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2.
PLoS One ; 15(5): e0232286, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32369525

RESUMEN

BACKGROUND: Creating National Sanitary City (CNSC) promotes appearance, environment sanitation and public health including vector management of cities in China. However, vector management especially mosquito management and the related administrative productivity of Patriotic Health Campaign System (PHCS) of National Sanitary Cities (NSCs) were questioned by many pest control professionals and citizens. In this study, we studied mosquito management of NSCs taking Wuhan as an example. The study aimed to (1) determine the distribution and abundance of immature mosquito habitats in built-up areas of Wuhan and (2) better understand the related administration procedure in CNSC. METHODS: Immature mosquito habitat surveillance was carried out in randomly selected premises of driving schools (DSs), schools or kindergartens (SKs), property management residential areas (PMRAs), construction sites (CSs), wide roads with storm drains (WRSDs) and urban creeks (UCs) in built-up areas of Wuhan from July to October 2015 followed by questionnaire interviews with one each of premise occupants and district departments responsible for mosquito management in these premises. RESULTS: Total of 64.1 km of route were inspected in 36 DSs, 36 SKs, 36 PMRAs, 36 CSs and 36 segments of WRSD and 2,158 potential mosquito habitats with 749 (35%) mosquito-positive habitats were found. The route index (RI) was 11.7, which was 14.6 times higher than the grade C criteria for vector density control (RI = 0.8 positive habitats/km) in CNSC. Occupants of 36 DSs, 36 SKs, 36 PMRAs, 34 CSs were interviewed and 77% of them reported no difference in mosquito infestation in their premises since 2013 and 80% of them knew about the responsibility and arrangements of PHCS of mosquito management in their premises. Only 15% had the awareness of larval source reduction strategy and 14% had implemented it. Receipt the electronic/paper edition of CNSC vector management specifications from the PHCS was very low (13%) and an official notification or bulletin for rectification mosquito-positive habitats was also very low (5%). Of the 75 responsible district departments interviewed, about half (55%) reported that they had held training courses/meetings related to CNSC vector management, the majority (96%) reported that they had not carried out independent on-site supervision of premises under their jurisdiction. No differences in larval indices were found between premises which were administrative intervened and with no administrative intervention. CONCLUSIONS: The administrative intervention of PHCS had not evidently improved mosquito management of the premises in built-up areas in Wuhan. It is a violation of the original intention of the National Patriotic Health Campaign Committee in organizing CNSC programs. To combat mosquito borne diseases, and to improve the quality of life of residents, we recommend that PHCS honestly reveals defects in urban mosquito management and seriously takes those exposed defects. The PHCS should strengthen Patriotic Health Campaign activities by strict adherence to NSC standards. Further research on sustained promotion of urban mosquito management of NSCs, which focus on effective administration, as well as on improvement of related sectors of NSC standards should be carried out.


Asunto(s)
Control de Mosquitos , Animales , China , Ciudades , Industria de la Construcción , Culicidae , Ecosistema , Humanos , Control de Mosquitos/métodos , Mosquitos Vectores , Salud Pública , Ríos , Instituciones Académicas , Encuestas y Cuestionarios , Transportes
3.
PLoS One ; 15(5): e0232909, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32379812

RESUMEN

BACKGROUND: Geographical variation may likely influence the effectiveness of prevention efforts for malaria across Indonesia, in addition to factors at the individual level, household level, and contextual factors. This study aimed to describe preventive practices at individual and a household levels applied by rural communities in five provinces in eastern Indonesia and its association with the incidence of malaria among adult (≥15 years) populations. METHODS: This study analyzed a subset of data of nationally representative community-based survey 2018 Riset Kesehatan Dasar (Riskesdas). Data for socio-demographic (age, gender, education and occupation) and preventive behaviors (use of mosquito bed nets while slept, insecticide-treated mosquito nets (ITNs), mosquito repellent, mosquito electric rackets, mosquito coil/electric anti-mosquito mats, and mosquito window screen) were collected. Data were analyzed using bivariate and multivariable logistic regression model. RESULTS: Total of 56,159 respondents (n = 23,070 households) living in rural areas in Maluku (n = 8044), North Maluku (n = 7356), East Nusa Tenggara (n = 23,254), West Papua (n = 5759) and Papua (n = 11,746) were included in the study. In the multivariable models, using a bed net while slept likely reduced the odds of self-reported malaria among Maluku participants. Reduced odds ratios of self-reported malaria were identified in those participants who used ITNs (North Maluku, ENT, Papua), repellent (Maluku, West Papua, Papua), anti-mosquito racket (ENT), coil (Maluku, North Maluku, Papua) and window screen (West Papua, Papua). CONCLUSION: Our study concluded that the protective effects of preventive practices were varied among localities, suggesting the need for specific intervention programs.


