Mathematical Model of the Role of Asymptomatic Infection in Outbreaks of Some Emerging Pathogens

Preparation for outbreaks of emerging infectious diseases is often predicated on beliefs that we will be able to understand the epidemiological nature of an outbreak early into its inception. However, since many rare emerging diseases exhibit different epidemiological behaviors from outbreak to outbreak, early and accurate estimation of the epidemiological situation may not be straightforward in all cases. Previous studies have proposed considering the role of active asymptomatic infections co-emerging and co-circulating as part of the process of emergence of a novel pathogen. Thus far, consideration of the role of asymptomatic infections in emerging disease dynamics have usually avoided considering some important sets of influences. In this paper, we present and analyze a mathematical model to explore the hypothetical scenario that some (re)emerging diseases may actually be able to maintain stable, endemic circulation successfully in an entirely asymptomatic state. We argue that an understanding of this potential mechanism for diversity in observed epidemiological dynamics may be of considerable importance in understanding and preparing for outbreaks of novel and/or emerging diseases.

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Dynamic analysis and evaluation of asymptomatic infection in the spread of COVID-19

10.1101/2021.12.07.21267442 ◽

2021 ◽

Author(s):

Chuanqing Xu ◽

Zonghao Zhang ◽

Xiaotong Huang ◽

Jingan Cui

Keyword(s):

Recovery Period ◽

Asymptomatic Infection ◽

Symptomatic Infection ◽

Actual Case ◽

Analysis And Evaluation ◽

Low Level ◽

Asymptomatic Infections ◽

Epidemic Development ◽

Short Time

AbstractCOVID-19 has spread worldwide for nearly two years. Many countries have experienced repeated epidemics, that is, after the epidemic has been controlled for a period of time, the number of new cases per day is low, and the outbreak will occur again a few months later. In order to study the relationship between this low level of infection and the number of asymptomatic infections, and to evaluate the role of asymptomatic infections in the development of the epidemic, we have established an improved infectious disease dynamics model that can be used to evaluate the spread of the COVID-19 epidemic, and fitted the epidemic data in the three flat periods in England. According to the obtained parameters, according to the calculation of the model, the proportion of asymptomatic infections in these three flat periods are 41%, 53% and 58% respectively. After the first flat period, the number of daily newly confirmed cases predicted by the model began to increase around July 1, 2020. After more than four months of epidemic spread, it reached a peak on November 12, which is consistent with the actual case situation. Unanimous. After the second flat period, the model predicts that the number of new confirmed cases per day will increase from about May 7, 2021, and after about 73 days of epidemic development, it will reach a peak on July 20, showing the overall trend of the epidemic. In the above, the predicted results of the model are consistent with the actual cases. After the third flat period, the number of daily newly diagnosed cases predicted by the model began to increase around December 1, 2021, and reached a peak in December, and the number of cases will drop to a very low level after May 2022. According to our research results, due to the large number of asymptomatic infections, the spread of the epidemic is not easy to stop completely in a short time. However, when the epidemic enters a period of flat time, nucleic acid testing is performed, and asymptomatic infections are isolated at home for 14 days (the recovery period of symptomatic infection is about 10 days) may be an option that can be considered to interrupt the transmission of the case.

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Emerging and Re-Emerging Diseases: Novel Challenges in Today’s World or More of the Same?

Animals ◽

10.3390/ani11082382 ◽

2021 ◽

Vol 11 (8) ◽

pp. 2382

Author(s):

João R. Mesquita

Keyword(s):

Infectious Diseases ◽

Disease Surveillance ◽

Emerging Infectious Diseases ◽

Hepatitis E ◽

Emerging Diseases ◽

Climatic Conditions ◽

Human Pathogens ◽

Special Issue ◽

Emerging Pathogens ◽

Human Environment

More than 61% of all human pathogens are zoonotic, representing 75% of all emerging pathogens during the past decade. Albeit significant technological leaps in diagnostics development and disease surveillance, zoonotic emerging infectious diseases are evermore a matter of concern, particularly in modern days where global warming keeps providing ideal climatic conditions to the introduction of exotic infectious agents or disease vectors in new territories. Worryingly, the 2019 novel coronavirus epidemic acts as an extreme reminder of the role animal reservoirs play in public health, accounting for over 4,200,000 deaths worldwide until today. In this Special Issue, we approach a myriad of zoonotic infectious diseases and their complex mechanisms. This Special Issue is composed of three reviews on zoonotic diseases of African Lions, hemogregarine classification, and hepatitis E virus in Brazil, followed by one letter and one opinion piece that broadens the spectrum of disease emergence to mechanistic aspects of emerging non-communicable diseases. The Special Issue is completed by six research papers covering a wide array of emerging and re-emerging diseases of poultry, bovine, poultry and tortoises, of various nature such as parasitic, bacterial, and viral. This is a brief but assertive collection that showcases the need to address health at the animal–human–environment interface, in a One Health perspective.

