Effectiveness Of Control Efforts Research Articles

Social contact patterns and implications for infectious disease transmission - a systematic review and meta-analysis of contact surveys.

Transmission of respiratory pathogens such as SARS-CoV-2 depends on patterns of contact and mixing across populations. Understanding this is crucial to predict pathogen spread and the effectiveness of control efforts. Most analyses of contact patterns to date have focused on high-income settings. Here, we conduct a systematic review and individual-participant meta-analysis of surveys carried out in low- and middle-income countries and compare patterns of contact in these settings to surveys previously carried out in high-income countries. Using individual-level data from 28,503 participants and 413,069 contacts across 27 surveys, we explored how contact characteristics (number, location, duration, and whether physical) vary across income settings. Contact rates declined with age in high- and upper-middle-income settings, but not in low-income settings, where adults aged 65+ made similar numbers of contacts as younger individuals and mixed with all age groups. Across all settings, increasing household size was a key determinant of contact frequency and characteristics, with low-income settings characterised by the largest, most intergenerational households. A higher proportion of contacts were made at home in low-income settings, and work/school contacts were more frequent in high-income strata. We also observed contrasting effects of gender across income strata on the frequency, duration, and type of contacts individuals made. These differences in contact patterns between settings have material consequences for both spread of respiratory pathogens and the effectiveness of different non-pharmaceutical interventions. This work is primarily being funded by joint Centre funding from the UK Medical Research Council and DFID (MR/R015600/1).

The sluggard has no locusts: From persistent pest to irresistible icon

Abstract Desert locusts Schistocerca gregaria are threatening the food security of millions of people and devastating economies in eastern Africa and northern India. The ongoing outbreak is the largest in seven decades. These events give us cause to reflect on the natural history of locusts, our fraught relationship with them, and how they are represented in American popular culture and others. Symbolic representations span millennia and most have roots in the natural life cycle of locusts—they transform, they swarm, they devastate specific food crops. There is strong tendency to exaggerate the body size of locusts and the effectiveness of control efforts. Expressions of human futility are rare except in the form of ironic humour. We conclude by suggesting that we humans indulge in hyperbole and humour to normalize and inure ourselves to the psychologically unbearable, and that this tendency is a precondition for the techno‐optimism that drives anti‐locust technologies. There is no substitute for effective monitoring and management programs, but the importance of new and emerging anti‐locust technologies is expected to increase with projections of increased cyclone activity in the northern Indian Ocean. A free Plain Language Summary can be found within the Supporting Information of this article.

Transmission of highly pathogenic avian influenza in the nomadic free-grazing duck production system in Viet Nam

The presence of free-grazing ducks (FGD) has consistently been shown to be associated with highly pathogenic avian influenza virus (HPAIV) H5N1 outbreaks in South-East Asia. However, the lack of knowledge about the transmission pathways limits the effectiveness of control efforts. To address this gap, we developed a probabilistic transmission model of HPAIV H5N1 in the nomadic FGD production system in Viet Nam, assuming different scenarios to address parameter uncertainty. Results suggested that HPAIV H5N1 could spread within the nomadic FGD production system, with an estimated flock-level effective reproduction number (re) ranging from 2.16 (95% confidence interval (CI): 1.39-3.49) to 6.10 (95%CI: 3.93-9.85) depending on the scenario. Indirect transmission via boats and trucks was shown to be the main transmission route in all scenarios. Results suggest that re could be reduced below one with 95% confidence if 86% of FGD flocks were vaccinated in the best-case scenario or 95% in the worst-case scenario. If vaccination was combined with cleaning and disinfection of transport vehicles twice a week, vaccination coverage could be lowered to 60% in the best-case scenario. These findings are of particular relevance for prioritising interventions for effective control of HPAIV in nomadic free-grazing duck production systems.