Asunto(s)
Malaria/prevención & control , Control de Mosquitos/métodos , Adolescente , Adulto , Antimaláricos/farmacología , Estudios Transversales , Composición Familiar , Femenino , Conocimientos, Actitudes y Práctica en Salud , Humanos , Incidencia , Indonesia/epidemiología , Repelentes de Insectos , Mosquiteros Tratados con Insecticida/estadística & datos numéricos , Malaria/epidemiología , Masculino , Oportunidad Relativa , Prevalencia , Población Rural/estadística & datos numéricos , Autoinforme , Encuestas y Cuestionarios/estadística & datos numéricos
4.
PLoS Negl Trop Dis ; 14(5): e0008273, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32392225

RESUMEN

Increasing urbanization is having a profound effect on infectious disease risk, posing significant challenges for governments to allocate limited resources for their optimal control at a sub-city scale. With recent advances in data collection practices, empirical evidence about the efficacy of highly localized containment and intervention activities, which can lead to optimal deployment of resources, is possible. However, there are several challenges in analyzing data from such real-world observational settings. Using data on 3.9 million instances of seven dengue vector containment activities collected between 2012 and 2017, here we develop and assess two frameworks for understanding how the generation of new dengue cases changes in space and time with respect to application of different types of containment activities. Accounting for the non-random deployment of each containment activity in relation to dengue cases and other types of containment activities, as well as deployment of activities in different epidemiological contexts, results from both frameworks reinforce existing knowledge about the efficacy of containment activities aimed at the adult phase of the mosquito lifecycle. Results show a 10% (95% CI: 1-19%) and 20% reduction (95% CI: 4-34%) reduction in probability of a case occurring in 50 meters and 30 days of cases which had Indoor Residual Spraying (IRS) and fogging performed in the immediate vicinity, respectively, compared to cases of similar epidemiological context and which had no containment in their vicinity. Simultaneously, limitations due to the real-world nature of activity deployment are used to guide recommendations for future deployment of resources during outbreaks as well as data collection practices. Conclusions from this study will enable more robust and comprehensive analyses of localized containment activities in resource-scarce urban settings and lead to improved allocation of resources of government in an outbreak setting.


Asunto(s)
Dengue/epidemiología , Dengue/prevención & control , Control de Mosquitos/métodos , Animales , Ciudades/epidemiología , Humanos , Incidencia , Pakistán/epidemiología , Análisis Espacio-Temporal , Población Urbana
5.
PLoS Negl Trop Dis ; 14(5): e0008239, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32392226

RESUMEN

Understanding mosquito breeding behavior as well as human perspectives and practices are crucial for designing interventions to control Aedes aegypti mosquito-borne diseases as these mosquitoes primarily breed in water-holding containers around people's homes. The objectives of this study were to identify productive mosquito breeding habitats in coastal Kenya and to understand household mosquito management behaviors and their behavioral determinants. The field team conducted entomological surveys in 444 households and semi-structured interviews with 35 female caregivers and 37 children in Kwale County, coastal Kenya, between May and December 2016. All potential mosquito habitats with or without water were located, abundances of mosquito immatures measured and their characteristics recorded. Interviews explored household mosquito management behaviors and their behavioral determinants. 2,452 container mosquito habitats were counted containing 1,077 larvae and 390 pupae, predominantly Aedes species. More than one-third of the positive containers were found outside houses in 1 of the 10 villages. Containers holding water with no intended purpose contained 55.2% of all immature mosquitoes. Containers filled with rainwater held 95.8% of all immature mosquitoes. Interviews indicated that households prioritize sleeping under bednets as a primary protection against mosquito-borne disease because of concern about night-time biting, malaria-transmitting Anopheles mosquitoes. Respondents had limited knowledge about the mosquito life cycle, especially with respect to day-time biting, container-breeding Aedes mosquitoes. Therefore, respondents did not prioritize source reduction. Most mosquitoes breed in containers that have no direct or immediate purpose ("no-purpose containers"). These containers may be left unattended for several days allowing rainwater to collect, and creating ideal conditions for mosquito breeding. An intervention that requires little effort and targets only the most productive containers could effectively reduce mosquito indices and, relatedly, mosquito-borne disease risk.


Asunto(s)
Aedes/crecimiento & desarrollo , Anopheles/crecimiento & desarrollo , Ecosistema , Composición Familiar , Conocimientos, Actitudes y Práctica en Salud , Control de Mosquitos/métodos , Adulto , Animales , Niño , Femenino , Humanos , Entrevistas como Asunto , Kenia , Masculino , Persona de Mediana Edad , Densidad de Población , Adulto Joven
6.
Nat Biotechnol ; 38(4): 482-492, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32265562

RESUMEN

The range of the mosquito Aedes aegypti continues to expand, putting more than two billion people at risk of arboviral infection. The sterile insect technique (SIT) has been used to successfully combat agricultural pests at large scale, but not mosquitoes, mainly because of challenges with consistent production and distribution of high-quality male mosquitoes. We describe automated processes to rear and release millions of competitive, sterile male Wolbachia-infected mosquitoes, and use of these males in a large-scale suppression trial in Fresno County, California. In 2018, we released 14.4 million males across three replicate neighborhoods encompassing 293 hectares. At peak mosquito season, the number of female mosquitoes was 95.5% lower (95% CI, 93.6-96.9) in release areas compared to non-release areas, with the most geographically isolated neighborhood reaching a 99% reduction. This work demonstrates the high efficacy of mosquito SIT in an area ninefold larger than in previous similar trials, supporting the potential of this approach in public health and nuisance-mosquito eradication programs.


