Global certification of wild poliovirus eradication: insights from modelling hard-to-reach subpopulations and confidence about the absence of transmission

ObjectiveTo explore the extent to which undervaccinated subpopulations may influence the confidence about no circulation of wild poliovirus (WPV) after the last detected case.Design and participantsWe used a hypothetical model to examine the extent to which the existence of an undervaccinated subpopulation influences the confidence about no WPV circulation after the last detected case as a function of different characteristics of the subpopulation (eg, size, extent of isolation). We also used the hypothetical population model to inform the bounds on the maximum possible time required to reach high confidence about no circulation in a completely isolated and unvaccinated subpopulation starting either at the endemic equilibrium or with a single infection in an entirely susceptible population.ResultsIt may take over 3 years to reach 95% confidence about no circulation for this hypothetical population despite high surveillance sensitivity and high vaccination coverage in the surrounding general population if: (1) ability to detect cases in the undervaccinated subpopulation remains exceedingly small, (2) the undervaccinated subpopulation remains small and highly isolated from the general population and (3) the coverage in the undervaccinated subpopulation remains very close to the minimum needed to eradicate. Fully-isolated hypothetical populations of 4000 people or less cannot sustain endemic transmission for more than 5 years, with at least 20 000 people required for a 50% chance of at least 5 years of sustained transmission in a population without seasonality that starts at the endemic equilibrium. Notably, however, the population size required for persistent transmission increases significantly for realistic populations that include some vaccination and seasonality and/or that do not begin at the endemic equilibrium.ConclusionsSignificant trade-offs remain inherent in global polio certification decisions, which underscore the need for making and valuing investments to maximise population immunity and surveillance quality in all remaining possible WPV reservoirs.

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Mathematical Modeling for Prediction Dynamics of the Coronavirus Disease 2019 (COVID-19) Pandemic, Quarantine Control Measures

Symmetry ◽

10.3390/sym12091404 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1404

Author(s):

Din Prathumwan ◽

Kamonchat Trachoo ◽

Inthira Chaiya

Keyword(s):

Endemic Equilibrium ◽

Control Measures ◽

Single Infection ◽

Model Parameters ◽

Asymptotically Stable ◽

Expected Number ◽

Susceptible Population ◽

Proposed Model ◽

The Stability ◽

Disease Free

A mathematical model for forecasting the transmission of the COVID-19 outbreak is proposed to investigate the effects of quarantined and hospitalized individuals. We analyze the proposed model by considering the existence and the positivity of the solution. Then, the basic reproduction number (R0)—the expected number of secondary cases produced by a single infection in a completely susceptible population—is computed by using the next-generation matrix to carry out the stability of disease-free equilibrium and endemic equilibrium. The results show that the disease-free equilibrium is locally asymptotically stable if R0<1, and the endemic equilibrium is locally asymptotically stable if R0>1. Numerical simulations of the proposed model are illustrated. The sensitivity of the model parameters is considered in order to control the spread by intervention strategies. Numerical results confirm that the model is suitable for the outbreak that occurred in Thailand.

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Different characteristics of infants diagnosed with congenital choledochal malformation prenatally or postnatally

Scientific Reports ◽

10.1038/s41598-020-79569-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Wei Chen ◽

Jia Geng ◽

Ya-lan Tan ◽

Lian Zhao ◽

Hui-hui Jia ◽

...

Keyword(s):

