito age and mosquito species when generating temperature-based suitability predictions of transmission.


Assuntos
Anopheles/parasitologia , Malária Falciparum/transmissão , Plasmodium falciparum , Fatores Etários , Animais , Feminino , Malária/transmissão , Mosquitos Vetores , Temperatura
18.
PLoS Negl Trop Dis ; 14(7): e0008385, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32614914

RESUMO

Anopheles sundaicus s.l. is an important malaria vector primarily found in coastal landscapes of western and central Indonesia. The species complex has a wide geographical distribution in South and Southeast Asia and exhibits ecological and behavioural variability over its range. Studies on understanding the distribution of different members in the complex and their bionomics related to malaria transmission might be important guiding more effective vector intervention strategies. Female An. sundaicus s.l. were collected from seven provinces, 12 locations in Indonesia representing Sumatra: North Sumatra, Bangka-Belitung, South Lampung, and Bengkulu; in Java: West Java; and the Lesser Sunda Islands: West Nusa Tenggara and East Nusa Tenggara provinces. Sequencing of ribosomal DNA ITS2 gene fragments and two mitochondrial DNA gene markers, COI and cytb, enabled molecular identification of morphologically indistinguishable members of the complex. Findings allowed inference on the distribution of the An. sundaicus s.l. present in Indonesia and further illustrate the phylogenetic relationships of An. epiroticus within the complex. A total of 370 An. sundaicus s.l specimens were analysed for the ITS2 fragment. The ITS2 sequence alignment revealed two consistent species-specific point mutations, a T>C transition at base 479 and a G>T transversion at base 538 that differentiated five haplotypes: TG, CG, TT, CT, and TY. The TG haplotype matched published An. epiroticus-indicative sequences from Thailand, Vietnam and peninsular Malaysia. The previously described insertion event (base 603) was observed in all identified specimens. Analysis of the COI and cytb genes revealed no consistent nucleotide variations that could definitively distinguish An. epiroticus from other members in the Sundaicus Complex. The findings indicate and support the existence of An. epiroticus in North Sumatra and Bangka-Belitung archipelago. Further studies are recommended to determine the full distributional extent of the Sundaicus complex in Indonesia and investigate the role of these species in malaria transmission.


Assuntos
Anopheles , Malária/transmissão , Mosquitos Vetores , Animais , Anopheles/genética , Citocromos b/genética , Demografia , Complexo IV da Cadeia de Transporte de Elétrons/genética , Feminino , Humanos , Indonésia , Filogenia
19.
Nat Commun ; 11(1): 3646, 2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32686679

RESUMO

Papua New Guinea (PNG) has the highest malaria transmission outside of Africa. Long-lasting insecticidal nets (LLINs) are believed to have helped to reduce average malaria prevalence in PNG from 16% in 2008 to 1% in 2014. Since 2015 malaria in PNG has resurged significantly. Here, we present observations documenting decreased bioefficacy of unused LLINs with manufacturing dates between 2013 and 2019 collected from villages and LLIN distributors in PNG. Specifically, we show that of n = 167 tested LLINs manufactured after 2013, only 17% are fulfilling the required World Health Organisation bioefficacy standards of ≥ 80% 24 h mortality or ≥ 95% 60 min knockdown in bioassays with pyrethroid susceptible Anopheles farauti mosquitoes. In contrast, all (100%, n = 25) LLINs with manufacturing dates prior to 2013 are meeting these bioefficacy standards. These results suggest that decreased bioefficacy of LLINs is contributing to the malaria resurgence in PNG and increased scrutiny of LLIN quality is warranted.


Assuntos
Malária , Controle de Mosquitos/métodos , Animais , Anopheles/efeitos dos fármacos , Humanos , Mosquiteiros Tratados com Inseticida , Inseticidas/farmacologia , Malária/epidemiologia , Malária/prevenção & controle , Malária/transmissão , Mosquitos Vetores/efeitos dos fármacos , Papua Nova Guiné/epidemiologia , Piretrinas/farmacologia
20.
BMC Infect Dis ; 20(1): 503, 2020 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-32660434

RESUMO

BACKGROUND: Understanding the relationship between malaria infection risk and disease outcomes represents a fundamental component of morbidity and mortality burden estimations. Contemporary data on severe malaria risks among populations of different parasite exposures are scarce. Using surveillance data, we compared rates of paediatric malaria hospitalisation in areas of varying parasite exposure levels. METHODS: Surveillance data at five public hospitals; Jinja, Mubende, Kabale, Tororo, and Apac were assembled among admissions aged 1 month to 14 years between 2017 and 2018. The address of each admission was used to define a local catchment population where national census data was used to define person-year-exposure to risk. Within each catchment, historical infection prevalence was assembled from previously published data and current infection prevalence defined using 33 population-based school surveys among 3400 children. Poisson regression was used to compute the overall and site-specific incidences with 95% confidence intervals. RESULTS: Both current and historical Plasmodium falciparum prevalence varied across the five sites. Current prevalence ranged from < 1% in Kabale to 54% in Apac. Overall, the malaria admission incidence rate (IR) was 7.3 per 1000 person years among children aged 1 month to 14 years of age (95% CI: 7.0, 7.7). The lowest rate was described at Kabale (IR = 0.3; 95 CI: 0.1, 0.6) and highest at Apac (IR = 20.3; 95 CI: 18.9, 21.8). There was a correlation between IR across the five sites and the current parasite prevalence in school children, though findings were not statistically significant. Across all sites, except Kabale, malaria admissions were concentrated among young children, 74% were under 5 years. The median age of malaria admissions at Kabale hospital was 40 months (IQR 20, 72), and at Apac hospital was 36 months (IQR 18, 69). Overall, severe anaemia (7.6%) was the most common presentation and unconsciousness (1.8%) the least common. CONCLUSION: Malaria hospitalisation rates remain high in Uganda particularly among young children. The incidence of hospitalized malaria in different locations in Uganda appears to be influenced by past parasite exposure, immune acquisition, and current risks of infection. Interruption of transmission through vector control could influence age-specific severe malaria risk.


Assuntos
Anemia/etiologia , Hospitalização , Hospitais Pediátricos , Malária/complicações , Malária/epidemiologia , Plasmodium falciparum/imunologia , Inconsciência/etiologia , Adolescente , Fatores Etários , Criança , Pré-Escolar , Feminino , Hospitais Públicos , Humanos , Incidência , Lactente , Malária/parasitologia , Malária/transmissão , Masculino , Morbidade , Plasmodium falciparum/isolamento & purificação , Prevalência , Estudos Retrospectivos , Uganda/epidemiologia
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