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Basic reproductive number

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https://www.readbyqxmd.com/read/28642061/the-basic-reproduction-number-of-vector-borne-plant-virus-epidemics
#1
Frank Van den Bosch, Michael J Jeger
The basic reproduction number R0 is a key parameter in plant disease epidemiology, which largely determines whether or not an epidemic will occur in a plant population. The next generation matrix approach to deriving and calculating the basic reproduction number of a plant virus epidemic is described. The approach is illustrated through a series of examples of increasing complexity, ranging from the simplest case of one vector transmitting one virus to a single host, to the case of multiple vectors, to combined horizontal (vector) and vertical (seed) transmission, and where vector control using insecticides is practised...
June 19, 2017: Virus Research
https://www.readbyqxmd.com/read/28637916/model-based-analysis-of-an-outbreak-of-bubonic-plague-in-cairo-in-1801
#2
Xavier Didelot, Lilith K Whittles, Ian Hall
Bubonic plague has caused three deadly pandemics in human history: from the mid-sixth to mid-eighth century, from the mid-fourteenth to the mid-eighteenth century and from the end of the nineteenth until the mid-twentieth century. Between the second and the third pandemics, plague was causing sporadic outbreaks in only a few countries in the Middle East, including Egypt. Little is known about this historical phase of plague, even though it represents the temporal, geographical and phylogenetic transition between the second and third pandemics...
June 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28631108/reproduction-number-and-asymptotic-stability-for-the-dynamics-of-a-honey-bee-colony-with-continuous-age-structure
#3
M I Betti, L M Wahl, M Zamir
A system of partial differential equations is derived as a model for the dynamics of a honey bee colony with a continuous age distribution, and the system is then extended to include the effects of a simplified infectious disease. In the disease-free case, we analytically derive the equilibrium age distribution within the colony and propose a novel approach for determining the global asymptotic stability of a reduced model. Furthermore, we present a method for determining the basic reproduction number [Formula: see text] of the infection; the method can be applied to other age-structured disease models with interacting susceptible classes...
June 19, 2017: Bulletin of Mathematical Biology
https://www.readbyqxmd.com/read/28620881/a-comparison-of-methods-for-calculating-the-basic-reproductive-number-for-periodic-epidemic-systems
#4
Christopher Mitchell, Christopher Kribs
When using mathematics to study epidemics, oftentimes the goal is to determine when an infection can invade and persist within a population. The most common way to do so uses threshold quantities called reproductive numbers. An infection's basic reproductive number (BRN), typically denoted [Formula: see text], measures the infection's initial ability to reproduce in a naive population and is tied mathematically to the stability of the disease-free equilibrium. Next-generation methods have long been used to derive [Formula: see text] for autonomous continuous-time systems; however, many diseases exhibit seasonal behavior...
June 15, 2017: Bulletin of Mathematical Biology
https://www.readbyqxmd.com/read/28613986/modelling-and-optimal-control-of-pneumonia-disease-with-cost-effective-strategies
#5
Getachew Teshome Tilahun, Oluwole Daniel Makinde, David Malonza
We propose and analyse a nonlinear mathematical model for the transmission dynamics of pneumonia disease in a population of varying size. The deterministic compartmental model is studied using stability theory of differential equations. The effective reproduction number is obtained and also the asymptotic stability conditions for the disease free and as well as for the endemic equilibria are established. The possibility of bifurcation of the model and the sensitivity indices of the basic reproduction number to the key parameters are determined...
June 14, 2017: Journal of Biological Dynamics
https://www.readbyqxmd.com/read/28610609/estimation-of-basic-reproduction-number-of-the-middle-east-respiratory-syndrome-coronavirus-mers-cov-during-the-outbreak-in-south-korea-2015
#6
Hyuk-Jun Chang
BACKGROUND: In South Korea, an outbreak of Middle East respiratory syndrome (MERS) occurred in 2015. It was the second largest MERS outbreak. As a result of the outbreak in South Korea, 186 infections were reported, and 36 patients died. At least 16,693 people were isolated with suspicious symptoms. This paper estimates the basic reproduction number of the MERS coronavirus (CoV), using data on the spread of MERS in South Korea. METHODS: The basic reproduction number of an epidemic is defined as the average number of secondary cases that an infected subject produces over its infectious period in a susceptible and uninfected population...
