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1.
Parasitol Int ; 86: 102483, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34678492

RESUMO

This study examines the biological efficacy of four mosquito mat vaporizers each containing different active ingredients: prallethrin with PBO, dimefluthrin, prallethrin, and d-allethrin. The glass chamber assay was used to evaluate their efficacy on Aedes albopictus (Skuse) (Diptera: Culicidae) from nine districts in Selangor, Malaysia. Aedes albopictus exhibited different knockdown rates, with 50% knockdown times, KT50, varying from 1.19 to 2.00 min, 1.22 to 2.20 min, 1.39 to 5.85 min, and 1.39 to 1.92 min for prallethrin with PBO, dimefluthrin, prallethrin and d-allethrin, respectively. In general, all populations of Ae. albopictus were completely knocked down after exposure to all active ingredients except Hulu Selangor population, which showed 96.00% knockdown against d-allethrin. On the contrary, mortality rates were observed from 84.00-100.00%, 84.00-100.00%, 90.67-100.00% and 90.67-100.00% in populations tested with prallethrin with PBO, dimefluthrin, prallethrin and d-allethrin, respectively. Moreover, significant correlations between mortality rates of prallethrin with PBO vs dimefluthrin (r = 0.836, P = 0.003), prallethrin with PBO vs prallethrin (r = 0.760, P = 0.011), and prallethrin vs d-allethrin (r = 0.694, P = 0.026) were also observed, suggesting cross-resistance among pyrethroids. d-allethrin was found to be high in insecticidal activity, followed by prallethrin, prallethrin with PBO, and dimefluthrin. In consistent with mortality due to insecticide exposure, elevated levels of enzyme activities were also demonstrated in Sabak Bernam, Hulu Selangor, Gombak, Petaling, Hulu Langat and Klang populations.


Assuntos
Aedes , Inseticidas , Controle de Mosquitos , Nebulizadores e Vaporizadores , Aedes/genética , Animais , Inativação Metabólica , Malásia , Fenótipo
2.
BMC Infect Dis ; 21(1): 1140, 2021 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-34749657

RESUMO

BACKGROUND: Despite a tremendous decline in the burden of malaria through public health interventions, it is yet remains a critical parasitic health problem in Ethiopia. Insecticide-treated nets and indoor residual spray are considered as the most effective preventive interventions against malaria. This study intended to determine the role of health extension workers in influencing the relationship between vector control strategies and malaria prevalence in Ethiopia. METHODS: The study adopted a descriptive study based on panel data collected from 10 regions of Ethiopia from 2010 to 2018. The data collected were analyzed using STATA version 13.0. Structural equation modelling was used to assess the mediating effect of health extension workers in the relationship. Further, the random effect model was employed to investigate the direct relationship among the study variables. RESULTS: We observed a strong mediating role of health extension workers to the relationship between strategic interventions and malaria prevalence, where the direct path is (ß = 0.64, p < 0.05), and the indirect path (ß = 0.72, p < 0.001) and (ß = 0.98, p < 0.001) confirming the mediation condition to appear. Our analysis revealed that, insecticide-treated nets and indoor residual spray significantly impacts the malaria prevalence (ß = 0.20, p < 0.05) and (ß = 0.70, p < 0.001) respectively. Further, our analysis suggests that the cumulative effect of indoor residual spray and insecticide-treated mosquito nets have helped better avert malaria prevalence (ß = 81.3%, P < 0.05). Moreover, the finding demonstrates the incremental rate of 30.2%, which is the indirect effect of the research [(ß = 0.813) - (ß1 = 0.511)]. CONCLUSION: The findings are potentially useful for the health sector in charge of infectious disease prevention and control, particularly in developing countries explaining how these group provided support to reduce malaria ensuring the provision of proper health message about the program.


Assuntos
Mosquiteiros Tratados com Inseticida , Inseticidas , Malária , Etiópia/epidemiologia , Humanos , Malária/epidemiologia , Malária/prevenção & controle , Controle de Mosquitos
3.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 33(5): 501-504, 2021 Aug 24.
Artigo em Chinês | MEDLINE | ID: mdl-34791848

