Individual Control Measures Research Articles

Modeling and global stability analysis of COVID-19 dynamics with optimal control and cost-effectiveness analysis

In addressing the global challenges posed by COVID-19, this study introduces a mathematical model aimed at investigating the transmission dynamics of COVID-19 and forwarding strategies for controlling it. By employing Lyapunov functions, we perform a thorough stability analysis of both disease-free and endemic equilibria. We calibrated the model using daily COVID-19 data from early 2022 in Ethiopia, after vaccination initiation. A global sensitivity analysis confirmed the robustness of the model. In addition, we extended the model to address optimal control by incorporating vaccination, public health education, and treatment. Our findings highlight the effectiveness of individual control measures and reveal that vaccination, public health educational campaign and treatment is the most cost-effective method for mitigating COVID-19 spread.

Analyzing nonlinear dynamics of dengue epidemics: A fractional order model with alert state and optimal control strategies

AbstractDengue fever is a viral disease that results in numerous fatalities and considerable financial burden. Although vaccines have been developed to treat it, some countries still have endemic cases of the disease. To manage the transmission of the disease in these areas, we create a new model that includes an alert compartment to analyze the dynamics of dengue using a fractional‐order approach. We conduct a qualitative analysis of the model and use the Pontryagin principle to develop and study an optimal control problem. Since there is no definitive treatment for dengue, it is essential to prioritize measures that control or prevent the transmission of the disease. We consider control measures, including prevention efforts, insecticides, educational campaigns, and treatment for humans. We can analyze their impact on the transmission dynamics through numerical simulations. We compare our model to an existing one in two ways: with alert and without alert. We analyze the memory effect and validate the results by interpreting parameters on the reproduction number. Our results indicate that individual control measures are insufficient to eliminate the disease, and a combination of all control measures with timely alerts to the population is necessary.

Assessment of control measures against livestock-associated methicillin-resistant Staphylococcus aureus in a farrow-to-finish pig herd using infectious disease modelling

Pigs are considered to be the main reservoir for livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA), which is a zoonotic opportunistic pathogen. As LA-MRSA is an occupational hazard, there is an incentive to control its spread in pig herds. Currently, knowledge about effective control measures which do not require culling the whole herd are limited, and the control strategies against LA-MRSA vary between countries. This study uses a stochastic compartment model to simulate possible control measures for LA-MRSA in a farrow-to-finish pig herd. The aims of the study were to (1) extend a previously published disease spread model with additional management and control measures; (2) use the extended model to study the effect of the individual LA-MRSA control measures on the within-herd LA-MRSA prevalence; (3) evaluate the effect of control measures when they are implemented in combinations. From the individual control measures tested in the study, thorough cleaning was found to be most effective in reducing the LA-MRSA prevalence in the herd. When the different control measures were combined, cleaning together with disease surveillance had the largest impact on reducing the LA-MRSA and a higher chance of causing disease elimination. The results of the study showed that achieving disease elimination once LA-MRSA had been introduced in the herd was challenging but was more likely when control measures were introduced early during the outbreak. This emphasises the importance of early detection of the pathogen and subsequent rapid implementation of LA-MRSA control measures.

Simulating the population dynamics of barley grass (Hordeum spp.) and impacts of weed management strategies in a southern Australian lucerne (Medicago sativa) pasture

