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1.
BMC Public Health ; 20(1): 1385, 2020 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-32912177

RESUMO

BACKGROUND: In El Salvador, Aedes aegypti mosquitoes transmitting Zika and other arboviruses use water storage containers as important oviposition sites. Promotion of water storage container cleaning is a key element of prevention programs. We explored community perceptions surrounding cleaning practices among pregnant women, male partners of pregnant women, and women likely to become pregnant. METHODS: Researchers conducted 11 focus groups and 12 in-depth interviews which included individual elicitations of Zika prevention measures practiced in the community. Focus group participants rated 18 images depicting Zika-related behaviors according to effectiveness and feasibility in the community context, discussed influencing determinants, voted on community intentions to perform prevention behaviors, and performed washbasin cleaning simulations. In-depth interviews with male partners of pregnant women used projective techniques with images to explore their perceptions on a subset of Zika prevention behaviors. RESULTS: General cleaning of the home, to ensure a healthy environment, was a strong community norm. In this context, participants gave water storage container cleaning a high rating, for both its effectiveness and feasibility. Participants were convinced that they cleaned their water storage containers effectively against Zika, but their actual skills were inadequate to destroy Aedes aegypti eggs. A further constraint was the schedule of water availability. Even during pregnancy, male partners rarely cleaned water storage containers because water became available in homes when they were at work. Furthermore, prevailing gender norms did not foster male participation in domestic cleaning activities. Despite these factors, many men were willing to provide substantial support with cleaning when their partners were pregnant, in order to protect their family. CONCLUSIONS: Behavior change programs for the prevention of Zika and other arboviruses need to improve community members' mosquito egg destruction skills rather than perpetuate the promotion of non-specific cleaning in and around the home as effective. Egg elimination must be clearly identified as the objective of water storage container maintenance and programs should highlight the effective techniques to achieve this goal. In addition, programs must build the skills of family members who support pregnant women to maintain the frequency of effective egg destruction in all water storage containers of the home.


Assuntos
Aedes/virologia , Conhecimentos, Atitudes e Prática em Saúde , Controle de Mosquitos/métodos , Abastecimento de Água , Água , Infecção por Zika virus/prevenção & controle , Zika virus , Adolescente , Adulto , Animais , El Salvador , Feminino , Grupos Focais , Humanos , Masculino , Pessoa de Meia-Idade , Gravidez , Pesquisa Qualitativa , Características de Residência , Adulto Jovem , Zika virus/crescimento & desenvolvimento , Infecção por Zika virus/transmissão , Infecção por Zika virus/virologia
2.
PLoS Negl Trop Dis ; 14(9): e0008716, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32966283

RESUMO

The concurrent circulation of dengue and coronavirus disease 2019 (COVID-19) may produce many unfavourable outcomes-such as co-infections; delays in diagnosis, treatment, and mitigation measures; overwhelming of the healthcare system; underreporting of cases; deterioration in surveillance and control interventions; and exacerbation of social inequalities. Indeed, lockdown is greatly compromising the effectiveness of vector control, especially social mobilization campaigns and preventive insecticide spraying in private spaces (indoor and peridomestic spraying). Thus, failure to appropriately implement the full range of vector control interventions can lead to a reduction in their overall effectiveness and an increasing risk of vector-borne diseases circulating. Consequently, the health community and policy makers should develop proactive policies and allocate adequate resources to prevent and manage the resurgence of dengue and other vector-borne diseases in the new era of COVID-19.


Assuntos
Infecções por Coronavirus/epidemiologia , Dengue/epidemiologia , Dengue/prevenção & controle , Controle de Mosquitos/métodos , Pneumonia Viral/epidemiologia , Prevenção Primária/métodos , Betacoronavirus , Assistência à Saúde , Humanos , Pandemias , Controle de Pragas/métodos , Saúde Pública , Tempo para o Tratamento
3.
PLoS Med ; 17(9): e1003248, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32946451

