scholarly journals Connectivity sustains disease transmission in environments with low potential for endemicity: modelling schistosomiasis with hydrologic and social connectivities

2008 ◽  
Vol 6 (35) ◽  
pp. 495-508 ◽  
Author(s):  
David Gurarie ◽  
Edmund Y.W. Seto
Keyword(s):  
Mathematical Model ◽  
Disease Transmission ◽  
Parasitic Diseases ◽  
Parasite Control ◽  
Optimum Control ◽  
Social Contacts ◽  
Transport Pathways ◽  
High Infection ◽  
Metapopulation Models ◽  
Host Movement

Social interaction and physical interconnections between populations can influence the spread of parasites. The role that these pathways play in sustaining the transmission of parasitic diseases is unclear, although increasingly realistic metapopulation models are being used to study how diseases persist in connected environments. We use a mathematical model of schistosomiasis transmission for a distributed set of heterogeneous villages to show that the transport of parasites via social (host movement) and environmental (parasite larvae movement) pathways has consequences for parasite control, spread and persistence. We find that transmission can be sustained regionally throughout a group of connected villages even when individual village conditions appear not to support endemicity. Optimum transmission is determined by an interplay between different transport pathways, and not necessarily by those that are the most dispersive (e.g. disperse social contacts may not be optimal for transmission). We show that the traditional targeting of villages with high infection, without regard to village interconnections, may not lead to optimum control. These findings have major implications for effective disease control, which needs to go beyond considering local variations in disease intensity, to also consider the degree to which populations are interconnected.

scholarly journals Addressing the COVID-19 transmission in inner Brazil by a mathematical model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
G. B. Almeida ◽  
T. N. Vilches ◽  
C. P. Ferreira ◽  
C. M. C. B. Fortaleza
Keyword(s):  
Mathematical Model ◽  
Disease Transmission ◽  
Abiotic Factors ◽  
Severe Pneumonia ◽  
Mitigation Strategies ◽  
Social Distancing ◽  
Control Disease ◽  
Set Up ◽  
Novel Coronavirus ◽  
Public Health Strategies

AbstractIn 2020, the world experienced its very first pandemic of the globalized era. A novel coronavirus, SARS-CoV-2, is the causative agent of severe pneumonia and has rapidly spread through many nations, crashing health systems and leading a large number of people to death. In Brazil, the emergence of local epidemics in major metropolitan areas has always been a concern. In a vast and heterogeneous country, with regional disparities and climate diversity, several factors can modulate the dynamics of COVID-19. What should be the scenario for inner Brazil, and what can we do to control infection transmission in each of these locations? Here, a mathematical model is proposed to simulate disease transmission among individuals in several scenarios, differing by abiotic factors, social-economic factors, and effectiveness of mitigation strategies. The disease control relies on keeping all individuals’ social distancing and detecting, followed by isolating, infected ones. The model reinforces social distancing as the most efficient method to control disease transmission. Moreover, it also shows that improving the detection and isolation of infected individuals can loosen this mitigation strategy. Finally, the effectiveness of control may be different across the country, and understanding it can help set up public health strategies.

Arthrocladiella mougeotii. [Descriptions of Fungi and Bacteria].

1998 ◽  
Author(s):  
V. P. Heluta
Keyword(s):  
Czech Republic ◽  
Geographical Distribution ◽  
Disease Transmission ◽  
Russian Far East ◽  
Far East ◽  
Republic Of Georgia ◽  
Lycium Barbarum ◽  
Initial Stage ◽  
High Infection

Abstract A description is provided for Arthrocladiella mougeotii. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Powdery mildew of Lycium species only. The mycelium, conidiophores, conidia and ascomata form first white, then dirty-grey patches on damaged green parts of the host. Infected parts are deformed slightly and, in cases of high infection, plants can lose their ornamental qualities. Damaged leaves can fall prematurely. HOSTS: Lycium barbarum (= L. europaeum), L. chinense, L. dasystemum, L. halimifolium, L. ovatum, L. potaninii, L. rhombifolium, L. ruthenicum. [Type host - Lycium barbarum] GEOGRAPHICAL DISTRIBUTION: Africa: Canary Islands. Asia (temperate areas only): Armenia, Azerbaijan, China, Republic of Georgia, Israel, Japan, Kazakhstan, Kirghizistan, Korea, Russia (Russian far east), Tadzhikistan, Taiwan, Turkey, Turkmenistan, Uzbekistan. Australasia: New Zealand (introduced). Europe: Austria, Belgium, Bulgaria, Czech Republic, Estonia, France, Germany, Hungary, Italy, Netherlands, Norway, Poland, Rumania, Slovakia, Sweden, Switzerland, UK, Ukraine (southern), former Yugoslavia. North America: USA (introduced). TRANSMISSION: By wind-dispersed conidia. The rôle of ascospores in disease transmission is unknown, although it has been supposed that they can cause the initial stage of the disease.

