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Basic reproductive number

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https://www.readbyqxmd.com/read/28431573/a-highly-pathogenic-simian-human-immunodeficiency-virus-effectively-produces-infectious-virions-compared-with-a-less-pathogenic-virus-in-cell-culture
#1
Shoya Iwanami, Yusuke Kakizoe, Satoru Morita, Tomoyuki Miura, Shinji Nakaoka, Shingo Iwami
BACKGROUND: The host range of human immunodeficiency virus (HIV) is quite narrow. Therefore, analyzing HIV-1 pathogenesis in vivo has been limited owing to lack of appropriate animal model systems. To overcome this, chimeric simian and human immunodeficiency viruses (SHIVs) that encode HIV-1 Env and are infectious to macaques have been developed and used to investigate the pathogenicity of HIV-1 in vivo. So far, we have many SHIV strains that show different pathogenesis in macaque experiments...
April 21, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28426775/dynamic-behaviors-of-a-modified-sir-model-in-epidemic-diseases-using-nonlinear-incidence-and-recovery-rates
#2
Gui-Hua Li, Yong-Xin Zhang
The transmission of infectious diseases has been studied by mathematical methods since 1760s, among which SIR model shows its advantage in its epidemiological description of spread mechanisms. Here we established a modified SIR model with nonlinear incidence and recovery rates, to understand the influence by any government intervention and hospitalization condition variation in the spread of diseases. By analyzing the existence and stability of the equilibria, we found that the basic reproduction number [Formula: see text] is not a threshold parameter, and our model undergoes backward bifurcation when there is limited number of hospital beds...
2017: PloS One
https://www.readbyqxmd.com/read/28417166/vaccine-impact-in-homogeneous-and-age-structured-models
#3
F M G Magpantay
A general model of an imperfect vaccine for a childhood disease is presented and the effects of different types of vaccine failure on transmission were investigated using models that consider both homogeneous and age-specific mixing. The models are extensions of the standard SEIR equations with an additional vaccinated component that allows for five different vaccine parameters: three types of vaccine failure in decreasing susceptibility to infection via failure in degree ("leakiness"), take ("all-or-nothingness") and duration (waning of vaccine-derived immunity); one parameter reflecting the relative reduction in infectiousness of vaccinated individuals who get infected; and one parameter that reflects the relative reduction in reporting probability of vaccinated individuals due to a possible reduction in severity of symptoms...
April 17, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28388665/dose-response-relationships-for-environmentally-mediated-infectious-disease-transmission-models
#4
Andrew F Brouwer, Mark H Weir, Marisa C Eisenberg, Rafael Meza, Joseph N S Eisenberg
Environmentally mediated infectious disease transmission models provide a mechanistic approach to examining environmental interventions for outbreaks, such as water treatment or surface decontamination. The shift from the classical SIR framework to one incorporating the environment requires codifying the relationship between exposure to environmental pathogens and infection, i.e. the dose-response relationship. Much of the work characterizing the functional forms of dose-response relationships has used statistical fit to experimental data...
April 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28381586/asexual-but-not-clonal-evolutionary-processes-in-automictic-populations
#5
Jan Engelstädter
Many parthenogenetically reproducing animals produce offspring not clonally but through different mechanisms collectively referred to as automixis. Here, meiosis proceeds normally but is followed by a fusion of meiotic products that restores diploidy. This mechanism typically leads to a reduction in heterozygosity among the offspring compared to the mother. Following a derivation of the rate at which heterozygosity is lost at one and two loci, depending on the number of crossovers between loci and centromere, a number of models are developed to gain a better understanding of basic evolutionary processes in automictic populations...
April 4, 2017: Genetics
https://www.readbyqxmd.com/read/28378145/spatial-spreading-model-and-dynamics-of-west-nile-virus-in-birds-and-mosquitoes-with-free-boundary
#6
Zhigui Lin, Huaiping Zhu
In this paper, a reaction-diffusion system is proposed to model the spatial spreading of West Nile virus in vector mosquitoes and host birds in North America. Transmission dynamics are based on a simplified model involving mosquitoes and birds, and the free boundary is introduced to model and explore the expanding front of the infected region. The spatial-temporal risk index [Formula: see text], which involves regional characteristic and time, is defined for the simplified reaction-diffusion model with the free boundary to compare with other related threshold values, including the usual basic reproduction number [Formula: see text]...
April 4, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28377897/relationship-of-number-of-embryos-transferred-with-perinatal-outcome-of-singleton-pregnancy
#7
Shilpa Bhandari, Ishita Ganguly, Pallavi Agarwal, Niharika Munaganuru, Nitika Gupta, Aparna Singh
BACKGROUND: Singleton pregnancy with a live birth beyond 37 weeks of gestation is the ultimate goal of any assisted reproductive technology. However, singletons conceived after ART are found to have a poor perinatal outcome in comparison to naturally conceived singletons. It was hypothesized that the outcome of singleton conceived after transfer of two or more embryos may be dependent on the sharing of uterine space with other embryos. METHODS: Patients who had single gestational sac visualized at 6 weeks after transfer of 4, 3 or 2 embryos were considered for the study...