Asunto(s)
Aedes/microbiología , Aedes/fisiología , Control de Mosquitos/métodos , Mosquitos Vectores/microbiología , Mosquitos Vectores/fisiología , Wolbachia/fisiología , Aedes/crecimiento & desarrollo , Migración Animal , Animales , California , Femenino , Larva/crecimiento & desarrollo , Larva/microbiología , Larva/fisiología , Masculino , Control de Mosquitos/estadística & datos numéricos , Mosquitos Vectores/crecimiento & desarrollo , Dinámica Poblacional , Caracteres Sexuales
7.
PLoS One ; 15(4): e0230910, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32236146

RESUMEN

Several sites, Z-7L, Z-5 and Z-14, in Sibu district, Sarawak, Malaysia, experienced intense dengue transmission in 2014 that continued into 2015. A pilot study with Bacillus thuringiensis israelensis (Bti) to control Aedes aegypti (L.) and Ae. albopictus (Skuse) was evaluated in Z-7L, a densely populated site of 12 ha. Bti treatments were conducted weekly from epidemiology week (EW) 24/2015 for 4 weeks, followed by fortnight treatments for 2 months, in addition to the routine control activities. Bti was directly introduced into potable containers and the outdoor artificial and natural containers were treated via a wide area spray application method using a backpack mister. Aedes indices significantly reduced during the treatment and post treatment phases, compared to the control site, Z-5 (p<0.05). A 51 fold reduction in the incidence rate per 100,000 population (IR) was observed, with one case in 25 weeks (EW 29-52). In Z-5 and Z-14, control sites, a 6 fold reduction in the IR was observed from EW 29-52. However, almost every week there were dengue cases in Z-14 and until EW 44 in Z-5. In 2016, dengue cases resurfaced in Z-7L from EW 4. Intensive routine control activities were conducted, but the IR continued to escalate. The wide area Bti spray misting of the outdoor containers was then included from EW 27 on fortnight intervals. A 6 fold reduction in IR was observed in the Bti treatment phase (EW 32-52) with no successive weekly cases after EW 37. However, in the control sites, there were dengue cases throughout the year from EW 1-52, particularly in Z-14. We feel that the wide area Bti spray application method is an integral component in the control program, in conjunction with other control measures carried out, to suppress the vector population in outdoor cryptic containers and to interrupt the disease transmission.


Asunto(s)
Bacillus thuringiensis , Agentes de Control Biológico , Dengue , Mosquitos Vectores , Aedes/microbiología , Aedes/virología , Animales , Dengue/epidemiología , Dengue/transmisión , Reservorios de Enfermedades/virología , Vectores de Enfermedades , Insecticidas , Larva/microbiología , Larva/virología , Malasia/epidemiología , Control de Mosquitos/métodos , Mosquitos Vectores/microbiología , Mosquitos Vectores/virología , Proyectos Piloto , Prevalencia
8.
PLoS One ; 15(4): e0231251, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32287300

RESUMEN

Outdoor residual spraying is proposed for the control of exophilic mosquitoes. However, the residual effect of insecticide mists applied to outdoor resting habitats of mosquitoes is not well characterized. The objective of this study was to assess the longevity of the residual insecticidal effect of three pyrethroid formulations applied to outdoor vegetation against the Southeast Asian malaria vector Anopheles dirus. Lambda-cyhalothrin capsule suspension, deltamethrin emulsifiable concentrate and bifenthrin wettable powder were sprayed on dense bamboo bushes on the Thailand-Myanmar border during the dry season 2018. The duration and magnitude of the residual insecticidal effect were assessed weekly with a standard cone assay, using freshly collected insecticide-treated bamboo leaves and a laboratory-adapted colony of Anopheles dirus sensu stricto susceptible to pyrethroids. The experiment was repeated during the rainy season to assess the persistence of the lambda-cyhalothrin formulation after natural rains and artificial washings. During the dry season (cumulative rainfall = 28 mm in 111 days), mortality and knockdown (KD) rates were >80% for 60 days with bifenthrin and 90 days with lambda-cyhalothrin and deltamethrin. The 50% knockdown time (TKD50) was <15 min with lambda-cyhalothrin and deltamethrin, and <30 min with bifenthrin. During the rainy season (cumulative rainfall = 465 mm in 51 days), mortality and KD rates were >80% for 42 days and TKD50 was <15 min with lambda-cyhalothrin. Additional artificial washing of the testing material with 10L of tap water before performing the cone tests had no significant effect on the residual insecticidal effect of this formulation. Long-lasting residual insecticidal effect can be obtained when spraying pyrethroid insecticides on the outdoor resting habitats of malaria vectors.