Movement Time to an Array of Controls

1993 ◽  
Vol 37 (9) ◽  
pp. 625-629 ◽  
Author(s):  
Errol R. Hoffmann
Keyword(s):  
Mathematical Model ◽  
Theoretical Result ◽  
Movement Time ◽  
Element Model ◽  
Optimum Control ◽  
Fitts Law ◽  
Model Based ◽  
Array Density

Two tasks in which subjects aim at an array of devices were considered: moving to one knob within an array and moving the finger on a numeric keypad. It was shown by a mathematical model based on Fitts' law, that when the array density is specified for the array of knobs or keys, there is an optimum control size for minimum movement time. The theoretical result was obtained by considering a two-element model of the movement, the first being a reach to the general location of the control and the second describing the insertion of the fingers into the space between adjacent controls. As the first element has a movement time that decreases with increase of control size and the second a time increasing with control size, there is an optimum control size where the movement time is a minimum.

scholarly journals Estimasi Reproduction Number Model Matematika Penyebaran Malaria di Sumba Tengah, Indonesia

2021 ◽  
Vol 2 (1) ◽  
pp. 13-19
Author(s):  
Ervin Mawo Banni ◽  
Maria A Kleden ◽  
Maria Lobo ◽  
Meksianis Zadrak Ndii
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Health Center ◽  
Disease Transmission ◽  
Reproduction Number ◽  
Transmission Dynamics ◽  
Awareness Program ◽  
Awareness Programs ◽  
Malaria Eradication

Malaria is transmitted via a bite of mosquitoes and it is dangerous if it is not properly treated. Mathematical modeling can be formulated to understand the disease transmission dynamics. In this paper, a mathematical model with an awareness program has been formulated and the reproduction number has been estimated against the data from Weeluri Health Center, Mamboro District, Central Sumba. The calculation showed that the reproduction number is R0 = 1.2562. Results showed that if the efficacy of the awareness program is lower than 20%, the reproduction number is still above unity. If the efficacy of the awareness program is higher than 20%, the reproduction number is lower than unity. This implies that the efficacy of awareness programs is the key to the success of Malaria eradication.

scholarly journals A mathematical model of infectious disease transmission

2020 ◽  
Vol 34 ◽  
pp. 02002
Author(s):  
Aurelia Florea ◽  
Cristian Lăzureanu
Keyword(s):  
Infectious Disease ◽  
Mathematical Model ◽  
Nonlinear System ◽  
Numerical Simulations ◽  
Disease Transmission ◽  
Three Dimensional ◽  
Type System ◽  
Epidemic Disease ◽  
Infectious Disease Transmission ◽  
The Stability

In this paper we consider a three-dimensional nonlinear system which models the dynamics of a population during an epidemic disease. The considered model is a SIS-type system in which a recovered individual automatically becomes a susceptible one. We take into account the births and deaths, and we also consider that susceptible individuals are divided into two groups: non-vaccinated and vaccinated. In addition, we assume a medical scenario in which vaccinated people take a special measure to quarantine their newborns. We study the stability of the considered system. Numerical simulations point out the behavior of the considered population.

Assessing the impact of agrochemicals on schistosomiasis transmission: A mathematical study

2021 ◽  
pp. 2150049
Author(s):  
Liming Cai ◽  
Peixia Yue ◽  
Mini Ghosh ◽  
Xuezhi Li
Keyword(s):  
Mathematical Model ◽  
Sensitivity Analysis ◽  
Numerical Simulations ◽  
Disease Transmission ◽  
Agricultural Pollution ◽  
Parasitic Disease ◽  
Mathematical Study ◽  
Proposed Model ◽  
Existence And Stability ◽  
The Impact