RESUMO

OBJECTIVE: To investigate the susceptibility of Anopheles sinensis to malathion, deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province, so as to provide the scientific basis for local malaria vector control. METHODS: An. sinensis was captured from Puyang County, Puyang City of Henan Province in September 2018 and July 2020, and the susceptibility of field captured An. sinensis to malathion, deltamethrin and lambda-cyhalothrin was tested using the filter-paper bioassay recommended by WHO. The insecticide resistance level was assessed based on the WHO criteria. RESULTS: In 2018 and 2010, the half knock-down times (KT50) of malathion were 91.08 min and 40.95 min for An. sinensis, with knock-down rates of 37.50% and 60.87% 60 min post-exposure to malathion and 24-hour mortality rates of 90.91% and 100%, respectively, and the insecticide resistance levels were moderately resistant (M) and susceptible (S). The KT50 of deltamethrin were 415.56 min and 341.19 min for An. sinensis in 2018 and 2020, with knock-down rates of 22.92% and 16.98% 60 min post-exposure to malathion and 24-hour mortality rates of 22.92% and 16.98%, and the insecticide resistance levels were all resistant (R). The KT50 of lambda-cyhalothrin were 164.22 min and 236.22 min for An. sinensis in 2018 and 2020, with knock-down rates of 30.39% and 38.30% 60 min postexposure to malathion and 24 h mortality rates of 19.60% and 21.28%, respectively, and the insecticide resistance levels were all R. CONCLUSIONS: An. sinensis is relatively susceptible to malathion but has developed high-level resistance to deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province..


Assuntos
Anopheles , Inseticidas , Malária , Piretrinas , Animais , Resistência a Inseticidas , Inseticidas/farmacologia , Controle de Mosquitos , Mosquitos Vetores , Nitrilas/farmacologia , Piretrinas/farmacologia
4.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 33(5): 544-550, 2021 Apr 15.
Artigo em Chinês | MEDLINE | ID: mdl-34791858

RESUMO

Mosquitoes are the main vectors of many infectious diseases, including malaria and yellow fever, which seriously threaten human health across the world. In addition to the use of chemical insecticides, genetic control is a new attempt to currently available interventions used for mosquito vector control. In terms of ecological safety, however, symbiotic control as a novel approach has been proposed for mosquito control. Since there are multiple symbiotic microflora inhabiting in a variety of tissues of mosquitoes, including the digestive tract, they may affect the transmission of mosquito-borne infectious diseases through affecting the lifespan, reproductive competence, and vector competence of the host. In this review, the interactions between symbionts in mosquitoes were summarized, and the research progress of mosquito-associated symbionts in the management of mosquitoborne infectious diseases was reviewed.


Assuntos
Inseticidas , Malária , Animais , Vetores de Doenças , Humanos , Malária/prevenção & controle , Controle de Mosquitos , Mosquitos Vetores
5.
J Insect Sci ; 21(5)2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34605546

RESUMO

To evaluate whether the presence of clear incandescent light was attractive or refractive to host-seeking mosquitoes in northern Colorado, a Bayesian hierarchical model was created to measure differences in trap effectiveness based on presence or absence of phototactic cues. A total of eight CDC miniature light traps (with and without light) were set weekly across four locations in northern Colorado between Weeks 23 and 32 of year 2020. Culex mosquitoes (Diptera: Culicidae) accounted for 81% of all collections in this study with two vectors of West Nile virus being represented. The probability of catching both Culex tarsalis Coquillett and Culex pipiens Linnaeus was reduced when traps were equipped with light, but the difference was not statistically significant for Culex tarsalis. The clear reduction in the number of Culex pipiens caught when these traps were equipped with light indicates negative phototactic behavior and underestimation with current surveillance strategies. Removal of light from these traps may aid our understanding of these species' distribution within the environment, improve collection efficiency, and help guide implementation of targeted control measures used in public health mosquito control.


Assuntos
Culex , Controle de Mosquitos/métodos , Animais , Colorado , Mosquitos Vetores , Estados Unidos , Febre do Nilo Ocidental/transmissão
6.
PLoS Genet ; 17(10): e1009740, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34610011

RESUMO

CRISPR-based homing gene drives can be designed to disrupt essential genes whilst biasing their own inheritance, leading to suppression of mosquito populations in the laboratory. This class of gene drives relies on CRISPR-Cas9 cleavage of a target sequence and copying ('homing') therein of the gene drive element from the homologous chromosome. However, target site mutations that are resistant to cleavage yet maintain the function of the essential gene are expected to be strongly selected for. Targeting functionally constrained regions where mutations are not easily tolerated should lower the probability of resistance. Evolutionary conservation at the sequence level is often a reliable indicator of functional constraint, though the actual level of underlying constraint between one conserved sequence and another can vary widely. Here we generated a novel adult lethal gene drive (ALGD) in the malaria vector Anopheles gambiae, targeting an ultra-conserved target site in a haplosufficient essential gene (AGAP029113) required during mosquito development, which fulfils many of the criteria for the target of a population suppression gene drive. We then designed a selection regime to experimentally assess the likelihood of generation and subsequent selection of gene drive resistant mutations at its target site. We simulated, in a caged population, a scenario where the gene drive was approaching fixation, where selection for resistance is expected to be strongest. Continuous sampling of the target locus revealed that a single, restorative, in-frame nucleotide substitution was selected. Our findings show that ultra-conservation alone need not be predictive of a site that is refractory to target site resistance. Our strategy to evaluate resistance in vivo could help to validate candidate gene drive targets for their resilience to resistance and help to improve predictions of the invasion dynamics of gene drives in field populations.


