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1.
Parasit Vectors ; 17(1): 66, 2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38365773

RESUMO

BACKGROUND: Efforts to evaluate the residual efficacy of new indoor residual spraying (IRS) formulations have identified limitations with the industry standard laboratory sprayer, the Potter Spray Tower (PT). Calibrating the PT can be time-consuming, and the dosing of surfaces may not be as accurate or uniform as previously assumed. METHODS: To address these limitations, the Micron Horizontal Track Sprayer with Spray Cabinet (TS) was developed to provide higher efficiency, ease of operation and deposition uniformity equal to or better than the PT. A series of studies were performed using a fluorescent tracer and three IRS formulations (Actellic® 300CS, K-Othrine WG250 and Suspend PolyZone) sprayed onto surfaces using either the PT or the TS. RESULTS: Deposition volumes could be accurately calibrated for both spray systems. However, the uniformity of spray deposits was higher for the TS compared to the PT. Less than 12% of the volume sprayed using the PT reaches the target surface, with the remaining 88% unaccounted for, presumably vented out of the fume hood or coating the internal surfaces of the tower. In contrast, the TS deposits most of the spray on the floor of the spray chamber, with the rest contained therein. The total sprayed surface area in one run of the TS is 1.2 m2, and the operational zone for spray target placement is 0.7 m2, meaning that 58% of the applied volume deposits onto the targets. The TS can treat multiple surfaces (18 standard 15 × 15 cm tiles) in a single application, whereas the PT treats one surface at a time and a maximum area of around 0.0225 m2. An assessment of the time taken to perform spraying, including the setup, calibration and cleaning, showed that the cost of application using the TS was around 25-35 × less per tile sprayed. Standard operating procedures (SOPs) for calibration and use of both the Potter Tower and Track Sprayer have been developed. CONCLUSIONS: Overall, the TS represents a significant improvement over the PT in terms of the efficiency and accuracy of IRS formulation applications onto test substrates and offers a useful additional tool for researchers and manufacturers wanting to screen new active ingredients or evaluate the efficacy of IRS or other sprayable formulations for insect control.


Assuntos
Anopheles , Inseticidas , Compostos Organotiofosforados , Animais , Controle de Insetos , Controle de Mosquitos/métodos
3.
PLoS One ; 18(9): e0290974, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37669287

RESUMO

The outbreak of a novel coronavirus causing severe acute respiratory syndrome in December 2019 has escalated into a worldwide pandemic. In this work, we propose a compartmental model to describe the dynamics of transmission of infection and use it to obtain the optimal vaccination control. The model accounts for the various stages of the vaccination, and the optimisation is focused on minimising the infections to protect the population and relieve the healthcare system. As a case study, we selected the Republic of Ireland. We use data provided by Ireland's COVID-19 Data-Hub and simulate the evolution of the pandemic with and without the vaccination in place for two different scenarios, one representative of a national lockdown situation and the other indicating looser restrictions in place. One of the main findings of our work is that the optimal approach would involve a vaccination programme where the older population is vaccinated in larger numbers earlier while simultaneously part of the younger population also gets vaccinated to lower the risk of transmission between groups. We compare our simulated results with those of the vaccination policy taken by the Irish government to explore the advantages of our optimisation method. Our comparison suggests that a similar reduction in cases may have been possible even with a reduced set of vaccinations available for use.


Assuntos
COVID-19 , Humanos , Controle de Doenças Transmissíveis , SARS-CoV-2 , Vacinação , Fatores Etários
4.
Sci Rep ; 13(1): 11126, 2023 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-37429898

RESUMO

Provenance studies demonstrate the important control of plate boundary mountain building on continental sediment routing systems. Less well understood is if subsidence and uplift in cratons also has the potential to affect the organization of sediment routing systems on continental scales. New detrital zircon provenance data from the Michigan Basin in the Midcontinent of North America preserve evidence of intrabasin provenance heterogeneity in Cambrian, Ordovician, and middle Devonian strata. These results suggest that cratonic basins serve as effective sediment barriers that prevent mixing within and across basins from 10 to 100 s of millions of years. Internal sediment mixing, sorting, and dispersal may be achieved by a combination of sedimentary processes and inherited low relief topography. These observations are consistent with provenance data sets from eastern Laurentian Midcontinent basins that show locally and regionally variable provenance signatures during the early Paleozoic. By the late Devonian, provenance signatures throughout the basins homogenized, consistent with the emergence of transcontinental sediment transport systems associated with Appalachian orogenesis at the plate margin. These results demonstrate the importance of cratonic basins on local and regional sediment routing systems suggesting that these features may impede the integration of continental-scale sediment routings systems, particularly during periods of plate margin quiescence.