Schistosomiasis is a snail-borne parasitic disease, which is affecting almost 240 million people worldwide. The number of humans affected by schistosomiasis is continuously increasing with the rise in the use of agrochemicals. In this paper, a mathematical model is formulated and analyzed to assess the effect of agrochemicals on the transmission of schistosomiasis. The proposed model incorporates the effects of fertilizers, herbicides and insecticides on susceptible snails and snail predators along with schistosomiasis disease transmission. The existence and stability of the equilibria in the model are discussed. Sensitivity analysis is performed to identify the key parameters of the proposed model, which contributes most in the transmission of this disease. Numerical simulations are also performed to assess the impact of fertilizers, herbicides and insecticides on schistosomiasis outbreaks. Our study reveals that the agricultural pollution can enhance the transmission intensity of schistosomiasis, and in order to prevent the outbreak of schistosomiasis, the use of pesticides should be controlled.

scholarly journals Modelling Excess Mortality in Covid-19-Like Epidemics

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1236
Author(s):  
Zdzislaw Burda
Keyword(s):  
Disease Transmission ◽  
Mitigation Strategies ◽  
System Capacity ◽  
Infectious Period ◽  
Cumulative Number ◽  
Epidemic Spreading ◽  
Social Contacts ◽  
Local Modes ◽  
Hybrid Strategy ◽  
The Usa

We develop an agent-based model to assess the cumulative number of deaths during hypothetical Covid-19-like epidemics for various non-pharmaceutical intervention strategies. The model simulates three interrelated stochastic processes: epidemic spreading, availability of respiratory ventilators and changes in death statistics. We consider local and non-local modes of disease transmission. The first simulates transmission through social contacts in the vicinity of the place of residence while the second through social contacts in public places: schools, hospitals, airports, etc., where many people meet, who live in remote geographic locations. Epidemic spreading is modelled as a discrete-time stochastic process on random geometric networks. We use the Monte–Carlo method in the simulations. The following assumptions are made. The basic reproduction number is R0=2.5 and the infectious period lasts approximately ten days. Infections lead to severe acute respiratory syndrome in about one percent of cases, which are likely to lead to respiratory default and death, unless the patient receives an appropriate medical treatment. The healthcare system capacity is simulated by the availability of respiratory ventilators or intensive care beds. Some parameters of the model, like mortality rates or the number of respiratory ventilators per 100,000 inhabitants, are chosen to simulate the real values for the USA and Poland. In the simulations we compare ‘do-nothing’ strategy with mitigation strategies based on social distancing and reducing social mixing. We study epidemics in the pre-vacine era, where immunity is obtained only by infection. The model applies only to epidemics for which reinfections are rare and can be neglected. The results of the simulations show that strategies that slow the development of an epidemic too much in the early stages do not significantly reduce the overall number of deaths in the long term, but increase the duration of the epidemic. In particular, a hybrid strategy where lockdown is held for some time and is then completely released, is inefficient.

scholarly journals Spatial Heterogeneity, Host Movement and Mosquito-Borne Disease Transmission

PLoS ONE ◽  
2015 ◽  
Vol 10 (6) ◽  
pp. e0127552 ◽  
Author(s):  
Miguel A. Acevedo ◽  
Olivia Prosper ◽  
Kenneth Lopiano ◽  
Nick Ruktanonchai ◽  
T. Trevor Caughlin ◽  
...  
Keyword(s):  
Spatial Heterogeneity ◽  
Disease Transmission ◽  
Host Movement

scholarly journals Investigating the Role of Environmental Transmission in COVID-19 Dynamics: A Mathematical Model Based Study

2020 ◽  
Author(s):  
Ibrahim M. ELmojtaba ◽  
Fatma Al-Musalhi ◽  
Asma Al-Ghassani ◽  
Nasser Al-Salti
Keyword(s):  
Mathematical Model ◽  
Disease Transmission ◽  
Reproduction Number ◽  
Equilibrium Points ◽  
Transmission Dynamics ◽  
Model Parameters ◽  
Environmental Transmission ◽  
Estimated Parameters ◽  
Existence And Stability

Abstract A mathematical model with environmental transmission has been proposed and analyzed to investigate its role in the transmission dynamics of the ongoing COVID-19 outbreak. Two expressions for the basic reproduction number R0 have been analytically derived using the next generation matrix method. The two expressions composed of a combination of two terms related to human to human and environment to human transmissions. The value of R0 has been calculated using estimated parameters corresponding to two datasets. Sensitivity analysis of the reproduction number to the corresponding model parameters has been carried out. Existence and stability analysis of disease free and endemic equilibrium points have been presented in relation with the obtained expressions of R0. Numerical simulations to demonstrate the effect of some model parameters related to environmental transmission on the disease transmission dynamics have been carried out and the results have been demonstrated graphically.

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