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1.
Article in English | MEDLINE | ID: mdl-33801616

ABSTRACT

The recent spread of invasive mosquito species, such as Aedes albopictus and the seasonal sporadic transmission of autochthonous cases of arboviral diseases (e.g., dengue, chikungunya, Zika) in temperate areas, such as Europe and North America, highlight the importance of effective mosquito-control interventions to reduce not only nuisance, but also major threats for public health. Local, regional, and even national mosquito control programs have been established in many countries and are executed on a seasonal basis by either public or private bodies. In order for these interventions to be worthwhile, funding authorities should ensure that mosquito control is (a) planned by competent scientific institutions addressing the local demands, (b) executed following the plan that is based on recommended and effective methods and strategies, (c) monitored regularly by checking the efficacy of the implemented actions, (d) evaluated against the set of targets, and (e) regularly improved according to the results of the monitoring. Adherence to these conditions can only be assured if a formal quality management system is adopted and enforced that ensures the transparency of effectiveness of the control operation. The current paper aims at defining the two components of this quality management system, quality assurance and quality control for mosquito control programs with special emphasis on Europe, but applicable over temperate areas.


Subject(s)
Aedes , Zika Virus Infection , Zika Virus , Animals , Europe , Mosquito Control , Mosquito Vectors , North America
2.
Pan Afr Med J ; 38: 44, 2021.
Article in English | MEDLINE | ID: mdl-33854673

ABSTRACT

Introduction: evidence-based mosquito control strategy is important for efficient and effective delivery of mosquito control interventions. This is hinged on effective community participation and thorough understanding of the Knowledge Attitude and Practices (KAPs) to achieve desired result. Such community dynamics are often understudied. We designed this study to assess the perception of four local communities on aspects of mosquito behavior, prevention and control in Lagos State, Nigeria. Methods: a cross-sectional survey was carried out using pretested semi-structured questionnaires to assess socio-demographic factors and KAPs in Kosofe, Alimosho, Ibeju-Lekki and Badagry Local Government Areas of Lagos State, Nigeria. Data analysis was carried out using IBM SPSS version 23. Results: a total of 746 questionnaires were analyzed. Socio-demographic profile of the sampled population reveals that majority of the study population (73.1%) was between 18 and 40 years which constitute 49% males and 51% females. The knowledge of mosquito as a disease vector was high among the respondents which correlates with their level of education (P<0.05). The use of insecticide aerosols and Insecticides Treated Nets (ITNs) are the main control measures employed for mosquito control by respondents. Cost, convenience of usage and awareness majorly influenced the type of control measures that respondents adopt. Reasons such as not being easy to setup, skin irritation and the filling of being caged are reasons why some individuals do not use ITNs. Indoors, 32.4% of the respondents indicate the use of dichlorvos (DDVP) for household control of mosquitoes. Conclusion: the knowledge of mosquito control is high among middle aged individuals in Lagos State. Insecticide aerosols and ITNs are two major mosquito control methods used with DDVP insecticides frequently used indoors. This can inform the design of appropriate control methods in Lagos State.


Subject(s)
Health Knowledge, Attitudes, Practice , Insecticide-Treated Bednets/statistics & numerical data , Insecticides/administration & dosage , Mosquito Control/methods , Adolescent , Adult , Cross-Sectional Studies , Educational Status , Female , Humans , Male , Mosquito Control/statistics & numerical data , Nigeria , Perception , Surveys and Questionnaires , Young Adult
3.
BMC Public Health ; 21(1): 687, 2021 04 08.
Article in English | MEDLINE | ID: mdl-33832475

ABSTRACT

BACKGROUND: The stay-at-home orders imposed in early April 2020 due to the COVID-19 pandemic in various states complicated mosquito control activities across the United States (US), and Florida was no exception. Mosquito control programs are the first line of defense against mosquito-borne pathogens. The purpose of this study was to examine the capabilities of Florida mosquito programs to implement key mosquito measures during the COVID-19 pandemic lockdown. METHODS: Using a self-administered online survey, we examined the capabilities of all Florida mosquito control programs (both state-approved mosquito districts, N = 63; and open programs, N = 27) at a time when the state of Florida was still under heightened awareness of, stay-at-home orders and planning a phase 1 reopening over the COVID-19 pandemic (June to July 2020). The final sample included mosquito control programs structured as the Board of County Commissioners (BOCC) (n = 42), independent tax district (n = 16), municipal (n = 10), and health or emergency department (n = 5). We used descriptive statistics to summarize information about the characteristics of responding programs, their implemented mosquito control and surveillance activities.  wWe used bivariate analysis to compare the characteristics of responding programs and the self-reported mosquito measures. RESULTS: Of the recruited mosquito control programs, 73 completed the survey (81.1% response rate; 73/90). Of these, 57.5% (n = 42) were Board of County Commissioners (BOCC) mosquito control programs, 21.9% (n = 16) were independent tax district programs, 13.7% (n = 10) were municipal mosquito control programs, and only 6.8% (n = 5) were either health or emergency department mosquito control programs. Except for arbovirus surveillance, most programs either fully or partially performed larval (61.8%) and adult (78.9%) surveillance; most programs conducted species-specific control for Aedes aegypti (85.2%, n = 54), Aedes albopictus (87.3%, n = 55), Culex quinquefasciatus (92.1%, n = 58), and Culex nigripalpus (91.9%, n = 57). CONCLUSIONS: Findings underscore the importance of ongoing mosquito control activities, and suggest that Florida mosquito control programs are vigilant and have significant capability to handle potential mosquito-borne disease threats, but arbovirus surveillance systems (laboratory testing of mosquito pools and testing of human and nonhuman specimens for arboviruses) are needed during pandemics as well.


