scholarly journals Respiratory virus transmission dynamics determine timing of asthma exacerbation peaks: Evidence from a population-level model

2016 ◽  
Vol 113 (8) ◽  
pp. 2194-2199 ◽  
Author(s):  
Rosalind M. Eggo ◽  
James G. Scott ◽  
Alison P. Galvani ◽  
Lauren Ancel Meyers
Keyword(s):  
Common Cold ◽  
Asthma Exacerbation ◽  
Virus Transmission ◽  
Population Level ◽  
Credible Interval ◽  
Geographic Area ◽  
Transmission Model ◽  
School Calendar ◽  
School Closures ◽  
Asthma Hospitalization

Asthma exacerbations exhibit a consistent annual pattern, closely mirroring the school calendar. Although respiratory viruses—the “common cold” viruses—are implicated as a principal cause, there is little evidence to link viral prevalence to seasonal differences in risk. We jointly fit a common cold transmission model and a model of biological and environmental exacerbation triggers to estimate effects on hospitalization risk. Asthma hospitalization rate, influenza prevalence, and air quality measures are available, but common cold circulation is not; therefore, we generate estimates of viral prevalence using a transmission model. Our deterministic multivirus transmission model includes transmission rates that vary when school is closed. We jointly fit the two models to 7 y of daily asthma hospitalizations in adults and children (66,000 events) in eight metropolitan areas. For children, we find that daily viral prevalence is the strongest predictor of asthma hospitalizations, with transmission reduced by 45% (95% credible interval =41–49%) during school closures. We detect a transient period of nonspecific immunity between infections lasting 19 (17–21) d. For adults, hospitalizations are more variable, with influenza driving wintertime peaks. Neither particulate matter nor ozone was an important predictor, perhaps because of the large geographic area of the populations. The school calendar clearly and predictably drives seasonal variation in common cold prevalence, which results in the “back-to-school” asthma exacerbation pattern seen in children and indirectly contributes to exacerbation risk in adults. This study provides a framework for anticipating the seasonal dynamics of common colds and the associated risks for asthmatics.

scholarly journals Research based on the development trend of world language

2018 ◽  
Vol 1 (4) ◽  
pp. 145
Author(s):  
Man Xiao ◽  
Long Mao ◽  
Hongmei Meng ◽  
Jinping Liu ◽  
Huan  Li ◽  
...  
Keyword(s):  
Virus Transmission ◽  
Development Trend ◽  
Transmission Model ◽  
General Tendency ◽  
Communication Model ◽  
Grey Prediction ◽  
Communication Tool ◽  
World Language ◽  
Language Communication ◽  
Set Up

Multicoloured languages play an irreplaceable role in the whole world as a useful communication tool. With the development of technology and science, varieties of languages have an ideal prospective tendency to evolution during the long and wonderful history. Will they be thriving or decaying?To begin with, aimed to gain general tendency about the quantity of languages’ speakers, we employ the Grey prediction to capture associative curve which can be seen in figure(1). From the trend of this vivid figure, we not only can come to the conclusion that the number of English and Chinese users tend to increase but also find that Spanish development will reach the period of stagnation.Secondly, for further improvement, we take birth rate, death rate, economic factors and the immigration into consideration and establish the language communication model. This model is deduced from the population prediction model and virus transmission model. After data normalization, the eventual curve indicates that current top-ten languages seem to be replace by other languages. This transformation phenomenon also occurs among such top-ten languages. For instance, Hindustani will replace Spanish in the future when seen from table(1).What’s more, after predicting the migration pattern, we can draw the conclusion that some range of languages’ dissemination has obvious change. As show in vivid figure(14), we know English will popularize widely among neighbouring countries such as Canada, Mexico, Cuba and Russia.Moreover, with regard to how to manage international offices’ quantity and locations in the world, we construct the efficiency model with combination of the Bayes’ probability theory and Fussy comprehensive assessment. As a result, we obtain 9 optimal plans to establish the international offices. Intelligible result is showed in table(4) and table(5).Furthermore, taking the variation of global communication and shortage of nature resource into consideration, therefore, we propose the international company to set up no more than 5 offices. And 5 offices tend to be the most optimal plan.In short, our model is reasonable and feasible, which can accommodate to different situation.