Context Barley grass (Hordeum spp. L.) is an annual, invasive grass weed of southern Australian crops and pastures, frequently associated with weight loss and carcass damage in sheep due to its sharp seeds. Knowledge gaps exist regarding optimal density thresholds for effective control to reduce impacts on animal production. The value of integrated weed management (IWM) over individual control options for reducing barley grass populations in pasture is also unknown. Aims We aimed to develop a model for simulating the population dynamics of barley grass within lucerne (Medicago sativa L.) pastures of southern Australia and to test the hypothesis that combining herbicides with mowing will be more effective for removing barley grass seedbanks over time than individual control measures. Methods The model was developed within Microsoft Excel and adapted from other annual grass models. The model takes a Monte Carlo approach to simulate control impacts on weed seedbanks over 10 years using five weed-control density thresholds. It was parameterised using data from recent experiments and available literature. Key results The most effective long-term control strategy for barley grass occurred with a density threshold of 5 seedlings m−2 by combining early and late herbicide applications, and by combining early and late herbicides with mowing, reducing the seedbank by 86% and 89%, respectively. Conclusions Simulation results showed that IWM programs were more effective than individual control options in reducing the barley grass seedbanks over 10 years, particularly at low weed densities (≤50 seedlings m−2). Implications Incorporation of this model into a bioeconomic grazing systems model will be valuable for determining the economic impacts and optimal weed-control strategies for minimising the effects of barley grass seed contamination in lamb production systems.

Investigation of asbestos concentration in ambient and lavage fluids of patients referred for bronchoscopy, Ahvaz.

The amount of fibers in the lungs is considered to reflect the cumulative intensity of past asbestos exposure, and bronchoalveolar lavage (BAL) has been proposed to be a good indicator of the presence and quantity of asbestos particles in the lungs. This study evaluated the asbestos concentration in BAL fluids of asbestos-exposed and unexposed pulmonary patients and the environment of Ahvaz city. This prospective study was conducted on 80 patients underwent diagnostic fiberoptic bronchoscopy referred to Imam Khomeini Hospital in Ahvaz, Iran, in 2019. Patients with Lung diseases were divided into three groups based on CT scan results: normal (n = 32), lung cancer (n = 40) and Interstitial lung disease (n = 8). The analysis of asbestos fiber concentration in BAL fluid was carried out by Scanning Electron Microscope (SEM). The positive asbestos test was detected in 69% of all subjects, including 64% of whom had asbestos-related jobs and 74.5% of those with non-related jobs (p = 0.240). The concentrations of asbestos fiber in the BAL in normal patients, lung cancer and interstitial fibrosis (ILD) were 8.13 ± 5.38, 9.66 ± 7.30 and 6.31 ± 1.98 f/ml, respectively (P = 0.492). There was no significant difference between the asbestos levels and exposure history (P = 0.877). The mean concentration of asbestos in the ambient air during the current year was 2.69 ± 0.57 f/ml (2.26-3.70), and the correlation between asbestos levels in BAL and the air was not significant (r = 0.147; P = 0.243). The exposure of different occupational and non-occupational groups to this carcinogenic substance indicates the need for environmental and individual control measures to reduce and prevent asbestos exposure.

Lane Change Control Combined with Ramp Metering: A Strategy to Manage Delays at On-Ramp Merging Sections

Control measures at merging locations aimed at either the mainline traffic or on-ramp traffic do not lead to a fairness in the distribution of total delay across the two streams. This paper presents a control strategy of combining a lane change control with a ramp metering system at motorway merges. The control strategy presents the opportunity to control the delays incurred at the two traffic streams of the merge. An optimization problem is formulated for a multilane motorway with an on-ramp with the aim to minimize the total travel time of the system. The proposed strategy is tested using an incentive-based lane-specific traffic flow model. Results revealed a 17% reduction in the total travel time due to the proposed strategy. Moreover, it was shown that the distribution of delays over the mainline and on-ramp could be controlled via the proposed strategy. The performance of the combined control was also compared to the individual control measures. It was observed that the individual control measures (lane change only and ramp metering only) lead to high delays on either the mainline or on-ramp compared to the combined control, where the balance between the delay for the drivers on the mainline and on-ramp could be regulated. The combined lane change and ramp metering control presents opportunities for the road authorities to manage the total delay distribution across the two traffic streams.

