scholarly journals Using Multiple Scale Space-Time Patterns to Determine the Number of Replicates and Burn-In Periods in Spatially Explicit Agent-Based Modeling of Vector-Borne Disease Transmission

2021 ◽  
Vol 10 (9) ◽  
pp. 604
Author(s):  
Jeon-Young Kang ◽  
Jared Aldstadt

(1) Background: The stochastic nature of agent-based models (ABMs) may be responsible for the variability of simulated outputs. Multiple simulation runs (i.e., replicates) need to be performed to have enough sample size for hypothesis testing and validating simulations. The simulation outputs in the early-stage of simulations from non-terminating ABMs may be underestimated (or overestimated). To avoid this initialization bias, the simulations need to be run for a burn-in period. This study proposes to use multiple scale space-time patterns to determine the number of required replicates and burn-in periods in spatially explicit ABMs, and develop an indicator for these purposes. (2) Methods: ABMs of vector-borne disease transmission were used as the case study. Particularly, we developed an index, D, which enables to take into consideration a successive coefficient of variance (CV) over replicates and simulation years. The comparison between the number of replicates and the burn-in periods determined by D and those chosen by CV was performed. (3) Results: When only a single pattern was used to determine the number of replicates and the burn-in periods, the results varied depending on the pattern. (4) Conclusions: As multiple scale space-time patterns were used for the purposes, the simulated outputs after the burn-in periods with a proper number of replicates would well reproduce multiple patterns of phenomena. The outputs may also be more useful for hypothesis testing and validation.

2018 ◽  
Vol 104 (2) ◽  
pp. 80-83
Author(s):  
D Biggs

AbstractIntroductionWhen on operational deployment, or where a vector-borne disease threat has been identified, military personnel wear uniform that has been pre-impregnated with permethrin insecticide to prevent insect bites, as part of an integrated approach to bite avoidance in order to reduce disease non-battle injury. This article reports a study that was carried out to investigate whether the clothing treatments currently in use are effective at preventing insect bites.MethodsA human volunteer study was conducted using two different species of mosquito and clothing subjected to different washing schedules. The number of landing events and probing events, and insect mortality, were recorded.ResultsThere was a marked increase in mosquito activity as the amount of viable permethrin was reduced through washing. There was a statistically significant difference between 50 washes and the negative control, and between 50 and 5 washes. As clothing is increasingly washed, its effectiveness is reduced.ConclusionThe use of pre-impregnated uniform does not provide complete protection against biting insects throughout the life of the garment. No single means of protection will prevent personnel from being bitten, and a suite of personal and communal measures should be employed to reduce the risk of vector-borne disease, including the use of insect repellent, mosquito nets, anti-malarial chemoprophylaxis and re-treatment of clothing against biting insects in order to reduce the risk of disease transmission. Since this study, alternative means of clothing treatment have been sought to reinforce the pre-treated uniforms issued. Advice and direction is available, specific to the environment personnel are deploying to, based upon risk.


2021 ◽  
Vol 288 (1949) ◽  
Author(s):  
Paul J. Huxley ◽  
Kris A. Murray ◽  
Samraat Pawar ◽  
Lauren J. Cator

Laboratory-derived temperature dependencies of life-history traits are increasingly being used to make mechanistic predictions for how climatic warming will affect vector-borne disease dynamics, partially by affecting abundance dynamics of the vector population. These temperature–trait relationships are typically estimated from juvenile populations reared on optimal resource supply, even though natural populations of vectors are expected to experience variation in resource supply, including intermittent resource limitation. Using laboratory experiments on the mosquito Aedes aegypti , a principal arbovirus vector, combined with stage-structured population modelling, we show that low-resource supply in the juvenile life stages significantly depresses the vector's maximal population growth rate across the entire temperature range (22–32°C) and causes it to peak at a lower temperature than at high-resource supply. This effect is primarily driven by an increase in juvenile mortality and development time, combined with a decrease in adult size with temperature at low-resource supply. Our study suggests that most projections of temperature-dependent vector abundance and disease transmission are likely to be biased because they are based on traits measured under optimal resource supply. Our results provide compelling evidence for future studies to consider resource supply when predicting the effects of climate and habitat change on vector-borne disease transmission, disease vectors and other arthropods.


Acta Tropica ◽  
2018 ◽  
Vol 188 ◽  
pp. 142-151 ◽  
Author(s):  
Robert T. Jones ◽  
Lucy S. Tusting ◽  
Hugh M.P. Smith ◽  
Sylvester Segbaya ◽  
Michael B. Macdonald ◽  
...  

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