scholarly journals Vaccinating Adolescents and Children Significantly Reduces COVID-19 Morbidity and Mortality across All Ages: A Popula-Tion-Based Modeling Study Using the UK as an Example

Vaccines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1180
Author(s):  
Tinevimbo Shiri ◽  
Marc Evans ◽  
Carla A. Talarico ◽  
Angharad R. Morgan ◽  
Maaz Mussad ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Age Groups ◽  
Population Level ◽  
Vital Role ◽  
Morbidity And Mortality ◽  
Transmission Model ◽  
Base Case ◽  
Global Public Health ◽  
The Uk ◽  
The Impact

Debate persists around the risk–benefit balance of vaccinating adolescents and children against COVID-19. Central to this debate is quantifying the contribution of adolescents and children to the transmission of SARS-CoV-2, and the potential impact of vaccinating these age groups. In this study, we present a novel SEIR mathematical disease transmission model that quantifies the impact of different vaccination strategies on population-level SARS-CoV-2 infections and clinical outcomes. The model employs both age- and time-dependent social mixing patterns to capture the impact of changes in restrictions. The model was used to assess the impact of vaccinating adolescents and children on the natural history of the COVID-19 pandemic across all age groups, using the UK as an example. The base case model demonstrates significant increases in COVID-19 disease burden in the UK following a relaxation of restrictions, if vaccines are limited to those ≥18 years and vulnerable adolescents (≥12 years). Including adolescents and children in the vaccination program could reduce overall COVID-related mortality by 57%, and reduce cases of long COVID by 75%. This study demonstrates that vaccinating adolescents and children has the potential to play a vital role in reducing SARS-CoV-2 infections, and subsequent COVID-19 morbidity and mortality, across all ages. Our results have major global public health implications and provide valuable information to inform a potential pandemic exit strategy.

scholarly journals Investigating the effects of accelerated partner therapy (APT) on chlamydia transmission in Britain: a mathematical modelling study

2020 ◽  
Author(s):  
Christian L Althaus ◽  
Catherine H Mercer ◽  
Jackie A Cassell ◽  
Claudia S Estcourt ◽  
Nicola Low
Keyword(s):  
Sexual Activity ◽  
Control Strategies ◽  
Controlled Trial ◽  
Partner Notification ◽  
Cluster Randomised Controlled Trial ◽  
Credible Interval ◽  
Population Based ◽  
Transmission Model ◽  
Transmitted Infection ◽  
Potential Increase

Understanding the effects of partner notification (PN) on the transmission of chlamydia, the most prevalent bacterial sexual transmitted infection worldwide, is critical for implementing optimal control strategies. Accelerated partner therapy (APT) aims to increase the numbers of partners treated and reduce the time to partner treatment. Our objective was to study the effects of APT interventions on partner treatment and chlamydia transmission in order to better understand the results of LUSTRUM, an APT cross-over cluster randomised controlled trial in the UK. We developed a novel deterministic, population-based chlamydia transmission model including the process of PN. We considered a population aged 16-34 years and calibrated the model to sexual behaviour data between people of the opposite-sex and chlamydia prevalence data reported by 3,671 participants in Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3, 2010-2012) using Approximate Bayesian Computation (ABC). We investigated the potential effects of APT on chlamydia transmission by increasing the number of treated partners and reducing the time to partner treatment compared to standard PN. The median prevalence of chlamydia in the model was 1.84% (95% credible interval, CrI: 1.60%-2.62%) in women and 1.78% (95% CrI: 1.13%-2.14%) in men. Chlamydia positivity was highest in partners of symptomatic index cases with low sexual activity. Infected partners were typically asymptomatic and belonged to the high sexual activity group, i.e., are naturally those infected individuals that will contribute most to onward transmission. Reducing the time to partner treatment without achieving higher numbers of partners treated had only minor effects on reducing chlamydia prevalence. In contrast, the model predicts that a potential increase in the number of partners treated from current levels in Britain (0.51, 95% CrI: 0.21-0.80) by 25% would reduce chlamydia prevalence by 18% (95% CrI: 5%-44%) in both women in men within 5 years. These results suggest that APT, through a potential increase in the proportion of partners treated, would be an effective method to reduce ongoing chlamydia transmission in Britain.