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The role of vectors in emerging and re-emerging diseases in the Eastern Mediterranean Region

Eastern Mediterranean Health Journal ◽

10.26719/1996.2.1.61 ◽

2021 ◽

Vol 2 (1) ◽

pp. 61-67

Author(s):

H. R. Rathor

Keyword(s):

Mediterranean Region ◽

Eastern Mediterranean ◽

Emerging Infectious Diseases ◽

Eastern Mediterranean Region ◽

Emerging Diseases ◽

Haemorrhagic Fever ◽

Global Level ◽

Vector Borne Diseases ◽

Vector Borne

Considerable attention has recently been drawn at a global level to the serious threat to humans by the new, emerging and re-emerging infectious diseases. Among the infectious vector-borne diseases, dengue, dengue haemorrhagic fever, yellow fever, plague, malaria, leishmaniasis, rodent-borne viruses and arboviruses are considered to be persisting, and sometimes re-emerging, with serious threats to human health. In the Eastern Mediterranean Region, dengue, malaria and leishmaniasis are the significant vector-borne diseases. This article discusses the role of vectors in the re-emergence of malaria, leishmaniasis and dengue fever and their control

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The Impact of Light Polarisation on Light Field of Scenes with Multiple Reflections

Light & Engineering ◽

10.33383/2019-023 ◽

2020 ◽

pp. 108-115 ◽

Cited By ~ 1

Author(s):

Vladimir P. Budak ◽

Anton V. Grimaylo

Keyword(s):

Mathematical Model ◽

Light Field ◽

Global Illumination ◽

Multiple Reflections ◽

Software Environment ◽

The Monte Carlo Method ◽

Mueller Matrices ◽

Volume Integration ◽

The Impact

The article describes the role of polarisation in calculation of multiple reflections. A mathematical model of multiple reflections based on the Stokes vector for beam description and Mueller matrices for description of surface properties is presented. On the basis of this model, the global illumination equation is generalised for the polarisation case and is resolved into volume integration. This allows us to obtain an expression for the Monte Carlo method local estimates and to use them for evaluation of light distribution in the scene with consideration of polarisation. The obtained mathematical model was implemented in the software environment using the example of a scene with its surfaces having both diffuse and regular components of reflection. The results presented in the article show that the calculation difference may reach 30 % when polarisation is taken into consideration as compared to standard modelling.

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COVID-19 vaccines that reduce symptoms but do not block infection need higher coverage and faster rollout to achieve population impact

Scientific Reports ◽

10.1038/s41598-021-94719-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

David A. Swan ◽

Chloe Bracis ◽

Holly Janes ◽

Mia Moore ◽

Laura Matrajt ◽

...

Keyword(s):

Mathematical Model ◽

No Reduction ◽

King County ◽

Symptomatic Disease ◽

Population Impact ◽

Susceptibility To Infection ◽

Infection Susceptibility ◽

Asymptomatic Infections ◽

The U.S

AbstractTrial results for two COVID-19 vaccines suggest at least 90% efficacy against symptomatic disease (VEDIS). It remains unknown whether this efficacy is mediated by lowering SARS-CoV-2 infection susceptibility (VESUSC) or development of symptoms after infection (VESYMP). We aim to assess and compare the population impact of vaccines with different efficacy profiles (VESYMP and VESUSC) satisfying licensure criteria. We developed a mathematical model of SARS-CoV-2 transmission, calibrated to data from King County, Washington. Rollout scenarios starting December 2020 were simulated with combinations of VESUSC and VESYMP resulting in up to 100% VEDIS. We assumed no reduction of infectivity upon infection conditional on presence of symptoms. Proportions of cumulative infections, hospitalizations and deaths prevented over 1 year from vaccination start are reported. Rollouts of 1 M vaccinations (5000 daily) using vaccines with 50% VEDIS are projected to prevent 23–46% of infections and 31–46% of deaths over 1 year. In comparison, vaccines with 90% VEDIS are projected to prevent 37–64% of infections and 46–64% of deaths over 1 year. In both cases, there is a greater reduction if VEDIS is mediated mostly by VESUSC. The use of a “symptom reducing” vaccine will require twice as many people vaccinated than a “susceptibility reducing” vaccine with the same 90% VEDIS to prevent 50% of the infections and death over 1 year. Delaying the start of the vaccination by 3 months decreases the expected population impact by more than 50%. Vaccines which prevent COVID-19 disease but not SARS-CoV-2 infection, and thereby shift symptomatic infections to asymptomatic infections, will prevent fewer infections and require larger and faster vaccination rollouts to have population impact, compared to vaccines that reduce susceptibility to infection. If uncontrolled transmission across the U.S. continues, then expected vaccination in Spring 2021 will provide only limited benefit.