������ ����������� �������� ������� �������

Objective. Research of theoretical bases of an estimation of efficiency of the state financial control. Methods. To achieve this goal, the authors used a systematic approach, methods of analysis, synthesis, comparative legal method and graphical presentation of research results. Results. It was found that the effectiveness of the system of state financial control over the implementation of local budgets is an important problem in the context of decentralization of financial resources of the state. It is established that there is no system of indicators of efficiency of the state financial control both in a part of separate controlling bodies, and control measures which they carry out. Scientific novelty. � set of criteria and indicators aimed at studying the qualitative characteristics of both individual control measures and individual controlling bodies that form the system of public financial control is determined. Practical significance. The expediency of application of the proposed criteria and indicators for assessing the effectiveness of control over the use of funds from local budgets is substantiated. Areas of improvement of control over the use of funds of local budgets. Key words: budget, evaluation system, quantitative indicators, qualitative indicators, evaluation criteria, state financial control.

Studies of COVID-19 Outbreak Control Using Agent-Based Modeling

An agent-based model was developed to study outbreaks and outbreak control for COVID-19, mainly in urban communities. Rules for people’s interactions and virus infectiousness were derived based on previous sociology studies and recently published data-driven analyses of COVID-19 epidemics. The calculated basic reproduction number of epidemics from the developed model coincided with reported values. There were three control measures considered in this paper: social distancing, self-quarantine and community quarantine. Each control measure was assessed individually at first. Later on, an artificial neural network was used to study the effects of different combinations of control measures. To help quantify the impacts of self-quarantine and community quarantine on outbreak control, both were scaled respectively. The results showed that self-quarantine was more effective than the others, but any individual control measure was ineffective in controlling outbreaks in urban communities. The results also showed that a high level of self-quarantine and general community quarantine, assisted with social distancing, would be recommended for outbreak control.

Occupational safety and health status of medical laboratories in Kajiado County, Kenya

IntroductionDespite the increasing interest in Occupational Safety and Health (OSH), seldom studies are available on OSH in medical laboratories from developing countries in general although a high number of injuries occur without proper documentation. It is estimated that every day 6,300 people die as a result of occupational accidents or work-related diseases resulting in over 2.3 million deaths per year. Medical laboratories handle a wide range of materials, potentially dangerous pathogenic agents and exposes health workers to numerous potential hazards. This study evaluated the status of OSH in medical laboratories in Kajiado County, Kenya. The objectives included establishment of biological, chemical and physical hazards; reviewing medical laboratories control measures; and enumerating factors hindering implementation of good practices in OSH.MethodsThis was a cross-sectional descriptive study research design. Observation check lists, interview schedules and structured questionnaires were used. The study was carried out in 108 medical laboratories among 204 sampled respondents. Data was analysed using statistical package for social science (SPSS) 20 software.ResultsThe commonest type of hazards in medical laboratories include; bacteria (80%) for Biological hazards; handling un-labelled and un-marked chemicals (38.2%) for chemical hazards; and laboratory equipment's dangerously placed (49.5%) for Physical hazards. According to Pearson's Product Moment Correlation analysis, not-wearing personal protective equipment's was statistically associated with exposure to hazards. Individual control measures were statistically significant at 0.01 significance level. Only 65.1% of the factors influencing implementation of OSH in medical laboratories were identified.ConclusionTraining has the highest contribution to good OSH practices.

Fatigue in transport: a review of exposure, risks, checks and controls

ABSTRACTHuman fatigue continues to threaten safe transport. There are claims that employers of operators should do more to mitigate the risks, and several regulators are promoting fatigue-risk management in the context of safety management systems (SMS). The current paper reviews fatigue-related risk and exposure factors and control measures for operators of land- and sea-based transport forms. Our review identifies 13 types of measures for the monitoring or control of fatigue risks: optimal staffing; optimal schedule design; optimisation of breaks/naps; monitoring of actual hours worked; optimisation of work content; monitoring and feedback of actual sleep; health screening and treatment; promotion of recovery from work; fitness-for-duty testing; monitoring of fatigue symptoms while operating; control of fatigue while operating; performance monitoring and assistance; and fatigue-proofing. We also identify two systemic measures needed to anchor risk mitigation in SMS: organisational learning and training/other. By structuring monitoring and control measures along Dawson and McCulloch’s [Managing fatigue: It’s about sleep. Sleep Medicine Reviews, 9(5), 365–380] fatigue-risk trajectory, a framework is obtained that acts as a guide for fatigue-risk management by transport employers. To inform transport managers further, evaluations are needed of the effectiveness of individual control measures as well as whole fatigue-risk management interventions.

