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The Cochrane Database of Systematic... Aug 2023Insecticide-based interventions, such as long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS), remain the backbone of malaria vector control.... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Insecticide-based interventions, such as long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS), remain the backbone of malaria vector control. These interventions target mosquitoes that prefer to feed and rest indoors, but have limited capacity to prevent transmission that occurs outdoors or outside regular sleeping hours. In low-endemicity areas, malaria elimination will require that these control gaps are addressed, and complementary tools are found. The use of topical repellents may be particularly useful for populations who may not benefit from programmatic malaria control measures, such as refugees, the military, or forest goers. This Cochrane Review aims to measure the effectiveness of topical repellents to prevent malaria infection among high- and non-high-risk populations living in malaria-endemic regions.
OBJECTIVES
To assess the effect of topical repellents alone or in combination with other background interventions (long-lasting insecticide-treated nets, or indoor residual spraying, or both) for reducing the incidence of malaria in high- and non-high-risk populations living in endemic areas.
SEARCH METHODS
We searched the following databases up to 11 January 2023: the Cochrane Infectious Diseases Group Specialised Register; CENTRAL (in the Cochrane Library); MEDLINE; Embase; CAB Abstracts; and LILACS. We also searched trial registration platforms and conference proceedings; and contacted organizations and companies for ongoing and unpublished trials.
SELECTION CRITERIA
We included randomized controlled trials (RCTs) and cluster-randomized controlled trials (cRCTs) of topical repellents proven to repel mosquitoes. We also included non-randomized studies that complied with pre-specified inclusion criteria: controlled before-after studies (CBA), controlled interrupted time series (ITS), and controlled cross-over trials.
DATA COLLECTION AND ANALYSIS
Four review authors independently assessed trials for inclusion, and extracted the data. Two authors independently assessed the risk of bias (RoB) using the Cochrane RoB 2 tool. A fifth review author resolved any disagreements. We analysed data by conducting a meta-analysis, stratified by whether studies included populations considered to be at high-risk of developing malaria infection (for example, refugees, forest goers, or deployed military troops). We combined results from cRCTs with RCTs by adjusting for clustering and presented results using forest plots. We used the GRADE framework to assess the certainty of the evidence. We only included data on Plasmodium falciparum infections in the meta-analysis.
MAIN RESULTS
Thirteen articles relating to eight trials met the inclusion criteria and were qualitatively described. We included six trials in the meta-analysis (five cRCTs and one RCT). Effect on malaria incidence Topical repellents may slightly reduce P falciparum infection and clinical incidence when both outcomes are considered together (incidence rate ratio (IRR) 0.74, 95% confidence interval (CI) 0.56 to 0.98; 3 cRCTs and 1 RCT, 61,651 participants; low-certainty evidence); but not when these two outcomes were considered independently. Two cRCTs and one RCT (12,813 participants) evaluated the effect of topical repellents on infection incidence (IRR 0.76, 95% CI 0.56 to 1.02; low-certainty evidence). One cRCT (48,838 participants) evaluated their effect on clinical case incidence (IRR 0.66, 95% CI 0.32 to 1.36; low-certainty evidence). Three studies (2 cRCTs and 1 RCT) included participants belonging to groups considered at high-risk of being infected, while only one cRCT did not include participants at high risk. Adverse events Topical repellents are considered safe. The prevalence of adverse events among participants who used topical repellents was very low (0.6%, 283/47,515) and limited to mild skin reactions. Effect on malaria prevalence Topical repellents may slightly reduce P falciparum prevalence (odds ratio (OR) 0.81, 95% CI 0.67 to 0.97; 3 cRCTs and 1 RCT; 55,366 participants; low-certainty evidence). Two of these studies (1 cRCT and 1 RCT) were carried out in refugee camps, and included exclusively high-risk populations that were not receiving any other background vector control intervention.
AUTHORS' CONCLUSIONS
There is insufficient evidence to conclude that topical repellents can prevent malaria in settings where other vector control interventions are in place. We found the certainty of evidence for all outcomes to be low, primarily due to the risk of bias. A protective effect was suggested among high-risk populations, specially refugees, who might not have access to other standard vector control measures. More adequately powered clinical trials carried out in refugee camps could provide further information on the potential benefit of topical repellents in this setting. Individually randomized studies are also likely necessary to understand whether topical repellents have an effect on personal protection, and the degree to which diversion to non-protected participants affects overall transmission dynamics. Despite this, the potential additional benefits of topical repellents are most likely limited in contexts where other interventions are available.
