scholarly journals The impact of adaptive mosquito behavior and insecticide-treated nets on malaria prevalence

2020 ◽  
Author(s):  
Calistus N. Ngonghala ◽  
Josephine Wairimu ◽  
Jesse Adamski ◽  
Hardik Desai
Keyword(s):  
Disease Control ◽  
Malaria Prevalence ◽  
Sub Saharan Africa ◽  
Chemical Degradation ◽  
Bed Nets ◽  
Bed Net ◽  
Insecticide Treated Nets ◽  
Net Use ◽  
Endemic Areas ◽  
The Impact

AbstractMalaria prevalence in sub-Saharan Africa remains high. Kenya for example, records about 3.5 million new cases and 11 thousand deaths each year [1]. Most of these cases and deaths are among children under five. The main control method in malaria endemic regions has been through the use of pyrethroid-treated bed nets. Although this approach has been fairly successful, the gains are threatened by mosquito-resistance to pyrethroids, physical and chemical degradation of ITNs that reduce their efficacy, inconsistent and improper use by humans, etc. We present a model to investigate the effects of insecticide-treated bed-net use and mosquito-resistance and adaptation to pyrethroids used to treat bed nets on malaria prevalence and control in malaria endemic regions. The model captures the development and loss of resistance to insecticides, the effects of bed-net use on malaria control in a setting where proper and consistent use is not guaranteed, as well as differentiated biting of human hosts by resistant and sensitive mosquitoes. Important thresholds, including the basic reproduction number R0, and two parameter groupings that are important for disease control and for establishing the existence of endemic equilibria to the model are calculated. Furthermore, a global sensitivity analysis is carried out to identify important parameters such as insecticide treated bed-net coverage, insecticide treated bed-net efficacy, the maximum biting rate of resistant mosquitoes, etc., that drive the system and that can be targeted for disease control. Threshold levels of bed-net coverage and bed-net efficacy required for containing the disease are identified and shown to depend on the type of insecticide-resistance. For example, when mosquito-resistance to insecticides is not permanent and is acquired only through recruitment and the efficacy of insecticide-treated nets is 90%, about 70% net coverage is required to contain malaria. However, for the same insecticide-treated net efficacy, i.e., 90%, approximately 93% net coverage is required to contain the disease when resistance to insecticides is permanent and is acquired through recruitment and mutation in mosquitoes. The model exhibits a backward bifurcation, which implies that simply reducing R0 slightly below unity might not be enough to contain the disease. We conclude that appropriate measures to reduce or eliminate mosquito-resistance to insecticides, ensure that more people in endemic areas own and use insecticide-treated nets properly, and that the efficacy of these nets remain high most of the times, as well as educating populations in malaria endemic areas on how to keep mosquito densities low and minimize mosquito bites are important for containing malaria.

scholarly journals IMPACT OF ADAPTIVE MOSQUITO BEHAVIOR AND INSECTICIDE-TREATED NETS ON MALARIA PREVALENCE

2020 ◽  
Vol 28 (02) ◽  
pp. 515-542
Author(s):  
CALISTUS N. NGONGHALA ◽  
JOSEPHINE WAIRIMU ◽  
JESSE ADAMSKI ◽  
HARDIK DESAI
Keyword(s):  
Disease Control ◽  
Control Method ◽  
Malaria Prevalence ◽  
Sub Saharan Africa ◽  
Chemical Degradation ◽  
Bed Nets ◽  
Insecticide Treated Nets ◽  
Itn Use ◽  
Endemic Areas ◽  
Sub Saharan

Malaria prevalence in sub-Saharan Africa remains high. Kenya for example, records about 3.5 million new cases and 11 thousand deaths each year.1 Most of these cases and deaths are among children under five. The main control method in malaria endemic regions has been through the use of insecticide-treated nets (ITNs). Although this approach has been fairly successful, the gains are threatened by mosquito-resistance to pyrethroids (insecticides on nets), physical and chemical degradation of ITNs that reduce their efficacy, inconsistent and improper use by humans, etc. We present a model to investigate the effects of ITN use and mosquito-resistance and adaptation to pyrethroids used to treat bed nets on malaria prevalence and control in malaria endemic regions. The model captures the development and loss of resistance to insecticides, the effects of ITN use on malaria control in a setting where proper and consistent use is not guaranteed, as well as differentiated biting of human hosts by resistant and sensitive mosquitoes. Important thresholds, including the basic reproduction number [Formula: see text], and two parameter groupings that are important for disease control and for establishing the existence of endemic equilibria to the model are calculated. Furthermore, a global sensitivity analysis is carried out to identify important parameters such as insecticide treated bed-net coverage, ITN, the maximum biting rate of resistant mosquitoes, etc., that drive the system and that can be targeted for disease control. Threshold levels of ITN coverage and ITN efficacy required for containing the disease are identified and shown to depend on the type of insecticide-resistance. For example, when mosquito-resistance to insecticides is not permanent and is acquired only through recruitment and the efficacy of ITNs is [Formula: see text], about [Formula: see text] net coverage is required to contain malaria. However, for the same ITN efficacy, i.e., [Formula: see text], approximately [Formula: see text] net coverage is required to contain the disease when resistance to insecticides is permanent and is acquired through recruitment and mutation in mosquitoes. The model exhibits a backward bifurcation, which implies that simply reducing [Formula: see text] slightly below unity might not be enough to contain the disease. We conclude that appropriate measures to reduce or eliminate mosquito-resistance to insecticides, ensure that more people in endemic areas own and use ITNs properly, and that the efficacy of these nets remain high most of the time, as well as educating populations in malaria endemic areas on how to keep mosquito densities low and minimize mosquito bites are important for containing malaria.

