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1.
Science ; 368(6491): 634-637, 2020 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-32381721

RESUMO

Some flying animals use active sensing to perceive and avoid obstacles. Nocturnal mosquitoes exhibit a behavioral response to divert away from surfaces when vision is unavailable, indicating a short-range, mechanosensory collision-avoidance mechanism. We suggest that this behavior is mediated by perceiving modulations of their self-induced airflow patterns as they enter a ground or wall effect. We used computational fluid dynamics simulations of low-altitude and near-wall flights based on in vivo high-speed kinematic measurements to quantify changes in the self-generated pressure and velocity cues at the sensitive mechanosensory antennae. We validated the principle that encoding aerodynamic information can enable collision avoidance by developing a quadcopter with a sensory system inspired by the mosquito. Such low-power sensing systems have major potential for future use in safer rotorcraft control systems.


Assuntos
Acidentes Aeronáuticos/prevenção & controle , Aeronaves , Culicidae/fisiologia , Voo Animal/fisiologia , Visão Noturna/fisiologia , Animais , Antenas de Artrópodes/fisiologia , Biônica , Simulação por Computador , Robótica/métodos
2.
PLoS Comput Biol ; 16(4): e1007446, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32320389

RESUMO

Mosquitoes are important vectors for pathogens that infect humans and other vertebrate animals. Some aspects of adult mosquito behavior and mosquito ecology play an important role in determining the capacity of vector populations to transmit pathogens. Here, we re-examine factors affecting the transmission of pathogens by mosquitoes using a new approach. Unlike most previous models, this framework considers the behavioral states and state transitions of adult mosquitoes through a sequence of activity bouts. We developed a new framework for individual-based simulation models called MBITES (Mosquito Bout-based and Individual-based Transmission Ecology Simulator). In MBITES, it is possible to build models that simulate the behavior and ecology of adult mosquitoes in exquisite detail on complex resource landscapes generated by spatial point processes. We also developed an ordinary differential equation model which is the Kolmogorov forward equations for models developed in MBITES under a specific set of simplifying assumptions. While mosquito infection and pathogen development are one possible part of a mosquito's state, that is not our main focus. Using extensive simulation using some models developed in MBITES, we show that vectorial capacity can be understood as an emergent property of simple behavioral algorithms interacting with complex resource landscapes, and that relative density or sparsity of resources and the need to search can have profound consequences for mosquito populations' capacity to transmit pathogens.


Assuntos
Comportamento Animal , Culicidae/fisiologia , Malária/transmissão , Mosquitos Vetores , Algoritmos , Animais , Biologia Computacional , Simulação por Computador , Vetores de Doenças , Ecologia , Ecossistema , Comportamento Alimentar , Feminino , Humanos , Masculino , Modelos Teóricos , Método de Monte Carlo , Oviposição , Probabilidade
3.
Proc Biol Sci ; 287(1919): 20192705, 2020 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-31964235

RESUMO

Most species of mosquitoes are detritivores that feed on decaying plant and animal materials in their aquatic environment. Studies of several detritivorous mosquito species indicate that they host relatively low diversity communities of microbes that are acquired from the environment while feeding. Our recent results also indicate that detritivorous species normally require a living gut microbiota to grow beyond the first instar. Less well known is that some mosquitoes, including those belonging to the genus Toxorhynchites, are predators that feed on other species of mosquitoes and nektonic prey. In this study, we asked whether predaceous Toxorhynchites amboinensis larvae still require living microbes in their gut in order to develop. Using the detritivorous mosquito Aedes aegypti as prey, we found that T. amboinensis larvae harbour bacterial communities that are highly similar to that of their prey. Functional assays showed that T. amboinensis first instars provided axenic (i.e. bacteria-free) prey failed to develop, while two bacterial species present in gnotobiotic (i.e. colonized by one or more known bacterial species) prey successfully colonized the T. amboinensis gut and rescued development. Axenic T. amboinensis larvae also displayed defects in growth consistent with previously identified roles for microbe-mediated gut hypoxia in nutrient acquisition and assimilation in A. aegypti. Collectively, these results support a conserved role for gut microbes in regulating the development of mosquitoes with different feeding strategies.


