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https://www.readbyqxmd.com/read/28538727/establishment-and-cryptic-transmission-of-zika-virus-in-brazil-and-the-americas
#1
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...
May 24, 2017: Nature
https://www.readbyqxmd.com/read/28508154/estimating-loss-of-brucella-abortus-antibodies-from-age-specific-serological-data-in-elk
#2
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
#3
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
#4
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
#5
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
https://www.readbyqxmd.com/read/28451589/rabies-vaccination-targets-for-stray-dog-populations
#6
Tiffany Leung, Stephen A Davis
The role of stray dogs in the persistence of domestic dog rabies, and whether removal of such dogs is beneficial, remains contentious issues for control programs seeking to eliminate rabies. While a community might reach the WHO vaccination target of 70% for dogs that can be handled, the stray or neighborhood dogs that are too wary of humans to be held are a more problematic population to vaccinate. Here, we present a method to estimate vaccination targets for stray dogs when the dog population is made up of stray, free-roaming, and confined dogs, where the latter two types are considered to have an identifiable owner...
2017: Frontiers in Veterinary Science
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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