scholarly journals Improved forecasts of influenza-associated hospitalization rates with Google Search Trends

2019 ◽  
Vol 16 (155) ◽  
pp. 20190080 ◽  
Author(s):  
Sasikiran Kandula ◽  
Sen Pei ◽  
Jeffrey Shaman
Keyword(s):  
Real Time ◽  
Age Groups ◽  
Forecast Accuracy ◽  
Population Level ◽  
Transmission Model ◽  
Surveillance Systems ◽  
Hospitalization Rates ◽  
The Usa ◽  
Near Term ◽  
Google Search

Reliable forecasts of influenza-associated hospitalizations during seasonal outbreaks can help health systems better prepare for patient surges. Within the USA, public health surveillance systems collect and distribute near real-time weekly hospitalization rates, a key observational metric that makes real-time forecast of this outcome possible. In this paper, we describe a method to forecast hospitalization rates using a population level transmission model in combination with a data assimilation technique. Using this method, we generated retrospective forecasts of hospitalization rates for five age groups and the overall population during five seasons in the USA and quantified forecast accuracy for both near-term and seasonal targets. Additionally, we describe methods to correct for under-reporting of hospitalization rates (backcast) and to estimate hospitalization rates from publicly available online search trends data (nowcast). Forecasts based on surveillance rates alone were reasonably accurate in predicting peak hospitalization rates (within ± 25% of the actual peak rate, three weeks before peak). The error in predicting rates one to four weeks ahead, remained constant for the duration of the seasons, even during periods of increased influenza incidence. An improvement in forecast quality across all age groups, seasons and targets was observed when backcasts and nowcasts supplemented surveillance data. These results suggest that the model-inference framework can provide reasonably accurate real-time forecasts of influenza hospitalizations; backcasts and nowcasts offer a way to improve system tolerance to observational errors.

scholarly journals Reactive school closure weakens the network of social interactions and reduces the spread of influenza

2019 ◽  
Vol 116 (27) ◽  
pp. 13174-13181 ◽  
Author(s):  
Maria Litvinova ◽  
Quan-Hui Liu ◽  
Evgeny S. Kulikov ◽  
Marco Ajelli
Keyword(s):  
Social Interactions ◽  
Influenza Season ◽  
School Closure ◽  
Transmission Model ◽  
Modeling Framework ◽  
School Closures ◽  
Student Absenteeism ◽  
Contact Survey ◽  
Closure Policy ◽  
The Impact

School-closure policies are considered one of the most promising nonpharmaceutical interventions for mitigating seasonal and pandemic influenza. However, their effectiveness is still debated, primarily due to the lack of empirical evidence about the behavior of the population during the implementation of the policy. Over the course of the 2015 to 2016 influenza season in Russia, we performed a diary-based contact survey to estimate the patterns of social interactions before and during the implementation of reactive school-closure strategies. We develop an innovative hybrid survey-modeling framework to estimate the time-varying network of human social interactions. By integrating this network with an infection transmission model, we reduce the uncertainty surrounding the impact of school-closure policies in mitigating the spread of influenza. When the school-closure policy is in place, we measure a significant reduction in the number of contacts made by students (14.2 vs. 6.5 contacts per day) and workers (11.2 vs. 8.7 contacts per day). This reduction is not offset by the measured increase in the number of contacts between students and nonhousehold relatives. Model simulations suggest that gradual reactive school-closure policies based on monitoring student absenteeism rates are capable of mitigating influenza spread. We estimate that without the implemented reactive strategies the attack rate of the 2015 to 2016 influenza season would have been 33% larger. Our study sheds light on the social mixing patterns of the population during the implementation of reactive school closures and provides key instruments for future cost-effectiveness analyses of school-closure policies.