5.
Malar J ; 22(1): 23, 2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36670398

RESUMO

The use of Unmanned Aerial Vehicles (UAVs) has expanded rapidly in ecological conservation and agriculture, with a growing literature describing their potential applications in global health efforts including vector control. Vector-borne diseases carry severe public health and economic impacts to over half of the global population yet conventional approaches to the surveillance and treatment of vector habitats is typically laborious and slow. The high mobility of UAVs allows them to reach remote areas that might otherwise be inaccessible to ground-based teams. Given the rapidly expanding examples of these tools in vector control programmes, there is a need to establish the current knowledge base of applications for UAVs in this context and assess the strengths and challenges compared to conventional methodologies. This review aims to summarize the currently available knowledge on the capabilities of UAVs in both malaria control and in vector control more broadly in cases where the technology could be readily adapted to malaria vectors. This review will cover the current use of UAVs in vector habitat surveillance and deployment of control payloads, in comparison with their existing conventional approaches. Finally, this review will highlight the logistical and regulatory challenges in scaling up the use of UAVs in malaria control programmes and highlight potential future developments.


Assuntos
Malária , Dispositivos Aéreos não Tripulados , Humanos , Malária/prevenção & controle , Agricultura , Ecossistema , Tecnologia
6.
Entropy (Basel) ; 24(9)2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36141110

RESUMO

Entering digits of a personal identification number (PIN) is a common form of authentication. One variant of this scheme is to request the digits from a random subset of positions, which is sometimes called a partial PIN. In this paper we consider strategies for guessing the PIN when a partial PIN scheme is in use, which allows the quantification of the strength of this mechanism. We suggest several strategies for guessing the PIN under the assumption that the organisation assigns PINs randomly and requests random positions from the PIN at each login. We present analytic and simulation results from the different strategies and explore their performance when guessing different sizes of PIN and requested subset. We find that the most effective strategies have a reasonable chance of recovering a PIN in tens to hundreds of guesses.

7.
Insects ; 13(6)2022 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-35735860

RESUMO

Indoor residual spraying (IRS) has changed little since its introduction in the 1940s. Manual spraying is still prone to variation in insecticide dose. To improve the application of IRS in experimental hut trials, an automated track sprayer was developed, which regulates the speed of application and the distance of the nozzle from the wall, two key sources of variation. The automated track sprayer was compared to manual spraying, firstly using fluorescein solution in controlled indoor settings, and secondly in experimental huts in Tanzania using several IRS products. Manual spraying produced greater variation with both fluorescein and insecticide applications. Both manual and automated spray methods under-dosed the actual dose sprayed compared to the target dose. Overall, the track sprayer treats surfaces more consistently, offering a potential improvement over manual spraying for experimental hut evaluation of new IRS formulations.

8.
Sci Rep ; 12(1): 9715, 2022 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-35690679

RESUMO

Long-lasting insecticide-treated nets (LLINs) play a crucial role in preventing malaria transmission. LLINs should remain effective for at least three years, even after repeated washings. Currently, monitoring insecticides in LLINs is cumbersome, costly, and requires specialized equipment and hazardous solvents. Our aim was to develop a simple, high-throughput and low-resource method for measuring insecticides in LLINs. To extract insecticides, polyethylene-LLIN samples were heated at 85 °C for 45 min in a non-hazardous solvent mix containing dicyclohexylphthalate as an internal standard. The extraction solvent was reduced from 50 to 5 ml using a 0.2 g sample, 90% smaller than the recommended sample size. By optimizing HPLC chromatography, we simultaneously detected pyrethroid and pyriproxyfen insecticides with high sensitivity in LLIN's extract. The method can quantify levels ≥ 0.0015% permethrin, 0.00045% alpha-cypermethrin and 0.00025% pyriproxyfen (w/w) in polyethylene, allowing for insecticide tracking before and after the use of LLINs. This method can be used to assess LLINs with 1% pyriproxyfen (pyriproxyfen-LLIN) or 2% permethrin (Olyset® Net), 1% pyriproxyfen and 2% permethrin (Olyset® Duo), or 0.55% pyriproxyfen and 0.55% alpha-cypermethrin (Royal Gaurd®). One can run 120 samples (40 nets) simultaneously with high precision and accuracy, improving throughput and reducing labour, costs, and environmental impact.