Assuntos
Sistemas CRISPR-Cas/genética , Sequência Conservada/genética , Animais , Anopheles/genética , Evolução Biológica , Tecnologia de Impulso Genético/métodos , Genes Essenciais/genética , Genótipo , Malária/parasitologia , Controle de Mosquitos/métodos , Mosquitos Vetores/genética
7.
Malar J ; 20(1): 415, 2021 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-34688285

RESUMO

Supplementary tools are required to address the limitations of insecticide-treated nets (ITNs) and indoor residual spraying (IRS), which are currently the core vector control methods against malaria in Africa. The eave ribbons technology exploits the natural house-entry behaviours of major malaria vectors to deliver mosquitocidal or repellent actives around eave spaces through which the Anopheles mosquitoes usually enter human dwellings. They confer protection by preventing biting indoors and in the peri-domestic outdoor spaces, and also killing a significant proportion of the mosquitoes. Current versions of eave ribbons are made of low-cost hessian fabric infused with candidate insecticides and can be easily fitted onto multiple house types without any additional modifications. This article reviews the evidence for efficacy of the technology, and discusses its potential as affordable and versatile supplementary approach for targeted and efficient control of mosquito-borne diseases, particularly malaria. Given their simplicity and demonstrated potential in previous studies, future research should investigate ways to optimize scalability and effectiveness of the ribbons. It is also important to assess whether the ribbons may constitute a less-cumbersome, but more affordable substitute for other interventions, such as IRS, by judiciously using lower quantities of selected insecticides targeted around eave spaces to deliver equivalent or greater suppression of malaria transmission.


Assuntos
Anopheles , Habitação , Inseticidas , Malária/prevenção & controle , Controle de Mosquitos , Mosquitos Vetores , África , Animais , Controle de Mosquitos/métodos , Pobreza
8.
PLoS One ; 16(10): e0255321, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34634069

RESUMO

BACKGROUND: An. funestus is a major Afrotropical vector of human malaria. This study sought to investigate the larval ecology, sporozoite infection rates and blood meal sources of An. funestus in western Kenya. METHODS: Larval surveys were carried out in Bungoma (Highland) and Kombewa (lowland) of western Kenya. Aquatic habitats were identified, characterized, georeferenced and carefully examined for mosquito larvae and predators. Indoor resting mosquitoes were sampled using pyrethrum spray catches. Adults and larvae were morphologically and molecularly identified to species. Sporozoite infections and blood meal sources were detected using real-time PCR and ELISA respectively. RESULTS: Of the 151 aquatic habitats assessed, 62/80 (78%) in Bungoma and 58/71(82%) in Kombewa were positive for mosquito larvae. Of the 3,193 larvae sampled, An. funestus larvae constitute 38% (1224/3193). Bungoma recorded a higher number of An. funestus larvae (85%, 95%, CI, 8.722-17.15) than Kombewa (15%, 95%, CI, 1.33-3.91). Molecular identification of larvae showed that 89% (n = 80) were An. funestus. Approximately 59%, 35% and 5% of An. funestus larvae co-existed with An. gambiae s.l, Culex spp and An. coustani in the same habitats respectively. Of 1,221 An. funestus s.l adults sampled, molecular identifications revealed that An. funestus constituted 87% (n = 201) and 88% (n = 179) in Bungoma and Kombewa, respectively. The Plasmodium falciparum sporozoite rate of An. funestus in Bungoma and Kombewa was 2% (3/174) and 1% (2/157), respectively, and the human blood index of An. funestus was 84% (48/57) and 89% (39/44) and for Bungoma and Kombewa, respectively. CONCLUSION: Man-made ponds had the highest abundance of An. funestus larvae. Multiple regression and principal component analyses identified the distance to the nearest house as the key environmental factor associated with the abundance of An. funestus larvae in aquatic habitats. This study serves as a guide for the control of An. funestus and other mosquito species to complement existing vector control strategies.