Subject(s)
Insect Bites and Stings , Mosquito Control , Florida/epidemiology , Humans , Insect Bites and Stings/prevention & control , Mosquito Control/organization & administration , Program Evaluation
4.
Nat Commun ; 12(1): 2290, 2021 04 16.
Article in English | MEDLINE | ID: mdl-33863888

ABSTRACT

Arthropod-borne viruses pose a major threat to global public health. Thus, innovative strategies for their control and prevention are urgently needed. Here, we exploit the natural capacity of viruses to generate defective viral genomes (DVGs) to their detriment. While DVGs have been described for most viruses, identifying which, if any, can be used as therapeutic agents remains a challenge. We present a combined experimental evolution and computational approach to triage DVG sequence space and pinpoint the fittest deletions, using Zika virus as an arbovirus model. This approach identifies fit DVGs that optimally interfere with wild-type virus infection. We show that the most fit DVGs conserve the open reading frame to maintain the translation of the remaining non-structural proteins, a characteristic that is fundamental across the flavivirus genus. Finally, we demonstrate that the high fitness DVG is antiviral in vivo both in the mammalian host and the mosquito vector, reducing transmission in the latter by up to 90%. Our approach establishes the method to interrogate the DVG fitness landscape, and enables the systematic identification of DVGs that show promise as human therapeutics and vector control strategies to mitigate arbovirus transmission and disease.


Subject(s)
Antiviral Agents/administration & dosage , Defective Viruses/genetics , Mosquito Vectors/drug effects , Zika Virus Infection/drug therapy , Zika Virus/genetics , Aedes/drug effects , Aedes/virology , Animals , Chlorocebus aethiops , Computational Biology , Directed Molecular Evolution , Disease Models, Animal , Female , Genetic Fitness , Genome, Viral/genetics , HEK293 Cells , Humans , Mice , Mosquito Control/methods , Mosquito Vectors/virology , Open Reading Frames/genetics , RNA, Viral/genetics , Vero Cells , Zika Virus Infection/transmission , Zika Virus Infection/virology
5.
Pan Afr Med J ; 38: 119, 2021.
Article in French | MEDLINE | ID: mdl-33912289

ABSTRACT

Long-lasting insecticidal mosquito nets (LLIMNs) are needed for malaria vector control. However, their distribution is not yet optimal in sub-Saharan regions. According to projections, COVID-19 pandemic will further delay the distribution of LLIMNs. In Niger, a distribution campaign of LLIMNs with a multi-sectoral approach (state-partner-civil society) was organized in compliance with barrier measures for preventing transmission of COVID-19. A door-to-door strategy was chosen to implement this campaign, in order to avoid entry into confined spaces and to engage community. A total of 13,994,681 people received LLIMNs (reflecting a success rate of 101%) in six targeted regions. A collective effort is needed to sustain the fight against malaria in the COVID-19 era.


Subject(s)
/prevention & control , Insecticide-Treated Bednets/supply & distribution , Malaria/prevention & control , /epidemiology , Humans , Mosquito Control , Mosquito Vectors , Niger
6.
Article in English | MEDLINE | ID: mdl-33673292

ABSTRACT

Mosquitoes have been a nuisance and health threat to humans for centuries due to their ability to transmit different infectious diseases. Biological control methods have emerged as an alternative or complementary approach to contain vector populations in light of the current spread of insecticide resistance in mosquitoes. Thus, this study aimed to evaluate the predation efficacy of selected potential predators against Anopheles mosquito larvae. Potential invertebrate predators and Anopheles larvae were collected from natural habitats, mainly (temporary) wetlands and ponds in southwest Ethiopia and experiments were conducted under laboratory conditions. Optimal predation conditions with respect to larval instar, water volume and number of predators were determined for each of the seven studied predators. Data analyses were carried out using the Poisson regression model using one way ANOVA at the 5% significant level. The backswimmer (Notonectidae) was the most aggressive predator on Anopheles mosquito larvae with a daily mean predation of 71.5 larvae (95% CI: [65.04;78.59]). Our study shows that larval instar, water volume and number of predators have a significant effect on each predator, except for dragonflies (Libellulidae), with regard to the preference of the larval instar. A selection of mosquito predators has the potential to control Anopheles mosquito larvae, suggesting that they can be used as complementary approach in an integrated malaria vector control strategy.


