scholarly journals A singularly perturbed vector-bias malaria model incorporating bed-net control

2021 ◽  
Author(s):  
Sanaa Salman
Keyword(s):  
Time Scale ◽  
Disease Model ◽  
Perturbation Parameter ◽  
Singularly Perturbed ◽  
Bed Nets ◽  
Bed Net ◽  
Model Dynamics ◽  
Insecticide Treated Bed Nets ◽  
Perturbed Model ◽  
Malaria Model

A malaria transmission disease model with host selectivity and Insecticide treated bed nets (ITNs), as an intervention for controlling the disease, is formulated. Since the vector is an insect, the vector time scale is much more expeditious than the host time scale. This leads to a singularly perturbed model with two distinctive intrinsic time scales, two-slow for the host and one-fast for the vector. The basic reproduction number R0 is calculated and the local stability analysis is performed at equilibria of the model when the perturbation parameter ɛ > 0. The model is analyzed when ɛ → 0 using asymptotic expansions technique. Merging bed-net control, vector-bias, and singular perturbation have a notable effect on the model dynamics. It is shown that if over %30 of humans use ITNs, malaria disease burden can be reduced. The dynamics on the slow surface indicate that the infected vectors decays very fast when ɛ = 0.001 according to the numerical simulations.

scholarly journals Analysis of a malaria model with mosquito host choice and bed-net control

2015 ◽  
Vol 08 (06) ◽  
pp. 1550077 ◽  
Author(s):  
Bruno Buonomo
Keyword(s):  
Reproduction Number ◽  
Host Choice ◽  
Bed Nets ◽  
Bed Net ◽  
Host Manipulation ◽  
Host Preferences ◽  
Insecticide Treated Bed Nets ◽  
The Impact ◽  
Malaria Model ◽  
Disease Free

A malaria model is formulated which includes the enhanced attractiveness of infectious humans to mosquitoes, as result of host manipulation by malaria parasite, and the human behavior, represented by insecticide-treated bed-nets usage. The occurrence of a backward bifurcation at R0 = 1 is shown to be possible, which implies that multiple endemic equilibria co-exist with a stable disease-free equilibrium when the basic reproduction number is less than unity. This phenomenon is found to be caused by disease-induced human mortality. The global asymptotic stability of the endemic equilibrium for R0 > 1 is proved, by using the geometric method for global stability. Therefore, the disease becomes endemic for R0 > 1 regardless of the number of initial cases in both the human and vector populations. Finally, the impact on system dynamics of vector's host preferences and bed-net usage behavior is investigated.

scholarly journals Control measures of malaria transmission in Rwanda based on SEIR SEI mathematical model

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Emmanuel Hakizimana ◽  
Jean Marie Ntaganda
Keyword(s):  
Mathematical Model ◽  
Optimal Control ◽  
Malaria Transmission ◽  
Optimal Control Problems ◽  
Control Strategies ◽  
Control Measures ◽  
Bed Nets ◽  
Infected People ◽  
Insecticide Treated Bed Nets ◽  
Malaria Model

This research paper investigated the dynamics of malaria transmission in Rwanda using the nonlinear forces of infections which are included in SEIR-SEI mathematical model for human and mosquito populations. The mathematical modeling of malaria studies the interaction among the human and mosquito populations in controlling malaria transmission and eventually eliminating malaria infection. This work investigates the optimal control strategies for minimizing the rate of malaria transmission by applying three control variables through Caputo fractional derivative. The optimal control problems for malaria model found the control parameters which minimize infection. The numerical simulation showed that the number of exposed and infected people and mosquito population are decreased due to the control strategies. Finally, this work found out that the transmission of malaria in Rwanda can be minimized by using the combination of controls like Insecticide Treated bed Nets (ITNs), Indoor Residual Spray (IRS) and Artemisinin based Combination Therapies (ACTs).

scholarly journals Host-feeding Preference of Anopheles Species under Prolonged Use of Insecticide-treated Bed Nets in Kamuli District, Uganda: Implications for Vector Control