Topics: Animals; Humans; Insecticides; Mosquito Vectors; Malaria, Falciparum; Controlled Before-After Studies; Culicidae
PubMed: 37602418
DOI: 10.1002/14651858.CD015422.pub2 -
PLoS Neglected Tropical Diseases Aug 2023Transmission models have a long history in the study of mosquito-borne disease dynamics. The mosquito biting rate (MBR) is an important parameter in these models,...
BACKGROUND
Transmission models have a long history in the study of mosquito-borne disease dynamics. The mosquito biting rate (MBR) is an important parameter in these models, however, estimating its value empirically is complex. Modeling studies obtain biting rate values from various types of studies, each of them having its strengths and limitations. Thus, understanding these study designs and the factors that contribute to MBR estimates and their variability is an important step towards standardizing these estimates. We do this for an important arbovirus vector Aedes aegypti.
METHODOLOGY/PRINCIPAL FINDINGS
We perform a systematic review using search terms such as 'biting rate' and 'biting frequency' combined with 'Aedes aegypti' ('Ae. aegypti' or 'A. aegypti'). We screened 3,201 articles from PubMed and ProQuest databases, of which 21 met our inclusion criteria. Two broader types of studies are identified: human landing catch (HLC) studies and multiple feeding studies. We analyze the biting rate data provided as well as the methodologies used in these studies to characterize the variability of these estimates across temporal, spatial, and environmental factors and to identify the strengths and limitations of existing methodologies. Based on these analyses, we present two approaches to estimate population mean per mosquito biting rate: one that combines studies estimating the number of bites taken per gonotrophic cycle and the gonotrophic cycle duration, and a second that uses data from histological studies. Based on one histological study dataset, we estimate biting rates of Ae. aegypti (0.41 and 0.35 bite/mosquito-day in Thailand and Puerto Rico, respectively).
CONCLUSIONS/SIGNIFICANCE
Our review reinforces the importance of engaging with vector biology when using mosquito biting rate data in transmission modeling studies. For Ae. aegypti, this includes understanding the variation of the gonotrophic cycle duration and the number of bites per gonotrophic cycle, as well as recognizing the potential for spatial and temporal variability. To address these variabilities, we advocate for site-specific data and the development of a standardized approach to estimate the biting rate.
Topics: Animals; Humans; Mosquito Vectors; Aedes; Insect Bites and Stings; Thailand; Feeding Behavior
PubMed: 37552669
DOI: 10.1371/journal.pntd.0010831 -
Journal of Vector Borne Diseases 2023The study aims to present an overview of the extent of insecticide resistance in the dengue vector Aedes aegypti in India. Published data on insecticide resistance in... (Review)
Review
The study aims to present an overview of the extent of insecticide resistance in the dengue vector Aedes aegypti in India. Published data on insecticide resistance in this species were systematically searched through online databases like PubMed, Google, and Google Scholar. From each study, data were extracted and analyzed to understand the spatial and temporal patterns. Particular emphasis was given to the commonly used insecticides for mosquito control. Forty-three studies met the inclusion criteria, of which 13 had adult bioassay data, 13 larval bioassay data and 17 contained both. Data demonstrated high resistance to DDT and resistance is also widespread against carbamates. There is mounting evidence of increased tolerance to pyrethroids and organophosphorus compounds, viz permethrin, deltamethrin, lambda-cyhalothrin, malathion, and temephos. The emergence of resistance to all the insecticide classes further justifies the need for annual resistance monitoring and to maintain a nationwide database that can provide a reference for formulating effective control strategies.
Topics: Animals; Insecticide Resistance; Aedes; Mosquito Vectors; Insecticides; Pyrethrins; India; Dengue
PubMed: 37417161
DOI: 10.4103/0972-9062.361174 -
EBioMedicine Jul 2023Because the evidence for the role of structural housing and combinations of interventions (domestic or peri-domestic) against Aedes mosquitoes or dengue is still... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Because the evidence for the role of structural housing and combinations of interventions (domestic or peri-domestic) against Aedes mosquitoes or dengue is still lacking, this systematic review and meta-analysis aimed to analyse and synthesize research focusing on the household as the unit of allocation.