Asunto(s)
Anopheles/efectos de los fármacos , Insectos Vectores/efectos de los fármacos , Resistencia a los Insecticidas , Insecticidas/farmacología , Control de Mosquitos/métodos , Nitrilos/farmacología , Piretrinas/farmacología , Animales , Anopheles/crecimiento & desarrollo , Insectos Vectores/crecimiento & desarrollo , Insecticidas/química , Mianmar , Nitrilos/química , Piretrinas/química , Tailandia
9.
PLoS Comput Biol ; 16(4): e1007743, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32310958

RESUMEN

Recent years have seen rising incidence of dengue and large outbreaks of Zika and chikungunya, which are all caused by viruses transmitted by Aedes aegypti mosquitoes. In most settings, the primary intervention against Aedes-transmitted viruses is vector control, such as indoor, ultra-low volume (ULV) spraying. Targeted indoor residual spraying (TIRS) has the potential to more effectively impact Aedes-borne diseases, but its implementation requires careful planning and evaluation. The optimal time to deploy these interventions and their relative epidemiological effects are, however, not well understood. We used an agent-based model of dengue virus transmission calibrated to data from Iquitos, Peru to assess the epidemiological effects of these interventions under differing strategies for deploying them. Specifically, we compared strategies where spray application was initiated when incidence rose above a threshold based on incidence in recent years to strategies where spraying occurred at the same time(s) each year. In the absence of spraying, the model predicted 361,000 infections [inter-quartile range (IQR): 347,000-383,000] in the period 2000-2010. The ULV strategy with the fewest median infections was spraying twice yearly, in March and October, which led to a median of 172,000 infections [IQR: 158,000-183,000], a 52% reduction from baseline. Compared to spraying once yearly in September, the best threshold-based strategy utilizing ULV had fewer median infections (254,000 vs. 261,000), but required more spraying (351 vs. 274 days). For TIRS, the best strategy was threshold-based, which led to the fewest infections of all strategies tested (9,900; [IQR: 8,720-11,400], a 94% reduction), and required fewer days spraying than the equivalent ULV strategy (280). Although spraying twice each year is likely to avert the most infections, our results indicate that a threshold-based strategy can become an alternative to better balance the translation of spraying effort into impact, particularly if used with a residual insecticide.


Asunto(s)
Biología Computacional/métodos , Dengue/prevención & control , Control de Mosquitos/métodos , Aedes/fisiología , Animales , Simulación por Computador , Dengue/epidemiología , Dengue/transmisión , Brotes de Enfermedades , Humanos , Incidencia , Insecticidas , Modelos Teóricos , Mosquitos Vectores , Infección por el Virus Zika/epidemiología , Infección por el Virus Zika/prevención & control , Infección por el Virus Zika/transmisión
10.
PLoS One ; 15(4): e0230486, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32236142

RESUMEN

Aedes aegypti transmitted arboviral diseases are of significant importance in Colombia, particularly since the 2014/2015 introduction of chikungunya and Zika in the Americas and the increasing spread of dengue. In response, the Colombian government initiated the scaling-up of a community-based intervention under inter and multi-sector partnerships in two out of four sectors in Girardot, one of the most hyper-endemic dengue cities in the country. Using a quasi-experimental research design a scaled-up community-led Aedes control intervention was assessed for its capacity to reduce dengue from January 2010 to August 2017 in Girardot, Colombia. Reported dengue cases, and associated factors were analysed from available data sets from the Colombian disease surveillance systems. We estimated the reduction in dengue cases before and after the intervention using, Propensity Score Matching and an Autoregressive Moving Average model for robustness. In addition, the differences in dengue incidence among scaling-up phases (pre-implementation vs sustainability) and between treatment groups (intervention and control areas) were modelled. Evidence was found in favour of the intervention, although to maximise impact the scaling-up of the intervention should continue until it covers the remaining sectors. It is expected that a greater impact of the intervention can be documented in the next outbreak of dengue in Girardot.


Asunto(s)
Aedes/fisiología , Dengue/patología , Control de Mosquitos/métodos , Evaluación de Programas y Proyectos de Salud , Aedes/virología , Animales , Ciudades , Colombia/epidemiología , Dengue/epidemiología , Brotes de Enfermedades , Humanos
11.
PLoS Negl Trop Dis ; 14(4): e0008097, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32275653