Subject(s)
Anopheles , Malaria , Odonata , Animals , Ecosystem , Ethiopia , Humans , Larva , Malaria/prevention & control , Mosquito Control , Mosquito Vectors
7.
J Infect Public Health ; 14(4): 527-532, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33744740

ABSTRACT

BACKGROUND: Due to a high burden imposed on public health from malaria disease in Sub-Saharan Africa, the vector control strategy is a significant concern. Despite the implementation of malaria control interventions in Ethiopia, it remains a major public health problem. Moreover, none of the prior researches was conducted in this title specifically. Therefore, this study investigates the impact of vector control interventions on malaria based on panel data of 10 malaria endemic-regions from 2000 to 2018. METHODS: A reflexive analysis study based on before-and-after assessment was used to evaluate the impact of vector control interventions on malaria with a difference-in-difference approach, representing Period I for before and Period II for after strategic intervention. The random-effect model was also employed to explore the direct relationship between the study variables. The data exported to Stata version 13.0 for analysis. RESULTS: The study results suggest that the negative relationship between intervention strategy and malaria cases reported in comparison with its counterfactual, showing the increase in malaria cases during Period II comparing to Period I. The study explores a remarkable achievement on the decline in mean malaria-related death in all regions after the implementation of the strategy. Furthermore, a significant relationship between indoor residual spraying, insecticide-treated mosquito nets, and malaria was demonstrated within the strategic periods. CONCLUSION: Better results achieved in Period I on mean malaria cases. The results of Period II showed a decline in mean malaria related-death, which was encouraging. The study calls for a supplementary strategy to align with the existing program. The study demonstrates the need for extra efforts on the implementation of the programme and progress about malaria.


Subject(s)
Insecticide-Treated Bednets , Insecticides , Malaria/prevention & control , Mosquito Control/methods , Ethiopia/epidemiology , Humans , Malaria/epidemiology
8.
J Vis Exp ; (169)2021 03 12.
Article in English | MEDLINE | ID: mdl-33779612

ABSTRACT

The control of such human diseases as dengue, Zika, and chikungunya relies on the control of their vector, the Aedes aegypti mosquito, because there is no prevention. Control of mosquito vectors can rely on chemicals applied to the immature and adult stages, which can contribute to the mortality of non-targets and more importantly, lead to insecticide resistance in the vector. The sterile insect technique (SIT) is a method of controlling populations of pests through the release of sterilized adult males that mate with wild females to produce non-viable offspring. This paper describes the process of producing sterile males for use in an operational SIT program for the control of Aedes aegypti mosquitoes. Outlined here are the steps used in the program including rearing and maintaining a colony, separating male and female pupae, irradiating and marking adult males, and shipping Aedes aegypti males to the release site. Also discussed are procedural caveats, program limitations, and future objectives.


Subject(s)
Aedes/physiology , Fertility/radiation effects , Insecticide Resistance , Mosquito Control/methods , Mosquito Vectors/physiology , Pupa/physiology , Sterilization, Reproductive/methods , Aedes/radiation effects , Animals , Female , Humans , Male , Mosquito Vectors/radiation effects , Pupa/radiation effects
9.
Ecotoxicol Environ Saf ; 213: 112013, 2021 Apr 15.
Article in English | MEDLINE | ID: mdl-33601173

ABSTRACT

Mosquito larvicides are an effective tool for reducing numbers of adult females that bite and potentially spread pathogenic organisms. Methionine, an essential amino acid in humans, has been previously demonstrated to be a highly effective larvicide against four (4) mosquito species in three (3) genera, Anopheles, Culex and Aedes. The aim of the present study was to determine the potential impact on non-target aquatic organisms of methionine applied as a mosquito larvicide. DL-methionine concentrations ranging from 0.06% to 1.00% were used; wherein the highest concentration of 1.00% would result in 100% mortality within 48 h in mosquitoes. Acute toxicity assays were conducted in accordance with the US Environmental Protection Agency (US EPA) guidelines for the water flea (Daphnia magna Straus; Cladocera: Daphniidae) and the fathead minnow (Pimephales promelas Rafinesque; Cypriniformes: Cyprinidae). Water fleas and fish were placed directly into the solutions in glass containers and tanks for 48-hours and 96-hours, respectively. When applied within the above-mentioned range of effective mosquito larvicide concentrations, DL-methionine meets US EPA criteria as a "practically non-toxic" pesticide for both species. These results suggest that methionine is a viable alternative to current mosquito larvicide options, which are typically classified as moderately to highly toxic and may be a valuable addition to a mosquito integrated pest management program.