Assuntos
Culicidae/microbiologia , Microbioma Gastrointestinal , Animais , Culicidae/fisiologia , Larva/crescimento & desenvolvimento , Larva/microbiologia
4.
Am J Trop Med Hyg ; 102(4): 707-710, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31989920

RESUMO

The value of baseline entomological data to any future area-wide release campaign relies on the application of consistent methods to produce results comparable across different times and places in a stepwise progression to larger releases. Traditionally, standard operating procedures (SOPs) and operational plans support this consistency and, thus, the validity of emergent data. When release plans include transgenic mosquitoes for vector control or other novel beneficial insects, additional factors come into play such as biosafety permits, stakeholder acceptance, and ethics approval, which require even greater coordination and thoroughness. An audit approach was developed to verify the correct use of SOPs and appropriate performance of tasks during mosquito mark, release, recapture (MRR) studies. Audit questions matched SOPs, permit terms and conditions, and other key criteria, and can be used to support subsequent "spot check" verification by field teams. An external team of auditors, however, was found to be effective for initial checks in this example before the use of a transgenic strain of laboratory mosquitoes. We recommend similar approaches for field studies using release of novel beneficial insects, to ensure useful and valid data as an outcome and to support confidence in the rigor of the step-wise process.


Assuntos
Culicidae/fisiologia , Mosquitos Vetores/fisiologia , Animais , Monitoramento Ambiental , Dinâmica Populacional
5.
PLoS One ; 14(12): e0226815, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31887129

RESUMO

Host seeking in the yellow fever mosquito, Aedes aegypti, and the African malaria mosquito, Anopheles coluzzii, relies on specific and generic host-derived odorants. Previous analyses indicate that the behavioral response of these species depends differentially on the presence of carbon dioxide (CO2) and other constituents in human breath for activation and attraction. In this study, we use a flight tube assay and electrophysiological analysis to assess the role of acetone, a major component of exhaled human breath, in modulating the behavioral and sensory neuronal response of these mosquito species, in the presence and absence of CO2. When presented alone at ecologically relevant concentrations, acetone increases attraction in Ae. aegypti, but not in An. coluzzii. Moreover, in combination with CO2, human breath-equivalents of acetone ranging between 0.1 and 10 ppm reproduces a behavioral response similar to that observed to human breath in host-seeking Ae. aegypti, but not in An. coluzzii. Acetone does, however, reduce attraction to CO2 in An. coluzzii, when presented at a higher concentration of 10 ppm. We identify the capitate peg A neuron of the maxillary palp of both species as a dual detector of CO2 and acetone. The sensory response to acetone, or binary blends of acetone and CO2, reflects the observed behavioral output in both Ae. aegypti and An. coluzzii. We conclude that host recognition is contextual and dependent on a combination of ecologically relevant odorants at naturally occurring concentrations that are encoded, in this case, by differences in the temporal structure of the neuronal response. This information should be considered when designing synthetic blends for that optimally attract mosquitoes for monitoring and control.


Assuntos
Acetona/farmacologia , Comportamento Animal/efeitos dos fármacos , Dióxido de Carbono/farmacologia , Culicidae/fisiologia , Olfato , Aedes/fisiologia , Animais , Anopheles/fisiologia , Expiração , Comportamento de Busca por Hospedeiro/efeitos dos fármacos , Humanos , Malária/transmissão , Odorantes , Febre Amarela/transmissão
6.
Nature ; 574(7778): 404-408, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31578527

RESUMO

Over the past two decades efforts to control malaria have halved the number of cases globally, yet burdens remain high in much of Africa and the elimination of malaria has not been achieved even in areas where extreme reductions have been sustained, such as South Africa1,2. Studies seeking to understand the paradoxical persistence of malaria in areas in which surface water is absent for 3-8 months of the year have suggested that some species of Anopheles mosquito use long-distance migration3. Here we confirm this hypothesis through aerial sampling of mosquitoes at 40-290 m above ground level and provide-to our knowledge-the first evidence of windborne migration of African malaria vectors, and consequently of the pathogens that they transmit. Ten species, including the primary malaria vector Anopheles coluzzii, were identified among 235 anopheline mosquitoes that were captured during 617 nocturnal aerial collections in the Sahel of Mali. Notably, females accounted for more than 80% of all of the mosquitoes that we collected. Of these, 90% had taken a blood meal before their migration, which implies that pathogens are probably transported over long distances by migrating females. The likelihood of capturing Anopheles species increased with altitude (the height of the sampling panel above ground level) and during the wet seasons, but variation between years and localities was minimal. Simulated trajectories of mosquito flights indicated that there would be mean nightly displacements of up to 300 km for 9-h flight durations. Annually, the estimated numbers of mosquitoes at altitude that cross a 100-km line perpendicular to the prevailing wind direction included 81,000 Anopheles gambiae sensu stricto, 6 million A. coluzzii and 44 million Anopheles squamosus. These results provide compelling evidence that millions of malaria vectors that have previously fed on blood frequently migrate over hundreds of kilometres, and thus almost certainly spread malaria over these distances. The successful elimination of malaria may therefore depend on whether the sources of migrant vectors can be identified and controlled.