RESUMEN

Dengue is one of the most important vector-borne diseases, resulting in an estimated hundreds of millions of infections annually throughout the tropics. Control of dengue is heavily dependent upon control of its primary mosquito vector, Aedes aegypti. Innovative interventions that are effective at targeting the adult stage of the mosquito are needed to increase the options for effective control. The use of insecticide-treated curtains (ITCs) has previously been shown to significantly reduce the abundance of Ae. aegypti in and around homes, but the impact of ITCs on dengue virus (DENV) transmission has not been rigorously quantified. A parallel arm cluster-randomized controlled trial was conducted in Iquitos, Peru to quantify the impact of ITCs on DENV seroconversion as measured through plaque-reduction neutralization tests. Seroconversion data showed that individuals living in the clusters that received ITCs were at greater risk to seroconverting to DENV, with an average seroconversion rate of 50.6 per 100 person-years (PY) (CI: 29.9-71.9), while those in the control arm had an average seroconversion rate of 37.4 per 100 PY (CI: 15.2-51.7). ITCs lost their insecticidal efficacy within 6 months of deployment, necessitating re-treatment with insecticide. Entomological indicators did not show statistically significant differences between ITC and non-ITC clusters. It's unclear how the lack of protective efficacy reported here is attributable to simple failure of the intervention to protect against Ae. aegypti bites, or the presence of a faulty intervention during much of the follow-up period. The higher risk of dengue seroconversion that was detected in the ITC clusters may have arisen due to a false sense of security that inadvertently led to less routine protective behaviors on the part of households that received the ITCs. Our study provides important lessons learned for conducting cluster randomized trials for vector control interventions against Aedes-transmitted virus infections.


Asunto(s)
Dengue/prevención & control , Dengue/transmisión , Transmisión de Enfermedad Infecciosa/prevención & control , Mosquiteros Tratados con Insecticida , Control de Mosquitos/métodos , Adolescente , Adulto , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/sangre , Niño , Preescolar , Virus del Dengue/inmunología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pruebas de Neutralización , Perú , Seroconversión , Resultado del Tratamiento , Adulto Joven
13.
Lancet ; 395(10233): 1361-1373, 2020 04 25.
Artículo en Inglés | MEDLINE | ID: mdl-32334702

RESUMEN

BACKGROUND: In low malaria-endemic settings, screening and treatment of individuals in close proximity to index cases, also known as reactive case detection (RACD), is practised for surveillance and response. However, other approaches could be more effective for reducing transmission. We aimed to evaluate the effectiveness of reactive focal mass drug administration (rfMDA) and reactive focal vector control (RAVC) in the low malaria-endemic setting of Zambezi (Namibia). METHODS: We did a cluster-randomised controlled, open-label trial using a two-by-two factorial design of 56 enumeration area clusters in the low malaria-endemic setting of Zambezi (Namibia). We randomly assigned these clusters using restricted randomisation to four groups: RACD only, rfMDA only, RAVC plus RACD, or rfMDA plus RAVC. RACD involved rapid diagnostic testing and treatment with artemether-lumefantrine and single-dose primaquine, rfMDA involved presumptive treatment with artemether-lumefantrine, and RAVC involved indoor residual spraying with pirimiphos-methyl. Interventions were administered within 500 m of index cases. To evaluate the effectiveness of interventions targeting the parasite reservoir in humans (rfMDA vs RACD), in mosquitoes (RAVC vs no RAVC), and in both humans and mosquitoes (rfMDA plus RAVC vs RACD only), an intention-to-treat analysis was done. For each of the three comparisons, the primary outcome was the cumulative incidence of locally acquired malaria cases. This trial is registered with ClinicalTrials.gov, number NCT02610400. FINDINGS: Between Jan 1, 2017, and Dec 31, 2017, 55 enumeration area clusters had 1118 eligible index cases that led to 342 interventions covering 8948 individuals. The cumulative incidence of locally acquired malaria was 30·8 per 1000 person-years (95% CI 12·8-48·7) in the clusters that received rfMDA versus 38·3 per 1000 person-years (23·0-53·6) in the clusters that received RACD; 30·2 per 1000 person-years (15·0-45·5) in the clusters that received RAVC versus 38·9 per 1000 person-years (20·7-57·1) in the clusters that did not receive RAVC; and 25·0 per 1000 person-years (5·2-44·7) in the clusters that received rfMDA plus RAVC versus 41·4 per 1000 person-years (21·5-61·2) in the clusters that received RACD only. After adjusting for imbalances in baseline and implementation factors, the incidence of malaria was lower in clusters receiving rfMDA than in those receiving RACD (adjusted incidence rate ratio 0·52 [95% CI 0·16-0·88], p=0·009), lower in clusters receiving RAVC than in those that did not (0·48 [0·16-0·80], p=0·002), and lower in clusters that received rfMDA plus RAVC than in those receiving RACD only (0·26 [0·10-0·68], p=0·006). No serious adverse events were reported. INTERPRETATION: In a low malaria-endemic setting, rfMDA and RAVC, implemented alone and in combination, reduced malaria transmission and should be considered as alternatives to RACD for elimination of malaria. FUNDING: Novartis Foundation, Bill & Melinda Gates Foundation, and Horchow Family Fund.