Subject(s)
Aquatic Organisms , Methionine/toxicity , Mosquito Control , Aedes , Animals , Anopheles , Culex , Cyprinidae , Daphnia , Female , Humans , Larva
10.
Cryobiology ; 99: 1-10, 2021 04.
Article in English | MEDLINE | ID: mdl-33556359

ABSTRACT

Mosquito-borne diseases are responsible for millions of human deaths every year, posing a massive burden on global public health. Mosquitoes transmit a variety of bacteria, parasites and viruses. Mosquito control efforts such as insecticide spraying can reduce mosquito populations, but they must be sustained in order to have long term impacts, can result in the evolution of insecticide resistance, are costly, and can have adverse human and environmental effects. Technological advances have allowed genetic manipulation of mosquitoes, including generation of those that are still susceptible to insecticides, which has greatly increased the number of mosquito strains and lines available to the scientific research community. This generates an associated challenge, because rearing and maintaining unique mosquito lines requires time, money and facilities, and long-term maintenance can lead to adaptation to specific laboratory conditions, resulting in mosquito lines that are distinct from their wild-type counterparts. Additionally, continuous rearing of transgenic lines can lead to loss of genetic markers, genes and/or phenotypes. Cryopreservation of valuable mosquito lines could help circumvent these limitations and allow researchers to reduce the cost of rearing multiple lines simultaneously, maintain low passage number transgenic mosquitoes, and bank lines not currently being used. Additionally, mosquito cryopreservation could allow researchers to access the same mosquito lines, limiting the impact of unique laboratory or field conditions. Successful cryopreservation of mosquitoes would expand the field of mosquito research and could ultimately lead to advances that would reduce the burden of mosquito-borne diseases, possibly through rear-and-release strategies to overcome mosquito insecticide resistance. Cryopreservation techniques have been developed for some insect groups, including but not limited to fruit flies, silkworms and other moth species, and honeybees. Recent advances within the cryopreservation field, along with success with other insects suggest that cryopreservation of mosquitoes may be a feasible method for preserving valuable scientific and public health resources. In this review, we will provide an overview of basic mosquito biology, the current state of and advances within insect cryopreservation, and a proposed approach toward cryopreservation of Anopheles stephensi mosquitoes.


Subject(s)
Anopheles , Mosquito Vectors , Animals , Bees , Cryopreservation/methods , Humans , Insecticide Resistance/genetics , Mosquito Control , Mosquito Vectors/genetics
11.
Sci Total Environ ; 773: 144708, 2021 Jun 15.
Article in English | MEDLINE | ID: mdl-33582339

ABSTRACT

Conflicts often exist between the use of pesticides for public health protection and organic farming. A prominent example is the use of insecticides for mosquito control in rice fields designated for organic farming. Rice fields, with static water and other conducive conditions, are favorable mosquito habitats. Best management practices are urgently needed to ensure the integrity of organic farming while addressing the need for public health protection. In this study, we evaluated aerial ultra-low-volume (ULV) applications of two classes of mosquito adulticides, pyrethrins and organophosphates, and their deposition and residues on rice plants throughout an active growing season in the Sacramento Valley of California. Frequent applications of pyrethrin synergized with piperonyl butoxide (PBO) and rotating applications of synergized pyrethrins and naled, an organophosphate, were carried out on two large blocks of rice fields. Aerial ULV application of either synergized pyrethrins or naled was able to generate uniform droplets above the fields with high efficacy for mosquito control. Rice leaf samples were collected before and after a subset of applications, and rice grains were sampled at harvest. Frequent applications of synergized pyrethrins resulted in some accumulation of the synergist PBO on rice leaves, but pyrethrins and naled dissipated rapidly from the leaves after each application with no noticeable accumulation over repeated applications. At harvest, no detectable residues of the pesticides or PBO were found in the rice grains. The absence of pesticide residues in the rice grains at harvest suggested that the ULV aerial application led to deposition of only very low levels of residues on rice plants during the growing season. When coupled with the short persistence and/or poor mobility of the insecticides, such applications resulted in negligible pesticide residues in rice grains.


Subject(s)
Insecticides , Oryza , Pesticide Residues , Pyrethrins , Mosquito Control , Organic Agriculture , Piperonyl Butoxide , Pyrethrins/analysis
12.
Parasite ; 28: 8, 2021.
Article in English | MEDLINE | ID: mdl-33528357