RESUMO

BACKGROUND: Two billion long-lasting insecticidal nets (LLINs) have been procured for malaria control. A functional LLIN is one that is present, is in good physical condition, and remains insecticidal, thereby providing protection against vector-borne diseases through preventing bites and killing disease vectors. The World Health Organization (WHO) prequalifies LLINs that remain adequately insecticidal 3 years after deployment. Therefore, institutional buyers often assume that prequalified LLINs are functionally identical with a 3-year lifespan. We measured the lifespans of 3 LLIN products, and calculated their cost per year of functional life, to demonstrate the economic and public health importance of procuring the most cost-effective LLIN product based on its lifespan. METHODS AND FINDINGS: A randomised double-blinded trial of 3 pyrethroid LLIN products (10,571 nets in total) was conducted at 3 follow-up points: 10 months (August-October 2014), 22 months (August-October 2015), and 36 months (October-December 2016) among 3,393 households in Tanzania using WHO-recommended methods. Primary outcome was LLIN functional survival (LLIN present and in serviceable condition). Secondary outcomes were (1) bioefficacy and chemical content (residual insecticidal activity) and (2) protective efficacy for volunteers sleeping under the LLINs (bite reduction and mosquitoes killed). Median LLIN functional survival was significantly different between the 3 net products (p = 0.001): 2.0 years (95% CI 1.7-2.3) for Olyset, 2.5 years (95% CI 2.2-2.8) for PermaNet 2.0 (hazard ratio [HR] 0.73 [95% CI 0.64-0.85], p = 0.001), and 2.6 years (95% CI 2.3-2.8) for NetProtect (HR = 0.70 [95% CI 0.62-0.77], p < 0.001). Functional survival was affected by accumulation of holes, leading to users discarding nets. Protective efficacy also significantly differed between products as they aged. Equivalent annual cost varied between US$1.2 (95% CI $1.1-$1.4) and US$1.5 (95% CI $1.3-$1.7), assuming that each net was priced identically at US$3. The 2 longer-lived nets (PermaNet and NetProtect) were 20% cheaper than the shorter-lived product (Olyset). The trial was limited to only the most widely sold LLINs in Tanzania. Functional survival varies by country, so the single country setting is a limitation. CONCLUSIONS: These results suggest that LLIN functional survival is less than 3 years and differs substantially between products, and these differences strongly influence LLIN value for money. LLIN tendering processes should consider local expectations of cost per year of functional life and not unit price. As new LLIN products come on the market, especially those with new insecticides, it will be imperative to monitor their comparative durability to ensure that the most cost-effective products are procured for malaria control.


Assuntos
Mosquiteiros Tratados com Inseticida/economia , Inseticidas/economia , Controle de Mosquitos/métodos , Animais , Culicidae/efeitos dos fármacos , Vetores de Doenças , Características da Família , Seguimentos , Humanos , Resistência a Inseticidas/efeitos dos fármacos , Mosquiteiros Tratados com Inseticida/tendências , Inseticidas/farmacologia , Malária/prevenção & controle , Controle de Mosquitos/economia , Mosquitos Vetores/efeitos dos fármacos , Piretrinas/farmacologia , Tanzânia/epidemiologia
4.
Mem Inst Oswaldo Cruz ; 115: e190431, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32935748

RESUMO

BACKGROUND: Long lasting insecticide-treated nets (LLINs) may be effective for vector control of cutaneous leishmaniasis (CL). Their efficacy, however, has not been sufficiently evaluated. OBJECTIVE: To evaluate the large-scale efficacy of LLINs on Lutzomyia longiflocosa entomological parameters up to two years post-intervention in the sub-Andean region of Colombia. METHODS: A matched-triplet cluster-randomised study of 21 rural settlements, matched by pre-intervention L. longiflocosa indoor density was used to compare three interventions: dip it yourself (DIY) lambda-cyhalothrin LLIN, deltamethrin LLIN, and untreated nets (control). Sand fly indoor density, feeding success, and parity were recorded using CDC light trap collections at 1, 6, 12, and 24 months post-intervention. FINDINGS: Both LLINs reduced significantly (74-76%) the indoor density and the proportion of fully engorged sand flies up to two years post-intervention without differences between them. Residual lethal effects of both LLINs and the use of all nets remained high throughout the two-year evaluation period. CONCLUSIONS: Both LLINs demonstrated high efficacy against L. longiflocosa indoors. Therefore, the deployment of these LLINs could have a significant impact on the reduction of CL transmission in the sub-Andean region. The DIY lambda-cyhalothrin kit may be used to convert untreated nets to LLINs increasing coverage.


Assuntos
Anopheles/efeitos dos fármacos , Insetos Vetores/efeitos dos fármacos , Mosquiteiros Tratados com Inseticida , Inseticidas/administração & dosagem , Leishmaniose Cutânea/prevenção & controle , Controle de Mosquitos/métodos , Animais , Colômbia , Resistência a Inseticidas , Leishmaniose Cutânea/parasitologia , Mosquitos Vetores , População Rural
6.
PLoS Negl Trop Dis ; 14(8): e0008428, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32853197