Control of plant virus diseases in cool-season grain legume crops.

Cool-season grain legume crops become infected with a wide range of viruses, many of which cause serious diseases and major yield losses. This review starts by discussing which viruses are important in the principal cool-season grain legume crops in different parts of the world, the losses they cause and their economic impacts in relation to control. It then describes the main types of control measures available: host resistance, phytosanitary measures, cultural measures, chemical control, and biological control. Examples are provided of successful deployment of the different types of measures to control virus epidemics in cool-season grain legume crops. Next it emphasizes the need for integrated approaches to control because single control measures used alone rarely suffice to adequately reduce virus-induced yield losses in these crops. Development of effective integrated disease management (IDM) strategies depends on an interdisciplinary team approach to (i) understand the ecological and climatic factors which lead to damaging virus epidemics and (ii) evaluate the effectiveness of individual control measures. In addition to using virus-resistant cultivars, other IDM components include sowing virus-tested seed stocks, selecting cultivars with low seed transmission rates, using diverse phytosanitary or cultural practices that minimize the virus source or reduce its spread, and using selective pesticides in an environmentally responsible way. The review finishes by briefly discussing the implications of climate change in increasing problems associated with control and the opportunities to control virus diseases more effectively through new technologies.

Effectiveness of Fortification of Drinking Water with Iron and Vitamin C in the Reduction of Anemia and Improvement of Nutritional Status in Children Attending Day-Care Centers in Belo Horizonte, Brazil

Because of the high prevalence of iron-deficiency anemia in Brazil, individual control measures tend to be ineffective, and fortification of foods with iron is considered the most effective method to fight anemia. To evaluate the effectiveness of fortification of drinking water with iron and vitamin C in the reduction of anemia in children in day-care centers in Belo Horizonte, Brazil. This before-and-after study evaluated 318 children aged 6 to 74 months. Identification data and data on socioeconomic variables were collected; anthropometric and biochemical measurements were performed before and after 5 months of fortification of water with 5 mg of elemental iron and 50 mg of ascorbic acid per liter. The fortified water was used for drinking and cooking at the day-care center. Wilcoxon's nonparametric test was used to evaluate the differences in continuous variables, and McNemar's test was used to compare the prevalence rates of anemia. The prevalence of anemia decreased significantly from 29.3% before fortification to 7.9% at the end of the study, with a significant increase in hemoglobin levels. Reductions in the prevalence rates of stunting and underweight were observed. Fortification of water with iron and vitamin C significantly reduced the prevalence of anemia and improved nutritional status among children attending day-care centers.

Case finding of Influenza A(H1N1)2009 in Belgium in the early pandemic

As soon as a possible worldwide spread of a new Influenza A virus was announced, Belgian health authorities decided to intervene in order to delay the spread of the new virus in the population [1,2]. The delaying strategy started on 26 April 2009 based on a systematic case finding of Influ-enza A(H1N1)2009 in travellers returning from affected areas and their contacts for the purpose of taking individual control measures. From 13 July onwards, the Interministerial Influenza Coordination Committee announced the switch to a mitigation phase [1]. This required appropriate surveillance of influenza-like illnesses. The sentinel general practitioners (SGPs) network for seasonal influenza was reinforced and took over the systematic case finding system [3]. We report on the enhanced case-based surveillance of the first cases of Influenza A(H1N1)2009 up to 13 July 2009 and the subsequent mitigation phase till the start (3 October 2009) of the classical seasonal flu period.