Assuntos
Migração Animal/fisiologia , Culicidae/fisiologia , Malária/transmissão , Mosquitos Vetores/fisiologia , Vento , África , Animais , Culicidae/parasitologia , Feminino , Mosquitos Vetores/parasitologia
7.
Int J Infect Dis ; 89: 169-174, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31606414

RESUMO

BACKGROUND: Arboviral diseases are a global growing problem due to climate change, urbanization, population density, and global transportation. However, new technologies currently being developed in research labs are expected to play a relevant role in combatting arboviral diseases in the future, reducing the health and economic burden imposed by these diseases. OBJECTIVES: This paper aims to anticipate the technologies that might be relevant for prevention and vector control of arboviral diseases in the future. METHODS: A web-based survey was conducted of over 2,000 experts from all over the world. Both the technologies and the respondents were identified from recent scientific publications on arboviral diseases indexed in the Web of Science Core Collection. RESULTS: Our results show that within 20 years the enveloped virus-like particles-based vaccine and the gene-edited mosquitoes through CRISPR/Cas9 will likely be the most promising technologies for, respectively, prevention and vector control of arboviral diseases. CONCLUSIONS: If these expectations are confirmed, these new technologies, when fully developed, may support global public health efforts aimed at reducing transmission, mortality and morbidity of arboviral diseases.


Assuntos
Infecções por Arbovirus/prevenção & controle , Arbovirus/fisiologia , Culicidae/virologia , Mosquitos Vetores/fisiologia , Animais , Infecções por Arbovirus/epidemiologia , Infecções por Arbovirus/transmissão , Infecções por Arbovirus/virologia , Culicidae/genética , Culicidae/fisiologia , Humanos , Controle de Mosquitos , Mosquitos Vetores/genética , Mosquitos Vetores/virologia , Saúde Pública , Vacinas Virais/administração & dosagem
8.
Parasit Vectors ; 12(1): 421, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31477155

RESUMO

BACKGROUND: Knowledge of mosquito movement would aid the design of effective intervention strategies against malaria. However, data on mosquito movement through mark-recapture or genetics studies are challenging to collect, and so are not available for many sites. An additional source of information may come from secondary analyses of data from trials of repellents where household mosquito densities are collected. Using the study design of published trials, we developed a statistical model which can be used to estimate the movement between houses for mosquitoes displaced by a spatial repellent. The method uses information on the different distributions of mosquitoes between houses when no households are using spatial repellents compared to when there is incomplete coverage. The parameters to be estimated are the proportion of mosquitoes repelled, the proportion of those repelled that go to another house and the mean distance of movement between houses. Estimation is by maximum likelihood. RESULTS: We evaluated the method using simulation and found that data on the seasonal pattern of mosquito densities were required, which could be additionally collected during a trial. The method was able to provide accurate estimates from simulated data, except when the setting has few mosquitoes overall, few repelled, or the coverage with spatial repellent is low. The trial that motivated our analysis was found to have too few mosquitoes caught and repelled for our method to provide accurate results. CONCLUSIONS: We propose that the method could be used as a secondary analysis of trial data to gain estimates of mosquito movement in the presence of repellents for trials with sufficient numbers of mosquitoes caught and repelled and with coverage levels which allow sufficient numbers of houses with and without repellent. Estimates from this method may supplement those from mark-release-recapture studies, and be used in designing effective malaria intervention strategies, parameterizing mathematical models and in designing trials of vector control interventions.