RESUMO

Vector-borne diseases are a major cause of morbidity and mortality worldwide. Aedes-borne diseases, in particular, including dengue, chikungunya, yellow fever, and Zika, are increasing at an alarming rate due to urbanisation, population movement, weak vector control programmes, and climate change. The World Health Organization calls for strengthening of vector control programmes in line with the Global Vector Control Response (GVCR) strategy, and many vector control programmes are transitioning to this new approach. The Singapore dengue control programme, situated within the country's larger vision of a clean, green, and sustainable environment for the health and well-being of its citizens, provides an excellent example of the GVCR approach in action. Since establishing vector control operations in the 1960s, the Singapore dengue control programme succeeded in reducing the dengue force of infection 10-fold by the 1990s and has maintained it at low levels ever since. Key to this success is consideration of dengue as an environmental disease, with a strong focus on source reduction and other environmental management methods as the dominant vector control strategy. The programme collaborates closely with other government ministries, as well as town councils, communities, the private sector, and academic and research institutions. Community engagement programmes encourage source reduction, and house-to-house inspections accompanied by a strong legislative framework with monetary penalties help to support compliance. Strong vector and epidemiological surveillance means that routine control activities can be heightened to specifically target dengue clusters. Despite its success, the programme continues to innovate to tackle challenges such as climate change, low herd immunity, and manpower constraints. Initiatives include development of novel vector controls such as Wolbachia-infected males and spatiotemporal models for dengue risk assessment. Lessons learnt from the Singapore programme can be applied to other settings, even those less well-resourced than Singapore, for more effective vector control.


Assuntos
Dengue/prevenção & controle , Controle de Mosquitos/métodos , Controle de Mosquitos/organização & administração , Aedes/virologia , Animais , Participação da Comunidade , Dengue/epidemiologia , Humanos , Mosquitos Vetores/virologia , Singapura/epidemiologia
7.
PLoS One ; 15(8): e0237353, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32785255

RESUMO

Airborne spatial repellency (SR) is characterized and distinguished from other chemical actions including contact locomotor excitation and toxicity. The use of volatile spatial repellents is a potential new intervention class for combatting mosquito-borne pathogen transmission; therefore, continuing investigations on the actions of these chemicals that modify mosquito host-seeking behavior (i.e., bite prevention) is needed. The objective of this study is to characterize the key behavioral avoidance actions of transfluthrin (TFT) to advance spatial repellent development into practical products. Behavioral avoidance responses were observed for adult laboratory strains of Aedes aegypti, Anopheles minimus and An. dirus, and two field populations of An. harrisoni and Ae. aegypti, respectively. Established TFT sublethal (LC50 and LC75), lethal concentrations (LC99) and discriminating concentrations (DCs) were selected corresponding to each mosquito test species. Spatial repellency and contact excitation ('irritancy') responses on adult mosquitoes to TFT were assessed using an excito-repellency assay system. At LC50, TFT exhibited strong avoidance with An. minimus (60.1% escape) and An. dirus (80% escape) laboratory strains, showing between 12 and 16x greater escape response than Ae. aegypti (5% escape). Repellency responses for field collected Ae. aegypti and An. harrisoni were 54.9 and 47.1% escape, respectively. After adjusting the initial contact escape response (a measure of combined irritancy and repellency) to estimate only escape due to contact, the LC50 and LC99 showed moderate escape irritancy with laboratory Ae. aegypti (41.4% escape) and no contact activity against the field population. Adjustment showed only weak contact activity (16.1% escape) in laboratory An. minimus at LC50. Spatial repellency is the predominant mode of action of TFT among colonized and field mosquitoes used in this study. Established baseline (susceptible) dose-response curves assist in optimizing SR products for mosquito control and pathogen transmission prevention.


Assuntos
Comportamento Animal/efeitos dos fármacos , Ciclopropanos/farmacologia , Fluorbenzenos/farmacologia , Repelentes de Insetos/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Compostos Orgânicos Voláteis/farmacologia , Aedes/efeitos dos fármacos , Aedes/fisiologia , Animais , Anopheles/efeitos dos fármacos , Anopheles/fisiologia , Aprendizagem da Esquiva , Relação Dose-Resposta a Droga , Feminino , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , Doenças Transmitidas por Vetores/prevenção & controle
8.
PLoS One ; 15(8): e0236920, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32745085