Assuntos
Anopheles/embriologia , Larva/crescimento & desenvolvimento , Malária Falciparum/transmissão , Controle de Mosquitos/métodos , Mosquitos Vetores/crescimento & desenvolvimento , Mosquitos Vetores/parasitologia , Animais , Anopheles/parasitologia , Ecologia , Humanos , Mosquiteiros Tratados com Inseticida , Inseticidas/farmacologia , Quênia , Larva/parasitologia , Plasmodium falciparum/isolamento & purificação
9.
Ig Sanita Pubbl ; 78(4): 564-582, 2021.
Artigo em Italiano | MEDLINE | ID: mdl-34525014

RESUMO

BACKGROUND: Countries in sub-Saharan Africa remain the most affected by malaria, with nearly 93% of cases and 94% of deaths in 2018 according to the World Health Organization (WHO). According to the WHO, in order to significantly reduce malaria- related incidence and mortality, at least 80% of the population should be covered with insecticide-treated mosquito nets (ITNs). Hence our objective which was on the one hand to determine the rates in terms of possession and use of ITNs in countries located in Sub- Saharan Africa between January 2015 and January 2020, and to determine the impact of the use of ITNs on the probability of being infected with malaria. METHODS: To achieve our goal, we conducted a systematic literature review followed by a meta-analysis. The article search was done in the Scopus, Medline via Ovid, BioRxiv, MedRxiv, Google and Google scholar databases. Data extracted from articles included in the meta-analysis were represented as P-value, Odds Ratio (OR) and 95% confidence interval (CI). RESULTS: We obtained 693 article references published between 2015 and 2020, of which 54 were used in our work. Of these articles, 20 were used to analyze association between ITNs use and the probability of being infected with malaria. We noted an average rate in terms of possession of 75.8%±15.2 and in terms of use of 58.3%±18. This represents a gap of approximately 43.1%±19.2. Many factors was significantly associated with this level of use. These included the wealth quintile, the number of children under 5 in the household, the education level of the head of the household, and the knowledge that sleeping under a mosquito net protects against malaria. Finally, we determined, basis on the meta-analysis, that ITNs use is significantly associated (OR=0.53; 95%CI=[0.45-0.62]) with a decrease in the probability of being infected with malaria. CONCLUSION: The results of this study highlight the huge gap between ITN ownership and use. It is therefore important to increase information and awareness campaigns on the importance of ITNs use against malaria in communities.


Assuntos
Mosquiteiros Tratados com Inseticida , Inseticidas , Malária , África ao Sul do Saara/epidemiologia , Criança , Humanos , Malária/epidemiologia , Malária/prevenção & controle , Controle de Mosquitos
10.
Trials ; 22(1): 613, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34507602

RESUMO

BACKGROUND: In cluster randomized trials (CRTs) of interventions against malaria, mosquito movement between households ultimately leads to contamination between intervention and control arms, unless they are separated by wide buffer zones. METHODS: This paper proposes a method for adjusting estimates of intervention effectiveness for contamination and for estimating a contamination range between intervention arms, the distance over which contamination measurably biases the estimate of effectiveness. A sigmoid function is fitted to malaria prevalence or incidence data as a function of the distance of households to the intervention boundary, stratified by intervention status and including a random effect for the clustering. The method is evaluated in a simulation study, corresponding to a range of rural settings with varying intervention effectiveness and contamination range, and applied to a CRT of insecticide treated nets in Ghana. RESULTS: The simulations indicate that the method leads to approximately unbiased estimates of effectiveness. Precision decreases with increasing mosquito movement, but the contamination range is much smaller than the maximum distance traveled by mosquitoes. For the method to provide precise and approximately unbiased estimates, at least 50% of the households should be at distances greater than the estimated contamination range from the discordant intervention arm. CONCLUSIONS: A sigmoid approach provides an appropriate analysis for a CRT in the presence of contamination. Outcome data from boundary zones should not be discarded but used to provide estimates of the contamination range. This gives an alternative to "fried egg" designs, which use large clusters (increasing costs) and exclude buffer zones to avoid bias.