Profiles of opinions among farmers and veterinarians towards the Tuberculosis Eradication Programme in cattle in Spain

The level of commitment among farmers and veterinarians may have a significant influence on the effectiveness of control efforts against tuberculosis in cattle (bTB), facilitating or hindering the achievement of its eradication. In this study, we investigated the opinions and attitudes of farmers and veterinarians towards the bTB eradication programme in Spain. Our aim was to assess the existence of groups of people that share the same arguments and outline their characteristic features. Data was collected through a structured questionnaire using a telephone survey in a random sample of 706 farmers and 180 veterinarians. The relationships between the variables and individuals were explored by using Multiple Correspondence Analysis. Afterwards, we applied Hierarchical Clustering on Principal Components in order to identify and characterise the opinion profiles. We identified three different groups of opinions characterised by the attitude towards bTB diagnostic tests, the perception on the importance and the zoonotic impact of bTB, and the perceived importance of other domestic reservoirs. There were people with positive and people with negative attitudes towards the programme, and a third group with a tendency to not respond. The presence of opposite profiles was observed among farmers. Veterinarians, on the other hand, were more homogeneous, especially the group of veterinarians working in the official veterinary services, as the vast majority of them expressed a positive attitude towards the programme. Nevertheless, there were also a few veterinarians who showed the same negative attitude as farmers. Education and communication are of paramount importance to ensure the adequate commitment of all people involved in the eradication programme, and our results highlight that, in Spain, both should be improved. However, this alone may not be enough to change people’s behaviours, and more complex change interventions might be necessary for people with a negative attitude. Such strategies should target the perception on the role of wildlife reservoirs, the uncertainty of ante-mortem tests results, as well as the beliefs on the importance of bTB.

Exponentially stable guaranteed cost control for continuous and discrete-time Takagi–Sugeno fuzzy systems

This paper investigates exponentially stable guaranteed cost control (GCC) for a class of nonlinear systems which is represented by Takagi–Sugeno (T–S) fuzzy systems. State feedback controllers of parallel distributed compensation (PDC) structure are designed by the means of GCC for continuous and discrete-time T–S fuzzy systems respectively. GCC methods in this paper adopt quadratic performance functions, which take effects of control efforts, regulation errors and convergence rates into consideration simultaneously, to provide desirable performance and fast response for closed-loop systems. Sufficient design conditions that guarantee exponential stabilities of resulting closed-loop systems with predefined convergence rates are presented. By setting different convergence rates, response speed of the closed-loop nonlinear system can be adjusted. The proposed design procedures are eventually converted into linear matrix inequalities (LMIs) problems of minimizing upper bounds of the guaranteed cost functions. Finally, a well-known nonlinear benchmark control example and a truck–trailer example demonstrate the effectiveness and feasibility of all the proposed methods.

Laboratory Handling of Didymosphenia geminata (Lyngbye) Schmidt and the Effect of Control Efforts on Viability

Didymosphenia geminata (Lyngbye) Schmidt is a type of diatom that exists in Chile as an introduced species, invading the country and its rivers. We collected samples of D. geminata from two sampling points in Chile, assessing their viability and response to control agents. Fresh D. geminata showed more than 90% of viable granular forms (containing granules in their cytoplasm); however, the dry form presents near 50% viability. By creating dry D. geminata through exposure to 38°C temperatures for 7 days, viability values of the granular form decreased to 20%. D. geminata kept at room temperature for more than 4 weeks reported values of granular forms at 50%, while samples that were refrigerated at 4°C maintained values of granular forms at 90% for 4 weeks. Previous studies suggest that high salt concentration affects the viability of D. geminata. When taking wet D. geminata samples and exposing them to a solution of 10% NaCl for 10 minutes, we observed no differences compared to the control samples, finding granular forms at 90%. When the D. geminata was exposed to a 5% soap solution, reductions of over 90% of the granular forms were observed. Our results suggest that the viability of D. geminata is associated with the granular content within their cytoplasm, and that it is possible to alter laboratory conditions for their study. These early studies are important in order to better manipulate the model in the laboratory, allowing us to obtain new evidence regarding the microalgae’s biology through in vitro studies.