Histopathological Examination ◽

Fibrous Tissue ◽

Operation Time ◽

Normal Diet ◽

Treatment Regimens ◽

Total Length ◽

Time Required ◽

Different Characteristics ◽

Length Of Hospitalization ◽

Choledochal Malformation

AbstractThe general condition, clinical and pathological characteristics, and treatment regimens of patients prenatally and postnatally diagnosed with congenital choledochal malformation (CM) were analyzed in order to investigate the clinical significance of early diagnosis, treatment, and intervention in CM. We retrospectively analyzed 33 children who were admitted to the Children’s Hospital of Soochow University between 1 March 2010 and 31 May 2019, and their diagnosis of CM was confirmed by radiological, surgical and pathological findings. All the patients were under 36 months of age. The patients were divided into prenatally diagnosed and postnatally diagnosed groups. There were 16 and 17 CM patients in the prenatally and postnatally diagnosed groups, respectively, with a preponderance of females in both groups. Compared with the prenatally diagnosed group, the postnatally diagnosed group had a higher incidence of abdominal pain and vomiting (p < 0.05) and higher AST, GGT, and TB levels (p < 0.05). Although postoperative histopathological examination showed inflammation in both groups, congestion in the cyst walls and fibrous tissue hyperplasia were more significant in the postnatally diagnosed group (p < 0.05). In addition, operation time, length of time required to resume a normal diet after surgery, and total length of hospitalization differed between the 2 groups (p < 0.05), with the prenatally diagnosed group having a relatively longer operation time and taking longer to resume a normal diet after surgery. However, the total length of hospitalization in the prenatally diagnosed group was shorter than that in the postnatally diagnosed group. Compared with prenatally diagnosed CM patients, more symptoms, greater severity of symptoms, and more time to recovery after surgery were observed in postnatally diagnosed CM patients.

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Cucumber mosaic virus satellite RNAs that induce similar symptoms in melon plants show large differences in fitness

Journal of General Virology ◽

10.1099/vir.0.032359-0 ◽

2011 ◽

Vol 92 (8) ◽

pp. 1930-1938 ◽

Cited By ~ 19

Author(s):

Mónica Betancourt ◽

Aurora Fraile ◽

Fernando García-Arenal

Keyword(s):

Cucumber Mosaic Virus ◽

Mosaic Virus ◽

Evolutionary Dynamics ◽

Plant Biomass ◽

Aphid Transmission ◽

Helper Virus ◽

Relative Fitness ◽

Single Infection ◽

Trade Offs ◽

Satellite Rnas

Two groups of Cucumber mosaic virus (CMV) satellite RNAs (satRNAs), necrogenic and non-necrogenic, can be differentiated according to the symptoms they cause in tomato plants, a host in which they also differ in fitness. In most other CMV hosts these CMV-satRNA cause similar symptoms. Here, we analyse whether they differ in traits determining their relative fitness in melon plants, in which the two groups of CMV-satRNAs cause similar symptoms. For this, ten necrogenic and ten non-necrogenic field satRNA genotypes were assayed with Fny-CMV as a helper virus. Neither type of CMV-satRNA modified Fny-CMV symptoms, and both types increased Fny-CMV virulence similarly, as measured by decreases in plant biomass and lifespan. Necrogenic and non-necrogenic satRNAs differed in their ability to multiply in melon tissues; necrogenic satRNAs accumulated to higher levels both in single infection and in competition with non-necrogenic satRNAs. Indeed, multiplication of some non-necrogenic satRNAs was undetectable. Transmission between hosts by aphids was less efficient for necrogenic satRNAs as a consequence of a more severe reduction of CMV accumulation in leaves. The effect of CMV accumulation on aphid transmission was not compensated for by differences in satRNA encapsidation efficiency or transmissibility to CMV progeny. Thus, necrogenic and non-necrogenic satRNAs differ in their relative fitness in melon, and trade-offs are apparent between the within-host and between-host components of satRNA fitness. Hence, CMV-satRNAs could have different evolutionary dynamics in CMV host-plant species in which they do not differ in pathogenicity.