ABSTRACT

In Cameroon, pyrethroid-only long-lasting insecticidal nets (LLINs) are still largely used for malaria control. The present study assessed the efficacy of such LLINs against a multiple-resistant population of the major malaria vector, Anopheles coluzzii, in the city of Yaoundé via a cone bioassay and release-recapture experimental hut trial. Susceptibility of field mosquitoes in Yaoundé to pyrethroids, DDT, carbamates and organophosphate insecticides was investigated using World Health Organization (WHO) bioassay tube tests. Mechanisms of insecticide resistance were characterised molecularly. Efficacy of unwashed PermaNet® 2.0 was evaluated against untreated control nets using a resistant colonised strain of An. coluzzii. Mortality, exophily and blood feeding inhibition were estimated. Field collected An. coluzzii displayed high resistance with mortality rates of 3.5% for propoxur (0.1%), 4.16% for DDT (4%), 26.9% for permethrin (0.75%), 50.8% for deltamethrin (0.05%), and 80% for bendiocarb (0.1%). High frequency of the 1014F west-Africa kdr allele was recorded in addition to the overexpression of several detoxification genes, such as Cyp6P3, Cyp6M2, Cyp9K1, Cyp6P4 Cyp6Z1 and GSTe2. A low mortality rate (23.2%) and high blood feeding inhibition rate (65%) were observed when resistant An. coluzzii were exposed to unwashed PermaNet® 2.0 net compared to control untreated net (p < 0.001). Furthermore, low personal protection (52.4%) was observed with the resistant strain, indicating reduction of efficacy. The study highlights the loss of efficacy of pyrethroid-only nets against mosquitoes exhibiting high insecticide resistance and suggests a switch to new generation bed nets to improve control of malaria vector populations in Yaoundé.


Subject(s)
Anopheles , Insecticide Resistance , Insecticide-Treated Bednets , Mosquito Control , Mosquito Vectors , Pyrethrins , Africa, Western , Animals , Anopheles/drug effects , Anopheles/genetics , Cameroon , Insecticide-Treated Bednets/standards , Insecticides/pharmacology , Malaria/prevention & control , Malaria/transmission , Mosquito Control/standards , Mosquito Vectors/drug effects , Prevalence , Pyrethrins/pharmacology
13.
BMC Infect Dis ; 21(1): 194, 2021 Feb 19.
Article in English | MEDLINE | ID: mdl-33607958

ABSTRACT

BACKGROUND: Long-lasting insecticidal nets (LLINs) are currently the primary method of malaria control in sub-Saharan Africa and have contributed to a significant reduction in malaria burden over the past 15 years. However, this progress is threatened by the wide-scale selection of insecticide-resistant malaria vectors. It is, therefore, important to accelerate the generation of evidence for new classes of LLINs. METHODS: This protocol presents a three-arm superiority, single-blinded, cluster randomized controlled trial to evaluate the impact of 2 novel dual-active ingredient LLINs on epidemiological and entomological outcomes in Benin, a malaria-endemic area with highly pyrethroid-resistant vector populations. The study arms consist of (i) Royal Guard® LLIN, a net combining a pyrethroid (alpha-cypermethrin) plus an insect growth regulator (pyriproxyfen), which in the adult female is known to disrupt reproduction and egg fertility; (ii) Interceptor G2® LLIN, a net incorporating two adulticides (alpha-cypermethrin and chlorfenapyr) with different modes of action; and (iii) the control arm, Interceptor® LLIN, a pyrethroid (alpha-cypermethrin) only LLIN. In all arms, one net for every 2 people will be distributed to each household. Sixty clusters were identified and randomised 1:1:1 to each study arm. The primary outcome is malaria case incidence measured over 24 months through active case detection in a cohort of 25 children aged 6 months to 10 years, randomly selected from each cluster. Secondary outcomes include 1) malaria infection prevalence (all ages) and prevalence of moderate to severe anaemia in children under 5 years old, measured at 6 and 18 months post-intervention; 2) entomological indices measured every 3 months using human landing catches over 24 months. Insecticide resistance intensity will also be monitored over the study period. DISCUSSION: This study is the second cluster randomised controlled trial to evaluate the efficacy of these next-generation LLINs to control malaria transmitted by insecticide-resistant mosquitoes. The results of this study will form part of the WHO evidence-based review to support potential public health recommendations of these nets and shape malaria control strategies of sub-Saharan Africa for the next decade. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03931473 , registered on 30 April 2019.


Subject(s)
Insecticide Resistance/drug effects , Insecticide-Treated Bednets , Malaria/prevention & control , Mosquito Control/methods , Mosquito Vectors/physiology , Animals , Benin/epidemiology , Humans , Incidence , Insecticides/pharmacology , Malaria/epidemiology , Malaria/transmission , Prevalence , Pyrethrins/pharmacology , Pyridines/pharmacology
14.
Article in English | MEDLINE | ID: mdl-33572650

ABSTRACT

Aedes aegypti is a cosmopolitan vector for arboviruses dengue, Zika and chikungunya, disseminated in all Brazilian states. The Eco-Bio-Social (EBS) strategy is vital in Aedes aegypti control as it mobilizes stakeholders (government, professionals, society, and academics) to promote healthy environments. This paper describes the rationale and methods of expanding the EBS strategy for Aedes aegypti control in Fortaleza, Northeast Brazil. A cluster, non-randomized controlled clinical trial was developed to analyze the strategy's effectiveness in vulnerable territories (high incidence of dengue and violent deaths; low HDI; substandard urban infrastructure, high population density, and water scarcity). We selected two intervention and two control groups, resulting in a sample of approximately 16,000 properties. The intervention consisted of environmental management by sealing large elevated water tanks, introduction of beta fish in waterholes, elimination of potential breeding sites, and mobilization and training of schoolchildren, endemic disease workers, health workers, social mobilizers, and community leaders; community surveillance of arboviruses; construction and validation of a booklet for the prevention of arboviruses in pregnant women. We analyzed the costs of arboviruses to government and households, the intervention cost-effectiveness, chikungunya's chronicity, and acceptance, sustainability, and governance of vector control actions. The primary outcome (infestation) was analyzed using the house, container, and Breteau indices. We hope that this study will help us understand how to scale up strategies to fight Aedes aegypti in vulnerable areas.


