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Basic reproductive number

Amanda Minter, Peter J Diggle, Federico Costa, James Childs, Albert I Ko, Mike Begon
Leptospirosis is a zoonosis that humans can contract via contact with animal reservoirs directly or with water contaminated with their urine. The primary reservoir of pathogenic leptospires within urban slum environments is the Norway rat (Rattus norvegicus). Motivated by the annual outbreaks of human leptospirosis in slum urban settings, the within population infection dynamics of the Norway rat were investigated in Pau da Lima, an community in Salvador, Brazil. A mechanistic model of the dynamics of leptospire infection was informed by extensive field and laboratory data was developed and explored analytically...
May 5, 2018: Epidemics
Noureldin Abuelfadl Ghazy, Takeshi Suzuki, Hiroshi Amano
Although laboratory observations provide basic knowledge of the development and reproduction of predacious and phytophagous mites, little is known of their behavior under natural conditions. Using a closed system designed to simulate natural climate patterns, we investigated the development and reproduction of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) and the pest mite Tetranychus urticae Koch (Acari: Tetranychidae) at air temperatures typical of June to October at three latitudes (Aomori, Tottori, and Naha) in Japan...
May 14, 2018: Environmental Entomology
T M Babu, R Perera, J T Wu, T Fitzgerald, C Nolan, B J Cowling, S Krauss, J T Treanor, M Peiris
Introduction: Influenza A pandemics cause significant mortality and morbidity. H2N2 viruses have caused prior pandemic, and are circulating in avian reservoirs. The age-related frequency of current population immunity to H2 viruses was evaluated. Methods: Hemagglutinin inhibition (HAI) assays against historical human and recent avian influenza A (H2N2) viruses were performed across age groups in Rochester, NY and Hong Kong, China. The impact of existing cross-reactive HAI immunity on the effective reproductive number(R) was modeled...
May 12, 2018: Journal of Infectious Diseases
Alexis Erich S Almocera, Van Kinh Nguyen, Esteban A Hernandez-Vargas
Multiscale models possess the potential to uncover new insights into infectious diseases. Here, a rigorous stability analysis of a multiscale model within-host and between-host is presented. The within-host model describes viral replication and the respective immune response while disease transmission is represented by a susceptible-infected model. The bridging of scales from within- to between-host considered transmission as a function of the viral load. Consequently, stability and bifurcation analyses were developed coupling the two basic reproduction numbers [Formula: see text] and [Formula: see text] for the within- and the between-host subsystems, respectively...
May 8, 2018: Journal of Mathematical Biology
Jummy Funke David
We develop an age of infection model with heterogeneous mixing in which indirect pathogen transmission is considered as a good way to describe contact that is usually considered as direct and we also incorporate virus shedding as a function of age of infection. The simplest form of SIRP epidemic model is introduced and it serves as a basis for the age of infection model and a 2-patch SIRP model where the risk of infection is solely dependent on the residence times and other environmental factors. The computation of the basic reproduction number [Formula: see text], the initial exponential growth rate and the final size relation is done and by mathematical analysis, we study the impact of patches connection and use the final size relation to analyse the ability of disease to invade over a short period of time...
December 2018: Journal of Biological Dynamics
Juan Xu, Yu Zuo
OBJECTIVE: To observe the efficacy differences between acupuncture combined with medication and medication alone for infertility patients with polycystic ovary syndrome (PCOS). METHODS: According to random number table, a total of 60 infertility patients with PCOS were randomly assigned into an observation group and a control group, 30 cases in each one. The patients in the control group were treated with diane-35 from the 3rd day into menstruation, and one menstrual cycle was taken as a session of treatment...
April 12, 2018: Zhongguo Zhen Jiu, Chinese Acupuncture & Moxibustion
Derdei Bichara, Abderrahman Iggidr, Laura Smith
A class of models that describes the interactions between multiple host species and an arthropod vector is formulated and its dynamics investigated. A host-vector disease model where the host's infection is structured into n stages is formulated and a complete global dynamics analysis is provided. The basic reproduction number acts as a sharp threshold, that is, the disease-free equilibrium is globally asymptotically stable (GAS) whenever [Formula: see text] and that a unique interior endemic equilibrium exists and is GAS if [Formula: see text]...