scholarly journals Development and Characterization of a Sin Nombre Virus Transmission Model in Peromyscus maniculatus

Viruses ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 183 ◽  
Author(s):  
Bryce Warner ◽  
Derek Stein ◽  
Bryan Griffin ◽  
Kevin Tierney ◽  
Anders Leung ◽  
...  
Keyword(s):  
Peromyscus Maniculatus ◽  
Deer Mouse ◽  
Virus Transmission ◽  
Transmission Model ◽  
Deer Mice ◽  
Sin Nombre Virus ◽  
Infection Model ◽  
Main Driver ◽  
Heat Shock Responses

In North America, Sin Nombre virus (SNV) is the main cause of hantavirus cardiopulmonary syndrome (HCPS), a severe respiratory disease with a fatality rate of 35–40%. SNV is a zoonotic pathogen carried by deer mice (Peromyscus maniculatus), and few studies have been performed examining its transmission in deer mouse populations. Studying SNV and other hantaviruses can be difficult due to the need to propagate the virus in vivo for subsequent experiments. We show that when compared with standard intramuscular infection, the intraperitoneal infection of deer mice can be as effective in producing SNV stocks with a high viral RNA copy number, and this method of infection provides a more reproducible infection model. Furthermore, the age and sex of the infected deer mice have little effect on viral replication and shedding. We also describe a reliable model of direct experimental SNV transmission. We examined the transmission of SNV between deer mice and found that direct contact between deer mice is the main driver of SNV transmission rather than exposure to contaminated excreta/secreta, which is thought to be the main driver of transmission of the virus to humans. Furthermore, increases in heat shock responses or testosterone levels in SNV-infected deer mice do not increase the replication, shedding, or rate of transmission. Here, we have demonstrated a model for the transmission of SNV between deer mice, the natural rodent reservoir for the virus. The use of this model will have important implications for further examining SNV transmission and in developing strategies for the prevention of SNV infection in deer mouse populations.

scholarly journals Human Papillomavirus Genotype Replacement: Still Too Early to Tell?

2020 ◽  
Author(s):  
Irene Man ◽  
Simopekka Vänskä ◽  
Matti Lehtinen ◽  
Johannes A Bogaards
Keyword(s):  
Human Papillomavirus ◽  
Hpv Vaccination ◽  
Population Level ◽  
Cross Protection ◽  
Transmission Model ◽  
Trade Off ◽  
Long Run ◽  
Vaccine Type ◽  
Cross Immunity ◽  
Different Levels

Abstract Background Although human papillomavirus (HPV) vaccines are highly efficacious in protecting against HPV infections and related diseases, vaccination may trigger replacement by nontargeted genotypes if these compete with the vaccine-targeted types. HPV genotype replacement has been deemed unlikely, based on the lack of systematic increases in the prevalence of nonvaccine-type (NVT) infection in the first decade after vaccination, and on the presence of cross-protection for some NVTs. Methods To investigate whether type replacement can be inferred from early postvaccination surveillance, we constructed a transmission model in which a vaccine type and an NVT compete through infection-induced cross-immunity. We simulated scenarios of different levels of cross-immunity and vaccine-induced cross-protection to the NVT. We validated whether commonly used measures correctly indicate type replacement in the long run. Results Type replacement is a trade-off between cross-immunity and cross-protection; cross-immunity leads to type replacement unless cross-protection is strong enough. With weak cross-protection, NVT prevalence may initially decrease before rebounding into type replacement, exhibiting a honeymoon period. Importantly, vaccine effectiveness for NVTs is inadequate for indicating type replacement. Conclusions Although postvaccination surveillance thus far is reassuring, it is still too early to preclude type replacement. Monitoring of NVTs remains pivotal in gauging population-level impacts of HPV vaccination.

scholarly journals West Nile virus transmission: results from the integrated surveillance system in Italy, 2008 to 2015