Asunto(s)
Antimaláricos/uso terapéutico , Combinación Arteméter y Lumefantrina/uso terapéutico , Malaria Falciparum/prevención & control , Administración Masiva de Medicamentos/métodos , Control de Mosquitos , Antimaláricos/administración & dosificación , Combinación Arteméter y Lumefantrina/administración & dosificación , Análisis por Conglomerados , Humanos , Malaria Falciparum/epidemiología , Control de Mosquitos/métodos , Namibia/epidemiología , Plasmodium falciparum , Estudios Seroepidemiológicos
14.
Parasit Vectors ; 13(1): 192, 2020 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-32293537

RESUMEN

BACKGROUND: Prior to a major release campaign of sterile insects, including the sterile insect technique, male mosquitoes must be marked and released (small scale) to determine key parameters including wild population abundance, dispersal and survival. Marking insects has been routinely carried out for over 100 years; however, there is no gold standard regarding the marking of specific disease-transmitting mosquitoes including Anopheles arabiensis, Aedes aegypti and Aedes albopictus. The research presented offers a novel dusting technique and optimal dust colour and quantities, suitable for small-scale releases, such as mark-release-recapture studies. METHODS: We sought to establish a suitable dust colour and quantity for batches of 100 male An. arabiensis, that was visible both by eye and under UV light, long-lasting and did not negatively impact longevity. A set of lower dust weights were selected to conduct longevity experiments with both Ae. aegypti and Ae. albopictus to underpin the optimal dust weight. A further study assessed the potential of marked male An. arabiensis to transfer their mark to undusted males and females. RESULTS: The longevity of male An. arabiensis marked with various dust colours was not significantly reduced when compared to unmarked controls. Furthermore, the chosen dust quantity (5 mg) did not negatively impact longevity (P = 0.717) and provided a long-lasting mark. Dust transfer was found to occur from marked An. arabiensis males to unmarked males and females when left in close proximity. However, this was only noticeable when examining individuals under a stereomicroscope and thus deemed negligible. Overall, male Ae. aegypti and Ae. albopictus displayed a greater sensitivity to dusting. Only the lowest dust weight (0.5 mg) did not significantly reduce longevity (P = 0.888) in Ae. aegypti, whilst the lowest two dust weights (0.5 and 0.75 mg) had no significant impact on longevity (P = 0.951 and 0.166, respectively) in Ae. albopictus. CONCLUSION: We have devised a fast, inexpensive and simple marking method and provided recommended dust quantities for several major species of disease-causing mosquitoes. The novel technique provides an evenly distributed, long-lasting mark which is non-detrimental. Our results will be useful for future MRR studies, prior to a major release campaign.


Asunto(s)
Aedes , Anopheles , Coloración y Etiquetado , Animales , Polvo , Colorantes Fluorescentes , Infertilidad Masculina , Longevidad , Masculino , Control de Mosquitos/métodos , Coloración y Etiquetado/métodos
15.
Parasit Vectors ; 13(1): 198, 2020 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-32303257

RESUMEN

BACKGROUND: Radiation induced sterility is the basis of the Sterile Insect Technique, by which a target insect pest population is suppressed by releasing artificially reared sterile males of the pest species in overflooding numbers over a target site. In order for the sterile males to be of high biological quality, effective standard irradiation protocols are required. Following studies investigating the effects of mosquito pupae irradiation in water versus in air, there is a need to investigate the oxy-regulatory behavior of mosquito pupae in water to better understand the consequences of irradiation in hypoxic versus normoxic conditions. METHODS: Pupae of Aedes aegypti, Ae. albopictus, and Anopheles arabiensis were submerged in water inside air-tight 2 ml glass vials at a density of 100 pupae/ml and the dissolved oxygen (DO) levels in the water were measured and plotted over time. In addition, male pupae of Ae. aegypti (aged 40-44 h), Ae. albopictus (aged 40-44 h) and An. arabiensis (aged 20-24 h) were irradiated in a gammacell220 at increasing doses in either hypoxic (water with < 0.5% O2 content) or normoxic (in air) conditions. The males were then mated to virgin females and resulting eggs were checked for induced sterility. RESULTS: All three species depleted the water of DO to levels under 0.5% within 30 minutes, with An. arabiensis consuming oxygen the fastest at under 10 minutes. Following irradiation, the protective effect of hypoxia was observed across species and doses (P < 0.0001), increasing at higher doses. This effect was most pronounced in An. arabiensis. CONCLUSIONS: The consumption of dissolved oxygen by pupae submerged in water was significantly different between species, indicating that their oxy-regulatory capacity seems to have possibly evolved according to their preferred breeding site characteristics. This needs to be considered when sterilizing male mosquitoes at pupal stage in water. Depending on species, their DO consumption rates and their density, irradiation doses needed to achieve full sterility may vary significantly. Further assessments are required to ascertain optimal conditions in terms of ambient atmosphere during pupal irradiation to produce competitive sterile males, and temperature and density dependent effects are expected.