Subject(s)
Aedes , Dengue , Zika Virus Infection , Zika Virus , Animals , Brazil/epidemiology , Child , Dengue/epidemiology , Dengue/prevention & control , Female , Humans , Mosquito Control , Mosquito Vectors , Pregnancy , Zika Virus Infection/epidemiology , Zika Virus Infection/prevention & control
15.
Mem Inst Oswaldo Cruz ; 115: e200313, 2021.
Article in English | MEDLINE | ID: mdl-33533870

ABSTRACT

BACKGROUND: Aedes aegypti is the sole vector of urban arboviruses in French Guiana. Overtime, the species has been responsible for the transmission of viruses during yellow fever, dengue, chikungunya and Zika outbreaks. Decades of vector control have produced resistant populations to deltamethrin, the sole molecule available to control adult mosquitoes in this French Territory. OBJECTIVES: Our surveillance aimed to provide public health authorities with data on insecticide resistance in Ae. aegypti populations and other species of interest in French Guiana. Monitoring resistance to the insecticide used for vector control and to other molecule is a key component to develop an insecticide resistance management plan. METHODS: In 2009, we started to monitor resistance phenotypes to deltamethrin and target-site mechanisms in Ae. aegypti populations across the territory using the WHO impregnated paper test and allelic discrimination assay. FINDINGS: Eight years surveillance revealed well-installed resistance and the dramatic increase of alleles on the sodium voltage-gated gene, known to confer resistance to pyrethroids (PY). In addition, we observed that populations were resistant to malathion (organophosphorous, OP) and alpha-cypermethrin (PY). Some resistance was also detected to molecules from the carbamate family. Finally, those populations somehow recovered susceptibility against fenitrothion (OP). In addition, other species distributed in urban areas revealed to be also resistant to pyrethroids. CONCLUSION: The resistance level can jeopardize the efficiency of chemical adult control in absence of other alternatives and conducts to strongly rely on larval control measures to reduce mosquito burden. Vector control strategies need to evolve to maintain or regain efficacy during epidemics.


Subject(s)
Aedes/drug effects , Insect Vectors/genetics , Insecticide Resistance/genetics , Insecticides/pharmacology , Mosquito Vectors/drug effects , Pyrethrins/pharmacology , Aedes/genetics , Aedes/virology , Animals , French Guiana , Insect Vectors/drug effects , Mosquito Control/methods , Mosquito Vectors/virology , Spatio-Temporal Analysis
16.
PLoS Negl Trop Dis ; 15(1): e0008993, 2021 01.
Article in English | MEDLINE | ID: mdl-33465094

ABSTRACT

Geographic pattern of dengue fever is changing due to the global environmental and climate changes in the 21st century. Evidence of community's knowledge, mosquito bite patterns and protective behavior practices in non-endemic regions is limited. This study examined the knowledge of dengue, mosquito bite patterns, protective behavior practices and their associated factors in Hong Kong, a non-endemic subtropical city. A population-based random telephone survey (n = 590) was conducted three weeks after the government announcement of a local dengue outbreak in August 2018. Sociodemographic status, awareness, knowledge, protective measures, bite patterns of mosquito were collected. Results indicated high level of community awareness of the local outbreak (95.2%), symptom identification (84.0%) and adoption of at least one mosquito protective measures (nearly 80%). About 40% of respondents reported that they were bitten by mosquitoes during the study period, a high mosquito season in Hong Kong. Mosquito bites were prevalent near grassy area (63.4%), at home (42.6%) and at public transportation waiting spots (39.6%). Younger people (< 25 years old), female, those who lived on lower floors (≤the 6th) and near grassy area were at higher risk of mosquito bites at home. Respondents perceived higher threat of dengue to society were more likely to practice mosquito prevention. While residential factors affected their indoor prevention, other socio-demographic factors affected the outdoor prevention. Practicing prevention behaviors were associated with self-reported mosquito bite at home. Furthermore, the general prevention uptake rate unchanged after the announcement of local dengue outbreak. Although the uptake rate of protective measures during August was high, 40% participants reported they were bitten. Also public locations are more common area for bites, which suggested stronger mosquito prevention and control on public environments and more personal protective behaviors should be advocated.