Assuntos
Culicidae , Inseticidas , Malária , Animais , Humanos , Malária/prevenção & controle , Controle de Mosquitos , Ensaios Clínicos Controlados Aleatórios como Assunto
11.
Malar J ; 20(1): 363, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34488778

RESUMO

BACKGROUND: Insecticide-treated nets (ITNs) undergo a series of tests to obtain listing by World Health Organization (WHO) Prequalification. These tests characterize the bioefficacy, physical and chemical properties of the ITN. ITN procurers assume that product specifications relate to product performance. Here, ITN test methods and their underlying assumptions are discussed from the perspective of the ITN manufacturing process and product characteristics. METHODS: Data were extracted from WHO Pesticide Evaluation Scheme (WHOPES) meeting reports from 2003 to 2017, supplemented with additional chemical analysis to critically evaluate ITNs bioassays with a focus on sampling, washing and wash resistance, and bioefficacy testing. Production methods for ITNs and their impact on testing outcomes are described. RESULTS AND RECOMMENDATIONS: ITNs are not homogenous products. They vary within panels and between the sides and the roof. Running tests of wash resistance using a before/after tests on the same sample or band within a net reduces test variability. As mosquitoes frequently interact with ITN roofs, additional sampling of the roof when evaluating ITNs is advisable because in nets where roof and sides are of the same material, the contribution of roof sample (20-25%) to the average is less than the tolerance for the specification (25%). Mosquito mortality data cannot be reliably used to evaluate net surface concentration to determine regeneration time (RT) and resistance to washing as nets may regenerate beyond the insecticide concentrations needed to kill 100% of susceptible mosquitoes. Chemical assays to quantify surface concentration are needed. The Wash Resistance Index (WRI) averaged over the first four washes is only informative if the product has a log linear loss rate of insecticide. Using a WRI that excludes the first wash off gives more reliable results. Storage conditions used for product specifications are lower than those encountered under product shipping and storage that may exceed 50 °C, and should be reconsidered. Operational monitoring of new ITNs and linking observed product performance, such as bioefficacy after 2 or 3 years of use, with product characteristics, such as WRI, will aid the development of more robust test methods and product specifications for new products coming to market.


Assuntos
Mosquiteiros Tratados com Inseticida/estatística & dados numéricos , Malária/prevenção & controle , Controle de Mosquitos/estatística & dados numéricos , Organização Mundial da Saúde
12.
Nat Commun ; 12(1): 5374, 2021 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-34508072

RESUMO

The mosquito Aedes aegypti is the principal vector for arboviruses including dengue/yellow fever, chikungunya, and Zika virus, infecting hundreds of millions of people annually. Unfortunately, traditional control methodologies are insufficient, so innovative control methods are needed. To complement existing measures, here we develop a molecular genetic control system termed precision-guided sterile insect technique (pgSIT) in Aedes aegypti. PgSIT uses a simple CRISPR-based approach to generate flightless females and sterile males that are deployable at any life stage. Supported by mathematical models, we empirically demonstrate that released pgSIT males can compete, suppress, and even eliminate mosquito populations. This platform technology could be used in the field, and adapted to many vectors, for controlling wild populations to curtail disease in a safe, confinable, and reversible manner.


Assuntos
Aedes/virologia , Infertilidade Masculina/veterinária , Controle de Mosquitos/métodos , Mosquitos Vetores/virologia , Aedes/genética , Animais , Animais Geneticamente Modificados , Arbovírus , Febre de Chikungunya/prevenção & controle , Febre de Chikungunya/transmissão , Febre de Chikungunya/virologia , Dengue/prevenção & controle , Dengue/transmissão , Dengue/virologia , Feminino , Humanos , Infertilidade Masculina/genética , Masculino , Modelos Biológicos , Mosquitos Vetores/genética , Febre Amarela/prevenção & controle , Febre Amarela/transmissão , Febre Amarela/virologia , Zika virus , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/transmissão , Infecção por Zika virus/virologia
13.
BMC Public Health ; 21(1): 1666, 2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34521374