2020 ◽  
pp. 16-25
Author(s):  
Fredrick G. Kabbale ◽  
Anne M. Akol ◽  
John B. Kaddu ◽  
Enock Matovu ◽  
Anne Kazibwe ◽  
...  
Keyword(s):  
Vector Control ◽  
Blood Meal ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Enzyme Linked Immunosorbent Assay ◽  
Host Feeding ◽  
Bed Net ◽  
Insecticide Treated Bed Nets ◽  
Intervention Zone ◽  
Blood Meals

Background: The blood-feeding patterns are crucial in incriminating disease vectors as well as facilitating the design and consolidation of effective vector control interventions in an area.  Objective: This study aimed to establish if prolonged use of insecticide-treated bed nets (ITNs) caused a shift in the preferred hosts of the common malaria vectors as the hosts were under the bed net. Such a shift would render ITNs less effective and would probably explain the continued morbidity and mortality due to malaria in the highly endemic Kamuli district. Methods: A total of 3,519 indoor and outdoor human biting female Anopheles gambiae sensu lato and An. funestus mosquitoes were collected from 48 households using human-baited bed net traps. All 187 indoor resting blood-fed anophelines collected were tested by direct enzyme-linked immunosorbent assay (ELISA) for blood meal host identification. Of these, 73 mid guts came from 24 households in villages with a 69% ITNs coverage, while 114 mid guts were from 24 households in non-ITN villages. Results: Blood meal hosts were identified in only 10.96% (n = 8) and 14.91% (n = 17) of the Anopheles blood meals from the intervention and non-intervention zones, respectively. Other blood meals could not be clearly identified.  Eight (100%) blood meals in the intervention zone were from humans, while in the non-intervention zone, 15 (88.24%), one (5.88%) and one (5.88%) came from humans, cattle and goat, respectively. These findings demonstrated that the malaria vectors in Kamuli district are anthropophilic, with nearly all the mosquitoes collected from both zones feeding on humans during every blood meal (p = 0.82). This indicated high vector-human contacts, and thus implicating these species as important in the transmission of Plasmodium species and probably other infections. Conclusion: The use of insecticide-treated bed nets is effective for controlling malaria vectors inside houses, evoking universal coverage of houses in the area.

Control of Closed Kinematic Chains Using A Singularly Perturbed Dynamics Model

2005 ◽  
Vol 128 (1) ◽  
pp. 142-151 ◽  
Author(s):  
Zhiyong Wang ◽  
Fathi H. Ghorbel
Keyword(s):  
Kinematic Chain ◽  
Perturbation Parameter ◽  
Parallel Robot ◽  
Differential Algebraic Equations ◽  
Singularly Perturbed ◽  
Algebraic Equations ◽  
Kinematic Chains ◽  
Novel Approach ◽  
Lyapunov Function Method ◽  
Perturbed Model

In this paper, we propose a novel approach to the control of closed kinematic chains (CKCs). This method is based on a recently developed singularly perturbed model for CKCs. Conventionally, the dynamics of CKCs are described by differential-algebraic equations (DAEs). Our approach transfers the control of the original DAE system to the control of an artificially created singularly perturbed system in which the slow dynamics corresponds to the original DAE when the perturbation parameter tends to zero. Compared to control schemes that rely on solving nonlinear algebraic constraint equations, the proposed method uses an ordinary differential equation (ODE) solver to obtain the dependent coordinates, hence, eliminates the need for Newton-type iterations and is amenable to real-time implementation. The composite Lyapunov function method is used to show that the closed-loop system, when controlled by typical open kinematic chain schemes, achieves asymptotic trajectory tracking. Simulations and experimental results on a parallel robot, the Rice planar Delta robot, are also presented to illustrate the efficacy of our method.

scholarly journals A minimal 3D model of mosquito flight behaviour around the human baited bed net

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Jeff Jones ◽  
Gregory P D Murray ◽  
Philip J McCall
Keyword(s):  
Spatial Scales ◽  
Video Tracking ◽  
Sub Saharan Africa ◽  
Bed Nets ◽  
State Transitions ◽  
Bed Net ◽  
Flight Behaviour ◽  
Individual Agent ◽  
Host Seeking ◽  
Mosquito Behaviour

