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 A minimal 3D model of mosquito flight behavior around the human baited bed net

2020 ◽  
Author(s):  
Jeff Jones ◽  
Greg Murray ◽  
Philip J McCall
Keyword(s):  
Spatial Scales ◽  
Video Tracking ◽  
Sub Saharan Africa ◽  
Flight Behavior ◽  
State Transitions ◽  
Bed Net ◽  
Insecticide Treated Nets ◽  
Individual Agent ◽  
Host Seeking ◽  
Mosquito Behavior

AbstractAdvances in digitized video-tracking and behavioral analysis have enabled accurate recording and quantification of mosquito flight and host-seeking behaviors, enabling development of Individual (agent) Based Models at much finer spatial scales than previously possible. We used such quantified behavioral parameters to create a novel virtual testing model, capable of accurately simulating indoor flight behavior by a virtual population of host-seeking mosquitoes as it interacts with and responds to simulated stimuli from a human-occupied bed net. We describe the model, including base mosquito behavior, state transitions, environmental representation and host stimulus representation. In the absence of a bed net and human bait, flight distribution of the model population is relatively uniform in the arena. Introducing an unbaited net induces a change in distribution due to landing events on the net surface, predominantly occurring on the sides and edges of the net. Presence of simulated human baited net strongly impacted flight distribution patterns, exploratory foraging, the number and distribution of net landing sites, depending on the bait orientation. As recorded in live mosquito experiments, contact with baited nets (a measure of exposure to the lethal insecticide) occurred predominantly on the top surface of the net. Number of net contacts and height of contacts decreased with increasing attractant dispersal noise. Results generated by the model are an accurate representation of actual mosquito behavior recorded at and around a human-occupied bed net in untreated and insecticide treated nets. In addition to providing insights into host-seeking behavior of endophilic vectors, this fine-grained model is highly flexible and has significant potential for in silico screening of novel bed net designs, accelerating the deployment of new and more effective tools for protecting against malaria in sub-Saharan Africa.

scholarly journals A novel video-tracking system to quantify the behaviour of nocturnal mosquitoes attacking human hosts in the field

2016 ◽  
Vol 13 (117) ◽  
pp. 20150974 ◽  
Author(s):  
N. C. Angarita-Jaimes ◽  
J. E. A. Parker ◽  
M. Abe ◽  
F. Mashauri ◽  
J. Martine ◽  
...  
Keyword(s):  
Tracking System ◽  
Adult Life ◽  
Field Tests ◽  
Video Tracking ◽  
Bed Net ◽  
Natural Habitats ◽  
Processing Strategies ◽  
Mosquito Behaviour ◽  
Irradiance Data ◽  
Video Tracking System

Many vectors of malaria and other infections spend most of their adult life within human homes, the environment where they bloodfeed and rest, and where control has been most successful. Yet, knowledge of peri-domestic mosquito behaviour is limited, particularly how mosquitoes find and attack human hosts or how insecticides impact on behaviour. This is partly because technology for tracking mosquitoes in their natural habitats, traditional dwellings in disease-endemic countries, has never been available. We describe a sensing device that enables observation and recording of nocturnal mosquitoes attacking humans with or without a bed net, in the laboratory and in rural Africa. The device addresses requirements for sub-millimetre resolution over a 2.0 × 1.2 × 2.0 m volume while using minimum irradiance. Data processing strategies to extract individual mosquito trajectories and algorithms to describe behaviour during host/net interactions are introduced. Results from UK laboratory and Tanzanian field tests showed that Culex quinquefasciatus activity was higher and focused on the bed net roof when a human host was present, in colonized and wild populations. Both C. quinquefasciatus and Anopheles gambiae exhibited similar behavioural modes, with average flight velocities varying by less than 10%. The system offers considerable potential for investigations in vector biology and many other fields.