Assuntos
Culicidae/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Distribuição Animal , Animais , Culicidae/fisiologia , Habitação , Funções Verossimilhança , Modelos Estatísticos , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia
9.
Sci Total Environ ; 690: 1237-1244, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470486

RESUMO

To improve risk assessment there is increasing attention for the effect of climate change on the sensitivity to contaminants and vice versa. Two important and connected topics have been largely ignored in this context: (i) the increase of daily temperature variation (DTV) as a key component of climate change, and (ii) differences in sensitivity to climate change and contaminants between developmental stages. We therefore investigated whether DTV magnified the negative effects of the organophosphate insecticide chlorpyrifos on mortality and heat tolerance and whether this effect was stronger in aquatic larvae than in terrestrial adults of the mosquito Culex pipiens. Exposure to chlorpyrifos at a constant temperature imposed mortality and reduced the heat tolerance in both larvae and adult males, but not in adult females. This provides the first evidence that the TICS ("toxicant-induced climate change sensitivity") concept can be sex-specific. DTV had no direct negative effects. Yet, consistent with the CITS ("climate-induced toxicant sensitivity") concept, DTV magnified the toxicity of the pesticide in terms of larval mortality. This was not the case in the adult stage indicating the CITS concept to be dependent on the developmental stage. Notably, chlorpyrifos reduced the heat tolerance of adult females only in the presence of DTV, thereby providing support for the reciprocal effects between DTV and contaminants, hence the coupling of the TICS and CITS concepts. Taken together, our results highlight the importance of integrating DTV and the developmental stage to improve risk assessment of contaminants under climate change.


Assuntos
Clorpirifos/toxicidade , Culicidae/fisiologia , Inseticidas/toxicidade , Temperatura , Animais , Mudança Climática , Feminino , Larva , Masculino
10.
Commun Biol ; 2: 273, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31372512

RESUMO

Fine-scale geographic variation in the transmission intensity of mosquito-borne diseases is primarily caused by variation in the density of female adult mosquitoes. Therefore, an understanding of fine-scale mosquito population dynamics is critical to understanding spatial heterogeneity in disease transmission and persistence at those scales. However, mathematical models of dengue and malaria transmission, which consider the dynamics of mosquito larvae, generally do not account for the fragmented structure of larval breeding sites. Here, we develop a stochastic metapopulation model of mosquito population dynamics and explore the impact of accounting for breeding site fragmentation when modelling fine-scale mosquito population dynamics. We find that, when mosquito population densities are low, fragmentation can lead to a reduction in population size, with population persistence dependent on mosquito dispersal and features of the underlying landscape. We conclude that using non-spatial models to represent fine-scale mosquito population dynamics may substantially underestimate the stochastic volatility of those populations.


Assuntos
Culicidae/fisiologia , Modelos Teóricos , Animais , Feminino , Dinâmica Populacional , Reprodução
11.
Emerg Microbes Infect ; 8(1): 1027-1042, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31287787

RESUMO

Francisella tularensis is a Gram-negative, intracellular bacterium causing the zoonosis tularemia. This highly infectious microorganism is considered a potential biological threat agent. Humans are usually infected through direct contact with the animal reservoir and tick bites. However, tularemia cases also occur after contact with a contaminated hydro-telluric environment. Water-borne tularemia outbreaks and sporadic cases have occurred worldwide in the last decades, with specific clinical and epidemiological traits. These infections represent a major public health and military challenge. Human contaminations have occurred through consumption or use of F. tularensis-contaminated water, and various aquatic activities such as swimming, canyoning and fishing. In addition, in Sweden and Finland, mosquitoes are primary vectors of tularemia due to infection of mosquito larvae in contaminated aquatic environments. The mechanisms of F. tularensis survival in water may include the formation of biofilms, interactions with free-living amoebae, and the transition to a 'viable but nonculturable' state, but the relative contribution of these possible mechanisms remains unknown. Many new aquatic species of Francisella have been characterized in recent years. F. tularensis likely shares with these species an ability of long-term survival in the aquatic environment, which has to be considered in terms of tularemia surveillance and control.