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Dynamics and asymptotic profiles of endemic equilibrium for two frequency-dependent SIS epidemic models with cross-diffusion

European Journal of Applied Mathematics ◽

10.1017/s0956792518000463 ◽

2018 ◽

Vol 31 (1) ◽

pp. 26-56 ◽

Cited By ~ 6

Author(s):

HUICONG LI ◽

RUI PENG ◽

TIAN XIANG

Keyword(s):

Infectious Disease ◽

Total Population ◽

Initial Boundary ◽

Endemic Equilibrium ◽

Diffusion Term ◽

Frequency Dependent ◽

Susceptible Population ◽

Cross Diffusion ◽

Special Cases ◽

Globally Stable

This paper is concerned with two frequency-dependent susceptible–infected–susceptible epidemic reaction–diffusion models in heterogeneous environment, with a cross-diffusion term modelling the effect that susceptible individuals tend to move away from higher concentration of infected individuals. It is first shown that the corresponding Neumann initial-boundary value problem in an n-dimensional bounded smooth domain possesses a unique global classical solution which is uniformly in-time bounded regardless of the strength of the cross-diffusion and the spatial dimension n. It is further shown that, even in the presence of cross-diffusion, the models still admit threshold-type dynamics in terms of the basic reproduction number $\mathcal {R}_0$ – i.e. the unique disease-free equilibrium is globally stable if $\mathcal {R}_0\lt1$, while if $\mathcal {R}_0\gt1$, the disease is uniformly persistent and there is an endemic equilibrium (EE), which is globally stable in some special cases with weak chemotactic sensitivity. Our results on the asymptotic profiles of EE illustrate that restricting the motility of susceptible population may eliminate the infectious disease entirely for the first model with constant total population but fails for the second model with varying total population. In particular, this implies that such cross-diffusion does not contribute to the elimination of the infectious disease modelled by the second one.

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A Framework for Automatic Behavior Generation in Multi-Function Swarms

Frontiers in Robotics and AI ◽

10.3389/frobt.2020.579403 ◽

2020 ◽

Vol 7 ◽

Author(s):

Sondre A. Engebraaten ◽

Jonas Moen ◽

Oleg A. Yakimenko ◽

Kyrre Glette

Keyword(s):

Communication Network ◽

Ad Hoc ◽

Moderate Number ◽

Automatic Behavior ◽

Area Of Interest ◽

Trade Offs ◽

Wide Range ◽

Multiple Tasks ◽

Behavior Characteristics ◽

Different Characteristics

Multi-function swarms are swarms that solve multiple tasks at once. For example, a quadcopter swarm could be tasked with exploring an area of interest while simultaneously functioning as ad-hoc relays. With this type of multi-function comes the challenge of handling potentially conflicting requirements simultaneously. Using the Quality-Diversity algorithm MAP-elites in combination with a suitable controller structure, a framework for automatic behavior generation in multi-function swarms is proposed. The framework is tested on a scenario with three simultaneous tasks: exploration, communication network creation and geolocation of Radio Frequency (RF) emitters. A repertoire is evolved, consisting of a wide range of controllers, or behavior primitives, with different characteristics and trade-offs in the different tasks. This repertoire enables the swarm to online transition between behaviors featuring different trade-offs of applications depending on the situational requirements. Furthermore, the effect of noise on the behavior characteristics in MAP-elites is investigated. A moderate number of re-evaluations is found to increase the robustness while keeping the computational requirements relatively low. A few selected controllers are examined, and the dynamics of transitioning between these controllers are explored. Finally, the study investigates the importance of individual sensor or controller inputs. This is done through ablation, where individual inputs are disabled and their impact on the performance of the swarm controllers is assessed and analyzed.

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Trade-offs between driving nodes and time-to-control in complex networks

Scientific Reports ◽

10.1038/srep39978 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 13

Author(s):

Sérgio Pequito ◽

Victor M. Preciado ◽

Albert-László Barabási ◽

George J. Pappas

Keyword(s):

Complex Networks ◽

Time Window ◽

Empirical Studies ◽

Practical Importance ◽

Network Models ◽

Small Time ◽

Synthetic Network ◽

Trade Offs ◽

Minimum Number ◽

Time Required

Abstract Recent advances in control theory provide us with efficient tools to determine the minimum number of driving (or driven) nodes to steer a complex network towards a desired state. Furthermore, we often need to do it within a given time window, so it is of practical importance to understand the trade-offs between the minimum number of driving/driven nodes and the minimum time required to reach a desired state. Therefore, we introduce the notion of actuation spectrum to capture such trade-offs, which we used to find that in many complex networks only a small fraction of driving (or driven) nodes is required to steer the network to a desired state within a relatively small time window. Furthermore, our empirical studies reveal that, even though synthetic network models are designed to present structural properties similar to those observed in real networks, their actuation spectra can be dramatically different. Thus, it supports the need to develop new synthetic network models able to replicate controllability properties of real-world networks.