RESUMO

BACKGROUND: Twenty-seven villages were selected in southwest Burkina Faso to implement new vector control strategies in addition to long lasting insecticidal nets (LLINs) through a Randomized Controlled Trial (RCT). We conducted entomological surveys in the villages during the dry cold season (January 2017), dry hot season (March 2017) and rainy season (June 2017) to describe malaria vectors bionomics, insecticide resistance and transmission prior to this trial. METHODS: We carried out hourly catches (from 17:00 to 09:00) inside and outside 4 houses in each village using the Human Landing Catch technique. Mosquitoes were identified using morphological taxonomic keys. Specimens belonging to the Anopheles gambiae complex and Anopheles funestus group were identified using molecular techniques as well as detection of Plasmodium falciparum infection and insecticide resistance target-site mutations. RESULTS: Eight Anopheles species were detected in the area. Anopheles funestus s.s was the main vector during the dry cold season. It was replaced by Anopheles coluzzii during the dry hot season whereas An. coluzzii and An. gambiae s.s. were the dominant species during the rainy season. Species composition of the Anopheles population varied significantly among seasons. All insecticide resistance mechanisms (kdr-w, kdr-e and ace-1 target site mutations) investigated were found in each members of the An. gambiae complex but at different frequencies. We observed early and late biting phenotypes in the main malaria vector species. Entomological inoculation rates were 2.61, 2.67 and 11.25 infected bites per human per month during dry cold season, dry hot season and rainy season, respectively. CONCLUSION: The entomological indicators of malaria transmission were high despite the universal coverage with LLINs. We detected early and late biting phenotypes in the main malaria vector species as well as physiological insecticide resistance mechanisms. These data will be used to evaluate the impact of complementary tools to LLINs in an upcoming RCT.


Assuntos
Anopheles , Resistência a Inseticidas/genética , Malária Falciparum/transmissão , Mosquitos Vetores/genética , Animais , Anopheles/classificação , Anopheles/genética , Anopheles/parasitologia , Burkina Faso/epidemiologia , Culex/classificação , Culex/genética , Culex/parasitologia , Culicidae/classificação , Culicidae/genética , Culicidae/parasitologia , Ecologia , Genótipo , Humanos , Malária Falciparum/prevenção & controle , Controle de Mosquitos/métodos , Controle de Mosquitos/organização & administração , Mosquitos Vetores/classificação , Mosquitos Vetores/parasitologia , Plasmodium falciparum/isolamento & purificação , Estações do Ano
9.
PLoS Med ; 17(8): e1003227, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797101

RESUMO

BACKGROUND: Malaria eradication remains the long-term vision of the World Health Organization (WHO). However, whether malaria elimination is feasible in areas of stable transmission in sub-Saharan Africa with currently available tools remains a subject of debate. This study aimed to evaluate a multiphased malaria elimination project to interrupt Plasmodium falciparum malaria transmission in a rural district of southern Mozambique. METHODS AND FINDINGS: A before-after study was conducted between 2015 and 2018 in the district of Magude, with 48,448 residents living in 10,965 households. Building on an enhanced surveillance system, two rounds of mass drug administrations (MDAs) per year over two years (phase I, August 2015-2017), followed by one year of reactive focal mass drug administrations (rfMDAs) (phase II, September 2017-June 2018) were deployed with annual indoor residual spraying (IRS), programmatically distributed long-lasting insecticidal nets (LLINs), and standard case management. The four MDA rounds covered 58%-72% of the population, and annual IRS reported coverage was >70%. Yearly parasite surveys and routine surveillance data were used to monitor the primary outcomes of the study-malaria prevalence and incidence-at baseline and annually since the onset of the project. Parasite prevalence by rapid diagnostic test (RDT) declined from 9.1% (95% confidence interval [CI] 7.0-11.8) in May 2015 to 2.6% (95% CI 2.0-3.4), representing a 71.3% (95% CI 71.1-71.4, p < 0.001) reduction after phase I, and to 1.4% (95% CI 0.9-2.2) after phase II. This represented an 84.7% (95% CI 81.4-87.4, p < 0.001) overall reduction in all-age prevalence. Case incidence fell from 195 to 75 cases per 1,000 during phase I (61.5% reduction) and to 67 per 1,000 during phase II (65.6% overall reduction). Interrupted time series (ITS) analysis was used to estimate the level and trend change in malaria cases associated with the set of project interventions and the number of cases averted. Phase I interventions were associated with a significant immediate reduction in cases of 69.1% (95% CI 57.5-77.6, p < 0.001). Phase II interventions were not associated with a level or trend change. An estimated 76.7% of expected cases were averted throughout the project (38,369 cases averted of 50,005 expected). One malaria-associated inpatient death was observed during the study period. There were 277 mild adverse events (AEs) recorded through the passive pharmacovigilance system during the four MDA rounds. One serious adverse event (SAE) that resulted in death was potentially related to the drug. The study was limited by the incomplete coverage of interventions, the quality of the routine and cross-sectional data collected, and the restricted accuracy of ITS analysis with a short pre-intervention period. CONCLUSION: In this study, we observed that the interventions deployed during the Magude project fell short of interrupting P. falciparum transmission with the coverages achieved. While new tools and strategies may be required to eventually achieve malaria elimination in stable transmission areas of sub-Saharan Africa, this project showed that innovative mixes of interventions can achieve large reductions in disease burden, a necessary step in the pathway towards elimination. TRIAL REGISTRATION: ClinicalTrials.gov NCT02914145.