scholarly journals Long Lasting Insecticide-treated Bed Net Ownership, Utilization and Associated Factors Among School-age Children in Dara Mallo and Uba Debretsehay Districts, Southern Ethiopia

2020 ◽  
Author(s):  
Zerihun Zerdo ◽  
Hilde Bastiaens ◽  
Sibyl Anthierens ◽  
Fekadu Massebo ◽  
Matios Masine ◽  
...  
Keyword(s):  
Controlled Trial ◽  
Statistical Significance ◽  
Malaria Prevention ◽  
Education Level ◽  
Sub Saharan Africa ◽  
School Age Children ◽  
Bed Nets ◽  
Southern Ethiopia ◽  
Bed Net ◽  
Previous Night

Abstract Background Malaria is one of the major causes of morbidity and mortality among school-aged children (SAC) in Sub-Saharan Africa. SAC account for more than 60% of the reservoir of malaria transmission, but they were given less emphasis on prioritizing malaria prevention interventions. This study was aimed at assessing the ownership of bed nets, its utilization and factors associated with ownership of bed nets by households and bed net utilization among SAC in malaria prone areas of Dara Mallo and Uba Debretsehay districts in Southern Ethiopia, October to December 2019. Methods This study is part of baseline assessment in a cluster randomized controlled trial. The data were collected through interview and observation following structured questionnaire from 2261 SAC households. Univariable and multivariable logistic regressions were used to assess the association between bed net ownership or utilization and potential predictor variables. Odds Ratio (OR) and corresponding 95% Confidence Interval (CI) were used to determine the strength and statistical significance of association. Results The ownership of at least one bed net by households of SAC was about 19.3% (95% CI: 17.7%-21.0%). It was affected by living in altitude ranged from 1100 to 1250 meters above sea level with Adjusted OR (AOR) of 0.5 (95%CI: 0.3–0.9) and presence of child age less than 5 years (AOR = 2.1; 95%CI: 1.2–3.7). About 7.8% (95% CI: 6.7%-10.0%) of all SAC participated in the study and 40.4% (95% CI: 57.4% − 66.7%) of children in households owning at bed net passed the previous night under bed net. Bed net utilization by SAC conditional to its presence was lower among children age > 9 years (AOR = 0.2; 95%CI: 0.03–0.8); higher in children with mothers who had an education level above grade six (AOR = 5.2; 95%CI: 1.8–17.0); and when the household size to bed net ratio was ≤ 2 (AOR = 37.8; 95%CI: 4.1–1106). Conclusion Ownership of bed net was lower than universal coverage of at least one bed net for two individuals. It is important to monitor replacement needs and educate mothers with low education level and their SAC on the benefit of consistent utilization of bed nets.

scholarly journals Long-lasting insecticide-treated bed net ownership, utilization and associated factors among school-age children in Dara Mallo and Uba Debretsehay districts, Southern Ethiopia

2020 ◽  
Author(s):  
Zerihun Zerdo ◽  
Hilde Bastiaens ◽  
Sibyl Anthierens ◽  
Fekadu Massebo ◽  
Matios Masine ◽  
...  
Keyword(s):  
Controlled Trial ◽  
Statistical Significance ◽  
Household Head ◽  
Education Level ◽  
Sub Saharan Africa ◽  
School Age Children ◽  
Bed Nets ◽  
Southern Ethiopia ◽  
Bed Net ◽  
School Age