Assuntos
Anopheles , Mosquiteiros Tratados com Inseticida , Inseticidas , Piretrinas , Animais , Cromatografia Líquida de Alta Pressão , Resistência a Inseticidas , Inseticidas/farmacologia , Controle de Mosquitos/métodos , Permetrina , Polietilenos , Piridinas , Solventes
9.
Malar J ; 21(1): 85, 2022 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-35279149

RESUMO

BACKGROUND: Distribution of long-lasting insecticidal bed nets (LLINs) is one of the main control strategies for malaria. Improving malaria prevention programmes requires understanding usage patterns in households receiving LLINs, but there are limits to what standard cross-sectional surveys of self-reported LLIN use can provide. This study was designed to assess the performance of an accelerometer-based approach for measuring a range of LLIN use behaviours as a proof of concept for more granular LLIN-use monitoring over longer time periods. METHODS: This study was carried out under controlled conditions from May to July 2018 in Liverpool, UK. A single accelerometer was affixed to the side panel of an LLIN and participants carried out five LLIN use behaviours: (1) unfurling a net; (2) entering an unfurled net; (3) lying still as if sleeping; (4) exiting from under a net; and, (5) folding up a net. The randomForest package in R, a supervised non-linear classification algorithm, was used to train models on 20-s epochs of tagged accelerometer data. Models were compared in a validation dataset using overall accuracy, sensitivity and specificity, receiver operating curves and the area under the curve (AUC). RESULTS: The five-category model had overall accuracy of 82.9% in the validation dataset, a sensitivity of 0.681 for entering a net, 0.632 for exiting, 0.733 for net down, and 0.800 for net up. A simplified four-category model, combining entering/exiting a net into one category had accuracy of 94.8%, and increased sensitivity for net down (0.756) and net up (0.829). A further simplified three-category model, identifying sleeping, net up, and a combined net down/enter/exit category had accuracy of 96.2% (483/502), with an AUC of 0.997 for net down and 0.987 for net up. Models for detecting entering/exiting by adults were significantly more accurate than for children (87.8% vs 70.0%; p < 0.001) and had a higher AUC (p = 0.03). CONCLUSIONS: Understanding how LLINs are used is crucial for planning malaria prevention programmes. Accelerometer-based systems provide a promising new methodology for studying LLIN use. Further work exploring accelerometer placement, frequency of measurements and other machine learning approaches could make these methods even more accurate in the future.


Assuntos
Mosquiteiros Tratados com Inseticida , Acelerometria , Adulto , Algoritmos , Criança , Estudos Transversais , Humanos , Aprendizado de Máquina , Controle de Mosquitos/métodos
10.
Insects ; 13(2)2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-35206686

RESUMO

Insecticides with novel modes of action are required to complement the pyrethroids currently relied upon for controlling malaria vectors. One example of this is the neonicotinoid clothianidin, the active ingredient in the indoor residual spray (IRS) SumiShield™ 50WG. In a preliminary experiment, the mortality of insecticide-susceptible and resistant An. gambiae adults exposed to filter papers treated with this IRS product reached 80% by 3 days post-exposure and 100% by 6 days post-exposure. Next, cement, wood, and mud tiles were treated with the clothianidin or a deltamethrin-based IRS formulation (K-Othrine WG250). Insecticide resistant and susceptible Anopheles and Aedes were exposed to these surfaces periodically for up to 18 months. Pyrethroid resistant Cx. quinquefasciatus was also exposed at 9 months. Between exposures, tiles were stored in heat and relative humidity conditions reflecting those found in the field. On these surfaces, the clothianidin IRS was effective at killing both susceptible and resistant An. gambiae for 18 months post-treatment, while mortality amongst the resistant strains when exposed to the deltamethrin IRS was not above that of the negative control. Greater efficacy of clothianidin was also demonstrated against insecticide resistant strains of An. funestus compared to deltamethrin, though the potency was lower when compared with An. gambiae. In general, higher efficacy of the clothianidin IRS was observed on cement and mud compared to wood, though it demonstrated poorer residual activity against Ae.aegypti and Cx. quinquefasciatus.