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Effect of density dependence on coinfection dynamics: part 2

Analysis and Mathematical Physics ◽

10.1007/s13324-021-00602-4 ◽

2021 ◽

Vol 11 (4) ◽

Author(s):

Jonathan Andersson ◽

Samia Ghersheen ◽

Vladimir Kozlov ◽

Vladimir G. Tkachev ◽

Uno Wennergren

Keyword(s):

Density Dependence ◽

Equilibrium Points ◽

Stable State ◽

Positive Cone ◽

Single Infection ◽

Susceptible Population ◽

Link Type ◽

Starting Point ◽

The Stability ◽

Coexistence Equilibrium

AbstractIn this paper we continue the stability analysis of the model for coinfection with density dependent susceptible population introduced in Andersson et al. (Effect of density dependence on coinfection dynamics. arXiv:2008.09987, 2020). We consider the remaining parameter values left out from Andersson et al. (Effect of density dependence on coinfection dynamics. arXiv:2008.09987, 2020). We look for coexistence equilibrium points, their stability and dependence on the carrying capacity K. Two sets of parameter value are determined, each giving rise to different scenarios for the equilibrium branch parametrized by K. In both scenarios the branch includes coexistence points implying that both coinfection and single infection of both diseases can exist together in a stable state. There are no simple explicit expression for these equilibrium points and we will require a more delicate analysis of these points with a new bifurcation technique adapted to such epidemic related problems. The first scenario is described by the branch of stable equilibrium points which includes a continuum of coexistence points starting at a bifurcation equilibrium point with zero single infection strain #1 and finishing at another bifurcation point with zero single infection strain #2. In the second scenario the branch also includes a section of coexistence equilibrium points with the same type of starting point but the branch stays inside the positive cone after this. The coexistence equilibrium points are stable at the start of the section. It stays stable as long as the product of K and the rate $${\bar{\gamma }}$$ γ ¯ of coinfection resulting from two single infections is small but, after this it can reach a Hopf bifurcation and periodic orbits will appear.

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Segmentation and shielding of the most vulnerable members of the population as elements of an exit strategy from COVID-19 lockdown

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2020.0275 ◽

2021 ◽

Vol 376 (1829) ◽

pp. 20200275

Author(s):

Bram A. D. van Bunnik ◽

Alex L. K. Morgan ◽

Paul R. Bessell ◽

Giles Calder-Gerver ◽

Feifei Zhang ◽

...

Keyword(s):

General Population ◽

Protective Measures ◽

Transmission Rates ◽

Population Immunity ◽

Contact Matrix ◽

Potential Applications ◽

Pandemic Response ◽

Future Policy ◽

The Uk ◽

Second Wave

This study demonstrates that an adoption of a segmenting and shielding strategy could increase the scope to partially exit COVID-19 lockdown while limiting the risk of an overwhelming second wave of infection. We illustrate this using a mathematical model that segments the vulnerable population and their closest contacts, the ‘shielders’. Effects of extending the duration of lockdown and faster or slower transition to post-lockdown conditions and, most importantly, the trade-off between increased protection of the vulnerable segment and fewer restrictions on the general population are explored. Our study shows that the most important determinants of outcome are: (i) post-lockdown transmission rates within the general and between the general and vulnerable segments; (ii) fractions of the population in the vulnerable and shielder segments; (iii) adherence to protective measures; and (iv) build-up of population immunity. Additionally, we found that effective measures in the shielder segment, e.g. intensive routine screening, allow further relaxations in the general population. We find that the outcome of any future policy is strongly influenced by the contact matrix between segments and the relationships between physical distancing measures and transmission rates. This strategy has potential applications for any infectious disease for which there are defined proportions of the population who cannot be treated or who are at risk of severe outcomes. This article is part of the theme issue ‘Modelling that shaped the early COVID-19 pandemic response in the UK’.