Asunto(s)
Aedes/efectos de la radiación , Anopheles/efectos de la radiación , Hipoxia , Pupa/efectos de la radiación , Esterilización/métodos , Animales , Femenino , Infertilidad Masculina , Masculino , Control de Mosquitos/métodos , Mosquitos Vectores/efectos de la radiación , Agua/química
16.
Parasit Vectors ; 13(1): 202, 2020 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-32307003

RESUMEN

BACKGROUND: Malaria vector mosquitoes acquire midgut microbiota primarily from their habitat. The homeostasis of these microbial communities plays an essential role in the mosquito longevity, the most essential factor in the mosquito vectorial capacity. Our recent study revealed that silencing genes involved in regulation of the midgut homeostasis including FN3D1, FN3D3 and GPRGr9 reduced the survival of female adult Anopheles arabiensis mosquitoes. In the present study, we investigate the stability of the gene silencing efficiency of mosquitoes reared in three different breeding conditions representing distinct larval habitat types: town brick pits in Jimma, flood pools in the rural land of Asendabo and roadside pools in Wolkite. METHODS: First-instar larvae of An. arabiensis mosquitoes were reared separately using water collected from the three breeding sites. The resulting adult females were micro-injected with dsRNA targeting the FN3D1 gene (AARA003032) and their survival was monitored. Control mosquitoes were injected with dsRNA Lacz. In addition, the load of midgut microbiota of these mosquitoes was determined using flow cytometry. RESULTS: Survival of naïve adult female mosquitoes differed between the three sites. Mosquitoes reared using water collected from brick pits and flood pools survived longer than mosquitoes reared using water collected from roadside. However, the FN3D1 gene silencing effect on survival did not differ between the three sites. CONCLUSIONS: The present study revealed that the efficacy of FN3D1 gene silencing is not affected by variation in the larval habitat. Thus, silencing this gene has potential for application throughout sub-Saharan Africa.


Asunto(s)
Anopheles/genética , Dominio de Fibronectina del Tipo III/genética , Interferencia de ARN/fisiología , Animales , Anopheles/fisiología , Cruzamiento , Ecosistema , Larva/genética , Larva/fisiología , Control de Mosquitos/métodos , Mosquitos Vectores/genética , Mosquitos Vectores/fisiología
17.
PLoS One ; 15(3): e0230748, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32208462

RESUMEN

Definable habitats at the neighborhood level provide a wide range of favorable habitats with optimal conditions and environmental resources for mosquito survival. Problematic habitats for controlling mosquitoes in urban environments such as tire shops, bromeliad patches, and construction sites must be taken into consideration in the development of effective mosquito management and control in urban areas. Cemeteries are often located in highly urbanized areas serving as a haven for populations of vector mosquito species due to the availability of natural resources present in most cemeteries. Even though Miami-Dade County, Florida was the most affected area in the United States during the Zika virus outbreak in 2016 and is currently under a mosquito-borne illness alert after 14 confirmed locally transmitted dengue cases, the role of cemeteries in the proliferation of vector mosquitoes is unknown. Therefore, our objective was to use a cross-sectional experimental design to survey twelve cemeteries across Miami-Dade County to assess if vector mosquitoes in Miami can be found in these areas. Our results are indicating that vector mosquitoes are able to successfully exploit the resources available in the cemeteries. Culex quinquefasciatus was the most abundant species but it was neither as frequent nor present in its immature form as Aedes aegypti and Aedes albopictus. This study revealed that vector mosquitoes, such as Ae. aegypti, Ae. albopictus, and Cx. quinquefasciatus are successfully exploiting the resources available in these areas being able to thrive and reach high numbers. Mosquito control strategies should consider both long-term strategies, based on changing human behavior to reduce the availability of aquatic habitats for vector mosquitoes; as well as short-term strategies such as drilling holes or adding larvicide to the flower vases. Simple practices would greatly help improve the effectiveness of mosquito management and control in these problematic urban habitats.


Asunto(s)
Cementerios/estadística & datos numéricos , Control de Mosquitos/métodos , Animales , Brotes de Enfermedades/prevención & control , Florida/epidemiología , Mosquitos Vectores/fisiología , Encuestas y Cuestionarios
18.
Am J Trop Med Hyg ; 102(5): 1033-1036, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32100683

RESUMEN

Malaria is the leading cause of morbidity and mortality in Uganda. The role of spatial repellent devices in preventing malaria is controversial. The goal of this study was to evaluate the populations' acceptability of a newly designed insecticide diffuser. We distributed to three families living in southern Uganda a device commercially available, the VAPE® portable set. This spatial repellent device offers several advantages compared with other traditional products. It is powered by lithium batteries that guarantee 20 days of uninterrupted delivery of insecticide; it contains two insecticides: empenthrin and transfluthrin; and it is simple to use, one switch to turn it "on" and/or "off." It is odorless, and it can be placed anywhere in the living/sleeping area. People can also carry it outside the house. We planned to evaluate people's compliance with its usage, its reliability, and its overall costs. We conducted a 5-month survey. We distributed the devices to three households, one device per bedroom. Ten males and 11 females, with a mean age of 26 ± 16 (range 10-51) years, lived in these houses. The compliance with the use of the device and its acceptability were high. No side effects were reported. No individual contracted malaria during the 5-month period. The major obstacle we found was the timely delivery of the devices to the evaluation area and initial compliance with the instructions on how to use the device. Larger randomized studies are needed to clarify whether there is a role for this type of spatial repellent devices in the global efforts to prevent malaria.


