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Full-Text Articles in Medicine and Health Sciences
Investigating Effects Of Between- And Within- Host Variability On Escherichia Coli O157 Shedding Pattern And Transmission, Shi Chen, Mike Sanderson, Cristina Lanzas
Investigating Effects Of Between- And Within- Host Variability On Escherichia Coli O157 Shedding Pattern And Transmission, Shi Chen, Mike Sanderson, Cristina Lanzas
Cristina Lanzas
Healthy cattle and their environment are the reservoir for the human pathogen Escherichia coli O157. In E. coli O157 epidemiology, supershedders have been loosely defined as cattle that shed high concentrations of E. coli O157 (≥104 colony-forming cells (CFU)/g of feces) at a single (or multiple) cross-section in time. Due to the variability in the pathogen shedding level among animals (between-host variability), as well as fluctuations in the level shed by a single animal (within-host variability), it is difficult to interpret fecal bacteria distributions, as well as to parse the relative contribution of between- and within-host variability to the observed …
Mathematical Modeling Of The Transmission And Control Of Foodborne Pathogens And Antimicrobial Resistance At Preharvest, Cristina Lanzas, Zhao Lu, Yrjo T. Grohn
Mathematical Modeling Of The Transmission And Control Of Foodborne Pathogens And Antimicrobial Resistance At Preharvest, Cristina Lanzas, Zhao Lu, Yrjo T. Grohn
Cristina Lanzas
Foodborne diseases are a significant health care and economical burden. Most foodborne pathogens are enteric pathogens harbored in the gastrointestinal tract of farm animals. Understanding the transmission of foodborne pathogens and dissemination of antimicrobial resistance at the farm level is necessary to design effective control strategies at preharvest. Mathematical models improve our understanding of pathogen dynamics by providing a theoretical framework in which factors affecting transmission and the control of the pathogens can be explicitly considered. In this review, we aim to present the principles underlying the mathematical modeling of foodborne pathogens and antimicrobial resistance at the farm level to …
Modeling On-Farm Escherichia Coli O157:H7 Population Dynamics, P Ayscue, Cristina Lanzas, R Ivanek, Y T. Grohn
Modeling On-Farm Escherichia Coli O157:H7 Population Dynamics, P Ayscue, Cristina Lanzas, R Ivanek, Y T. Grohn
Cristina Lanzas
Escherichia coli O157:H7 is a potentially fatal foodborne pathogen with a putative reservoir for human infection in feedlot cattle. In order to more effectively identify targets for intervention strategies, we aimed to (1) assess the role of various feedlot habitats in E. coli O157:H7 propagation and (2) provide a framework for examining the relative contributions of animals and the surrounding environment to observed pathogen dynamics. To meet these goals we developed a mathematical model based on an ecological metapopulation framework to track bacterial population dynamics inside and outside the host. We used E. coli O157:H7 microbiological and epidemiological literature to …
The Effect Of Heterogeneous Infectious Period And Contagiousness On The Dynamics Of Salmonella Transmission In Dairy Cattle, Cristina Lanzas, S Brien, R Ivanek, Y Lo, P P. Chapagain, K A. Ray, P Ayscue, L D. Warnick, Y T. Grohn
The Effect Of Heterogeneous Infectious Period And Contagiousness On The Dynamics Of Salmonella Transmission In Dairy Cattle, Cristina Lanzas, S Brien, R Ivanek, Y Lo, P P. Chapagain, K A. Ray, P Ayscue, L D. Warnick, Y T. Grohn
Cristina Lanzas
The objective of this study was to address the impact of heterogeneity of infectious period and contagiousness on Salmonella transmission dynamics in dairy cattle populations. We developed three deterministic SIR-type models with two basic infected stages (clinically and subclinically infected). In addition, model 2 included long-term shedders, which were defined as individuals with low contagiousness but long infectious period, and model 3 included super-shedders (individuals with high contagiousness and long infectious period). The simulated dynamics, basic reproduction number (R0) and critical vaccination threshold were studied. Clinically infected individuals were the main force of infection transmission for models 1 and 2. …
The Risk And Control Of Salmonella Outbreaks In Calf-Raising Operations: A Mathematical Modeling Approach, Cristina Lanzas, L D. Warnick, R Ivanek, P Ayscue, D V. Nydam, Y T. Grohn
The Risk And Control Of Salmonella Outbreaks In Calf-Raising Operations: A Mathematical Modeling Approach, Cristina Lanzas, L D. Warnick, R Ivanek, P Ayscue, D V. Nydam, Y T. Grohn
Cristina Lanzas
Salmonellosis in calves has economic and welfare implications, and serves as a potential source of human infections. Our objectives were to assess the risk of Salmonella spread following its introduction into a herd of pre-weaned calves and to evaluate the efficacy of control strategies to prevent and control outbreaks. To meet these objectives, we developed a model of Salmonella transmission within a pre-weaned group of calves based on a well documented outbreak of salmonellosis in a calf-raising operation and other literature. Intervention scenarios were evaluated in both deterministic and stochastic versions of the model. While the basic reproduction number (R0) …