Assuntos
Tularemia/microbiologia , Doenças Transmitidas pela Água/microbiologia , Animais , Culicidae/microbiologia , Culicidae/fisiologia , Francisella tularensis/genética , Francisella tularensis/isolamento & purificação , Francisella tularensis/fisiologia , Humanos , Doenças Transmitidas pela Água/transmissão , Zoonoses/epidemiologia , Zoonoses/microbiologia , Zoonoses/transmissão
12.
PLoS One ; 14(7): e0219249, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31291316

RESUMO

In this work we analyze potential environmental drivers of malaria cases in Northwestern Argentina. We inspect causal links between malaria and climatic variables by means of the convergent cross mapping technique, which provides a causality criterion from the theory of dynamic systems. Analysis is based on 12 years of weekly malaria P. vivax cases in Tartagal, Salta, Argentina-at the southern fringe of malaria incidence in the Americas-together with humidity and temperature time-series spanning the same period. Our results show that there are causal links between malaria cases and both maximum temperature, with a delay of five weeks, and minimum temperature, with delays of zero and twenty two weeks. Humidity is also a driver of malaria cases, with thirteen weeks delay between cause and effect. Furthermore we also determined the sign and strength of the effects. Temperature has always a positive non-linear effect on cases, with maximum temperature effects more pronounced above 25°C and minimum above 17°C, while effects of humidity are more intricate: maximum humidity above 85% has a negative effect, whereas minimum humidity has a positive effect on cases. These results might be signaling processes operating at short (below 5 weeks) and long (over 12 weeks) time delays, corresponding to effects related to parasite cycle and mosquito population dynamics respectively. The non-linearities found for the strength of the effect of temperature on malaria cases make warmer areas more prone to higher increases in the disease incidence. Moreover, our results indicate that an increase of extreme weather events could enhance the risks of malaria spreading and re-emergence beyond the current distribution. Both situations, warmer climate and increase of extreme events, will be remarkably increased by the end of the century in this hot spot of climate change.


Assuntos
Mudança Climática , Culicidae/patogenicidade , Malária Vivax/epidemiologia , Animais , Argentina/epidemiologia , Culicidae/fisiologia , Humanos , Umidade , Malária Vivax/parasitologia , Temperatura
13.
J Med Entomol ; 56(6): 1734-1738, 2019 10 28.
Artigo em Inglês | MEDLINE | ID: mdl-31283827

RESUMO

Surveillance for blood-fed female mosquitoes was performed between August 2015 and February 2016 at sites along the periphery of the Aripo Savannas Environmentally Reserve (ASSR) located in northeastern Trinidad, West Indies. We collected engorged female mosquitoes representing 13 species. DNA extractions from dissected abdomens were subjected to PCR amplification with three primer pairs targeting the mitochondrial cytochrome oxidase I and cytochrome b gene sequences. High-quality sequence information and host identification were obtained for 42 specimens representing eight mosquito species with at least one primer combination. A broad range of vertebrates including humans were identified, but the majority were nonhuman mammals, both domestic and wild. Domestic dogs were the most common host and may represent potential sentinel species for monitoring local enzootic arbovirus activity in Trinidad. Culex declarator Dyer and Knab and Culex nigripalpus Theobald were the most common blood-fed mosquito species comprising 79.1% of the total number identified. These species obtained blood meals from birds, nonhuman mammals, and human hosts, and therefore pose significant risks as potential bridge vectors for epizootic arbovirus transmission in the ASSR area as well as other sylvan areas in Trinidad. These data represent the first such results for Trinidad.


Assuntos
Culicidae/fisiologia , Cadeia Alimentar , Mosquitos Vetores/fisiologia , Animais , Arbovirus , Aves , Dieta , Comportamento Alimentar , Feminino , Humanos , Mamíferos , Trinidad e Tobago
14.
Elife ; 82019 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-31246169

RESUMO

Female mosquitos require a specific ion-channel protein to sense the presence of fresh water in which they can lay their eggs.


Assuntos
Culicidae/fisiologia , Ovos , Canais Epiteliais de Sódio/genética , Paladar/genética , Animais , Sistemas CRISPR-Cas/genética , Culicidae/genética , Feminino , Água Doce/química , Genoma de Inseto/genética , Neurônios/metabolismo , Paladar/fisiologia
15.
Emerg Microbes Infect ; 8(1): 920-933, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31237479