11.
PLoS Pathog ; 17(11): e1010090, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34793581

RESUMO

Natural Killer (NK) cells contribute to HIV control in adults, but HLA-B-mediated T-cell activity has a more substantial impact on disease outcome. However, the HLA-B molecules influencing immune control in adults have less impact on paediatric infection. To investigate the contribution NK cells make to immune control, we studied >300 children living with HIV followed over two decades in South Africa. In children, HLA-B alleles associated with adult protection or disease-susceptibility did not have significant effects, whereas Bw4 (p = 0.003) and low HLA-A expression (p = 0.002) alleles were strongly associated with immunological and viral control. In a comparator adult cohort, Bw4 and HLA-A expression contributions to HIV disease outcome were dwarfed by those of protective and disease-susceptible HLA-B molecules. We next investigated the immunophenotype and effector functions of NK cells in a subset of these children using flow cytometry. Slow progression and better plasma viraemic control were also associated with high frequencies of less terminally differentiated NKG2A+NKp46+CD56dim NK cells strongly responsive to cytokine stimulation and linked with the immunogenetic signature identified. Future studies are indicated to determine whether this signature associated with immune control in early life directly facilitates functional cure in children.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Infecções por HIV/imunologia , HIV-1/imunologia , Antígenos HLA-B/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Células Matadoras Naturais/imunologia , Receptores KIR3DL1/metabolismo , Adolescente , Criança , Pré-Escolar , Estudos de Coortes , Infecções por HIV/metabolismo , Infecções por HIV/virologia , Humanos , Ativação Linfocitária
12.
Mil Med ; 186(5-6): 549-555, 2021 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-33681971

RESUMO

INTRODUCTION: The worldwide COVID-19 pandemic poses challenges to healthcare capacity and infrastructure. The authors discuss the structure and efficacy of the U.S. Navy's response to COVID-19 and evaluate the utility of this endeavor, with the objective of providing future recommendations for managing worldwide healthcare and medical operational demands from the perspective of Navy Neurosurgery. MATERIALS AND METHODS: The authors present an extensive review of topics and objectively highlight the efforts of U.S. Navy Neurosurgery as it pertains to the humanitarian mission during the COVID-19 pandemic. RESULTS: During the humanitarian mission (March 27, 2020-April 14, 2020), the response of active duty and reserve neurosurgeons in the U.S. Navy was robust. Neurosurgical coverage was present on board the U.S. Navy Ships Mercy and Comfort, with additional neurosurgical deployment to New York City for intensive care unit management and coverage. CONCLUSIONS: The U.S. Navy neurosurgical response to the COVID-19 pandemic was swift and altruistic. Although neurosurgical pathologies were limited among the presenting patients, readiness and manpower continue to be strong influences within the Armed Forces. The COVID-19 response demonstrates that neurosurgical assets can be rapidly mobilized and deployed in support of wartime, domestic, and global humanitarian crises to augment both trauma and critical care capabilities.


Assuntos
COVID-19 , Desastres , Humanos , Neurocirurgiões , Pandemias , SARS-CoV-2
13.
PLoS One ; 16(3): e0248026, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33657179