Asunto(s)
Repelentes de Insectos/administración & dosificación , Malaria/prevención & control , Control de Mosquitos/métodos , Adulto , Países en Desarrollo , Vivienda , Humanos , Masculino , Adulto Joven
19.
BMC Public Health ; 20(1): 216, 2020 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-32050923

RESUMEN

BACKGROUND: Despite rapid upscale of insecticide-treated nets (ITNs) and indoor residual spraying (IRS), malaria remains a major source of morbidity and mortality in Zambia. Uptake and utilization of these and novel interventions are often affected by knowledge, attitudes and practices (KAP) amongst persons living in malaria-endemic areas. The aims of this study were to assess malaria KAP of primary caregivers and explore trends in relation to ITN use, IRS acceptance and mosquito density in two endemic communities in Luangwa and Nyimba districts, Zambia. METHODS: A cohort of 75 primary caregivers were assessed using a cross-sectional, forced-choice malaria KAP survey on ITN use, IRS acceptance and initial perception of a novel spatial repellent (SR) product under investigation. Entomological sampling was performed in participant homes using CDC Miniature Light Traps to relate indoor mosquito density with participant responses. RESULTS: Ninety-nine percent of participants cited bites of infected mosquitoes as the route of malaria transmission although other routes were also reported including drinking dirty water (64%) and eating contaminated food (63%). All caregivers agreed that malaria was a life-threatening disease with the majority of caregivers having received malaria information from health centers (86%) and community health workers (51%). Cumulatively, self-reported mosquito net use was 67%. Respondents reportedly liked the SR prototype product but improvements on color, shape and size were suggested. Overall, 398 mosquitoes were captured from light-trap collections, including 49 anophelines and 349 culicines. Insecticide treated nets use was higher in households from which at least one mosquito was captured. CONCLUSIONS: The current study identified misconceptions in malaria transmission among primary caregivers indicating remaining knowledge gaps in educational campaigns. Participant responses also indicated a misalignment between a low perception of IRS efficacy and high stated acceptance of IRS, which should be further examined to better understand uptake and sustainability of other vector control strategies. While ITNs were found to be used in study households, misperceptions between presence of mosquitoes and bite protection practices did exist. This study highlights the importance of knowledge attitudes and practice surveys, with integration of entomological sampling, to better guide malaria vector control product development, strategy acceptance and compliance within endemic communities.


Asunto(s)
Cuidadores/psicología , Conocimientos, Actitudes y Práctica en Salud , Malaria/prevención & control , Población Rural , Adulto , Cuidadores/estadística & datos numéricos , Estudios de Cohortes , Estudios Transversales , Femenino , Vivienda , Humanos , Mosquiteros Tratados con Insecticida/estadística & datos numéricos , Insecticidas/administración & dosificación , Malaria/epidemiología , Control de Mosquitos/métodos , Población Rural/estadística & datos numéricos , Zambia/epidemiología
20.
Public Health Rep ; 135(2): 230-237, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32040922

RESUMEN

OBJECTIVES: From September 2015 through March 2016, Hawaii had the largest outbreak of locally transmitted dengue since 1944. We report on the Hawaii Department of Health's (HDOH's) investigation, findings, and response to the outbreak. METHODS: We defined cases of dengue using a modified version of the Council of State and Territorial Epidemiologists' case definition for dengue virus infections. We conducted epidemiologic investigations, including interviews with case-persons, review of medical records, laboratory testing, genetic sequencing of specimens, and geographic information system (GIS) data analysis. Outbreak response included community outreach and vector-control activities. RESULTS: We identified 264 confirmed cases of dengue; illness onset dates ranged from September 11, 2015, to March 17, 2016, all with reported travel to or residence on the Island of Hawaii. Of 264 persons with confirmed dengue, 238 (90.2%) were Hawaii residents. Thirty-seven (14.0%) persons required hospitalization; no cases of severe dengue or death were reported. GIS hot-spot analysis identified a cluster of cases on the western side of the island. Established risk factors for dengue exposure included holes in window or door screens, presence of standing water, and not using insect repellent or wearing protective clothing. CONCLUSIONS: To prevent or mitigate the spread of future arboviral introductions and outbreaks, the public health response should focus on behavioral and cultural attitudes, emphasizing personal mosquito protection and mosquito control at the community level. Outbreak responses can also be enhanced through the use of advanced GIS techniques, such as hot-spot analysis, to provide situational awareness and guide response efforts.


Asunto(s)
Virus del Dengue/aislamiento & purificación , Dengue/epidemiología , Brotes de Enfermedades/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Dengue/transmisión , Virus del Dengue/genética , Femenino , Sistemas de Información Geográfica , Hawaii/epidemiología , Hospitalización/estadística & datos numéricos , Humanos , Inmunoglobulina M/inmunología , Lactante , Masculino , Persona de Mediana Edad , Control de Mosquitos/métodos , Mosquitos Vectores , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Viaje
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