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TMOD-01. THE ROLE OF PERSISTENCE, PROLIFERATION, AND TUMOR CELL KILLING EFFICIENCY IN DETERMINING RESPONSE TO CAR T-CELL THERAPY IN GLIOBLASTOMA: A MATHEMATICAL MODEL AND ANALYSIS

Neuro-Oncology ◽

10.1093/neuonc/noy148.1114 ◽

2018 ◽

Vol 20 (suppl_6) ◽

pp. vi268-vi268

Author(s):

Prativa Sahoo ◽

Daniel Abler ◽

Vikram Adhikarla ◽

Davide Maestrini ◽

Russell Rockne

Keyword(s):

Mathematical Model ◽

T Cell ◽

Cell Therapy ◽

Tumor Cell ◽

T Cell Therapy ◽

Car T Cell ◽

Car T Cell Therapy ◽

Car T ◽

Tumor Cell Killing

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Where to go to in chlamydia control? From infection control towards infectious disease control

Sexually Transmitted Infections ◽

10.1136/sextrans-2021-054992 ◽

2021 ◽

pp. sextrans-2021-054992

Author(s):

Jan E A M van Bergen ◽

Bernice Maria Hoenderboom ◽

Silke David ◽

Febe Deug ◽

Janneke C M Heijne ◽

...

Keyword(s):

Chlamydia Infection ◽

Limited Evidence ◽

Future Directions ◽

Tubal Factor Infertility ◽

Effectiveness Analysis ◽

Population Prevalence ◽

Tubal Factor ◽

Health Relevance ◽

Asymptomatic Infections

ObjectivesThe clinical and public health relevance of widespread case finding by testing for asymptomatic chlamydia infections is under debate. We wanted to explore future directions for chlamydia control and generate insights that might guide for evidence-based strategies. In particular, we wanted to know the extent to which we should pursue testing for asymptomatic infections at both genital and extragenital sites.MethodsWe synthesised findings from published literature and from discussions among national and international chlamydia experts during an invitational workshop. We described changing perceptions in chlamydia control to inform the development of recommendations for future avenues for chlamydia control in the Netherlands.ResultsDespite implementing a range of interventions to control chlamydia, there is no practice-based evidence that population prevalence can be reduced by screening programmes or widespread opportunistic testing. There is limited evidence about the beneficial effect of testing on pelvic inflammatory disease prevention. The risk of tubal factor infertility resulting from chlamydia infection is low and evidence on the preventable fraction remains uncertain. Overdiagnosis and overtreatment with antibiotics for self-limiting and non-viable infections have contributed to antimicrobial resistance in other pathogens and may affect oral, anal and genital microbiota. These changing insights could affect the outcome of previous cost–effectiveness analysis.ConclusionThe balance between benefits and harms of widespread testing to detect asymptomatic chlamydia infections is changing. The opinion of our expert group deviates from the existing paradigm of ‘test and treat’ and suggests that future strategies should reduce, rather than expand, the role of widespread testing for asymptomatic chlamydia infections.

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Stochastic and deterministic mathematical model of cholera disease dynamics with direct transmission

Advances in Difference Equations ◽

10.1186/s13662-020-03130-w ◽

2020 ◽

Vol 2020 (1) ◽

Author(s):

Getachew Teshome Tilahun ◽

Woldegebriel Assefa Woldegerima ◽

Aychew Wondifraw

Keyword(s):

Mathematical Model ◽

Stochastic Model ◽

Deterministic Model ◽

Equilibrium Points ◽

Invariant Solution ◽

Stochastic Approach ◽

Disease Dynamics ◽

Treatment Rate ◽

Invariant Region ◽

Contact Transmission

AbstractIn this paper we develop a stochastic mathematical model of cholera disease dynamics by considering direct contact transmission pathway. The model considers four compartments, namely susceptible humans, infectious humans, treated humans, and recovered humans. Firstly, we develop a deterministic mathematical model of cholera. Since the deterministic model does not consider the randomness process or environmental factors, we converted it to a stochastic model. Then, for both types of models, the qualitative behaviors, such as the invariant region, the existence of a positive invariant solution, the two equilibrium points (disease-free and endemic equilibrium), and their stabilities (local as well as global stability) of the model are studied. Moreover, the basic reproduction numbers are obtained for both models and compared. From the comparison, we obtained that the basic reproduction number of the stochastic model is much smaller than that of the deterministic one, which means that the stochastic approach is more realistic. Finally, we performed sensitivity analysis and numerical simulations. The numerical simulation results show that reducing contact rate, improving treatment rate, and environmental sanitation are the most crucial activities to eradicate cholera disease from the community.

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