The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform
Rachael M. Jones - One of the best experts on this subject based on the ideXlab platform.
-
aerosol transmission of infectious disease
Journal of Occupational and Environmental Medicine, 2015Co-Authors: Rachael M. Jones, Lisa M BrosseauAbstract:Objective: The concept of aerosol transmission is developed to resolve limitations in conventional definitions of airborne and droplet transmission. Methods: The method was literature review. Results: An infectious aerosol is a collection of pathogen-laden particles in air. Aerosol particles may deposit onto or be inhaled by a Susceptible Person. Aerosol transmission is biologically plausible when infectious aerosols are generated by or from an infectious Person, the pathogen remains viable in the environment for some period of time, and the target tissues in which the pathogen initiates infection are accessible to the aerosol. Biological plausibility of aerosol transmission is evaluated for Severe Acute Respiratory Syndrome coronavirus and norovirus and discussed for Mycobacterium tuberculosis, influenza, and Ebola virus. Conclusions: Aerosol transmission reflects a modern understanding of aerosol science and allows physically appropriate explanation and intervention selection for infectious diseases.
-
Influenza infection risk and predominate exposure route: uncertainty analysis.
Risk Analysis, 2011Co-Authors: Rachael M. Jones, Elodie AdidaAbstract:An effective nonpharmaceutical intervention for influenza interrupts an exposure route that contributes significantly to infection risk. Herein, we use uncertainty analysis (point†interval method) and Monte Carlo simulation to explore the magnitude of infection risk and predominant route of exposure. We utilized a previously published mathematical model of a Susceptible Person attending a bed†ridden infectious Person. Infection risk is sensitive to the magnitude of virus emission and contact rates. The contribution of droplet spray exposure to infection risk increases with cough frequency, and decreases with virus concentration in cough particles. We consider two infectivity scenarios: greater infectivity of virus deposited in the upper respiratory tract than virus inhaled in respirable aerosols, based on human studies; and equal infectivity in the two locations, based on studies in guinea pigs. Given that virus have equal probability of infection throughout the respiratory tract, the mean overall infection risk is 9.8 A— 10−2 (95th percentile 0.78). However, when virus in the upper respiratory tract is less infectious than inhaled virus, the overall infection risk is several orders of magnitude lower. In this event, inhalation is a significant exposure route. Contact transmission is important in both infectivity scenarios. The presence of virus in only respirable particles increases the mean overall infection risk by 1–3 orders of magnitude, with inhalation contributing ≥99% of the infection risk. The analysis indicates that reduction of uncertainties in the concentration of virus in expiratory particles of different sizes, expiratory event frequency, and infectivity at different sites in the respiratory tract will clarify the predominate exposure routes for influenza.
Elodie Adida - One of the best experts on this subject based on the ideXlab platform.
-
Influenza infection risk and predominate exposure route: uncertainty analysis.
Risk Analysis, 2011Co-Authors: Rachael M. Jones, Elodie AdidaAbstract:An effective nonpharmaceutical intervention for influenza interrupts an exposure route that contributes significantly to infection risk. Herein, we use uncertainty analysis (point†interval method) and Monte Carlo simulation to explore the magnitude of infection risk and predominant route of exposure. We utilized a previously published mathematical model of a Susceptible Person attending a bed†ridden infectious Person. Infection risk is sensitive to the magnitude of virus emission and contact rates. The contribution of droplet spray exposure to infection risk increases with cough frequency, and decreases with virus concentration in cough particles. We consider two infectivity scenarios: greater infectivity of virus deposited in the upper respiratory tract than virus inhaled in respirable aerosols, based on human studies; and equal infectivity in the two locations, based on studies in guinea pigs. Given that virus have equal probability of infection throughout the respiratory tract, the mean overall infection risk is 9.8 A— 10−2 (95th percentile 0.78). However, when virus in the upper respiratory tract is less infectious than inhaled virus, the overall infection risk is several orders of magnitude lower. In this event, inhalation is a significant exposure route. Contact transmission is important in both infectivity scenarios. The presence of virus in only respirable particles increases the mean overall infection risk by 1–3 orders of magnitude, with inhalation contributing ≥99% of the infection risk. The analysis indicates that reduction of uncertainties in the concentration of virus in expiratory particles of different sizes, expiratory event frequency, and infectivity at different sites in the respiratory tract will clarify the predominate exposure routes for influenza.
Lisa M Brosseau - One of the best experts on this subject based on the ideXlab platform.
-
aerosol transmission of infectious disease
Journal of Occupational and Environmental Medicine, 2015Co-Authors: Rachael M. Jones, Lisa M BrosseauAbstract:Objective: The concept of aerosol transmission is developed to resolve limitations in conventional definitions of airborne and droplet transmission. Methods: The method was literature review. Results: An infectious aerosol is a collection of pathogen-laden particles in air. Aerosol particles may deposit onto or be inhaled by a Susceptible Person. Aerosol transmission is biologically plausible when infectious aerosols are generated by or from an infectious Person, the pathogen remains viable in the environment for some period of time, and the target tissues in which the pathogen initiates infection are accessible to the aerosol. Biological plausibility of aerosol transmission is evaluated for Severe Acute Respiratory Syndrome coronavirus and norovirus and discussed for Mycobacterium tuberculosis, influenza, and Ebola virus. Conclusions: Aerosol transmission reflects a modern understanding of aerosol science and allows physically appropriate explanation and intervention selection for infectious diseases.