RESUMO

BACKGROUND: Despite widespread use of long-lasting insecticidal nets (LLINs) and other tools, malaria caused 409,000 deaths worldwide in 2019. While indoor residual spraying (IRS) is an effective supplement, IRS is moderately expensive and logistically challenging. In endemic areas, IRS requires yearly application just before the main rainy season and potential interim reapplications. A new technology, insecticide-treated wall liner (ITWL), might overcome these challenges. METHODS: We conducted a 44-cluster two-arm randomized controlled trial in Muheza, Tanzania from 2015 to 2016 to evaluate the cost and efficacy of a non-pyrethroid ITWL to supplement LLINs, analyzing operational changes over three installation phases. The estimated efficacy (with 95% confidence intervals) of IRS as a supplement to LLINs came mainly from a published randomized trial in Muleba, Tanzania. We obtained financial costs of IRS from published reports and conducted a household survey of a similar IRS program near Muleba to determine household costs. The costs of ITWL were amortized over its 4-year expected lifetime and converted to 2019 US dollars using Tanzania's GDP deflator and market exchange rates. RESULTS: Operational improvements from phases 1 to 3 raised ITWL coverage from 35.1 to 67.1% of initially targeted households while reducing economic cost from $34.18 to $30.56 per person covered. However, 90 days after installing ITWL in 5666 households, the randomized trial was terminated prematurely because cone bioassay tests showed that ITWL no longer killed mosquitoes and therefore could not prevent malaria. The ITWL cost $10.11 per person per year compared to $5.69 for IRS. With an efficacy of 57% (3-81%), IRS averted 1162 (61-1651) disability-adjusted life years (DALYs) per 100,000 population yearly. Its incremental cost-effectiveness ratio (ICER) per DALY averted was $490 (45% of Tanzania's per capita gross national income). CONCLUSIONS: These findings provide design specifications for future ITWL development and implementation. It would need to be efficacious and more effective and/or less costly than IRS, so more persons could be protected with a given budget. The durability of a previous ITWL, progress in non-pyrethroid tools, economies of scale and competition (as occurred with LLINs), strengthened community engagement, and more efficient installation and management procedures all offer promise of achieving these goals. Therefore, ITWLs merit ongoing study. FIRST POSTED: 2015 ( NCT02533336 ).


Assuntos
Mosquiteiros Tratados com Inseticida , Inseticidas , Malária , Animais , Análise Custo-Benefício , Humanos , Malária/prevenção & controle , Controle de Mosquitos , Tanzânia
15.
Artigo em Inglês | MEDLINE | ID: mdl-34501636

RESUMO

Malaria accounts for 14% of child deaths in the Democratic Republic of the Congo, and one of the key interventions used to prevent malaria is to distribute insecticide-treated bednets (ITNs), especially long-lasting insecticidal nets (LLINs). The global health community and the Roll Back Malaria initiative have been struggling to achieve universal health coverage using ITNs, and recent studies have reported mixed results about the effects of door-to-door visits and mass distribution campaigns. We aimed to compare LLIN use for those provided by door-to-door hang-up visits and by conventional fixed distribution from distribution centers accompanied by a mass distribution campaign. A cluster randomized control trial was conducted in rural areas of Maniema Province, Democratic Republic of the Congo (DR Congo). Cross-sectional surveys were conducted on 2120 and 2156 households, respectively, with at least one child aged less than five in 76 villages. We assessed the effectiveness of door-to-door hang-up visits on the use of LLINs by exploring the interaction between the "intervention group" and "time" using generalized estimating equation models. Increased LLINs use was observed in all age groups in both arms, but usage differences were not significantly different (relative risk (RR) of LLINs use among children < 5 in the intervention group versus the control group after adjusted for clustering: 1.06, 95% CI: 0.85-1.33). We conclude that the door-to-door hang-up visits are not sufficient to persuade individuals (pregnant woman, children < 5, or all study participants) to use LLINs, although it did appear to be effective for the youngest children in the household.


Assuntos
Mosquiteiros Tratados com Inseticida , Inseticidas , Criança , Estudos Transversais , República Democrática do Congo , Feminino , Humanos , Controle de Mosquitos , Gravidez
16.
BMC Public Health ; 21(1): 1688, 2021 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-34530799

RESUMO

BACKGROUND: The engagement of schools in malaria control is an emerging strategy. Little is known about the involvement of students in the development of malaria messages. This study evaluated the message content of primary school students' malaria poems. METHODS: A qualitative content analysis was conducted to explore malaria messages conveyed in poems produced by students. Twenty poems were purposively selected from twenty schools across rural villages in five districts of the Jimma Zone. Data were analyzed using Atlas.ti version 7.1.4 software. The message contents were quantified in terms of frequency, and including metaphors, presented using central themes, categories, and supportive quotations. RESULTS: A total of 602 malarial contents were generated, and organized into 21 categories under five central themes. 1) Malaria-related knowledge (causation and modes of transmission, mosquito breeding and biting behavior, signs and symptoms, care for insecticide-treated nets (ITNs), and prevention methods), 2) Perceived threats from malaria, 3)The effectiveness of prevention methods (i.e., related to the adaption of ITNs, environmental cleaning, indoor residual spray (IRS), treatment for fever, and drug adherence practices), 4) Misconceptions, beliefs, and malpractices regarding the cause of malaria and drug use) and 5) Direct calls to the adopt ITN, IRS, clean surroundings, treatment, and drug use. The most commonly conveyed message contents were about the severity of malaria, distinguishable signs and symptoms, calls for community participation for malaria elimination, knowledge of preventive methods, and effectiveness of ITN use. Metaphoric expressions (war and death) were used to convey messages about the severity and the need to manage the prognosis of malaria through the active ITN use, which itself was metaphorically represented as 'a trap' to mosquitoes. CONCLUSIONS: The poetic analysis indicated that the students developed and disseminated rich malarial messages, especially on malarial knowledge, and perceptions, beliefs, norms and practices of the local community to prevent and control malaria. Therefore, primary school students can be a source of information and would effectively communicate knowledge, perceptions, and promote malaria related practices, particularly in rural settings.