January 2017: Journal of Reproduction & Infertility
https://www.readbyqxmd.com/read/28373644/modeling-nosocomial-infections-of-methicillin-resistant-staphylococcus-aureus-with-environment-contamination
#8
Lei Wang, Shigui Ruan
In this work, we investigate the role of environmental contamination on the clinical epidemiology of antibiotic-resistant bacteria in hospitals. Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that causes infections in different parts of the body. It is tougher to treat than most strains of Staphylococcus aureus or staph, because it is resistant to some commonly used antibiotics. Both deterministic and stochastic models are constructed to describe the transmission characteristics of MRSA in hospital setting...
April 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28367934/distribution-of-serum-25-hydroxyvitamin-d-levels-of-reproductive-age-japanese-women
#9
Nobuko Takaoka, Masanori Nagao, Mitsumasa Umezawa, Toshimi Sairenchi, Yasuo Haruyama, Gen Kobashi
Objectives The distribution of serum 25-hydroxyvitamin D [25(OH)D] levels among reproductive age Japanese perinatal (prepartum, intrapartum, postpartum) and non-perinatal women remains unknown. In addition to this, vitamin D deficiency cut-off values, which consider the effects of these levels during the perinatal period and infant development, have not been determined. Thus, we systematically reviewed the distribution of serum 25(OH)D levels among reproductive age Japanese women, in order to provide basic data to determine vitamin D deficiency cut-off values...
2017: [Nihon Kōshū Eisei Zasshi] Japanese Journal of Public Health
https://www.readbyqxmd.com/read/28358899/a-systematic-review-of-rodent-pest-research-in-afro-malagasy-small-holder-farming-systems-are-we-asking-the-right-questions
#10
Lourens H Swanepoel, Corrie M Swanepoel, Peter R Brown, Seth J Eiseb, Steven M Goodman, Mark Keith, Frikkie Kirsten, Herwig Leirs, Themb'alilahlwa A M Mahlaba, Rhodes H Makundi, Phanuel Malebane, Emil F von Maltitz, Apia W Massawe, Ara Monadjem, Loth S Mulungu, Grant R Singleton, Peter J Taylor, Voahangy Soarimalala, Steven R Belmain
Rodent pests are especially problematic in terms of agriculture and public health since they can inflict considerable economic damage associated with their abundance, diversity, generalist feeding habits and high reproductive rates. To quantify rodent pest impacts and identify trends in rodent pest research impacting on small-holder agriculture in the Afro-Malagasy region we did a systematic review of research outputs from 1910 to 2015, by developing an a priori defined set of criteria to allow for replication of the review process...
2017: PloS One
https://www.readbyqxmd.com/read/28357614/a-mathematical-study-to-control-visceral-leishmaniasis-an-application-to-south-sudan
#11
Indrajit Ghosh, Tridip Sardar, Joydev Chattopadhyay
In this manuscript, we propose and analyze a compartmental model of visceral leishmaniasis (VL). We model the human population with six compartments including asymptomatic, symptomatic and PKDL-infected, animal population as second host and sandfly population as the vector. Furthermore, the non-adult stage of the sandfly population is introduced in the system, which was not considered before in the literature. We show that the increase in the number of host of sandfly population generates a backward bifurcation...
March 29, 2017: Bulletin of Mathematical Biology
https://www.readbyqxmd.com/read/28347332/an-outbreak-vector-host-epidemic-model-with-spatial-structure-the-2015-2016-zika-outbreak-in-rio-de-janeiro
#12
W E Fitzgibbon, J J Morgan, G F Webb
BACKGROUND: A deterministic model is developed for the spatial spread of an epidemic disease in a geographical setting. The disease is borne by vectors to susceptible hosts through criss-cross dynamics. The model is focused on an outbreak that arises from a small number of infected hosts imported into a subregion of the geographical setting. The goal is to understand how spatial heterogeneity of the vector and host populations influences the dynamics of the outbreak, in both the geographical spread and the final size of the epidemic...
March 27, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28344900/temporal-patterns-and-geographic-heterogeneity-of-zika-virus-zikv-outbreaks-in-french-polynesia-and-central-america
#13
Ying-Hen Hsieh
BACKGROUND: Zika virus (ZIKV) transmission has been reported in 67 countries/territories in the Oceania region and the Americas since 2015, prompting the World Health Organization (WHO) to declare ZIKV as a Public Health Emergency of International Concern in February 2016, due to its strong association with medical complications such as microcephaly and Guillain-Barré Syndrome (GBS). However, a substantial gap in knowledge still exists regarding differing temporal pattern and potential of transmission of ZIKV in different regions of the world...