RESUMO

In early 2017, an outbreak caused by an unknown and supposedly viral agent in the Marilena region of southern Brazil was investigated. Since the etiological agent causing the outbreak was not identified from human samples, mosquitoes from this region were collected. Three out of 121 mosquito pools collected from the region tested positive for alphavirus in molecular tests. Next generation sequencing results revealed the presence of a novel alphavirus, tentatively named here as Caainguá virus (CAAV). DNA barcoding analyses indicated that different species of Culex are hosts for CAAV. This new virus was basal to the New World encephalitic alphaviruses in a comprehensive and robust phylogenetic approach using complete genomes. Viral particles were observed in the cytosol and inside of intracellular compartments of cells in mosquito-derived cell cultures. Despite being noninfectious in vertebrate derived cell cultures, primary culturing of CAAV in human mononuclear cells suggests monocytes and lymphocytes as CAAV targets. However, the epidemiological link of CAAV on the human outbreak should be further explored.


Assuntos
Alphavirus/isolamento & purificação , Encefalite/virologia , Adulto , Alphavirus/classificação , Alphavirus/genética , Alphavirus/fisiologia , Animais , Brasil/epidemiologia , Culicidae/fisiologia , Culicidae/virologia , Encefalite/epidemiologia , Feminino , Humanos , Linfócitos/virologia , Masculino , Monócitos/virologia , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Filogenia , Adulto Jovem
16.
Curr Opin Insect Sci ; 34: 21-26, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31247413

RESUMO

Mosquito-borne diseases such as Dengue fever, Chikungunya, and Malaria are critical threats to public health in many parts of the world. Female mosquitoes have evolved multiple adaptive mechanisms to hematophagy, including the ability to efficiently draw and digest blood, as well as the ability to eliminate excess fluids and toxic by-products of blood digestion. Pathogenic agents enter the mosquito digestive tract with the blood meal and need to travel through the midgut and into the hemocele in order to reach the salivary glands and infect a new host. Pathogens need to adjust to these hostile gut, hemocele, and salivary gland environments, and when possible influence the physiology and behavior of their hosts to enhance transmission.


Assuntos
Adaptação Fisiológica , Culicidae/fisiologia , Mosquitos Vetores/fisiologia , Animais , Culicidae/microbiologia , Digestão , Ingestão de Alimentos , Comportamento Alimentar , Mosquitos Vetores/microbiologia
17.
Curr Opin Insect Sci ; 34: 7-11, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31247421

RESUMO

Blood feeding in arthropods has evolved in multiple lineages. This feeding preference provides a source of ample proteins and lipids for egg production and survival, but ingestion of a large warm blood-meal can boost the arthropod's body temperature 15°-20°C within seconds to minutes. This represents one of, if not the most, rapid thermal change documented under a natural setting. Here, we describe mechanisms of thermoregulation and thermotolerance in arthropods during blood feeding. The ability to prevent blood-induced thermal damage is a fundamental physiological adaptation linked to the use of warm-blooded vertebrates as food sources. Specific functional and comparative studies have identified unique and divergent mechanisms that suppress or repair thermal stress during blood feeding. These mechanisms include countercurrent heat exchange, evaporative cooling, and upregulation of stress associated proteins.


Assuntos
Culicidae/fisiologia , Rhodnius/fisiologia , Termotolerância , Carrapatos/fisiologia , Animais , Regulação da Temperatura Corporal , Comportamento Alimentar
18.
Malar J ; 18(1): 211, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31234879

RESUMO

BACKGROUND: Understanding the complex heterogeneity of risk factors that can contribute to an increased risk of malaria at the individual and household level will enable more effective use of control measures. The objective of this study was to understand individual and household factors that influence clinical malaria infection among individuals in the highlands of Western Kenya. METHODS: This was a matched case-control study undertaken in the Western Kenya highlands. Clinical malaria cases were recruited from health facilities and matched to asymptomatic individuals from the community who served as controls. Each participant was screened for malaria using microscopy. Follow-up surveys were conducted with individual households to collect socio-economic data. The houses were also checked using pyrethrum spray catches to collect mosquitoes. RESULTS: A total of 302 malaria cases were matched to 604 controls during the surveillance period. Mosquito densities were similar in the houses of both groups. A greater percentage of people in the control group (64.6%) used insecticide-treated bed nets (ITNs) compared to the families of malaria cases (48.3%). Use of ITNs was associated with lower level of clinical malaria episodes (odds ratio 0.51; 95% CI 0.39-0.68; P < 0.0001). Low income was the most important factor associated with higher malaria infections (adj. OR 4.70). Use of malaria prophylaxis was the most important factor associated with less malaria infections (adj OR 0.36). Mother's (not fathers) employment status (adj OR 0.48) and education level (adj OR 0.54) was important malaria risk factor. Houses with open eaves was an important malaria risk factor (adj OR 1.72). CONCLUSION: The identification of risk factors for clinical malaria infection provides information on the local malaria epidemiology and has the potential to lead to a more effective and targeted use of malaria control measures. These risk factors could be used to assess why some individuals acquire clinical malaria whilst others do not and to inform how intervention could be scaled at the local level.