June 13, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28599266/expansion-of-the-lyme-disease-vector-ixodes-scapularis-in-canada-inferred-from-cmip5-climate-projections
#7
(no author information available yet)
BACKGROUND: A number of studies have assessed possible climate change impacts on the Lyme disease vector, Ixodes scapularis. However, most have used surface air temperature from only one climate model simulation and/or one emission scenario, representing only one possible climate future. OBJECTIVES: We quantified effects of different Representative Concentration Pathway (RCP) and climate model outputs on the projected future changes in the basic reproduction number () of I...
May 31, 2017: Environmental Health Perspectives
https://www.readbyqxmd.com/read/28596525/mathematical-modeling-and-stability-analysis-of-pine-wilt-disease-with-optimal-control
#8
M A Khan, K Ali, E Bonyah, K O Okosun, S Islam, A Khan
This paper presents and examine a mathematical system of equations which describes the dynamics of pine wilt disease (PWD). Firstly, we examine the model with constant controls. Here, we investigate the disease equilibria and calculate the basic reproduction number of the disease. Secondly, we incorporate time dependent controls into the model and then analyze the conditions that are necessary for the disease to be controlled optimally. Finally, the numerical results for the model are presented.
June 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28589490/bifurcation-thresholds-and-optimal-control-in-transmission-dynamics-of-arboviral-diseases
#9
Hamadjam Abboubakar, Jean Claude Kamgang, Leontine Nkague Nkamba, Daniel Tieudjo
In this paper, we derive and analyse a model for the control of arboviral diseases which takes into account an imperfect vaccine combined with some other control measures already studied in the literature. We begin by analysing the basic model without control. We prove the existence of two disease-free equilibrium points and the possible existence of up to two endemic equilibrium points (where the disease persists in the population). We show the existence of a transcritical bifurcation and a possible saddle-node bifurcation and explicitly derive threshold conditions for both, including defining the basic reproduction number, [Formula: see text], which provides whether the disease can persist in the population or not...
June 6, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28573467/branching-process-approach-for-epidemics-in-dynamic-partnership-network
#10
Abid Ali Lashari, Pieter Trapman
We study the spread of sexually transmitted infections (STIs) and other infectious diseases on a dynamic network by using a branching process approach. The nodes in the network represent the sexually active individuals, while connections represent sexual partnerships. This network is dynamic as partnerships are formed and broken over time and individuals enter and leave the sexually active population due to demography. We assume that individuals enter the sexually active network with a random number of partners, chosen according to a suitable distribution and that the maximal number of partners that an individual can have at a time is finite...
June 1, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28552262/inferring-epidemiological-dynamics-of-infectious-diseases-using-tajima-s-d-statistic-on-nucleotide-sequences-of-pathogens
#11
Kiyeon Kim, Ryosuke Omori, Kimihito Ito
The estimation of the basic reproduction number is essential to understand epidemic dynamics, and time series data of infected individuals are usually used for the estimation. However, such data are not always available. Methods to estimate the basic reproduction number using genealogy constructed from nucleotide sequences of pathogens have been proposed so far. Here, we propose a new method to estimate epidemiological parameters of outbreaks using the time series change of Tajima's D statistic on the nucleotide sequences of pathogens...
May 1, 2017: Epidemics
https://www.readbyqxmd.com/read/28550462/a-case-control-study-of-the-risk-factors-for-obstetric-fistula-in-tigray-ethiopia
#12
L Lewis Wall, Shewaye Belay, Tesfahun Haregot, Jonathan Dukes, Eyoel Berhan, Melaku Abreha
INTRODUCTION AND HYPOTHESIS: We tested the null hypothesis that there were no differences between patients with obstetric fistula and parous controls without fistula. METHODS: A unmatched case-control study was carried out comparing 75 women with a history of obstetric fistula with 150 parous controls with no history of fistula. Height and weight were measured for each participant, along with basic socio-demographic and obstetric information. Descriptive statistics were calculated and differences between the groups were analyzed using Student's t test, Mann-Whitney U test where appropriate, and Chi-squared or Fisher's exact test, along with backward stepwise logistic regression analyses to detect predictors of obstetric fistula...