2016 ◽  
Vol 21 (37) ◽  
Author(s):  
Caterina Rizzo ◽  
Christian Napoli ◽  
Giulietta Venturi ◽  
Simonetta Pupella ◽  
Letizia Lombardini ◽  
...  
Keyword(s):  
West Nile Virus ◽  
Data Exchange ◽  
Virus Disease ◽  
Virus Transmission ◽  
Geographic Area ◽  
Activity Period ◽  
Surveillance Systems ◽  
Time Data ◽  
West Nile ◽  
West Nile Virus Transmission

In Italy a national Plan for the surveillance of imported and autochthonous human vector-borne diseases (chikungunya, dengue, Zika virus disease and West Nile virus (WNV) disease) that integrates human and veterinary (animals and vectors) surveillance, is issued and revised annually according with the observed epidemiological changes. Here we describe results of the WNV integrated veterinary and human surveillance systems in Italy from 2008 to 2015. A real time data exchange protocol is in place between the surveillance systems to rapidly identify occurrence of human and animal cases and to define and update the map of affected areas i.e. provinces during the vector activity period from June to October. WNV continues to cause severe illnesses in Italy during every transmission season, albeit cases are sporadic and the epidemiology varies by virus lineage and geographic area. The integration of surveillance activities and a multidisciplinary approach made it possible and have been fundamental in supporting implementation of and/or strengthening preventive measures aimed at reducing the risk of transmission of WNV trough blood, tissues and organ donation and to implementing further measures for vector control.

scholarly journals The Effects of Postplanting Environment on the Incidence of Soilborne Viral Diseases in Winter Cereals

2004 ◽  
Vol 94 (5) ◽  
pp. 527-534 ◽  
Author(s):  
L. Cadle-Davidson ◽  
G. C. Bergstrom
Keyword(s):  
Soil Temperature ◽  
Mosaic Virus ◽  
Disease Incidence ◽  
Virus Transmission ◽  
Systemic Infection ◽  
Differential Response ◽  
Yield Potential ◽  
Transmission Model ◽  
Winter Cereals ◽  
Environmental Requirements

Soilborne wheat mosaic virus (SBWMV) and Wheat spindle streak mosaic virus (WSSMV) are putatively transmitted to small grains by the obligate parasite Polymyxa graminis, but little is known about environmental requirements for transmission and the resulting disease incidence. We planted susceptible wheat and triticale cultivars in field nurseries on different autumn dates in 3 years and observed the incidence of symptomatic plants in each following spring. Autumn postplanting environment explained most of the variation in disease caused by both viruses. Little apparent transmission, based on eventual symptom development, of either virus occurred after the average soil temperature dropped below 7°C for the remainder of the winter. To forecast disease, we tested an SBWMV transmission model in the field, based on laboratory results, that predicts opportunities for transmission based on soil temperature and soil moisture being simultaneously conducive. This model was predictive of soilborne wheat mosaic in 2 of 3 years. Zoospores of P. graminis have optimal activity at temperatures similar to those in the SBWMV transmission model. Furthermore, the matric potential threshold (as it relates to waterfilled pore sizes) in the SBWMV transmission model fits well with P. graminis as vector given the size restrictions of P. graminis zoospores. Conditions optimal for SBWMV transmission in the laboratory were not conducive for WSSMV transmission in the laboratory or for wheat spindle streak mosaic development in the field. This differential response to environment after emergence, as indicated by disease symptoms, may be due to virus-specific environmental conditions required to establish systemic infection via the same vector. Alternatively, the differential response may have been due to the involvement of a different vector in our WSSMV nursery than in our SBWMV nursery. Our results suggest that, as a control tactic for SBWMV or WSSMV, earliness or lateness of planting is less important in determining virus transmission and disease than the specific postplanting environment. Improved models based on the postplanting environment might predict virus-induced losses of yield potential, and in some cases, growers might avoid purchase of spring inputs such as pesticides and fertilizer for fields with greatly reduced yield potential.

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