Fecundity in Captivity of the Green Anoles,Anolis carolinensis, Established on the Ogasawara Islands

The iguanid lizard, green anole Anolis carolinensis, has currently established breeding colonies on several tropical and subtropical Pacific islands. In the Ogasawara Islands, predation by the green anole has collapsed the endemic insect community. Now that the Ogasawara Islands have been inscribed on the World Heritage List as a natural heritage by UNESCO, it is necessary to study the current status and ecological aspects of the green anole there to improve the effectiveness of control efforts. When planning population management for an alien species, information regarding its fecundity (number of eggs laid per female per year) is essential. This species lays only one egg at a time, but lays multiple times during an extensive reproductive season each year. It is therefore difficult to estimate fecundity by ordinary methods, such as gonadal examination by necropsy. In the present study, we maintained 10 female anoles from Chichijima Island in indoor captivity under conditions similar to those of the Ogasawara Islands to record their egg-laying conditions. Egg-laying occurred from April to October with a peak in August, during which each female laid 0.95 eggs/week on an average. The average number of eggs laid by a female in a year was 13.7. Sites selected for laying were spaces between the leaves of ferns and in hollows on the ground. We consider that for efficient control of this species, we should intensively hunt females in April, before their egg-laying frequency begins to increase.

Gene Flow Pattern AmongAedes aegyptiPopulations in Mexico

Patterns of gene flow vary greatly among Aedes aegypti populations throughout Mexico. The populations are panmictic along the Pacific coast, isolated by distance in northeast Mexico, and exhibit moderate gene flow across the Yucatan peninsula. Nine Ae. aegypti collections from 6 cities in Oaxaca, Mexico, were taken to examine the local patterns of gene flow. Genetic variation was examined in a 387-bp region of the nicotinamide adenine dinucleotide dehydrogenase subunit 4 mitochondrial gene (ND4) using single-strand conformation polymorphism analysis, and 3 haplotypes were detected. Cluster analysis on the linearized FST genetic distances failed to group collections in geographic proximity. Regression analysis of linear or road distances on linearized F(ST) indicated that proximal collections were as diverse as distant collections across an approximately 800-km range. The geographical distribution of the Mexican mosquito haplotype frequencies was determined for the ND4 sequences from 524 individuals from Oaxaca (this study) and 2,043 individuals from our previous studies. Herein, we report on yet another pattern dominated by genetic drift among 9 Ae. aegypti collections from 6 cities in Oaxaca, Mexico, and compare it to those reported in other regions of Mexico. Molecular analysis of variance showed that there was as much genetic variation among collections 4 km apart as there was among all collections. The numbers of haplotypes and the amount of genetic diversity among the collections from Oaxaca were much lower than detected in previous studies in other regions of Mexico and may reflect the effects of control efforts or adaptations to the altitudinal limits (1,500 m) of the species in Mexico. The geographical distribution of mosquito haplotypes in Mexico is also reported. Furthermore, based on the distribution of the mosquito haplotypes in America, we suggest that mosquito dispersion is very efficient, most likely due to commercial transportation.

An assessment of the effectiveness of a large, national-scale invasive alien plant control strategy in South Africa

This paper presents an assessment of a large, national-scale alien plant control program that has operated in South Africa for 15years. We reviewed data from three national-level estimates of the extent of invasion, records of the costs and spatial extent of invasive species control operations, assessments of the effectiveness of biological control, and smaller-scale studies. The 19 most important invasive taxa, mainly trees, in terrestrial biomes were identified. The effectiveness of control efforts on the extent of invasion of these taxa was assessed. Control costs over 15years amounted to 3.2 billion rands (US$457 million), more than half of which was spent on 10 taxa, the most prominent being in the genera Acacia, Prosopis, Pinus and Eucalyptus. Despite substantial spending, control operations were in many cases applied to a relatively small portion of the estimated invaded area, and invasions appear to have increased, and remain a serious threat, in many biomes. Our findings suggest that South Africa’s national-scale strategy to clear invasive alien plants should be substantially modified if impacts are to be effectively mitigated. Rather than attempting to control all species, and to operate in all areas, a more focused approach is called for. This would include prioritising both the species and the areas, and setting goals and monitoring the degree to which they are achieved, within a framework of adaptive management. A greater portion of funding should also be directed towards biological control, where successes have been most notable.