Abstract Background Malaria is one of the major causes of morbidity and mortality among school-age children (SAC) in sub-Saharan Africa. SAC account for more than 60% of the reservoir of malaria transmission, but they are given less emphasis in prioritizing malaria prevention interventions. This study was aimed at assessing the ownership of long-lasting insecticide treated bed nets (LLINs), its utilization and factors associated with ownership of LLINs by households and LLINs utilization among SAC in malaria-prone areas of Dara Mallo and Uba Debretsehay districts in Southern Ethiopia, October to December 2019. Methods This study is part of a baseline assessment in a cluster-randomized controlled trial. The data was collected through interview and observation, following a structured questionnaire, of 2,261 SAC households. Univariable and multivariable multilevel logistic regressions were used to assess the association between LLINs ownership and utilization and potential predictor variables. Odds ratio (OR) and corresponding 95% confidence interval (CI) were used to determine the strength and statistical significance of association.Results The ownership of at least one LLIN by households of SAC was about 19.3% (95% CI: 17.7-21.0%) but only 10.3% % (95% CI: 7.7-13.7%) of these households had adequate access of bed nets to the household members. Ownership of bed net was marginally affected by living in semi-urban area (adjusted OR= 2.6; 95% CI: 1.0-6.9) and occupational status of the household head being a civil servant (adjusted OR= 2.7; 95% CI: 0.9-7.9). About 7.8% (95% CI: 6.7-10.0%) of all SAC participated in the study and 40.4% (95% CI: 57.4-66.7%) of children in households owning at least one LLIN passed the previous night under LLIN. LLIN utilization by SAC conditional to presence of at least one net in the household was significantly correlated with education level of mother above grade 6 (adjusted OR= 3.4; 95% CI: 1.3-9.3) and the household size to bed net ratio less than or equal to 2 (adjusted OR= 20.7; 95% CI: 4.7-132.5). Conclusion Ownership of bed net was lower than universal coverage of at least one bed net for two individuals. It is important to monitor replacement needs and educate mothers with low education level with their SAC on the benefit of consistent utilization of bed nets.

scholarly journals Long-lasting insecticide-treated bed net ownership, utilization and associated factors among school-age children in Dara Mallo and Uba Debretsehay districts, Southern Ethiopia

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Zerihun Zerdo ◽  
Hilde Bastiaens ◽  
Sibyl Anthierens ◽  
Fekadu Massebo ◽  
Matewos Masne ◽  
...  
Keyword(s):  
Controlled Trial ◽  
Statistical Significance ◽  
Household Head ◽  
Education Level ◽  
Sub Saharan Africa ◽  
School Age Children ◽  
Bed Nets ◽  
Southern Ethiopia ◽  
Bed Net ◽  
School Age

Abstract Background Malaria is one of the major causes of morbidity and mortality among school-age children (SAC) in sub-Saharan Africa. SAC account for more than 60% of the reservoir of malaria transmission, but they are given less emphasis in prioritizing malaria prevention interventions. This study was aimed at assessing the ownership of long-lasting insecticide treated bed nets (LLINs), its utilization and factors associated with ownership of LLINs by households and LLINs utilization among SAC in malaria-prone areas of Dara Mallo and Uba Debretsehay districts in Southern Ethiopia, October to December 2019. Methods This study is part of a baseline assessment in a cluster-randomized controlled trial. The data was collected through interview and observation, following a structured questionnaire, of 2261 SAC households. Univariable and multivariable multilevel logistic regressions were used to assess the association between LLINs ownership and utilization and potential predictor variables. Odds ratio (OR) and corresponding 95% confidence interval (CI) were used to determine the strength and statistical significance of association. Results The ownership of at least one LLIN by households of SAC was about 19.3% (95% CI 17.7–21.0%) but only 10.3% % (95% CI 7.7–13.7%) of these households had adequate access of bed nets to the household members. Ownership of bed net was marginally affected by living in semi-urban area (adjusted OR = 2.6; 95% CI 1.0–6.9) and occupational status of the household head being a civil servant (adjusted OR = 2.7; 95% CI 0.9–7.9). About 7.8% (95% CI 6.7–10.0%) of all SAC participated in the study and 40.4% (95% CI 57.4–66.7%) of children in households owning at least one LLIN passed the previous night under LLIN. LLIN utilization by SAC conditional to presence of at least one net in the household was significantly correlated with education level of mother above grade 6 (adjusted OR = 3.4; 95% CI 1.3–9.3) and the household size to bed net ratio less than or equal to 2 (adjusted OR = 20.7; 95% CI 4.7–132.5). Conclusion Ownership of bed net was lower than universal coverage of at least one bed net for two individuals. It is important to monitor replacement needs and educate mothers with low education level with their SAC on the benefit of consistent utilization of bed nets.