April 25, 2018: Bulletin of Mathematical Biology
C M Saad-Roy, Junling Ma, P van den Driessche
Zika virus is a human disease that may lead to neurological disorders in affected individuals, and may be transmitted vectorially (by mosquitoes) or sexually. A mathematical model of Zika virus transmission is formulated, taking into account mosquitoes, sexually active males and females, inactive individuals, and considering both vector transmission and sexual transmission from infectious males to susceptible females. Basic reproduction numbers are computed, and disease control strategies are evaluated. The effect of the incidence function used to model sexual transmission from infectious males to susceptible females is investigated...
April 25, 2018: Journal of Mathematical Biology
Cheryl Susan Rosenfeld, Angela B Javurek, Sarah A Johnson, Zhentian Lei, Lloyd W Summer, Rex A Hess
Paternal environment can induce detrimental developmental origins of health and disease (DOHaD) effects in resulting offspring and even future descendants. Such paternal-induced DOHaD effects might originate from alterations in a possible seminal fluid microbiome (SFM) and composite metabolome. Seminal vesicles secrete a slightly basic product enriched with fructose and other carbohydrates, providing an ideal habitat for microorganisms. Past studies confirm the existence of a SFM that is influenced by genetic and nutritional status...
April 24, 2018: Reproduction: the Official Journal of the Society for the Study of Fertility
Rui Mu, Youping Yang
An SEIR type of compartmental model with nonlinear incidence and recovery rates was formulated to study the combined impacts of psychological effect and available resources of public health system especially the number of hospital beds on the transmission and control of A(H7N9) virus. Global stability of the disease-free and endemic equilibria is determined by the basic reproduction number as a threshold parameter and is obtained by constructing Lyapunov function and second additive compound matrix. The results obtained reveal that psychological effect and available resources do not change the stability of the steady states but can indeed diminish the peak and the final sizes of the infected...
2018: Computational and Mathematical Methods in Medicine
Ardavan Farhadi, Muzaffer Mustafa Harlıoğlu, Seyfettin Gür, Tutku Can Acısu
Determination and control of spermatozoa quality in crustacean aquaculture is an important issue for successful and controlled reproduction. Investigation of spermatozoa number in spermatophores is a basic and common parameter for determining the reproductive quality in farmed decapods. In the present study, spermatozoa extraction from spermatophores located in the ductus deferens was conducted in Pontastacus leptodactylus using different incubation times and temperatures. The results indicate that the duration of incubation and temperature affected (P < 0...
April 14, 2018: Animal Reproduction Science
Beatriz Vidondo
The popularly known 20-80 rule or Pareto rule states that 20% of efforts leads to 80% of results. This rule has been applied to the study of infection transmission in contact networks, and specifically, contact networks between cattle farms. Woolhouse and collaborators showed that targeting interventions for disease control and prevention to the 20% of the farms that contribute the most to the basic reproduction number (Ro), could reduce it by 80%. The rule results from the number of incoming and outgoing contacts per farm being highly heterogeneous...
2018: PloS One
Faruque Ahmed, Nicole Zviedrite, Amra Uzicanin
BACKGROUND: Social distancing is one of the community mitigation measures that may be recommended during influenza pandemics. Social distancing can reduce virus transmission by increasing physical distance or reducing frequency of congregation in socially dense community settings, such as schools or workplaces. We conducted a systematic review to assess the evidence that social distancing in non-healthcare workplaces reduces or slows influenza transmission. METHODS: Electronic searches were conducted using MEDLINE, Embase, Scopus, Cochrane Library, PsycINFO, CINAHL, NIOSHTIC-2, and EconLit to identify studies published in English from January 1, 2000, through May 3, 2017...
April 18, 2018: BMC Public Health
Ka Chun Chong, Benny Chung Ying Zee, Maggie Haitian Wang
BACKGROUND: In an influenza pandemic, arrival times of cases are a proxy of the epidemic size and disease transmissibility. Because of intense surveillance of travelers from infected countries, detection is more rapid and complete than on local surveillance. Travel information can provide a more reliable estimation of transmission parameters. METHOD: We developed an Approximate Bayesian Computation algorithm to estimate the basic reproduction number (R0 ) in addition to the reporting rate and unobserved epidemic start time, utilizing travel, and routine surveillance data in an influenza pandemic...