METHODS
We searched MEDLINE, LILACS, and Web of Science databases until February 2023 using three general keyword categories: (1) "Aedes" or "dengue"; (2) structural housing interventions including "house", "water", or "drainage"; and (3) vector control interventions of potential relevance and their combinations. We performed a qualitative content analysis and a meta-analysis for 13 entries on dengue seroconversion data.
FINDINGS
14,272 articles were screened by titles, 615 by abstracts, 79 by full-text. 61 were selected. Satisfactory data quality allowed for detailed content analysis. Interventions at the household level against the immature mosquito stages (21 studies, 34%) showed positive or mixed results in entomological and epidemiological outcomes (86% and 75% respectively). Combined interventions against immature and adult stages (11 studies, 18%) performed similarly (91% and 67%) while those against the adult mosquitoes (29 studies, 48%) performed less well (79%, 22%). A meta-analysis on seroconversion outcomes showed a not-statistically significant reduction for interventions (log odds-ratio: -0.18 [-0.51, 0.14 95% CI]).
INTERPRETATION
No basic research on housing structure or modification was eligible for this systematic review but many interventions with clear impact on vector indices and, to a lesser extent, on dengue were described. The small and not-statistically significant effect size of the meta-analysis highlights the difficulty of proving effectiveness against this highly-clustered disease and of overcoming practical implementation obstacles (e.g. efficacy loss, compliance). The long-term success of interventions depends on suitability, community commitment and official support and promotion. The choice of a specific vector control package needs to take all these context-specific aspects into consideration.
FUNDING
This work was funded by a grant from the World Health Organization (2021/1121668-0, PO 202678425, NTD/VVE).
Topics: Animals; Humans; Mosquito Vectors; Aedes
PubMed: 37352828
DOI: 10.1016/j.ebiom.2023.104660 -
Pest Management Science Oct 2023Southern rice black-streaked dwarf virus (SRBSDV) is one of the most damaging rice viruses. The virus decreases rice quality and yield, and poses a serious threat to... (Review)
Review
Southern rice black-streaked dwarf virus (SRBSDV) is one of the most damaging rice viruses. The virus decreases rice quality and yield, and poses a serious threat to food security. From this perspective, this review performed a survey of published studies in recent years to understand the current status of SRBSDV and white-backed planthopper (WBPH, Sogatella furcifera) transmission processes in rice. Recent studies have shown that the interactions between viral virulence proteins and rice susceptibility factors shape the transmission of SRBSDV. Moreover, the transmission of SRBSDV is influenced by the interactions between viral virulence proteins and S. furcifera susceptibility factors. This review focused on the molecular mechanisms of key genes or proteins associated with SRBSDV infection in rice via the S. furcifera vector, and the host defense response mechanisms against viral infection. A sustainable control strategy using RNAi was summarized to address this pest. Finally, we also present a model for screening anti-SRBSDV inhibitors using viral proteins as targets. © 2023 Society of Chemical Industry.
Topics: Animals; Insect Vectors; Oryza; Reoviridae; Hemiptera; Plant Diseases
PubMed: 37291065
DOI: 10.1002/ps.7605 -
Journal of Arthropod-borne Diseases Sep 2022Scabies is referred to the infestation of skin by an ectoparasite, . Having considerable financial consequences, this disease is a public health concern in several... (Review)
Review
BACKGROUND
Scabies is referred to the infestation of skin by an ectoparasite, . Having considerable financial consequences, this disease is a public health concern in several countries. In this review, we aimed to determine the current status of scabies in different provinces of Iran.
METHODS
Google Scholar, PubMed, Scopus, Science Direct, Scientific Information Database (SID), Sci-explore, Civilica, Magiran, Iranian Research Institute for Information Science and Technology and Elmnet databases were searched to find the related data in the time period within 2000-2022. To have a better insight into the status of prevalence of scabies in Iran, a meta-analysis and meta-regression was performed.