Assuntos
Antimaláricos/administração & dosagem , Controle de Infecções/métodos , Malária Falciparum/prevenção & controle , Malária Falciparum/transmissão , Controle de Mosquitos/métodos , Adolescente , Adulto , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Controle de Infecções/tendências , Malária Falciparum/epidemiologia , Masculino , Pessoa de Meia-Idade , Controle de Mosquitos/tendências , Moçambique , Adulto Jovem
10.
PLoS Negl Trop Dis ; 14(8): e0008528, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32764763

RESUMO

House Index, Container Index, and Breteau Index are the most commonly used indices for dengue vector surveillance. However, these larval indices are a poor proxy for measuring the adult population-which is responsible for disease transmission. Information on the adult distribution and density are important for assessing transmission risk as well as for developing effective control strategies. This study introduces a new entomological index, Gravitrap aegypti index (GAI), which estimates the adult female Aedes aegypti population in the community and presents its association with dengue cases. Gravitraps were deployed across 34 treatment sites in Singapore from September 2013 to September 2016. The GAI, derived from the Gravitrap surveillance data, was analysed to investigate the spatio-temporal patterns of the Ae. aegypti population in Singapore. The index was further categorised into low, moderate, and high-risk groups and its association with dengue cases were examined. A Before-After Control Impact analysis was performed to evaluate the epidemiology impact of Gravitrap system on dengue transmission. The Ae. aegypti population exhibits a seasonal pattern, and spatial heterogeneity in Ae. aegypti abundance was observed among treatment sites. The Ae. aegypti population was also found to be unevenly distributed among floors of an apartment block, with low floors (floors 1-4) having a higher abundance of mosquitoes trapped than mid (floors 5-8) and high (floors ≥9) floors. Areas with high GAI were shown to have higher dengue case count. Gravitrap has also demonstrated to be a good dengue control tool. The contribution of cases by treatment sites to the national numbers was lower after Gravitraps deployment. The GAI, which is of better relevance to dengue transmission risk, could be recommended as an indicator for decision making in vector control efforts, and to monitor the spatio-temporal variability of the adult Aedes population in the country. In addition, findings from this study indicate that Gravitraps can be used as a dengue control tool to reduce dengue transmission.


Assuntos
Aedes/fisiologia , Surtos de Doenças/prevenção & controle , Controle de Mosquitos/instrumentação , Controle de Mosquitos/métodos , Aedes/virologia , Animais , Dengue/epidemiologia , Vírus da Dengue , Meio Ambiente , Feminino , Insetos Vetores , Densidade Demográfica , Singapura
11.
PLoS One ; 15(8): e0237675, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797066

RESUMO

RNA interference (RNAi), a technique used to investigate gene function in insects and other organisms, is attracting attention as a potential new technology for mosquito control. Saccharomyces cerevisiae (baker's yeast) was recently engineered to produce interfering RNA molecules that silence genes required for mosquito survival, but which do not correspond to genes in humans or other non-target organisms. The resulting yeast pesticides, which facilitate cost-effective production and delivery of interfering RNA to mosquito larvae that eat the yeast, effectively kill mosquitoes in laboratory and semi-field trials. In preparation for field evaluation of larvicides in Trinidad, a Caribbean island with endemic diseases resulting from pathogens transmitted by Aedes mosquitoes, adult residents living in the prospective trial site communities of Curepe, St. Augustine, and Tamana were engaged. Open community forums and paper surveys were used to assess the potential acceptability, societal desirability, and sustainability of yeast interfering RNA larvicides. These assessments revealed that Trinidadians have good working knowledge of mosquitoes and mosquito-borne illnesses. A majority of the respondents practiced some method of larval mosquito control and agreed that they would use a new larvicide if it were proven to be safe and effective. During the community engagement forums, participants were educated about mosquito biology, mosquito-borne diseases, and the new yeast larvicides. When invited to provide feedback, engagement forum attendees were strongly supportive of the new technology, raised few concerns, and provided helpful advice regarding optimal larvicide formulations, insecticide application, operational approaches for using the larvicides, and pricing. The results of these studies suggest that the participants are supportive of the potential use of yeast interfering RNA larvicides in Trinidad and that the communities assessed in this investigation represent viable field sites.


