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Sulyok CJ, Fox L, Ritchie H, Lanzas C, Lenhart S, Day J. Mathematically modeling the effect of touch frequency on the environmental transmission of Clostridioides difficile in healthcare settings. Math Biosci 2021; 340:108666. [PMID: 34310932 DOI: 10.1016/j.mbs.2021.108666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 07/13/2021] [Accepted: 07/13/2021] [Indexed: 10/20/2022]
Abstract
Clostridioides difficile, formerly Clostridium difficile, is the leading cause of infectious diarrhea and one of the most common healthcare acquired infections in United States hospitals. C. difficile persists well in healthcare environments because it forms spores that can survive for long periods of time and can be transmitted to susceptible patients through contact with contaminated hands and fomites, objects or surfaces that can harbor infectious agents. Fomites can be classified as high-touch or low-touch based on the frequency they are contacted. The mathematical model in this study investigates the relative contribution of high-touch and low-touch fomites on new cases of C. difficile colonization among patients of a hospital ward. The dynamics of transmission are described by a system of ordinary differential equations representing four patient population classes and two pathogen environmental reservoirs. Parameters that have a significant effect on incidence, as determined by a global sensitivity analysis, are varied in stochastic simulations of the system to identify feasible strategies to prevent disease transmission. Results indicate that on average, under one-quarter of asymptomatically colonized patients are exposed to C. difficile via low-touch fomites. In comparison, over three-quarters of colonized patients are colonized through high-touch fomites, despite additional cleaning of high-touch fomites. Increased contacts with high-touch fomites increases the contribution of these fomites to the incidence of colonized individuals and decreasing the duration of a hospital visit reduces the amount of pathogen in the environment. Thus, enhanced efficacy of disinfection upon discharge and extra cleaning of high-touch fomites, reduced contact with high-touch fomites, and higher discharge rates, among other control measures, could lead to a decrease in the incidence of colonized individuals.
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Affiliation(s)
- Cara Jill Sulyok
- Department of Mathematics, University of Tennessee, Knoxville, 1403 Circle Drive, Knoxville, TN 37996, United States of America.
| | - Lindsey Fox
- Department of Mathematics, Eckerd College, 4200 54th Ave S, St. Petersburg, FL 33711, United States of America
| | - Hannah Ritchie
- Department of Population Health and Pathobiology, North Carolina State University, 1051 William Moore Drive, Raleigh, NC 27607, United States of America
| | - Cristina Lanzas
- Department of Population Health and Pathobiology, North Carolina State University, 1051 William Moore Drive, Raleigh, NC 27607, United States of America
| | - Suzanne Lenhart
- Department of Mathematics, University of Tennessee, Knoxville, 1403 Circle Drive, Knoxville, TN 37996, United States of America
| | - Judy Day
- Departments of Mathematics and Electrical Engineering and Computer Science, University of Tennessee, Knoxville, 1403 Circle Drive, Knoxville, TN 37996, United States of America
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Oh HS, Yang Y, Jeong SY, Ryu M. Hand-to-Environment Contact During Indoor Activities in Senior Welfare Centers Among Korean Older Adults: A Pilot Study. Healthcare (Basel) 2021; 9:healthcare9020105. [PMID: 33498284 PMCID: PMC7909237 DOI: 10.3390/healthcare9020105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/13/2021] [Accepted: 01/18/2021] [Indexed: 11/16/2022] Open
Abstract
(1) Background: This study aimed to describe the characteristics of hand-to-environment contact (HEC) and identify the influencing factors of HEC behavior during the indoor daily life of Korean older adults in senior welfare centers. (2) Methods: A cross-sectional observational study was used with 30 participants over 65 years of age attending programs in senior welfare centers. Video recordings of the 30 participants were collected for two hours a day for participants selected from 20 November to 4 December 2018. Contact frequency, density, and duration were measured. (3) Results: Video recordings of 3,930 HEC cases were analyzed. Furniture surface (25.0%), tableware and cooking utensils (5.4%), phones (5.3%), and door handles (0.1%) were found to be the items with the most frequent contact, in this order. The average contact frequency and contact density (frequency-duration/min/person) of HEC for two hours were highest for the Category I equipment (personally used, accounting for 70.4%), and the average contact duration of HEC was highest in the Category III equipment (commonly used, 47.7 s/contact/person). Contact density was as high as 266.5 (frequency-duration/min/person). Participants above 75 years of age and the unemployed showed high HEC with Category III. (4) Conclusions: Older adults need to be educated to avoid unnecessary hand contact with items in Category III. In particular, hand hygiene and sanitization through the regular and thorough disinfection of furniture surfaces and shared equipment are very important to prevent the spread of pathogens.