RESULTS
A total of 943 relevant studies were retrieved from the databases, and 62 eligible studies met all the needed criteria for inclusion in this systematic review. Scabies was investigated and reported in at least 22 and 21 provinces of Iran respectively. Most of the studies were conducted in Tehran, Razavi Khorasan, Hormozgan, Fars and Guilan Provinces. Positive samples of scabies belonged to humans, sheep, goats, dogs, rabbits, mice and gazelles. Meta-analysis showed that the overall estimated presence of scabies in Iran during 2000-2022 was 7% (95% CI 4.7-10.3%, P< 0.001).
CONCLUSION
Infestations due to in Iran occur in different geographical locations and different climates. As a neglected tropical disease, the literature about the burden of scabies in Iran is inadequate. The present review highlights the importance of development of comprehensive strategies for the diagnosis and control of scabies, especially the provinces with high infestation rates.
PubMed: 37056644
DOI: 10.18502/jad.v16i3.12034 -
The American Journal of Tropical... May 2023Arboviruses receive heightened research attention during major outbreaks or when they cause unusual or severe clinical disease, but they are otherwise...
Arboviruses receive heightened research attention during major outbreaks or when they cause unusual or severe clinical disease, but they are otherwise undercharacterized. Global change is also accelerating the emergence and spread of arboviral diseases, leading to time-sensitive questions about potential interactions between viruses and novel vectors. Vector competence experiments help determine the susceptibility of certain arthropods to a given arbovirus, but these experiments are often conducted in real time during outbreaks, rather than with preparedness in mind. We conducted a systematic review of reported mosquito-arbovirus competence experiments, screening 570 abstracts to arrive at 265 studies testing in vivo arboviral competence. We found that more than 90% of potential mosquito-virus combinations are untested in experimental settings and that entire regions and their corresponding vectors and viruses are undersampled. These knowledge gaps stymie outbreak response and limit attempts to both build and validate predictive models of the vector-virus network.
Topics: Animals; Humans; Arboviruses; Culicidae; Mosquito Vectors; Arbovirus Infections; Disease Outbreaks; Aedes
PubMed: 37037424
DOI: 10.4269/ajtmh.22-0511 -
Malaria Journal Mar 2023As many countries aim to eliminate malaria, use of comprehensive approaches targeting the mosquito vector and environment are needed. Integrated malaria prevention...
BACKGROUND
As many countries aim to eliminate malaria, use of comprehensive approaches targeting the mosquito vector and environment are needed. Integrated malaria prevention advocates the use of several malaria prevention measures holistically at households and in the community. The aim of this systematic review was to collate and summarize the impact of integrated malaria prevention in low- and middle-income countries on malaria burden.
METHODS
Literature on integrated malaria prevention, defined as the use of two or more malaria prevention methods holistically, was searched from 1st January 2001 to 31st July 2021. The primary outcome variables were malaria incidence and prevalence, while the secondary outcome measures were human biting and entomological inoculation rates, and mosquito mortality.
RESULTS
A total of 10,931 studies were identified by the search strategy. After screening, 57 articles were included in the review. Studies included cluster randomized controlled trials, longitudinal studies, programme evaluations, experimental hut/houses, and field trials. Various interventions were used, mainly combinations of two or three malaria prevention methods including insecticide-treated nets (ITNs), indoor residual spraying (IRS), topical repellents, insecticide sprays, microbial larvicides, and house improvements including screening, insecticide-treated wall hangings, and screening of eaves. The most common methods used in integrated malaria prevention were ITNs and IRS, followed by ITNs and topical repellents. There was reduced incidence and prevalence of malaria when multiple malaria prevention methods were used compared to single methods. Mosquito human biting and entomological inoculation rates were significantly reduced, and mosquito mortality increased in use of multiple methods compared to single interventions. However, a few studies showed mixed results or no benefits of using multiple methods to prevent malaria.
CONCLUSION
Use of multiple malaria prevention methods was effective in reducing malaria infection and mosquito density in comparison with single methods. Results from this systematic review can be used to inform future research, practice, policy and programming for malaria control in endemic countries.