Subject(s)
Dengue/prevention & control , Health Knowledge, Attitudes, Practice , Insect Bites and Stings/epidemiology , Mosquito Vectors , Adult , Aged , Dengue/epidemiology , Dengue/transmission , Disease Outbreaks/prevention & control , Female , Hong Kong/epidemiology , Humans , Insect Bites and Stings/prevention & control , Male , Middle Aged , Mosquito Control/methods , Sociological Factors , Surveys and Questionnaires
17.
PLoS Negl Trop Dis ; 15(1): e0009005, 2021 01.
Article in English | MEDLINE | ID: mdl-33465098

ABSTRACT

BACKGROUND: The integration of house-screening and long-lasting insecticidal nets, known as insecticide-treated screening (ITS), can provide simple, safe, and low-tech Aedes aegypti control. Cluster randomised controlled trials in two endemic localities for Ae. aegypti of south Mexico, showed that ITS conferred both, immediate and sustained (~2 yr) impact on indoor-female Ae. aegypti infestations. Such encouraging results require further validation with studies quantifying more epidemiologically-related endpoints, including arbovirus infection in Ae. aegypti. We evaluated the efficacy of protecting houses with ITS on Ae. aegypti infestation and arbovirus infection during a Zika outbreak in Merida, Yucatan, Mexico. METHODOLOGY/PRINCIPAL FINDINGS: A two-arm cluster-randomised controlled trial evaluated the entomological efficacy of ITS compared to the absence of ITS (with both arms able to receive routine arbovirus vector control) in the neighbourhood Juan Pablo II of Merida. Cross-sectional entomological surveys quantified indoor adult mosquito infestation and arbovirus infection at baseline (pre-ITS installation) and throughout two post-intervention (PI) surveys spaced at 6-month intervals corresponding to dry/rainy seasons over one year (2016-2017). Household-surveys assessed the social reception of the intervention. Houses with ITS were 79-85% less infested with Aedes females than control houses up to one-year PI. A similar significant trend was observed for blood-fed Ae. aegypti females (76-82%). Houses with ITS had significantly less infected female Ae. aegypti than controls during the peak of the epidemic (OR = 0.15, 95%CI: 0.08-0.29), an effect that was significant up to a year PI (OR = 0.24, 0.15-0.39). Communities strongly accepted the intervention, due to its perceived mode of action, the prevalent risk for Aedes-borne diseases in the area, and the positive feedback from neighbours receiving ITS. CONCLUSIONS/SIGNIFICANCE: We show evidence of the protective efficacy of ITS against an arboviral disease of major relevance, and discuss the relevance of our findings for intervention adoption.


Subject(s)
Aedes/virology , Mosquito Control/methods , Mosquito Nets/statistics & numerical data , Zika Virus Infection/prevention & control , Animals , Chikungunya virus/isolation & purification , Dengue Virus , Female , Housing , Humans , Insect Bites and Stings/prevention & control , Insecticides , Mexico , Mosquito Vectors , Zika Virus/isolation & purification , Zika Virus Infection/epidemiology
18.
PLoS One ; 16(1): e0244284, 2021.
Article in English | MEDLINE | ID: mdl-33417600

ABSTRACT

BACKGROUND: Mosquito-borne diseases remain a significant public health problem in tropical regions. Housing improvements such as screening of doors and windows may be effective in reducing disease transmission, but the impact remains unclear. OBJECTIVES: To examine whether housing interventions were effective in reducing mosquito densities in homes and the impact on the incidence of mosquito-borne diseases. METHODS: In this systematic review and meta-analysis, we searched 16 online databases, including NIH PubMed, CINAHL Complete, LILACS, Ovid MEDLINE, and Cochrane Central Register of Controlled Trials for randomized trials published from database inception to June 30, 2020. The primary outcome was the incidence of any mosquito-borne diseases. Secondary outcomes encompassed entomological indicators of the disease transmission. I2 values were used to explore heterogeneity between studies. A random-effects meta-analysis was used to assess the primary and secondary outcomes, with sub-group analyses for type of interventions on home environment, study settings (rural, urban, or mixed), and overall house type (traditional or modern housing). RESULTS: The literature search yielded 4,869 articles. After screening, 18 studies were included in the qualitative review, of which nine were included in the meta-analysis. The studies enrolled 7,200 households in Africa and South America, reporting on malaria or dengue only. The type of home environmental interventions included modification to ceilings and ribbons to close eaves, screening doors and windows with nets, insecticide-treated wall linings in homes, nettings over gables and eaves openings, mosquito trapping systems, metal-roofed houses with mosquito screening, gable windows and closed eaves, and prototype houses using southeast Asian designs. Pooled analysis depicted a lower risk of mosquito-borne diseases in the housing intervention group (OR = 0.68; 95% CI = 0.48 to 0.95; P = 0.03). Subgroup analysis depicted housing intervention reduced the risk of malaria in all settings (OR = 0.63; 95% CI = 0.39 to 1.01; P = 0.05). In urban environment, housing intervention was found to decrease the risk of both malaria and dengue infections (OR = 0.52; 95% CI = 0.27 to 0.99; P = 0.05).Meta-analysis of pooled odds ratio showed a significant benefit of improved housing in reducing indoor vector densities of both Aedes and Anopheles (OR = 0.35; 95% CI = 0.23 to 0.54; P<0.001). CONCLUSIONS: Housing intervention could reduce transmission of malaria and dengue among people living in the homes. Future research should evaluate the protective effect of specific house features and housing improvements associated with urban development.