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Affiliation(s)
- Hyang Soon Oh
- Department of Nursing, College of Life Science and Natural Resources, Sunchon National University, Suncheon 57922, Korea;
| | - Youngran Yang
- College of Nursing, Research Institute of Nursing Science, Jeonbuk National University, Jeonju 54896, Korea
- Correspondence:
| | - Sun Young Jeong
- College of Nursing, Konyang University, Daejeon 35365, Korea;
| | - Mikyung Ryu
- Department of Nursing, Daegu University, Daegu 42400, Korea;
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McGahan I, Powell J, Spencer E. 28 Models Later: Model Competition and the Zombie Apocalypse. Bull Math Biol 2021; 83:22. [PMID: 33452943 PMCID: PMC7811353 DOI: 10.1007/s11538-020-00845-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 12/09/2020] [Indexed: 11/06/2022]
Abstract
Between Fall 2011 and Fall 2012 students at Utah State University played several rounds of Humans versus Zombies (HvZ), a role-playing variant of tag popular on college campuses. The goal of the game is for the zombies to tag humans, converting them into more zombies. Based on portrayals of 'zombieism' in popular culture, one might treat HvZ as a disease system. However, a traditional SIR model with mass-action dynamics does a poor job of modeling HvZ, leading to the natural question: What mechanisms drive the dynamics of the HvZ system? We use model competition, with Bayesian Information Criterion as arbiter, to answer this question. First, we develop a suite of models with a variety of transmission mechanisms and fit to data from fall 2011. We use model competition to determine which model(s) have the most support from the data, thereby offering insight into driving mechanisms for HvZ. Bootstrapping is used to both assess the significance of individual mechanisms and to determine confidence in the performance of our models. Finally, we test predictions of the best models with data from fall 2012. Results indicate that through both years of the game humans tend to cluster defensively, zombies tend to hunt in groups, some zombies are more proficient hunters, and some humans leave the game.
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Affiliation(s)
- Ian McGahan
- Department of Mathematics and Statistics, Utah State University, Logan, USA.
| | - James Powell
- Department of Mathematics and Statistics, Utah State University, Logan, USA
| | - Elizabeth Spencer
- Department of Statistics and Applied Probability, University of California Santa Barbara, Santa Barbara, USA
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Chen S, Owolabi Y, Li A, Lo E, Robinson P, Janies D, Lee C, Dulin M. Patch dynamics modeling framework from pathogens' perspective: Unified and standardized approach for complicated epidemic systems. PLoS One 2020; 15:e0238186. [PMID: 33057348 PMCID: PMC7561140 DOI: 10.1371/journal.pone.0238186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 08/11/2020] [Indexed: 11/25/2022] Open
Abstract
Mathematical models are powerful tools to investigate, simulate, and evaluate potential interventions for infectious diseases dynamics. Much effort has focused on the Susceptible-Infected-Recovered (SIR)-type compartment models. These models consider host populations and measure change of each compartment. In this study, we propose an alternative patch dynamic modeling framework from pathogens' perspective. Each patch, the basic module of this modeling framework, has four standard mechanisms of pathogen population size change: birth (replication), death, inflow, and outflow. This framework naturally distinguishes between-host transmission process (inflow and outflow) and within-host infection process (replication) during the entire transmission-infection cycle. We demonstrate that the SIR-type model is actually a special cross-sectional and discretized case of our patch dynamics model in pathogens' viewpoint. In addition, this patch dynamics modeling framework is also an agent-based model from hosts' perspective by incorporating individual host's specific traits. We provide an operational standard to formulate this modular-designed patch dynamics model. Model parameterization is feasible with a wide range of sources, including genomics data, surveillance data, electronic health record, and from other emerging technologies such as multiomics. We then provide two proof-of-concept case studies to tackle some of the existing challenges of SIR-type models: sexually transmitted disease and healthcare acquired infections. This patch dynamics modeling framework not only provides theoretical explanations to known phenomena, but also generates novel insights of disease dynamics from a more holistic viewpoint. It is also able to simulate and handle more complicated scenarios across biological scales such as the current COVID-19 pandemic.