Topics: Humans; Animals; Developing Countries; Insecticides; Culicidae; Insect Repellents; Mosquito Vectors
PubMed: 36879237
DOI: 10.1186/s12936-023-04500-x -
PLoS Neglected Tropical Diseases Mar 2023Over the past decades, several viral diseases transmitted by Aedes mosquitoes-dengue, chikungunya, Zika-have spread outside of tropical areas. To limit the transmission...
BACKGROUND
Over the past decades, several viral diseases transmitted by Aedes mosquitoes-dengue, chikungunya, Zika-have spread outside of tropical areas. To limit the transmission of these viruses and preserve human health, the use of mosquito traps has been developed as a complement or alternative to other vector control techniques. The objective of this work was to perform a systematic review of the existing scientific literature to assess the efficacy of interventions based on adult mosquito trap to control Aedes population densities and the diseases they transmit worldwide.
METHODS AND FINDINGS
Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review was conducted using the PubMed and Scopus databases. Among the 19 selected papers, lethal ovitraps were used in 16 studies, host-seeking female traps in 3 studies. Furthermore, 16 studies focused on the control of Ae. aegypti. Our review showed great heterogeneity in the indicators used to assess trap efficacy: e.g., the number of host-seeking females, the number of gravid females, the proportion of positive containers, the viral infection rate in female mosquitoes or serological studies in residents. Regardless of the type of studied traps, the results of various studies support the efficacy of mass trapping in combination with classical integrated vector control in reducing Aedes density. More studies with standardized methodology, and indicators are urgently needed to provide more accurate estimates of their efficacy.
CONCLUSIONS
This review highlights gaps in the demonstration of the efficacy of mass trapping of mosquitoes in reducing viral transmission and disease. Thus, further large-scale cluster randomized controlled trials conducted in endemic areas and including epidemiological outcomes are needed to establish scientific evidence for the reduction of viral transmission risk by mass trapping targeting gravid and/or host-seeking female mosquitoes.
Topics: Adult; Animals; Female; Humans; Aedes; Mosquito Vectors; Mosquito Control; Zika Virus; Zika Virus Infection
PubMed: 36877728
DOI: 10.1371/journal.pntd.0011153 -
PLoS Neglected Tropical Diseases Mar 2023Despite the use of numerous methods of control measures, mosquito populations and mosquito-borne diseases are still increasing globally. Evidence-based action thresholds...
BACKGROUND
Despite the use of numerous methods of control measures, mosquito populations and mosquito-borne diseases are still increasing globally. Evidence-based action thresholds to initiate or intensify control activities have been identified as essential in reducing mosquito populations to required levels at the correct/optimal time. This systematic review was conducted to identify different mosquito control action thresholds existing across the world and associated surveillance and implementation characteristics.
METHODOLOGY/PRINCIPAL FINDINGS
Searches for literature published from 2010 up to 2021 were performed using two search engines, Google Scholar and PubMed Central, according to PRISMA guidelines. A set of inclusion/exclusion criteria were identified and of the 1,485 initial selections, only 87 were included in the final review. Thirty inclusions reported originally generated thresholds. Thirteen inclusions were with statistical models that seemed intended to be continuously utilized to test the exceedance of thresholds in a specific region. There was another set of 44 inclusions that solely mentioned previously generated thresholds. The inclusions with "epidemiological thresholds" outnumbered those with "entomological thresholds". Most of the inclusions came from Asia and those thresholds were targeted toward Aedes and dengue control. Overall, mosquito counts (adult and larval) and climatic variables (temperature and rainfall) were the most used parameters in thresholds. The associated surveillance and implementation characteristics of the identified thresholds are discussed here.
CONCLUSIONS/SIGNIFICANCE
The review identified 87 publications with different mosquito control thresholds developed across the world and published during the last decade. Associated surveillance and implementation characteristics will help organize surveillance systems targeting the development and implementation of action thresholds, as well as direct awareness towards already existing thresholds for those with programs lacking available resources for comprehensive surveillance systems. The findings of the review highlight data gaps and areas of focus to fill in the action threshold compartment of the IVM toolbox.
Topics: Animals; Mosquito Control; Asia; Mosquito Vectors; Aedes; Dengue
PubMed: 36867651
DOI: 10.1371/journal.pntd.0011173