Assuntos
Aedes/genética , Engenharia Genética/métodos , Controle de Mosquitos/métodos , Interferência de RNA , Saccharomyces cerevisiae/genética , Adulto , Animais , Feminino , Humanos , Larva/genética , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/genética , Controle Biológico de Vetores/métodos , RNA Interferente Pequeno/genética , Características de Residência , Inquéritos e Questionários , Trinidad e Tobago
12.
Nat Commun ; 11(1): 3646, 2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32686679

RESUMO

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


Assuntos
Malária , Controle de Mosquitos/métodos , Animais , Anopheles/efeitos dos fármacos , Humanos , Mosquiteiros Tratados com Inseticida , Inseticidas/farmacologia , Malária/epidemiologia , Malária/prevenção & controle , Malária/transmissão , Mosquitos Vetores/efeitos dos fármacos , Papua Nova Guiné/epidemiologia , Piretrinas/farmacologia
13.
Arch Environ Contam Toxicol ; 79(2): 233-245, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32613299

RESUMO

Natural resource managers are concerned about the impacts of aerial ultra-low volume spray (ULV) of insecticides for mosquito control (i.e., mosquito adulticides) and seek science-driven management recommendations that reduce risk but allow vector control for nearby human populations. Managers at the National Key Deer Refuge (Florida Keys, FL) are concerned for ULV effects upon conservation efforts for imperiled butterflies (Florida leafwing [Anaea troglodyta floridalis] and Bartram's hairstreak [Strymon acis bartrami] butterflies). No-spray zones were designated for protection of those butterflies, but their effectiveness for mitigation is unclear. To address this uncertainty, cholinesterase activity (ChE) and mortality were monitored for caged butterflies gulf fritillary [Agraulis vanilla] and great southern white [Ascia monuste]) deployed on the Refuge during three aerial ULV applications of the insecticide naled. Residue samplers also were deployed to estimate butterfly exposure. Spray efficacy against mosquitoes was assessed by deploying caged mosquitoes at the same locations as the butterflies. Average naled residue levels on filter paper samplers in the target area (1882-2898 µg/m2) was significantly greater than in the no-spray zone (9-1562 µg/m2). Differences between the no-spray zone and target area for butterfly mortality and ChE were inconsistent. Average mortality was significantly lower, and average ChE was significantly higher in the no-spray zone for larvae of one species but not for larvae of the other species. Mosquito mortality did not differ significantly between the two areas. Data from the present study reflect the inconsistent effectiveness of no-spray zones on the Refuge using standard methods employed at the time by the vector control agency in the Florida Keys and possibly by other vector control agencies in similar coastal environments. Furthermore, these findings helped to guide the design and to improve the conservation value of future no-spray zone delineations while allowing for treatment in areas where mosquito control is necessary for vector-borne disease reduction.


Assuntos
Borboletas/fisiologia , Inibidores da Colinesterase/toxicidade , Controle de Mosquitos/métodos , Naled/toxicidade , Animais , Borboletas/efeitos dos fármacos , Colinesterases/metabolismo , Cervos , Florida , Humanos , Inseticidas , Larva/efeitos dos fármacos , Medição de Risco
14.
J Toxicol Environ Health B Crit Rev ; 23(6): 243-254, 2020 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-32515686

RESUMO

Arthropod-borne viruses are a group of etiologic agents accounting for different incapacitating diseases that progress to severe and lethal forms in animal and human targets consequently representing a significant burden on public health and global economies. Although attempts were undertaken to combat Aedes aegypti, the primary urban mosquito vector of several life-threatening diseases, the misuse of chemical pesticides, development of resistance, and toxicity on non-target species still need to be overcome. In this context, it is imperative for development of long-lasting, novel approaches envisioning effective control of Aedes aegypti, mainly in endemic regions. Thus, the present review was undertaken to describe safe and eco-friendly approaches as potential weapons against Aedes aegypti. Accordingly, the findings discussed indicated that biological larvicides and genetic engineering technologies constitute noteworthy alternatives of future mosquito-borne arbovirus disease control efforts.