Incidence of Dirofilaria Immitis (Leidy) in Client Owned Dogs from the Greater Metropolitan Manila Area of Luzon Island in The Philippines

Serum samples were collected from each of 290 healthy dogs 6 months of age or older living in the Greater Metropolitan Manila (GMM) area over a 12 month period. These samples were examined by the Synbiotics DiroChek ® antigen capture test (San Diego, CA) for evidence of Dirofilaria immitis circulating antigen. At the time of the first sample 220 out of 290 examined were negative by the DiroChek test. Twelve months later 175 of the original 220 uninfected dogs were still uninfected. This is an incidence rate of 20%. This is the first incidence study on client owned dogs reported for D. immitis and illustrates that owners will participate in such studies which are essential if canine populations are to be monitored to evaluate the effect of control efforts.

Demographic Stochasticity, Environmental Variability, and Windows of Invasion Risk for Bythotrephes Longimanus in North America

Biological invasions are a leading threat to freshwater biodiversity worldwide. A central unanswered question of invasion ecology is why some introduced populations establish while most fail. Answering this question will allow resource managers to increase the specificity and effectiveness of control efforts and policy. We studied the establishment of spiny water flea (Bythotrephes longimanus) in the United States and Canada by modeling introduction failure caused by demographic stochasticity, environmental variation, and seasonal environmental forcing. We compared predicted establishment rates with observed invasions of inland lakes in Ontario, Canada. Our findings suggest that environmental forcing can cause “windows” of invasion opportunity so that timing of introductions might be a greater determinant of population establishment than demographic stochasticity and random environmental variation. We expect this phenomenon to be exhibited by species representing a wide range of life histories. For spiny water flea in North America, a large window of invasion opportunity opens around the fourth week of May, persists through the summer, and closes with decreasing water temperatures in autumn. These results show how timing of introductions with respect to seasonally forced environmental drivers can be a key determinant of establishment success. By focusing on introductions during windows of invasion opportunity, resource managers can more effectively control invasion rates.

Modeling Regional Externalities with Heterogeneous Incentives and Fixed Boundaries: Applications to Foot and Mouth Disease Control in South America*

F or over a century, the countries of South America's Southern Cone1 have struggled to control or eradicate foot and mouth disease (FMD). These efforts have been undermined by a pronounced spatial spillover of the FMD virus. Because the virus spreads readily, the effectiveness of control efforts in one country, or on one ranch, is influenced by control efforts in nearby countries or ranches. These spatial effects are compounded by variations in incentives to control the disease and diverse sensitivities to neighbors. This paper demonstrates how control behavior is affected by spatial spillovers of varied intensity and by heterogeneous incentives to control disease. The decision to control disease is framed as a spatial game in which the behavior of neighbors influences the payoffs to individuals from control effort. Because trade, geographic, and policy factors can leave some individuals more susceptible to their neighbors' actions than others, we impose hard boundaries that constrain disease spread and modulate the intensity of spillovers. Divergent incentives to control disease are modeled by fixing some individuals in specific

Results of Predator Reduction on Brook Trout and Brown Trout in 4.2 Miles (6.76 km) of the North Branch of the Au Sable River

Abstract During the autumns of 1964, 1965 and 1966, brown trout 12.0–25.1 inches (305–638 mm) in length were removed from 4.2 miles (6.76 km) of the North Branch of the Au Sable River (Dam 2-County Line), and American mergansers were harassed in the same area each winter as time permitted. The objective was to decrease losses among the smaller salmonids which would otherwise be eaten by the large trout and mergansers. Effects of control efforts were assayed by comparison of 1965–1967 angling results and population estimates with similar data accumulated on the test section and two other stream sections of the North Branch during 1961–1964 when predator manipulation was not carried on. In 1964, 561 large brown throut (66% of the estimated population) were removed. In 1965 and 1966, the actual removals were 346 and 104, or 63 and 40% of the population, respectively. The only major change noted was an increase during 1965, 1966 and 1967 in numbers of brook trout larger than 9 inches (229 ram) in the populati...