Subject(s)
Housing , Malaria/prevention & control , Mosquito Control/methods , Vector Borne Diseases/prevention & control , Aedes/drug effects , Aedes/physiology , Animals , Humans , Insecticides/pharmacology , Malaria/transmission , Odds Ratio , Risk Factors , Vector Borne Diseases/transmission
19.
Parasit Vectors ; 14(1): 9, 2021 Jan 06.
Article in English | MEDLINE | ID: mdl-33407825

ABSTRACT

BACKGROUND: With widespread insecticide resistance in mosquito vectors, there is a pressing need to evaluate alternatives with different modes of action. Blood containing the antihelminthic drug ivermectin has been shown to have lethal and sub-lethal effects on mosquitoes. Almost all work to date has been on Anopheles spp., but impacts on other anthropophagic vectors could provide new options for their control, or additional value to anti-malarial ivermectin programmes. METHODS: Using dose-response assays, we evaluated the effects of ivermectin delivered by membrane feeding on daily mortality (up to 14 days post-blood feed) and fecundity of an Indian strain of Aedes aegypti. RESULTS: The 7-day lethal concentration of ivermectin required to kill 50% of adult mosquitoes was calculated to be 178.6 ng/ml (95% confidence intervals 142.3-218.4) for Ae. aegypti, which is much higher than that recorded for Anopheles spp. in any previous study. In addition, significant effects on fecundity and egg hatch rates were only recorded at high ivermectin concentrations (≥ 250 ng/ul). CONCLUSION: Our results suggest that levels of ivermectin present in human blood at current dosing regimes in mass drug administration campaigns, or even those in a recent higher-dose anti-malaria trial, are unlikely to have a substantial impact on Ae. aegypti. Moreover, owing to the strong anthropophagy of Ae. aegypti, delivery of higher levels of ivermectin in livestock blood is also unlikely to be an effective option for its control. However, other potential toxic impacts of ivermectin metabolites, accumulation in tissues, sublethal effects on behaviour, or antiviral action might increase the efficacy of ivermectin against Ae. aegypti and the arboviral diseases it transmits, and require further investigation.


Subject(s)
Aedes/drug effects , Arbovirus Infections/prevention & control , Ivermectin/pharmacology , Animals , Anthelmintics/administration & dosage , Anthelmintics/pharmacology , Arbovirus Infections/transmission , Fertility/drug effects , Ivermectin/administration & dosage , Mortality , Mosquito Control/methods , Mosquito Vectors/drug effects
20.
Viruses ; 13(1)2021 Jan 14.
Article in English | MEDLINE | ID: mdl-33466915

ABSTRACT

Mosquito-borne arthropod-borne viruses (arboviruses) such as the dengue virus (DENV), Zika virus (ZIKV), and chikungunya virus (CHIKV) are important human pathogens that are responsible for significant global morbidity and mortality. The recent emergence and re-emergence of mosquito-borne viral diseases (MBVDs) highlight the urgent need for safe and effective vaccines, therapeutics, and vector-control approaches to prevent MBVD outbreaks. In nature, arboviruses circulate between vertebrate hosts and arthropod vectors; therefore, disrupting the virus lifecycle in mosquitoes is a major approach for combating MBVDs. Several strategies were proposed to render mosquitoes that are refractory to arboviral infection, for example, those involving the generation of genetically modified mosquitoes or infection with the symbiotic bacterium Wolbachia. Due to the recent development of high-throughput screening methods, an increasing number of drugs with inhibitory effects on mosquito-borne arboviruses in mammalian cells were identified. These antivirals are useful resources that can impede the circulation of arboviruses between arthropods and humans by either rendering viruses more vulnerable in humans or suppressing viral infection by reducing the expression of host factors in mosquitoes. In this review, we summarize recent advances in small-molecule antiarboviral drugs in mammalian and mosquito cells, and discuss how to use these antivirals to block the transmission of MBVDs.


Subject(s)
Aedes/virology , Antiviral Agents/pharmacology , Arbovirus Infections/transmission , Arbovirus Infections/virology , Arboviruses/drug effects , Mosquito Vectors/virology , Aedes/drug effects , Animals , Antiviral Agents/chemistry , Antiviral Agents/therapeutic use , Arbovirus Infections/drug therapy , Arboviruses/classification , Cells, Cultured , Drug Discovery/methods , Drug Evaluation, Preclinical , Humans , Mosquito Control/methods , Vector Borne Diseases/drug therapy , Vector Borne Diseases/transmission , Vector Borne Diseases/virology , Virus Replication/drug effects
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