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Segmentation and shielding of the most vulnerable members of the population as elements of an exit strategy from COVID-19 lockdown

10.1101/2020.05.04.20090597 ◽

2020 ◽

Cited By ~ 7

Author(s):

Bram A.D. van Bunnik ◽

Alex L.K. Morgan ◽

Paul R. Bessell ◽

Giles Calder-Gerver ◽

Feifei Zhang ◽

...

Keyword(s):

General Population ◽

Vulnerable Population ◽

Infection Prevention And Control ◽

Close Monitoring ◽

Transmission Rates ◽

Epidemic Curve ◽

Population Immunity ◽

Public Health Initiative ◽

Potential Applications ◽

Future Policy

AbstractIn this study we demonstrate that the adoption of a segmenting and shielding (S&S) strategy could increase scope to partially exit COVID-19 lockdown while limiting the risk of an overwhelming second wave of infection.The S&S strategy has an antecedent in the “cocooning” of infants by immunisation of close family members (Forsyth et al., 2015), and forms a pillar of infection, prevention and control (IPC) strategies (RCN, 2017). We are unaware of it being proposed as a major public health initiative previously.We illustrate the S&S strategy using a mathematical model that segments the vulnerable population and their closest contacts, the “shielders”. We explore the effects on the epidemic curve of a gradual ramping up of protection for the vulnerable population and a gradual ramping down of restrictions on the non-vulnerable population over a period of 12 weeks after lockdown.The most important determinants of outcome are: i) post-lockdown transmission rates within the general population segment and between the general and vulnerable segments; ii) the fraction of the population in the vulnerable and shielder segments; iii) adherence with need to be protected; and iv) the extent to which population immunity builds up in all segments.We explored the effects of extending the duration of lockdown and faster or slower transition to post-lockdown conditions and, most importantly, the trade-off between increased protection of the vulnerable segment and fewer restrictions on the general population.We illustrate how the potential for the relaxation of restrictions interacts with specific policy objectives. We show that the range of options for relaxation in the general population can be increased by maintaining restrictions on the shielder segment and by intensive routine screening of shielders.We find that the outcome of any future policy is strongly influenced by the contact matrix between segments and the relationships between physical distancing measures and transmission rates. These relationships are difficult to quantify so close monitoring of the epidemic would be essential during and after the exit from lockdown.More generally, S&S has potential applications for any infectious disease for which there are defined proportions of the population who cannot be treated or who are at risk of severe outcomes.

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Older Adult Segmentation According to Residentially-Based Lifestyles and Analysis of Their Needs for Smart Home Functions

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17228492 ◽

2020 ◽

Vol 17 (22) ◽

pp. 8492

Author(s):

Jiyeon Yu ◽

Angelica de Antonio ◽

Elena Villalba-Mora

Keyword(s):

Quality Of Life ◽

Older Adults ◽

General Population ◽

Older Adult ◽

Smart Home ◽

Social Care ◽

Social Events ◽

Care Systems ◽

Different Characteristics

Globally, the percentage of older people in the general population is growing. Smart homes have the potential to help older adults to live independently and healthy, improving their quality of life, and relieving the pressure on the healthcare and social care systems. For that, we need to understand how older adults live and their needs. Thus, this study aims to analyze the residentially-based lifestyles (RBL) of older adults and segment them to compare and analyze the real needs of smart home functions for each group. To identify a person’s RBL, a questionnaire was designed to include questions about activities at home, social events, quality of life, etc. This study surveyed 271 older Koreans. As a result of the survey on RBL, five groups with different characteristics were clustered. Finally, each groups’ features and the differences in their needs for smart home functions were compared and analyzed. The priority of needed functions for each group was found to be significantly different. In a total of 26 smart home functions, there were meaningful differences in the needs for 16 functions among the groups. This study presents the results in South Korea, according to older adults’ RBL and their smart home needs.

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