RESUMO

Novel chemistry for vector control is urgently needed to counter insecticide resistance in mosquitoes. Here a new meta-diamide insecticide, broflanilide (TENEBENALTM), was evaluated in East African experimental huts in Moshi, northern Tanzania. Two consecutive experimental hut trials with broflanilide 50WP were conducted; the first evaluating the efficacy of three concentrations, 50 mg/m2, 100 mg/m2, and 200 mg/m2 using a prototype formulation, and the second trial evaluating an improved formulation. The IRS treatments were applied on both mud and concrete surfaces and efficacy was monitored over time. The mortality, blood-feeding inhibition and exiting behaviour of free-flying wild mosquitoes was compared between treatment arms. Additionally, cone assays with pyrethroid-susceptible and resistant mosquito strains were conducted in the huts to determine residual efficacy. The first trial showed a dosage-mortality response of the prototype formulation and 3-8 months of residual activity, with longer activity on concrete than mud. The second trial with an improved formulation showed prolonged residual efficacy of the 100 mg/m2 concentration to 5-6 months on mud, and mosquito mortality on the concrete surface ranged between 94-100% for the full duration of the trial. In both trials, results with free-flying, wild Anopheles arabiensis echoed the mortality trend shown in cone assays, with the highest dose inducing the highest mortality and the improved formulation showing increased mortality rates. No blood-feeding inhibition or insecticide-induced exiting effects were observed with broflanilide. Broflanilide 50WP was effective against both susceptible and pyrethroid-resistant mosquito strains, demonstrating an absence of cross resistance between broflanilide and pyrethroids. The improved formulation, which has now been branded VECTRONTM T500, resulted in a prolonged residual efficacy. These results indicate the potential of this insecticide as an addition to the arsenal of IRS products needed to maintain both control of malaria and resistance management of malaria-transmitting mosquitoes.


Assuntos
Anopheles/efeitos dos fármacos , Benzamidas/toxicidade , Inseticidas/toxicidade , Controle de Mosquitos , Mosquitos Vetores/efeitos dos fármacos , Piretrinas/toxicidade , Animais , Humanos , Resistência a Inseticidas/efeitos dos fármacos , Malária/epidemiologia , Malária/prevenção & controle , Malária/transmissão , Controle de Mosquitos/métodos , Tanzânia/epidemiologia
14.
Entropy (Basel) ; 22(4)2020 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-33286152

RESUMO

Password guessing is one of the most common methods an attacker will use for compromising end users. We often hear that passwords belonging to website users have been leaked and revealed to the public. These leaks compromise the users involved but also feed the wealth of knowledge attackers have about users' passwords. The more informed attackers are about password creation, the better their password guessing becomes. In this paper, we demonstrate using proofs of convergence and real-world password data that the vulnerability of users increases as a result of password leaks. We show that a leak that reveals the passwords of just 1% of the users provides an attacker with enough information to potentially have a success rate of over 84% when trying to compromise other users of the same website. For researchers, it is often difficult to quantify the effectiveness of guessing strategies, particularly when guessing different datasets. We construct a model of password guessing that can be used to offer visual comparisons and formulate theorems corresponding to guessing success.

15.
Malar J ; 19(1): 398, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33168015

RESUMO

BACKGROUND: There is an urgent need for insecticides with novel modes of action against mosquito vectors. Broflanilide is a meta-diamide, discovered and named Tenebenal™ by Mitsui Chemicals Agro, Inc., which has been identified as a candidate insecticide for use in public health products. METHODS: To evaluate its potential for use in public health, Tenebenal™ was screened using an array of methodologies against Anopheles and Aedes strains. Initially it was assessed for intrinsic efficacy by topical application. Tarsal contact bioassays were then conducted to further investigate its efficacy, as well as its potency and speed of action. The potential of the compound for use in indoor residual spray (IRS) applications was investigated by testing the residual efficacy of a prototype IRS formulation on a range of typical house building substrates, and its potential for use in long-lasting insecticidal nets (LLIN) was tested using dipped net samples. Finally, bioassays using well-characterized insecticide-resistant mosquito strains and an in silico screen for mutations in the insecticide's target site were performed to assess the risk of cross-resistance to Tenebenal™. RESULTS: Tenebenal™ was effective as a tarsal contact insecticide against both Aedes and Anopheles mosquitoes, with no apparent cross-resistance caused by mechanisms that have evolved to insecticides currently used in vector control. Topical application showed potent intrinsic activity against a Kisumu reference strain and an insecticide-resistant strain of Anopheles gambiae. Applied to filter paper in a WHO tube bioassay, Tenebenal™ was effective in killing 100% of susceptible and resistant strains of An. gambiae and Aedes aegypti at a concentration of 0.01%. The discriminating concentration of 11.91 µg/bottle shows it to be very potent relative to chemistries previously identified as having potential for vector control. Mortality occurs within 24 h of exposure, 80% of this mortality occurring within the first 10 h, a speed of kill somewhat slower than seen with pyrethroids due to the mode of action. The potential of Tenebenal™ for development in LLIN and IRS products was demonstrated. At least 12 months residual efficacy of a prototype IRS formulation applied at concentrations up to 200 mg of AI/sq m was demonstrated on a range of representative wall substrates, and up to 18 months on more inert substrates. A dipped net with an application rate of around 2 g/sq m Tenebenal™ killed 100% of exposed mosquitoes within a 3-min exposure in a WHO cone test. CONCLUSIONS: Tenebenal™ is a potent insecticide against adult Aedes and Anopheles mosquitoes, including strains resistant to classes of insecticide currently used in vector control. The compound has shown great potential in laboratory assessment and warrants further investigation into development for the control of pyrethroid-resistant mosquitoes.