Assuntos
Mosquiteiros Tratados com Inseticida , Malária , Animais , Etiópia/epidemiologia , Humanos , Malária/prevenção & controle , Controle de Mosquitos , População Rural , Instituições Acadêmicas , Estudantes
17.
Malar J ; 20(1): 387, 2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34583682

RESUMO

BACKGROUND: Long-lasting efficacy of insecticide-treated nets is a balance between adhesion, retention and migration of insecticide to the surface of netting fibres. ICON® Maxx is a twin-sachet 'home-treatment kit' of pyrethroid plus binding agent, recommended by the World Health Organization (WHO) for long-lasting, wash-fast treatment of polyester nets. While knitted polyester netting is widely used, fine woven polyethylene netting is increasingly available and nets made of cotton and nylon are common in Africa and Asia. It is important to investigate whether ICON Maxx is able to fulfill the WHO criteria of long-lasting treatment on a range of domestic fabrics to widen the scope for malaria protection. METHODS: This study was a controlled comparison of the bio-efficacy and wash-fastness of lambda-cyhalothrin CS, with or without binder, on nets made of cotton, polyethylene, nylon, dyed and undyed polyester. Evaluation compared an array of bioassays: WHO cone and cylinder, median time to knockdown and WHO tunnel tests using Anopheles mosquitoes. Chemical assay revealed further insight. RESULTS: ICON Maxx treated polyethylene and polyester netting met the WHO cone and tunnel test bio-efficacy criteria for LLIN after 20 standardized washes. Although nylon and cotton netting failed to meet the WHO cone and cylinder criteria, both materials passed the WHO tunnel test criterion of 80% mortality after 20 washes. All materials treated with standard lambda-cyhalothrin CS without binder failed to meet any of the WHO bio-efficacy criteria within 5 washes. CONCLUSION: The bio-efficacy of ICON Maxx against mosquitoes on netting washed up to 20 times demonstrated wash durability on a range of synthetic polymer and natural fibres: polyester, polyethylene, nylon and cotton. This raises the prospect of making insecticide-binder kits into an effective approach for turning untreated nets, curtains, military clothing, blankets-and tents and tarpaulins as used in disasters and humanitarian emergencies-into effective malaria prevention products. It may provide a solution to the problem of reduced LLIN coverage between campaigns by converting commercially sourced untreated nets into LLINs through community or home treatment. It may also open the door to binding of non-pyrethroid insecticides to nets and textiles for control of pyrethroid resistant vectors.


Assuntos
Anopheles , Mosquiteiros Tratados com Inseticida/estatística & dados numéricos , Inseticidas , Controle de Mosquitos , Mosquitos Vetores , Nitrilas , Piretrinas , Animais , Feminino , Malária/prevenção & controle , Polímeros/análise
18.
Pestic Biochem Physiol ; 178: 104912, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34446188

RESUMO

Intracellular effects exerted by phytochemicals eliciting insect growth-retarding responses during vector control intervention remain largely underexplored. We studied the effects of Zanthoxylum chalybeum Engl. (Rutaceae) (ZCE) root derivatives against malaria (Anopheles gambiae) and arbovirus vector (Aedes aegypti) larvae to decipher possible molecular targets. We report dose-dependent biphasic effects on larval response, with transient exposure to ZCE and its bioactive fraction (ZCFr.5) inhibiting acetylcholinesterase (AChE) activity, inducing larval lethality and growth retardation at sublethal doses. Half-maximal lethal concentrations (LC50) for ZCE against An. gambiae and Ae. aegypti larvae after 24-h exposure were 9.00 ppm and 12.26 ppm, respectively. The active fraction ZCFr.5 exerted LC50 of 1.58 ppm and 3.21 ppm for An. gambiae and Ae. aegypti larvae, respectively. Inhibition of AChE was potentially linked to larval toxicity afforded by 2-tridecanone, palmitic acid (hexadecanoic acid), linoleic acid ((Z,Z)-9,12-octadecadienoic acid), sesamin, ß-caryophyllene among other compounds identified in the bioactive fraction. In addition, the phenotypic larval retardation induced by ZCE root constituents was exerted through transcriptional modulation of ecdysteroidogenic CYP450 genes. Collectively, these findings provide an explorative avenue for developing potential mosquito control agents from Z. chalybeum root constituents.