Abstract Background Advances in digitized video-tracking and behavioural analysis have enabled accurate recording and quantification of mosquito flight and host-seeking behaviours, facilitating development of individual (agent) based models at much finer spatial scales than previously possible. Methods Quantified behavioural parameters were used to create a novel virtual testing model, capable of accurately simulating indoor flight behaviour by a virtual population of host-seeking mosquitoes as they interact with and respond to simulated stimuli from a human-occupied bed net. The model is described, including base mosquito behaviour, state transitions, environmental representation and host stimulus representation. Results In the absence of a bed net and human host bait, flight distribution of the model population was relatively uniform throughout the arena. Introducing an unbaited untreated bed net induced a change in distribution with an increase in landing events on the net surface, predominantly on the sides of the net. Adding the presence of a simulated human bait dramatically impacted flight distribution patterns, exploratory foraging and, the number and distribution of landing positions on the net, which were determined largely by the orientation of the human within. The model replicates experimental results with free-flying living mosquitoes at human-occupied bed nets, where contact occurs predominantly on the top surface of the net. This accuracy is important as it quantifies exposure to the lethal insecticide residues that may be unique to the net roof (or theoretically any other surface). Number of net contacts and height of contacts decreased with increasing attractant dispersal noise. Conclusions Results generated by the model are an accurate representation of actual mosquito behaviour recorded at and around a human-occupied bed net in untreated and insecticide-treated nets. This fine-grained model is highly flexible and has significant potential for in silico screening of novel bed net designs, potentially reducing time and cost and accelerating the deployment of new and more effective tools for protecting against malaria in sub-Saharan Africa.

scholarly journals Analysis of Immunity to Febrile Malaria in Children That Distinguishes Immunity from Lack of Exposure

2009 ◽  
Vol 77 (5) ◽  
pp. 1917-1923 ◽  
Author(s):  
Philip Bejon ◽  
George Warimwe ◽  
Claire L. Mackintosh ◽  
Margaret J. Mackinnon ◽  
Sam M. Kinyanjui ◽  
...  
Keyword(s):  
Cell Surface ◽  
Antibody Response ◽  
Observational Studies ◽  
Asymptomatic Infection ◽  
Bed Nets ◽  
Bed Net ◽  
Red Cell ◽  
Vaccine Trials ◽  
Net Use ◽  
Malaria Episodes

ABSTRACT In studies of immunity to malaria, the absence of febrile malaria is commonly considered evidence of “protection.” However, apparent “protection” may be due to a lack of exposure to infective mosquito bites or due to immunity. We studied a cohort that was given curative antimalarials before monitoring began and documented newly acquired asymptomatic parasitemia and febrile malaria episodes during 3 months of surveillance. With increasing age, there was a shift away from febrile malaria to acquiring asymptomatic parasitemia, with no change in the overall incidence of infection. Antibodies to the infected red cell surface were associated with acquiring asymptomatic infection rather than febrile malaria or remaining uninfected. Bed net use was associated with remaining uninfected rather than acquiring asymptomatic infection or febrile malaria. These observations suggest that most uninfected children were unexposed rather than “immune.” Had they been immune, we would have expected the proportion of uninfected children to rise with age and that the uninfected children would have been distinguished from children with febrile malaria by the protective antibody response. We show that removing the less exposed children from conventional analyses clarifies the effects of immunity, transmission intensity, bed nets, and age. Observational studies and vaccine trials will have increased power if they differentiate between unexposed and immune children.

scholarly journals Bio-efficacy of new long-lasting insecticide-treated bed nets against Anopheles funestus and Anopheles gambiae from central and northern Mozambique

2015 ◽  
Vol 14 (1) ◽  
Author(s):  
Ana Paula Abílio ◽  
Pelágio Marrune ◽  
Nilsa de Deus ◽  
Francisco Mbofana ◽  
Pedro Muianga ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
Anopheles Funestus ◽  
Bed Nets ◽  
Insecticide Treated Bed Nets
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