Bovine Fasciolose in der Schweiz: Bedeutung und Bekämpfung

In Switzerland, bovine fasciolosis is an economically important but often overlooked disease of dairy cows. The intermediate host of Fasciola hepatica in Switzerland is Galba truncatula, an amphibious snail living in humid habitats which are infected by miracidia from recently hatched Fasciola eggs. The definitive hosts include cattle, sheep, goats, horses, and free-living ruminants. Infection of these hosts occur from metacercariae, usually encysted on vegetation. Infection risk depends on the location of the habitat on the farm. There is a lower risk for the intermediate host to become infected on pastures for young stock and dry cows than on pastures for dairy cows. This in turn results in a lower infection risk for young stock and dry cows than for dairy cows. When controlling the disease, epidemiologic factors such as treatment and pasture management strategies should be taken into account. If individual control measures are followed, infection pressure and prevalence in a herd can be significantly reduced. To support veterinarians and farmers in the control of fasciolosis, an interactive map showing potential risk areas for fasciolosis was created on the basis of geographical, meteorological, and biological data of the intermediate host and the free-living parasite stages.

Effectiveness of malaria control during changing climate conditions in Eritrea, 1998–2003

To assess the effectiveness of impregnated mosquito nets, indoor residual spraying and larval control relative to the impacts of climate variability in the decline of malaria cases in Eritrea. Monthly data on clinical malaria cases by subzoba (district) in three zobas (zones) of Eritrea for 1998-2003 were used in Poisson regression models to determine whether there is statistical evidence for reduction in cases by DDT, malathion, impregnated nets and larval control used over the period, while analysing the effects of satellite-derived climate variables in the same geographic areas. Both indoor residual spraying (with DDT or malathion) and impregnated nets were independently and significantly negatively associated with reduction in malaria cases, as was larval control in one zoba. Malaria cases were significantly positively related to differences in current and previous months' vegetation (NDVI) anomalies. The relationship to rainfall differences 2 and 3 months previously was also significant, but the direction of the effect varied by zoba. Standardized regression coefficients indicated a greater effect of climate in the zoba with less intense malaria transmission. The results support the view that both indoor residual spraying and impregnated nets have been independently effective against malaria, and that larval control was also effective in one area. Thus climate, while significant, is not the only explanation for the recent decline in malaria cases in Eritrea. If appropriate statistical approaches are used, routine surveillance data from cases attending health facilities can be useful for assessing control programme success and providing estimates of the effectiveness of individual control measures. Effectiveness estimates suitable for use in cost-effectiveness analysis have been obtained.

Linking Ramp Metering and Variable Highway Speed Limits

Pilot schemes for variable speed limits and ramp metering respectively have been implemented on the UK highway network since the mid 1990's. The outcomes of the pilot studies show that these traffic management techniques can assist in the reduction of accidents, traffic congestion and emissions. The performance of these individual control measures may be improved by linking the control of ramp metering and variable speed limits. This paper suggests a new approach using the mainline speed as a control variable and investigates possible benefits and the feasibility of such a system.

Using epidemiological information to develop effective integrated virus disease management strategies