Assuntos
Aedes , Anopheles , Diamida , Inseticidas , Controle de Mosquitos , Mosquitos Vetores , Animais , Feminino
16.
Sci Rep ; 10(1): 16232, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-33004954

RESUMO

Fenazaquin, pyridaben, tolfenpyrad and fenpyroximate are Complex I inhibitors offering a new mode of action for insecticidal malaria vector control. However, extended exposure to pyrethroid based products such as long-lasting insecticidal nets (LLINs) has created mosquito populations that are largely pyrethroid-resistant, often with elevated levels of P450s that can metabolise and neutralise diverse substrates. To assess cross-resistance liabilities of the Complex I inhibitors, we profiled their susceptibility to metabolism by P450s associated with pyrethroid resistance in Anopheles gambiae (CYPs 6M2, 6P3, 6P4, 6P5, 9J5, 9K1, 6Z2) and An. funestus (CYP6P9a). All compounds were highly susceptible. Transgenic An. gambiae overexpressing CYP6M2 or CYP6P3 showed reduced mortality when exposed to fenpyroximate and tolfenpyrad. Mortality from fenpyroximate was also reduced in pyrethroid-resistant strains of An. gambiae (VK7 2014 and Tiassalé 13) and An. funestus (FUMOZ-R). P450 inhibitor piperonyl butoxide (PBO) significantly enhanced the efficacy of fenpyroximate and tolfenpyrad, fully restoring mortality in fenpyroximate-exposed FUMOZ-R. Overall, results suggest that in vivo and in vitro assays are a useful guide in the development of new vector control products, and that the Complex I inhibitors tested are susceptible to metabolic cross-resistance and may lack efficacy in controlling pyrethroid resistant mosquitoes.


Assuntos
Anopheles/enzimologia , Sistema Enzimático do Citocromo P-450/metabolismo , Complexo I de Transporte de Elétrons/antagonistas & inibidores , Resistência a Inseticidas , Inseticidas/metabolismo , Piretrinas/metabolismo , Animais , Animais Geneticamente Modificados , Anopheles/efeitos dos fármacos , Anopheles/genética , Anopheles/metabolismo , Cromatografia Líquida de Alta Pressão , Sistema Enzimático do Citocromo P-450/genética , Feminino
17.
Landslides ; 17(9): 2003, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32837490
18.
Evol Appl ; 13(4): 738-751, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32211064

RESUMO

Persistent insecticides sprayed onto house walls, and incorporated into insecticide-treated bednets, provide long-acting, cost-effective control of vector-borne diseases such as malaria and leishmaniasis. The high concentrations that occur immediately postdeployment may kill both resistant and susceptible insects. However, insecticide concentration, and therefore killing ability, declines in the months after deployment. As concentrations decline, resistant insects start to survive, while susceptible insects are still killed. The period of time after deployment, within which the mortality of resistant individuals is lower than that of susceptible ones, has been termed the "window of selection" in other contexts. It is recognized as driving resistance in bacteria and malaria parasites, both of which are predominantly haploid. We argue that paying more attention to these mortality differences can help understand the evolution of insecticide resistance. Because insects are diploid, resistance encoded by single genes generates heterozygotes. This gives the potential for a narrower "window of dominance," within the window of selection, where heterozygote mortality is lower than that of susceptible homozygotes. We explore the general properties of windows of selection and dominance in driving resistance. We quantify their likely effect using data from new laboratory experiments and published data from the laboratory and field. These windows can persist months or years after insecticide deployments. Differential mortalities of resistant, susceptible and heterozygous genotypes, after public health deployments, constitute a major challenge to controlling resistance. Greater attention to mortality differences by genotype would inform strategies to reduce the evolution of resistance to existing and new insecticides.