Assuntos
Aedes , Culex , Inseticidas , Zanthoxylum , Animais , Transtornos do Crescimento , Inseticidas/toxicidade , Larva , Controle de Mosquitos , Mosquitos Vetores , Extratos Vegetais
19.
PLoS Negl Trop Dis ; 15(8): e0009603, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34370734

RESUMO

BACKGROUND: The COVID-19 pandemic has induced unprecedented reductions in human mobility and social contacts throughout the world. Because dengue virus (DENV) transmission is strongly driven by human mobility, behavioral changes associated with the pandemic have been hypothesized to impact dengue incidence. By discouraging human contact, COVID-19 control measures have also disrupted dengue vector control interventions, the most effective of which require entry into homes. We sought to investigate how and why dengue incidence could differ under a lockdown scenario with a proportion of the population sheltered at home. METHODOLOGY & PRINCIPAL FINDINGS: We used an agent-based model with a realistic treatment of human mobility and vector control. We found that a lockdown in which 70% of the population sheltered at home and which occurred in a season when a new serotype invaded could lead to a small average increase in cumulative DENV infections of up to 10%, depending on the time of year lockdown occurred. Lockdown had a more pronounced effect on the spatial distribution of DENV infections, with higher incidence under lockdown in regions with higher mosquito abundance. Transmission was also more focused in homes following lockdown. The proportion of people infected in their own home rose from 54% under normal conditions to 66% under lockdown, and the household secondary attack rate rose from 0.109 to 0.128, a 17% increase. When we considered that lockdown measures could disrupt regular, city-wide vector control campaigns, the increase in incidence was more pronounced than with lockdown alone, especially if lockdown occurred at the optimal time for vector control. CONCLUSIONS & SIGNIFICANCE: Our results indicate that an unintended outcome of lockdown measures may be to adversely alter the epidemiology of dengue. This observation has important implications for an improved understanding of dengue epidemiology and effective application of dengue vector control. When coordinating public health responses during a syndemic, it is important to monitor multiple infections and understand that an intervention against one disease may exacerbate another.


Assuntos
COVID-19/prevenção & controle , Dengue/epidemiologia , SARS-CoV-2 , Animais , Dengue/prevenção & controle , Dengue/transmissão , Humanos , Incidência , Controle de Mosquitos , Saúde Pública
20.
Artigo em Inglês | MEDLINE | ID: mdl-34406289

RESUMO

Infections caused by arboviruses that have mostly impacted the Brazilian morbidity and mortality are caused by the same vector, Aedes aegypti. Preventive actions related to the vector are the most effective strategies in the prevention and control of these diseases. This study aimed to associate the knowledge on the vector that transmits dengue, Zika and chikungunya with the sociodemographic and behavioral preventive practices towards Aedes aegypti in the municipality of Tangara da Serra, Mato Grosso State, in the Brazilian Legal Amazon. A probabilistic urban population sampling was obtained by clusters: census sectors and households. The sample size calculation considered 10% of loss and a 1.5 design effect. This is a cross-sectional research carried out through a household survey in February and March 2018. There were 583 participants. The study variables were knowledge on the vector, sociodemographic characteristics and preventive practices related to the vector. The statistical analysis was based on a bivariate analysis and Poisson multiple regressions. Inadequate or insufficient knowledge on the vector Aedes aegypti remained associated with education in the categories illiterate (p<0.001) and 8 years of study or less (p<0.001), in addition to not adopting practices of capping and cleaning the water tank (p=0.002) and not using insecticides at home (p=0.007). It is concluded that there is a need for health communication actions that consider characteristics the population, especially the level of education and previous knowledge on the vector, allowing a dialogical approach and enabling the community participation in preventive practices and control of the vector Aedes aegypti .


Assuntos
Aedes , Dengue , Infecção por Zika virus , Zika virus , Animais , Estudos Transversais , Dengue/prevenção & controle , Humanos , Controle de Mosquitos , Mosquitos Vetores , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/prevenção & controle
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