Virus diseases cause serious losses in yield and quality of cultivated plants worldwide. These losses and the resulting financial damage can be limited by controlling epidemics using measures that minimise virus infection sources or suppress virus spread. For each combination of virus, cultivated plant and production system, there is an ‘economic threshold’ above which the financial damage is sufficient to justify using such measures. However, individual measures used alone may bring only small benefits and they may become ineffective, especially over the long term. When diverse control measures that act in different ways are combined and used together, their effects are complementary resulting in far more effective overall control. Such experiences have led to the development of integrated management concepts for virus diseases that combine available host resistance, cultural, chemical and biological control measures. Selecting the ideal mix of measures for each pathosystem and production situation requires detailed knowledge of the epidemiology of the causal virus and the mode of action of each individual control measure so that diverse responses can be devised to meet the unique features of each of the different scenarios considered. The strategies developed must be robust and necessitate minimal extra expense, labour demands and disruption to standard practices. Examples of how epidemiological information can be used to develop effective integrated disease management (IDM) strategies for diverse situations are described. They involve circumstances where virus transmission from plant-to-plant occurs in four different ways: by contact, non-persistently or persistently by insect vectors, and by root-infecting fungi. The examples are: Subterranean clover mottle virus (SCMoV) (contact-transmitted) and Bean yellow mosaic virus (BYMV) (non-persistently aphid-transmitted) in annually self-regenerating clover pasture; three seed-borne viruses (all non-persistently aphid-transmitted) plots of pasture legume improvement programmes; Tomato spotted wilt virus (TSWV) (persistently thrips-transmitted) in vegetables in seedling nurseries, protected cropping or field systems; and lettuce big-vein disease (fungus-transmitted) in lettuce in seedling nursery, hydroponic, infested field or uninfested field situations. By describing the kinds of approaches required, this article is intended to help future research and extension programmes devise integrated disease management strategies that not only function effectively to diminish the losses caused by economically important plant virus diseases but also fulfill the requirement of being environmentally and socially responsible.

Developing Integrated Disease Management Strategies Against Non-persistently Aphid-borne Viruses: A Model Programme

There is a need to develop integrated disease management strategies that are comprehensive and can protect farmers from the economic hardship that arises when epidemics of non-persistently aphid-borne viruses damage their crops. The aim of this review is to provide a model for future programmes to use when developing such strategies for different combinations of non-persistently aphid-borne viruses and crops. The model programme described is a 15-year study to develop integrated management strategies against two non-persistently aphid-borne viruses causing damaging diseases of lupins and to get them adopted by farmers. The success of the programme depended on an interdisciplinary team approach, obtaining a detailed understanding of the factors favouring virus epidemics, field evaluation for virus resistance, and field experiments that determined the effectiveness of individual control measures. The strategies developed were designed to cause few additional labour demands, and minimal disruption to normal farming operations or extra expense.

4. Vector study and vector control in the control of malaria and babesiosis: The current state of studies of malaria vectors and the antivectorial campaign in West Africa

Most malaria transmission in West Africa is by Anopheles funestus and An. gambiae s.l. An. funestus is not very polymorphic and is generally susceptible to currently used insecticides. An. gambiae in contrast is very polymorphic. On the basis of chromosomal polymorphism An. gambiae can be divided into forest and savannah forms. The savannah forms in turn exist as several types, viz. Bissau, Mopti and Bamako. Insecticide susceptibility does not correlate with chromosomal type in most cases; nevertheless, correct identification of vectors is necessary if a successful antimalarial campaign is to be developed. It is particularly important to determine which of the mosquitoes in the region under study are the important vectors of malaria. In the light of the difficulties encountered in mass vector control programmes, individual control measures such as home spraying and use of impregnated bed nets and curtains may be considered for malaria control.

Prevalence of antibodies to toxoplasma in farm animals in the Netherlands and its implication for meat inspection.

A serological survey on toxoplasmosis was carried out amongst horses, sheep, cattle, pigs and poultry in the Netherlands. Sera were obtained from slaughter animals and the results were compared with those of previous studies of this kind in the Netherlands. In horses and cattle the percentage of seropositive animals remained the same in the past 20 years. In sheep and particularly in pigs, however, a remarkable decline of seropositive animals was found. This is probably due to the age of the animals examined and a change in present day methods of farming. In poultry it was shown that only free scratching hens were seropositive in up to 30 per cent of the animals tested, whereas broilers and battery animals were seronegative. Since as yet no individual control measures in the slaughterhouse exist with regard to toxoplasmosis it is recommended to carry out periodic epizootiological surveys amongst farm animals to be able to follow trends of the infection.