Assuntos
Aedes , Infecções por Arbovirus/prevenção & controle , Infecções por Arbovirus/transmissão , Controle de Mosquitos/métodos , Animais , Arbovirus , Engenharia Genética , Humanos , Inseticidas/toxicidade , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos
15.
PLoS One ; 15(6): e0234572, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32555588

RESUMO

The Asian mosquito, Aedes albopictus (Skuse), is an invasive mosquito which has become one of the most important vectors of dengue, Zika, and chikungunya viruses worldwide. This species was reported for the first time in Cameroon in early 2000s and became the dominant Aedes species in the urban areas in the southern part of Cameroon but remain poorly characterized. Here, we assessed the susceptibility profile of A. albopictus collected throughout Cameroon and investigated the potential resistance mechanisms involved. Immature stages of A. albopictus were collected between March and July 2017 in 15 locations across Cameroon and reared until G1/G2 generation. Larval, adult bioassays, and synergists [piperonyl butoxide (PBO) and diethyl maleate (DEM)] assays were carried out according to WHO recommendations. F1534C mutation was genotyped in field collected adults (Go) using allele specific PCR. All tested populations were susceptible to both larvicides, temephos and Bacillus thuringiensis israelensis (Bti), after larval bioassays. Adult bioassays revealed a high level of resistance of A. albopictus to 4% DDT with mortality rates ranging from 12.42% in Bafang to 75.04% in Kumba. The resistance was reported also in 0.05% deltamethrin, 0.25% permethrin, and 0.1% propoxur in some locations. A loss of susceptibility to 0.1% bendiocarb was found in one of three populations analysed. A full susceptibility to 1% fenitrothion were observed across the country. A full recovery or partial of susceptibility was observed in A. albopictus when pre-exposed to PBO or DEM and then to DDT and permethrin, respectively. The F1534C kdr mutation was not detected in A. albopictus. This study showed that the susceptibility profile of A. albopictus to insecticide vary according to the sampling location and insecticides used. These findings are useful to planning vector control program against arbovirus vectors in Cameroon and can be used as baseline data for further researches.


Assuntos
Aedes/fisiologia , Resistência a Inseticidas/efeitos dos fármacos , Inseticidas/farmacologia , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , Doenças Transmitidas por Vetores/transmissão , Animais , Camarões , Larva/fisiologia
16.
PLoS One ; 15(6): e0234242, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32520941

RESUMO

Many vector-borne diseases circulate in the Republic of Cabo Verde. These include malaria during the colonization of the archipelago by the Portuguese explorers and several arboviruses such as yellow fever (now eradicated), dengue and zika. To control these vector-borne diseases, an integrated vector control program was implemented. The main targeted mosquito vectors are Aedes aegypti and Anopheles arabiensis, and in a lesser extent the potential arbovirus vector Culex pipiens s.l. The main control strategy is focused on mosquito aquatic stages using diesel oil and Temephos. This latter has been applied in Cabo Verde since 1979. Its continuous use was followed by the emergence of resistance in mosquito populations. We investigated the current susceptibility to Temephos of the three potential mosquito vectors of Cabo Verde through bioassays tests. Our results showed various degrees of susceptibility with 24h post-exposure mortality rates ranging from 43.1% to 90.9% using WHO diagnostic doses. A full susceptibility was however observed with Bacillus thurigiensis var israelensis with mortality rates from 99.6% to 100%.


Assuntos
Bacillus thuringiensis/fisiologia , Controle de Mosquitos/métodos , Mosquitos Vetores/microbiologia , Temefós , Animais , Bioensaio , Cruzamento , Cabo Verde , Larva/efeitos dos fármacos , Larva/microbiologia , Estatística como Assunto
18.
PLoS Negl Trop Dis ; 14(6): e0008205, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32530915

RESUMO

Dengue is the most rapidly spreading arboviral disease in the world. The current lack of fully protective vaccines and clinical therapeutics creates an urgent need to identify more effective means of controlling Aedes mosquitos, principally Aedes aegypti, as the main vector of dengue. Pyriproxyfen (PPF) is an increasingly used hormone analogue that prevents juvenile Aedes mosquitoes from becoming adults and being incapable of transmitting dengue. The objectives of the review were to (1) Determine the effect of PPF on endpoints including percentage inhibition of emergence to adulthood, larval mortality, and resistance ratios; and (2) Determine the different uses, strengths, and limitations of PPF in control of Aedes. A systematic search was applied to Pubmed, EMBASE, Web of Science, LILACS, Global Health, and the Cochrane database of Systematic Reviews. Out of 1,369 records, 90 studies met the inclusion criteria. Nearly all fit in one of the following four categories 1) Efficacy of granules, 2) Auto-dissemination/horizontal transfer, 3) use of ultra-low volume thermal fogging (ULV), thermal fogging (TF), or fumigant technologies, and 4) assessing mosquito resistance. PPF granules had consistently efficacious results of 90-100% inhibition of emergence for up to 90 days. The evidence is less robust but promising regarding PPF dust for auto-dissemination and the use of PPF in ULV, TF and fumigants. Several studies also found that while mosquito populations were still susceptible to PPF, the lethal concentrations increased among temephos-resistant mosquitoes compared to reference strains. The evidence is strong that PPF does increase immature mortality and adult inhibition in settings represented in the included studies, however future research should focus on areas where there is less evidence (e.g. auto-dissemination, sprays) and new use cases for PPF. A better understanding of the biological mechanisms of cross-resistance between PPF, temephos, and other insecticides will allow control programs to make better informed decisions.