2017: PeerJ
https://www.readbyqxmd.com/read/28333929/the-rise-and-fall-of-rabies-in-japan-a-quantitative-history-of-rabies-epidemics-in-osaka-prefecture-1914-1933
#14
Aiko Kurosawa, Kageaki Tojinbara, Hazumu Kadowaki, Katie Hampson, Akio Yamada, Kohei Makita
Japan has been free from rabies since the 1950s. However, during the early 1900s several large-scale epidemics spread throughout the country. Here we investigate the dynamics of these epidemics between 1914 and 1933 in Osaka Prefecture, using archival data including newspapers. The association between dog rabies cases and human population density was investigated using Mixed-effects models and epidemiological parameters such as the basic reproduction number (R0), the incubation and infectious period and the serial interval were estimated...
March 2017: PLoS Neglected Tropical Diseases
https://www.readbyqxmd.com/read/28324189/stability-of-a-stochastic-model-of-an-sir-epidemic-with-vaccination
#15
P J Witbooi
We prove almost sure exponential stability for the disease-free equilibrium of a stochastic differential equations model of an SIR epidemic with vaccination. The model allows for vertical transmission. The stochastic perturbation is associated with the force of infection and is such that the total population size remains constant in time. We prove almost sure positivity of solutions. The main result concerns especially the smaller values of the diffusion parameter, and describes the stability in terms of an analogue [Formula: see text] of the basic reproduction number [Formula: see text] of the underlying deterministic model, with [Formula: see text]...
March 21, 2017: Acta Biotheoretica
https://www.readbyqxmd.com/read/28320240/immunogenesis-of-preeclampsia-lessons-from-donor-gametes
#16
Richard P Porreco, Kent D Heyborne
BACKGROUND: Preeclampsia remains an important complication of pregnancy. It is associated with mortality and morbidity for both maternal and fetal/newborn patients. Although major inroads have been made in understanding the pathophysiology of preeclampsia in recent decades, the initial primary cause of its occurrence in some women and not others has escaped clarification. REVIEW: There have been a number of clinical clues pointing to an immune genesis of this disease, including most recently the use of donor gametes in assisted reproductive technology (ART)...
March 20, 2017: Journal of Maternal-fetal & Neonatal Medicine
https://www.readbyqxmd.com/read/28288565/healthcare-workers-behaviors-and-personal-determinants-associated-with-providing-adequate-sexual-and-reproductive-healthcare-services-in-sub-saharan-africa-a-systematic-review
#17
Kim Jonas, Rik Crutzen, Bart van den Borne, Priscilla Reddy
BACKGROUND: Healthcare workers may affect the utilization of sexual and reproductive healthcare (SRH) services, and quality of care thereof, for example by their behaviours or attitudes they hold. This can become a hindrance to accessing and utilizing SRH services, particularly by young people, and thus a better understanding of these behaviours and associated factors is needed to improve access to and utilization of SRH services. METHODS: A systematic review of literature was conducted to identify studies focusing on healthcare workers' behaviors and personal determinants associated with providing adequate SRH services in sub-Saharan Africa (January 1990 - October 2015)...
March 13, 2017: BMC Pregnancy and Childbirth
https://www.readbyqxmd.com/read/28287496/model-based-evaluation-of-strategies-to-control-brucellosis-in-china
#18
Ming-Tao Li, Gui-Quan Sun, Wen-Yi Zhang, Zhen Jin
Brucellosis, the most common zoonotic disease worldwide, represents a great threat to animal husbandry with the potential to cause enormous economic losses. Brucellosis has become a major public health problem in China, and the number of human brucellosis cases has increased dramatically in recent years. In order to evaluate different intervention strategies to curb brucellosis transmission in China, a novel mathematical model with a general indirect transmission incidence rate was presented. By comparing the results of three models using national human disease data and 11 provinces with high case numbers, the best fitted model with standard incidence was used to investigate the potential for future outbreaks...
March 12, 2017: International Journal of Environmental Research and Public Health
https://www.readbyqxmd.com/read/28284964/optimal-control-of-a-malaria-model-with-asymptomatic-class-and-superinfection
#19
Liming Cai, Xuezhi Li, Necibe Tuncer, Maia Martcheva, Abid Ali Lashari
In this paper, we introduce a malaria model with an asymptomatic class in human population and exposed classes in both human and vector populations. The model assumes that asymptomatic individuals can get re-infected and move to the symptomatic class. In the case of an incomplete treatment, symptomatic individuals move to the asymptomatic class. If successfully treated, the symptomatic individuals recover and move to the susceptible class. The basic reproduction number, R0, is computed using the next generation approach...
March 9, 2017: Mathematical Biosciences
https://www.readbyqxmd.com/read/28275824/from-homogeneous-eigenvalue-problems-to-two-sex-population-dynamics
#20
Horst R Thieme
Enclosure theorems are derived for homogeneous bounded order-preserving operators and illustrated for operators involving pair-formation functions introduced by Karl-Peter Hadeler in the late 1980s. They are applied to a basic discrete-time two-sex population model and to the relation between the basic turnover number and the basic reproduction number.
March 8, 2017: Journal of Mathematical Biology
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