April 10, 2018: Travel Medicine and Infectious Disease
P van den Driessche, Abdul-Aziz Yakubu
We focus on discrete-time infectious disease models in populations that are governed by constant, geometric, Beverton-Holt or Ricker demographic equations, and give a method for computing the basic reproduction number, [Formula: see text]. When [Formula: see text] and the demographic population dynamics are asymptotically constant or under geometric growth (non-oscillatory), we prove global asymptotic stability of the disease-free equilibrium of the disease models. Under the same demographic assumption, when [Formula: see text], we prove uniform persistence of the disease...
April 12, 2018: Bulletin of Mathematical Biology
Ryota Matsuyama, Andrei R Akhmetzhanov, Akira Endo, Hyojung Lee, Takayuki Yamaguchi, Shinya Tsuzuki, Hiroshi Nishiura
Background: A Rohingya refugee camp in Cox's Bazar, Bangladesh experienced a large-scale diphtheria epidemic in 2017. The background information of previously immune fraction among refugees cannot be explicitly estimated, and thus we conducted an uncertainty analysis of the basic reproduction number, R 0 . Methods: A renewal process model was devised to estimate the R 0 and ascertainment rate of cases, and loss of susceptible individuals was modeled as one minus the sum of initially immune fraction and the fraction naturally infected during the epidemic...
2018: PeerJ
Tahir Khan, Gul Zaman, Ali Saleh Alshomrani
Hepatitis B infection caused by the hepatitis B virus. It is one of the serious viral infection and a global health problem. In the transmission of hepatitis B infection different phases, i.e., acute and chronic carrier stages play an important role. The chronic carries individuals do not exhibit any symptoms and are able to transmit the infection. Here we assessed the transmissibility associated with different infection stages of hepatitis B and generated an epidemic model with nonlinear incidence rate. In order to do this, first we formulate the model by splitting the infectious class into two subclasses, namely acutely infected and chronic carries with both horizontal and vertical transmission...
2018: PloS One
Andréia Gonçalves Arruda, Carles Vilalta, Pere Puig, Andres Perez, Anna Alba
Industry-driven voluntary disease control programs for swine diseases emerged in North America in the early 2000's, and, since then, those programs have been used for monitoring diseases of economic importance to swine producers. One example of such initiatives is Dr. Morrison's Swine Health Monitoring Project, a nation-wide monitoring program for swine diseases including the porcine reproductive and respiratory syndrome (PRRS). PRRS has been extensively reported as a seasonal disease in the U.S., with predictable peaks that start in fall and are extended through the winter season...
2018: PloS One
Iacopo Baussano, Fulvio Lazzarato, Guglielmo Ronco, Silvia Franceschi
International variations in the prevalence of HPV infection derive from differences in sexual behaviors, which are also a key factor of the basic reproductive number (R0 ) of HPV infection in different populations. R0 affects the strength of herd protection and hence the impact of a vaccination program. Similar vaccination programs may therefore generate different levels of impact depending upon the population's pre-vaccination HPV prevalence. We used IARC's transmission model to estimate a) the overall effectiveness of vaccination versus no vaccination in women aged 15 to 34 years measured as percent prevalence reduction (%PR) of HPV16, and b) the corresponding herd protection in populations with gender-equal and traditional sexual behavior and with different levels of sexual activity, corresponding to pre-vaccination HPV16 prevalence from 1% to 8% as observed worldwide...
March 30, 2018: International Journal of Cancer. Journal International du Cancer
Juan Xiao, Xun Wang, Yi Luo, Xiao-Kai Li, Xue-Wei Li
The semen quality is a basic and the most important indicator of male reproductive health. Mammalian spermatozoa undergo a series of complex structural and functional changes in the epididymis to mature and achieve fertilization capacity. Sperm cell maturation is mediated by a complex physiological process, which is synergistically regulated by a large number of transcription factors, hormones and other signaling molecules. In recent years, there is increasing evidence supporting the notion that functional proteins and sRNA (small RNAs) in epididymosomes participate in sperm maturation and fertilization process...
March 20, 2018: Yi Chuan, Hereditas
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