Assuntos
Aedes/efeitos dos fármacos , Inseticidas/farmacologia , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , Piridinas/farmacologia , Aedes/crescimento & desenvolvimento , Animais , Bioensaio , Feminino , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Mosquitos Vetores/crescimento & desenvolvimento , Análise de Sobrevida
19.
PLoS Negl Trop Dis ; 14(6): e0007870, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32569323

RESUMO

Emerging mosquito-borne viruses like Zika, dengue, and chikungunya pose a major threat to public health, especially in low-income regions of Central and South America, southeast Asia, and the Caribbean. Outbreaks of these diseases are likely to have long-term social and economic consequences due to Zika-induced congenital microcephaly and other complications. Larval control of the container-inhabiting mosquitoes that transmit these infections is an important tool for mitigating outbreaks. However, metapopulation theory suggests that spatiotemporally uneven larvicide treatment can impede control effectiveness, as recolonization compensates for mortality within patches. Coordinating the timing of treatment among patches could therefore substantially improve epidemic control, but we must also consider economic constraints, since coordination may have costs that divert resources from treatment. To inform practical disease management strategies, we ask how coordination among neighbors in the timing of mosquito control efforts influences the size of a mosquito-borne infectious disease outbreak under the realistic assumption that coordination has costs. Using an SIR (Susceptible-Infectious-Recovered)/metapopulation model of mosquito and disease dynamics, we examine whether sharing surveillance information and coordinating larvicide treatment among neighboring patches reduces human infections when incorporating coordination costs. We examine how different types of coordination costs and different surveillance methods jointly influence the effectiveness of larval control. We find that the effect of coordination depends on both costs and the type of surveillance used to inform treatment. With epidemiological surveillance, coordination improves disease outcomes, even when costly. With demographic surveillance, coordination either improves or hampers disease control, depending on the type of costs and surveillance sensitivity. Our results suggest coordination among neighbors can improve management of mosquito-borne epidemics under many, but not all, assumptions about costs. Therefore, estimating coordination costs is an important step for most effectively applying metapopulation theory to strategies for managing outbreaks of mosquito-borne viral infections.


Assuntos
Custos e Análise de Custo , Transmissão de Doença Infecciosa/prevenção & controle , Controle de Mosquitos/métodos , Controle de Mosquitos/organização & administração , Doenças Transmitidas por Vetores/prevenção & controle , Infecção por Zika virus/prevenção & controle , Humanos , Modelos Teóricos , Controle de Mosquitos/economia , Doenças Transmitidas por Vetores/transmissão , Infecção por Zika virus/transmissão
20.
PLoS Genet ; 16(6): e1008822, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32497040

RESUMO

Insecticide resistance in malaria vectors threatens to reverse recent gains in malaria control. Deciphering patterns of gene flow and resistance evolution in malaria vectors is crucial to improving control strategies and preventing malaria resurgence. A genome-wide survey of Anopheles funestus genetic diversity Africa-wide revealed evidences of a major division between southern Africa and elsewhere, associated with different population histories. Three genomic regions exhibited strong signatures of selective sweeps, each spanning major resistance loci (CYP6P9a/b, GSTe2 and CYP9K1). However, a sharp regional contrast was observed between populations correlating with gene flow barriers. Signatures of complex molecular evolution of resistance were detected with evidence of copy number variation, transposon insertion and a gene conversion between CYP6P9a/b paralog genes. Temporal analyses of samples before and after bed net scale up suggest that these genomic changes are driven by this control intervention. Multiple independent selective sweeps at the same locus in different parts of Africa suggests that local evolution of resistance in malaria vectors may be a greater threat than trans-regional spread of resistance haplotypes.


Assuntos
Anopheles/genética , Evolução Molecular , Genoma de Inseto/genética , Resistência a Inseticidas/genética , Malária/prevenção & controle , Mosquitos Vetores/genética , África , Alelos , Animais , Anopheles/parasitologia , Família 6 do Citocromo P450/genética , Variações do Número de Cópias de DNA , Elementos de DNA Transponíveis/genética , Fluxo Gênico , Loci Gênicos , Haplótipos , Humanos , Proteínas de Insetos/genética , Malária/parasitologia , Malária/transmissão , Metagenômica , Controle de Mosquitos/métodos , Polimorfismo Genético , Piretrinas , Sequenciamento Completo do Genoma
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