Assuntos
Habitação/estatística & dados numéricos , Malária/epidemiologia , Adolescente , Adulto , Animais , Estudos de Casos e Controles , Criança , Pré-Escolar , Culicidae/fisiologia , Feminino , Humanos , Lactente , Mosquiteiros Tratados com Inseticida , Quênia/epidemiologia , Modelos Logísticos , Malária/prevenção & controle , Masculino , Controle de Mosquitos/normas , Densidade Demográfica , Fatores de Risco
19.
BMC Bioinformatics ; 20(1): 312, 2019 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-31185887

RESUMO

BACKGROUND: Mathematical and computational models are widely used to study the transmission, pathogenicity, and propagation of infectious diseases. Unfortunately, complex mathematical models are difficult to define, reuse and reproduce because they are composed of several concerns that are intertwined. The problem is even worse for computational models because the epidemiological concerns are also intertwined with low-level implementation details that are not easily accessible to non-computing scientists. Our goal is to make compartmental epidemiological models easier to define, reuse and reproduce by facilitating implementation of different simulation approaches with only very little programming knowledge. RESULTS: We achieve our goal through the definition of a domain-specific language (DSL), Kendrick, that relies on a very general mathematical definition of epidemiological concerns as stochastic automata that are combined using tensor-algebra operators. A very large class of epidemiological concerns, including multi-species, spatial concerns, control policies, sex or age structures, are supported and can be defined independently of each other and combined into models to be simulated by different methods. Implementing models does not require sophisticated programming skills any more. The various concerns involved within a model can be changed independently of the others as well as reused within other models. They are not plagued by low-level implementation details. CONCLUSIONS: Kendrick is one of the few DSLs for epidemiological modelling that does not burden its users with implementation details or required sophisticated programming skills. It is also currently the only language for epidemiology modelling that supports modularity through clear separation of concerns hence fostering reproducibility and reuse of models and simulations. Future work includes extending Kendrick to support non-compartmental models and improving its interoperability with existing complementary tools.


Assuntos
Algoritmos , Métodos Epidemiológicos , Idioma , Modelos Teóricos , Animais , Simulação por Computador , Culicidae/fisiologia , Vetores de Doenças , Interações Hospedeiro-Parasita , Reprodutibilidade dos Testes , Processos Estocásticos
20.
Insect Biochem Mol Biol ; 111: 103174, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31129164

RESUMO

Controlling Ae. aegypti populations and the prevention of mosquito bites includes the development of monitoring, repelling and attract-and-kill strategies that are based on understanding the chemical ecology of these pests. Olfactory-mediated attraction to mammals has recently been linked to the mosquito Aedes aegypti odorant receptor Or4, which is activated by animal-released 6-Methyl-5-hepten-2-one (sulcatone). This odorant is also a major component of flower scents and may play a role outside animal-host seeking. To explore the role of this chemical cue, we looked at the interaction between sulcatone and an Or4 homolog expressed in the antennae of the strict nectar-feeding mosquito Toxorhynchites amboinensis. Using the two-electrode voltage clamp of Xenopus oocytes as a heterologous expression system, we show that this receptor is a high intensity sulcatone receptor comparable to its Aedes counterparts. We also show that OR4 is activated by other aliphatic ketones and is inhibited by DEET. This pharmacological characterization suggests that sulcatone may be operating in more than one context in the Culicidae family.


Assuntos
Culicidae/fisiologia , Cetonas/farmacologia , Receptores Odorantes/fisiologia , Animais , Antenas de Artrópodes/fisiologia , Culicidae/genética , DEET/farmacologia , Fenômenos Eletrofisiológicos , Repelentes de Insetos/farmacologia , Oócitos , Técnicas de Patch-Clamp , Receptores Odorantes/genética , Xenopus
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