May 26, 2017: International Urogynecology Journal
https://www.readbyqxmd.com/read/28545047/the-natural-history-of-varicella-zoster-virus-infection-in-norway-further-insights-on-exogenous-boosting-and-progressive-immunity-to-herpes-zoster
#13
Luigi Marangi, Grazina Mirinaviciute, Elmira Flem, Gianpaolo Scalia Tomba, Giorgio Guzzetta, Birgitte Freiesleben de Blasio, Piero Manfredi
We use age-structured models for VZV transmission and reactivation to reconstruct the natural history of VZV in Norway based on available pre-vaccination serological data, contact matrices, and herpes zoster incidence data. Depending on the hypotheses on contact and transmission patterns, the basic reproduction number of varicella in Norway ranges between 3.7 and 5.0, implying a vaccine coverage between 73 and 80% to effectively interrupt transmission with a 100% vaccine efficacy against infection. The varicella force of infection peaks during early childhood (3-5 yrs) and shows a prolonged phase of higher risk during the childbearing period, though quantitative variations can occur depending on contact patterns...
2017: PloS One
https://www.readbyqxmd.com/read/28540311/impacts-of-anti-dsdna-antibody-on-in-vitro-fertilization-embryo-transfer-and-frozen-thawed-embryo-transfer
#14
Jiao Fan, Yiping Zhong, Cuina Chen
Our purpose is to explore whether anti-dsDNA antibody, which was demonstrated to enter living cells and induced apoptosis, could adversely affect reproductive outcomes. A total of 259 women receiving the in vitro fertilization-embryo transfer (IVF) cycle were enrolled in this study, including 52 women with positive ANA and anti-dsDNA (ANA+/anti-dsDNA+ group), 86 women with positive ANA and negative anti-dsDNA (ANA+/anti-dsDNA- group), and 121 women with negative ANA and anti-dsDNA (ANA-/anti-dsDNA- group). 136 nonpregnant women among 259 patients in the IVF-ET cycle were enrolled in the hormone replacement therapy frozen-thawed embryo transfer (HRT-TET) cycle...
2017: Journal of Immunology Research
https://www.readbyqxmd.com/read/28538727/establishment-and-cryptic-transmission-of-zika-virus-in-brazil-and-the-americas
#15
N R Faria, J Quick, I M Claro, J Thézé, J G de Jesus, M Giovanetti, M U G Kraemer, S C Hill, A Black, A C da Costa, L C Franco, S P Silva, C-H Wu, J Raghwani, S Cauchemez, L du Plessis, M P Verotti, W K de Oliveira, E H Carmo, G E Coelho, A C F S Santelli, L C Vinhal, C M Henriques, J T Simpson, M Loose, K G Andersen, N D Grubaugh, S Somasekar, C Y Chiu, J E Muñoz-Medina, C R Gonzalez-Bonilla, C F Arias, L L Lewis-Ximenez, S A Baylis, A O Chieppe, S F Aguiar, C A Fernandes, P S Lemos, B L S Nascimento, H A O Monteiro, I C Siqueira, M G de Queiroz, T R de Souza, J F Bezerra, M R Lemos, G F Pereira, D Loudal, L C Moura, R Dhalia, R F França, T Magalhães, E T Marques, T Jaenisch, G L Wallau, M C de Lima, V Nascimento, E M de Cerqueira, M M de Lima, D L Mascarenhas, J P Moura Neto, A S Levin, T R Tozetto-Mendoza, S N Fonseca, M C Mendes-Correa, F P Milagres, A Segurado, E C Holmes, A Rambaut, T Bedford, M R T Nunes, E C Sabino, L C J Alcantara, N J Loman, O G Pybus
Transmission of Zika virus (ZIKV) in the Americas was first confirmed in May 2015 in northeast Brazil. Brazil has had the highest number of reported ZIKV cases worldwide (more than 200,000 by 24 December 2016) and the most cases associated with microcephaly and other birth defects (2,366 confirmed by 31 December 2016). Since the initial detection of ZIKV in Brazil, more than 45 countries in the Americas have reported local ZIKV transmission, with 24 of these reporting severe ZIKV-associated disease. However, the origin and epidemic history of ZIKV in Brazil and the Americas remain poorly understood, despite the value of this information for interpreting observed trends in reported microcephaly...