scholarly journals The impact of bed-net use on malaria prevalence

2013 ◽  
Vol 320 ◽  
pp. 58-65 ◽  
Author(s):  
Folashade B. Agusto ◽  
Sara Y. Del Valle ◽  
Kbenesh W. Blayneh ◽  
Calistus N. Ngonghala ◽  
Maria J. Goncalves ◽  
...  
Keyword(s):  
Malaria Prevalence ◽  
Bed Net ◽  
Net Use ◽  
The Impact

scholarly journals Ownership and disuse of bed nets in Kenyan children under five years of age

2012 ◽  
Vol 2 (1) ◽  
pp. 1 ◽  
Author(s):  
Kacey Ernst ◽  
Mona Arora ◽  
Stephen Munga
Keyword(s):  
Rural Communities ◽  
Marital Status ◽  
Health Survey ◽  
Demographic And Health Survey ◽  
Bed Nets ◽  
Bed Net ◽  
Insecticide Treated Nets ◽  
Under Five ◽  
Net Use ◽  
Llin Use

Recent campaigns to increase the percentage of households owning a bed net have been very successful yet there remains a subset of the population who do not sleep under bed nets. We used data from the 2008 Kenya Demographic and Health Survey (KDHS) to compare children under the age of five years of age who slept under any bed net to children sleeping without a bed net who resided in households with: i) no bed net; ii) all bed nets used (intra-household access); and iii) at least one unused bed net. Ownership, intra-household access, and non-use of available bed nets were all associated with the child’s age and the mother’s relationship to the head of the household. Intra-household access was strongly associated with provincial residence, where the child was born and frequency of reading newspapers. Furthermore, disuse of available nets for children was associated with marital status, bed net use of the head of the household, and residing in rural communities at higher elevations. Improving bed net/long-lasting insecticide treated nets (LLIN) use in Kenya requires a multi-faceted approach that addresses the complexity of the behavioral, social and economic drivers of non-use.

scholarly journals Modeling the Impact of Bed-Net Use and Treatment on Malaria Transmission Dynamics

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Bello Gimba ◽  
Saminu Iliyasu Bala
Keyword(s):  
Sensitivity Analysis ◽  
Malaria Transmission ◽  
Intervention Strategy ◽  
Transmission Dynamics ◽  
Necessary Condition ◽  
Bed Nets ◽  
Bed Net ◽  
Net Use ◽  
Biting Rate ◽  
The Impact

We modeled the impact of bed-net use and insecticide treated nets (ITNs), temperature, and treatment on malaria transmission dynamics using ordinary differential equations. To achieve this we formulated a simple model of mosquito biting rate that depends on temperature and usage of insecticides treated bed nets. We conducted global uncertainty and sensitivity analysis using Latin Hypercube Sampling (LHC) and Partial Rank Correlation Coefficient (PRCC) in order to find the most effective parameters that affect malaria transmission dynamics. We established the existence of the region where the model is epidemiologically feasible. We conducted the stability analysis of the disease-free equilibrium by the threshold parameter. We found the condition for the existence of the endemic equilibrium and provided necessary condition for its stability. Our results show that the peak of mosquitoes biting rate occurs at a range of temperature values not on a single value as previously reported in literature. The results also show that the combination of treatment and ITNs usage is the most effective intervention strategy towards control and eradication of malaria transmissions. Sensitivity analysis results indicate that the biting rate and the mosquitoes death rates are the most important parameters in the dynamics of malaria transmission.

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 Cross-Study of Malaria Prevalence in History, Bed Net Utilization, and Knowledge about the Disease among Tanzanian College Students

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Yakobo Nyahoga ◽  
Zanda Bochkaeva
Keyword(s):  
Malaria Prevention ◽  
Cross Sectional Study ◽  
Malaria Prevalence ◽  
Bed Nets ◽  
Bed Net ◽  
Prevention Measures ◽  
Cross Sectional ◽  
University Campuses ◽  
High Prevalence ◽  
Two Factors

University campuses are potential reservoirs of infectious diseases, but they are not in the research focus. It is obvious that the use of malaria preventive tools is extremely necessary in campus conditions in endemic countries. This study is the first malaria survey, conducted in a student campus in Tanzania. This cross-sectional study uncovered a surprisingly high prevalence of malaria history among students: 89,4% of 246 random respondents assume that they had malaria in history, among whom 145 (58,9%) suffered from the disease during the last year. And although students are relatively confident about the vector, parasite, and prevention measures of the disease, only 44,7% of the students use bed nets and 4,5% use a body spray or ointment daily. The others seldom use spray or ointment or do not care about the problem at all. This situation was found to be associated with two factors, financial and educational. Current results show that students are relatively educated on malaria, but they do not follow the malaria prevention guidance. It has become clear that at least proper informational propaganda of bed net use is required in Tanzanian university campuses.

scholarly journals Use of Bed Nets and Factors That Influence Bed Net Use among Jinuo Ethnic Minority in Southern China

PLoS ONE ◽  
2014 ◽  
Vol 9 (7) ◽  
pp. e103780 ◽  
Author(s):  
Jian-wei Xu ◽  
Yuan-mei Liao ◽  
Hui Liu ◽  
Ren-hua Nie ◽  
Joshua Havumaki
Keyword(s):  
Ethnic Minority ◽  
Southern China ◽  
Bed Nets ◽  
Bed Net ◽  
Net Use

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.

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