Donald A Goldmann - One of the best experts on this subject based on the ideXlab platform.
-
a randomized controlled trial of a multifaceted intervention including alcohol based hand sanitizer and hand hygiene education to reduce illness transmission in the home
Pediatrics, 2005Co-Authors: Thomas J Sandora, Elsie M Taveras, Meichiung Shih, Elissa A Resnick, Dennis Rossdegnan, Donald A GoldmannAbstract:Objective.Good hand hygiene may reduce the spread of infections in families with children who are in out-of-home child care. Alcohol-based hand sanitizers rapidly kill viruses that are commonly associated with respiratory and gastrointestinal (GI) infections. The objective of this study was to determine whether a multifactorial campaign centered on increasing alcohol-based hand sanitizer use and hand-hygiene education reduces illness transmission in the home. Methods.A cluster randomized, controlled trial was conducted of homes of 292 families with children who were enrolled in out-of-home child care in 26 child care centers. Eligible families had ≥1 child who was 6 months to 5 years of age and in child care for ≥10 hours/week. Intervention families received a supply of hand sanitizer and biweekly hand-hygiene educational materials for 5 months; control families received only materials promoting good nutrition. Primary caregivers were phoned biweekly and reported respiratory and GI illnesses in family members. Respiratory and GI-illness–transmission rates (measured as secondary illnesses per Susceptible Person-month) were compared between groups, adjusting for demographic variables, hand-hygiene practices, and previous experience using hand sanitizers. Results.Baseline demographics were similar in the 2 groups. A total of 1802 respiratory illnesses occurred during the study; 443 (25%) were secondary illnesses. A total of 252 GI illnesses occurred during the study; 28 (11%) were secondary illnesses. The secondary GI-illness rate was significantly lower in intervention families compared with control families (incidence rate ratio [IRR]: 0.41; 95% confidence interval [CI]: 0.19–0.90). The overall rate of secondary respiratory illness was not significantly different between groups (IRR: 0.97; 95% CI: 0.72-1.30). However, families with higher sanitizer usage had a marginally lower secondary respiratory illness rate than those with less usage (IRR: 0.81; 95% CI: 0.65-1.09). Conclusions.A multifactorial intervention emphasizing alcohol-based hand sanitizer use in the home reduced transmission of GI illnesses within families with children in child care. Hand sanitizers and multifaceted educational messages may have a role in improving hand-hygiene practices within the home setting.
Jorge Pedrosa - One of the best experts on this subject based on the ideXlab platform.
-
influenza infectious dose may explain the high mortality of the second and third wave of 1918 1919 influenza pandemic
PLOS ONE, 2010Co-Authors: Cristina A Paulo, Tiago Domingos, Alberto G. Murta, Margarida Correianeves, Jorge PedrosaAbstract:Background It is widely accepted that the shift in case-fatality rate between waves during the 1918 influenza pandemic was due to a genetic change in the virus. In animal models, the infectious dose of influenza A virus was associated to the severity of disease which lead us to propose a new hypothesis. We propose that the increase in the case-fatality rate can be explained by the dynamics of disease and by a dose-dependent response mediated by the number of simultaneous contacts a Susceptible Person has with infectious ones. Methods We used a compartment model with seasonality, waning of immunity and a Holling type II function, to model simultaneous contacts between a Susceptible Person and infectious ones. In the model, infected Persons having mild or severe illness depend both on the proportion of infectious Persons in the population and on the level of simultaneous contacts between a Susceptible and infectious Persons. We further allowed for a high or low rate of waning immunity and volunteer isolation at different times of the epidemic. Results In all scenarios, case-fatality rate was low during the first wave (Spring) due to a decrease in the effective reproduction number. The case-fatality rate in the second wave (Autumn) depended on the ratio between the number of severe cases to the number of mild cases since, for each 1000 mild infections only 4 deaths occurred whereas for 1000 severe infections there were 20 deaths. A third wave (late Winter) was dependent on the rate for waning immunity or on the introduction of new Susceptible Persons in the community. If a group of Persons became voluntarily isolated and returned to the community some days latter, new waves occurred. For a fixed number of infected Persons the overall case-fatality rate decreased as the number of waves increased. This is explained by the lower proportion of infectious individuals in each wave that prevented an increase in the number of severe infections and thus of the case-fatality rate. Conclusion The increase on the proportion of infectious Persons as a proxy for the increase of the infectious dose a Susceptible Person is exposed, as the epidemic develops, can explain the shift in case-fatality rate between waves during the 1918 influenza pandemic.