June 15, 2017: Nature
https://www.readbyqxmd.com/read/28535806/the-past-matters-estimating-intrinsic-hookworm-transmission-intensity-in-areas-with-past-mass-drug-administration-to-control-lymphatic-filariasis
#16
Marleen Werkman, James E Truscott, Jaspreet Toor, James E Wright, Roy M Anderson
BACKGROUND: Current WHO guidelines for soil-transmitted helminth (STH) control focus on mass drug administration (MDA) targeting preschool-aged (pre-SAC) and school-aged children (SAC), with the goal of eliminating STH as a public health problem amongst children. Recently, attention and funding has turned towards the question whether MDA alone can result in the interruption of transmission for STH. The lymphatic filariasis (LF) elimination programme, have been successful in reaching whole communities...
May 23, 2017: Parasites & Vectors
https://www.readbyqxmd.com/read/28508154/estimating-loss-of-brucella-abortus-antibodies-from-age-specific-serological-data-in-elk
#17
J A Benavides, D Caillaud, B M Scurlock, E J Maichak, W H Edwards, P C Cross
Serological data are one of the primary sources of information for disease monitoring in wildlife. However, the duration of the seropositive status of exposed individuals is almost always unknown for many free-ranging host species. Directly estimating rates of antibody loss typically requires difficult longitudinal sampling of individuals following seroconversion. Instead, we propose a Bayesian statistical approach linking age and serological data to a mechanistic epidemiological model to infer brucellosis infection, the probability of antibody loss, and recovery rates of elk (Cervus canadensis) in the Greater Yellowstone Ecosystem...
May 15, 2017: EcoHealth
https://www.readbyqxmd.com/read/28507229/spread-of-competing-viruses-on-heterogeneous-networks
#18
Shanshan Chen, Kaihua Wang, Mengfeng Sun, Xinchu Fu
In this paper, we propose a model where two strains compete with each other at the expense of common susceptible individuals on heterogeneous networks by using pair-wise approximation closed by the probability-generating function (PGF). All of the strains obey the susceptible-infected-recovered (SIR) mechanism. From a special perspective, we first study the dynamical behaviour of an SIR model closed by the PGF, and obtain the basic reproduction number via two methods. Then we build a model to study the spreading dynamics of competing viruses and discuss the conditions for the local stability of equilibria, which is different from the condition obtained by using the heterogeneous mean-field approach...
June 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28501456/assessing-age-dependent-susceptibility-to-measles-in-japan
#19
Ryo Kinoshita, Hiroshi Nishiura
BACKGROUND: Routine vaccination against measles in Japan started in 1978. Whereas measles elimination was verified in 2015, multiple chains of measles transmission were observed in 2016. We aimed to reconstruct the age-dependent susceptibility to measles in Japan so that future vaccination strategies can be elucidated. METHODS: An epidemiological model was used to quantify the age-dependent immune fraction using datasets of vaccination coverage and seroepidemiological survey...
June 5, 2017: Vaccine
https://www.readbyqxmd.com/read/28472445/defining-the-population-attributable-fraction-for-infectious-diseases
#20
Ellen Brooks-Pollock, Leon Danon
Background: The population attributable fraction (PAF) is used to quantify the contribution of a risk group to disease burden. For infectious diseases, high-risk individuals may increase disease risk for the wider population in addition to themselves; therefore methods are required to estimate the PAF for infectious diseases. Methods: A mathematical model of disease transmission in a population with a high-risk group was used to compare existing approaches for calculating the PAF...
May 4, 2017: International Journal of Epidemiology
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