19.
Sci Rep ; 10(1): 2081, 2020 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-32034167

RESUMO

Direct-acting antivirals (DAAs) have dramatically improved the management of chronic hepatitis C (CHC). In this study, we investigated the effects of hepatitis C virus clearance on markers of systemic inflammation measured in plasma samples from CHC patients before, during and after DAA therapy. We identified a plasma soluble protein profile associated with CHC. Successful DAA therapy rapidly normalised the plasma inflammatory milieu, with the notable exception of soluble (s)CD163, a marker of macrophage activation, which remained elevated after viral clearance and segregated patients with high and low levels of cirrhosis. Patients who received DAA in combination with Ribavirin maintained elevated levels of CXCL10, consistent with an immune-stimulatory role of Ribavirin. As anticipated, DAA-treated patients experienced durable improvement in liver fibrosis measurements. Interestingly, pre-treatment levels of fatty acid-binding protein 4 (FABP4) were inversely associated with reduction of APRI and FIB-4 scores during treatment. Together, these results support the notion of a rapid restoration of many aspects of the inflammatory state in CHC patients in response to DAA therapy. Furthermore, the associations with sCD163 and FABP4 warrant further investigation into the role of macrophages in residual liver disease and fibrosis resolution after viral clearance.


Assuntos
Antivirais/uso terapêutico , Proteínas de Ligação a Ácido Graxo/metabolismo , Hepacivirus/efeitos dos fármacos , Hepatite C Crônica/tratamento farmacológico , Fígado/patologia , Ribavirina/uso terapêutico , Citocinas/sangue , Proteínas de Ligação a Ácido Graxo/sangue , Feminino , Hepacivirus/metabolismo , Hepatite C Crônica/sangue , Hepatite C Crônica/metabolismo , Hepatite C Crônica/patologia , Humanos , Fígado/virologia , Cirrose Hepática/patologia , Masculino , Pessoa de Meia-Idade
20.
Gates Open Res ; 3: 1464, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31259317

RESUMO

Background: With insecticide resistance in malaria vectors spreading in geographical range and intensity, there is a need for compounds with novel modes of action to maintain the successes achieved to date by long-lasting insecticidal nets and indoor residual sprays, used as part of an insecticide resistance management strategy. Screening existing registered pesticides, predominantly those developed for use in agriculture, may provide a more rapid and less logistically challenging route to identifying active ingredients of value to public health than screening and chemical synthesis programmes for novel compounds. Methods: Insecticides and acaricides from all IRAC classes, including those with unclassified modes of action, were assessed for inclusion in a laboratory bioassay testing cascade against adult female Anopheles gambiae mosquitoes. A longlist of representative candidate compounds was selected, excluding those with safety concerns, unsuitable physiochemical properties, and likely hurdles to registration for public health use.  An initial screen using topical application eliminated compounds with insufficient intrinsic activity, and a tarsal contact assay identified those with activity at an appropriate concentration. Compounds of interest were ranked by relative potency using dose response assays and discriminating dose calculations. Results: Inclusion of an adjuvant enhanced the tarsal efficacy of several compounds, facilitating the promotion of chemistries with great potential, given suitable formulation, which would not progress based on activity of compound alone. Comparison of data between stages in the testing cascade suggest that a more streamlined approach, topical application to test for intrinsic activity and determining the discriminating dose to compare relative potency of compounds, may be sufficient to identify compounds with potential value for use in long lasting insecticidal nets and indoor residual spray products. Conclusions: Identified were 11 compounds of interest as vector control agents (in descending order of potency): clothianidin, spinetoram, metaflumizone, dinotefuran, indoxacarb, abamectin, sulfoxaflor, oxazosulfyl, triflumezopyrim, fenpyroximate, and tolfenpyrad.

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