scholarly journals Insecticide-free trapping bed-net can mitigate insecticide resistance threat in malaria vector control strategies

2020 ◽  
Author(s):  
Chouaibou S. Mouhamadou ◽  
Kun Luan ◽  
Behi Kouadio Fodjo ◽  
Andre West ◽  
Marian McCord ◽  
...  
Keyword(s):  
Mosquito Control ◽  
Pyrethroid Resistance ◽  
Control Strategies ◽  
Three Dimensional ◽  
Sub Saharan Africa ◽  
Bed Nets ◽  
Malaria Vector Control ◽  
Bed Net ◽  
Worst Case ◽  
Crowd Modeling

AbstractMosquito-borne malaria kills 429,000 people each year with the problem acute in sub-Saharan Africa. The successes gained with long-lasting pyrethroid treated bed-nets is now in jeopardy because of wide-spread, pyrethroid-resistance in mosquitoes. Using crowd modeling theory normalized for standard bed-net architecture, we were able to design an attract-trap-kill mechanism for mosquitoes that does not require insecticides. Using three-dimensional polyester knitting and heat fixation, trap funnels were developed with high capture efficacy, no egression under worst-case laboratory conditions, and greater durability than current bed-nets sold. Field testing in Africa in WHO huts with Gen1-3 T (trap)-Nets validated our model, and as predicted, Gen3 had the highest efficacy with a 4.3-fold greater trap-kill rate with no deterrence or repellency compared to Permanet 2.0, the most common bed-net in Africa. A T-Net population model was developed based on field data to predict community level mosquito control compared to a pyrethroid bed-net. This model showed the Gen3 T-Net under field conditions in Africa against pyrethroid resistant mosquitoes was 12.7-fold more efficacious than single chemical, pyrethroid treated nets, demonstrating significantly greater mosquito control using bed-nets without insecticides.

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 Multimodal in vivo recording using transparent graphene microelectrodes illuminates spatiotemporal seizure dynamics at the microscale

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Nicolette Driscoll ◽  
Richard E. Rosch ◽  
Brendan B. Murphy ◽  
Arian Ashourvan ◽  
Ramya Vishnubhotla ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Spatial Scales ◽  
Epileptic Seizures ◽  
Therapeutic Interventions ◽  
State Transitions ◽  
Integrated Analysis ◽  
High Temporal Resolution ◽  
Seizure Onset ◽  
Acute Seizures

AbstractNeurological disorders such as epilepsy arise from disrupted brain networks. Our capacity to treat these disorders is limited by our inability to map these networks at sufficient temporal and spatial scales to target interventions. Current best techniques either sample broad areas at low temporal resolution (e.g. calcium imaging) or record from discrete regions at high temporal resolution (e.g. electrophysiology). This limitation hampers our ability to understand and intervene in aberrations of network dynamics. Here we present a technique to map the onset and spatiotemporal spread of acute epileptic seizures in vivo by simultaneously recording high bandwidth microelectrocorticography and calcium fluorescence using transparent graphene microelectrode arrays. We integrate dynamic data features from both modalities using non-negative matrix factorization to identify sequential spatiotemporal patterns of seizure onset and evolution, revealing how the temporal progression of ictal electrophysiology is linked to the spatial evolution of the recruited seizure core. This integrated analysis of multimodal data reveals otherwise hidden state transitions in the spatial and temporal progression of acute seizures. The techniques demonstrated here may enable future targeted therapeutic interventions and novel spatially embedded models of local circuit dynamics during seizure onset and evolution.

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.

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