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Affiliation(s)
- Shi Chen
- Department of Public Health Sciences, University of North Carolina Charlotte, Charlotte, NC, United States of America
- School of Data Science, University of North Carolina Charlotte, Charlotte, NC, United States of America
| | - Yakubu Owolabi
- Department of Public Health Sciences, University of North Carolina Charlotte, Charlotte, NC, United States of America
- Division of HIV and TB, Centers for Disease Control and Prevention, Atlanta, GA, United States of America
| | - Ang Li
- State Key Laboratory of Vegetation and Environmental Change, Chinese Academy of Sciences, Beijing, China
| | - Eugenia Lo
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, United States of America
| | - Patrick Robinson
- Department of Public Health Sciences, University of North Carolina Charlotte, Charlotte, NC, United States of America
- Academy of Population Health Innovation, University of North Carolina Charlotte, Charlotte, NC, United States of America
| | - Daniel Janies
- Department of Bioinformatics, University of North Carolina Charlotte, Charlotte, NC, United States of America
| | - Chihoon Lee
- School of Business, Stevens Institute of Technology, Hoboken, NJ, United States of America
| | - Michael Dulin
- Department of Public Health Sciences, University of North Carolina Charlotte, Charlotte, NC, United States of America
- Academy of Population Health Innovation, University of North Carolina Charlotte, Charlotte, NC, United States of America
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Metapopulation Model from Pathogen's Perspective: A Versatile Framework to Quantify Pathogen Transfer and Circulation between Environment and Hosts. Sci Rep 2019; 9:1694. [PMID: 30737423 PMCID: PMC6368549 DOI: 10.1038/s41598-018-37938-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 12/18/2018] [Indexed: 02/06/2023] Open
Abstract
Metapopulation models have been primarily explored in infectious disease epidemiology to study host subpopulation movements and between-host contact structures. They also have the potential to investigate environmental pathogen transferring. In this study, we demonstrate that metapopulation models serve as an ideal modeling framework to characterize and quantify pathogen transfer between environment and hosts. It therefore unifies host, pathogen, and environment, collectively known as the epidemiological triad, a fundamental concept in epidemiology. We develop a customizable and generalized pathogen-transferring model where pathogens dwell in and transferring (via contact) between environment and hosts. We analyze three specific case studies: pure pathogen transferring without pathogen demography, source-sink dynamics, and pathogen control via external disinfection. We demonstrate how pathogens circulate in the system between environment and hosts, as well as evaluate different controlling efforts for healthcare-associated infections (HAIs). For pure pathogen transferring, system equilibria can be derived analytically to explicitly quantify long-term pathogen distribution in the system. For source-sink dynamics and pathogen control via disinfection, we demonstrate that complete eradication of pathogens can be achieved, but the rates of converging to system equilibria differ based on specific model parameterization. Direct host-host pathogen transferring and within-host dynamics can be future directions of this modeling framework by adding specific modules.
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