A model of hyperparasite regulation of the gall rust–lodgepole pine pathosystem

1996 ◽  
Vol 26 (7) ◽  
pp. 1256-1265 ◽  
Author(s):  
Bart J. Van Der Kamp ◽  
Peter V. Blenis
Keyword(s):  
Simulation Model ◽  
Environmental Conditions ◽  
Stable Equilibrium ◽  
Mortality Rates ◽  
Control Measures ◽  
First Year ◽  
Infection Rates ◽  
Breeding For Resistance ◽  
Simple Simulation ◽  
Equilibrium Level

Endocronartiumharknessii (J.P. Moore) Hirat. populations never approach the level where all susceptible Pinuscontorta Dougl. ex Loud. var. latifolia Engelm. tissue is infected, even in years when environmental conditions are favourable for infection. A simple simulation model was developed to determine whether a hyperparasite could regulate the rust population and maintain it at an equilibrium level far below host saturation. The model assumed that galls begin sporulating and first become susceptible to parasitism 2 years after formation and requires specification of infection rates for the rust and the hyperparasite, mortality rates for normal and parasitized galls, and the degree to which aeciospore production is reduced following hyperparasite infection. Analysis of the model showed that the hyperparasite could regulate the rust population, producing a stable equilibrium, but only if the various rates were such that healthy galls, in their lifetime, produced enough aeciospores to give rise to more than one new gall, while galls that were parasitized during the first year of aeciospore production produced, in their lifetime, fewer than one new gall. The model of hyperparasite regulation provides one possible explanation of the dynamics of the gall rust pathosystem. It shows that control measures such as sanitation and breeding for resistance may reduce the effectiveness of the hyperparasite in regulating the system and, thus, may fail to achieve the anticipated goals.

scholarly journals The epidemiology of louping ill in Ayrshire: the first year of studies in sheep

1964 ◽  
Vol 62 (1) ◽  
pp. 53-68 ◽  
Author(s):  
C. E. Gordon Smith ◽  
Dolores A McMahon ◽  
K. J O'Reilly ◽  
A. L Wilson ◽  
J. M Robertson
Keyword(s):  
Neutralizing Antibody ◽  
Early Summer ◽  
Control Measures ◽  
Clinical Disease ◽  
First Year ◽  
Infection Rates ◽  
Long Term Study ◽  
Louping Ill ◽  
The Difference ◽  
Almost All

1. Following an epizootic of louping ill on certain farms in south-west Ayrshire in 1960, a long-term study of several farms was initiated.2. The flocks on two hirsels of one farm were studied during spring and early summer of 1961. Although only one lamb death was confirmed as due to louping ill, the infection rates in sentinel hoggs on the two hirsels were 50–60. and 11% respectively. The difference between the hirsels is probably attributable to the difference in the amount of tick habitat on them.3. The ewes were bled in March and June and their lambs in June. Haemagglutinin inhibition (HI) and neutralization tests revealed that the HI antibody is much shorter lasting than neutralizing antibody. Many ewes, therefore, had neutralizing but not HI antibody. Otherwise agreement between the tests was good. In March almost all the ewes aged 3 years or more had antibody. Of the gimmers (2-year-olds) about two-thirds on one hirsel and one-third on the other had antibody in March: by June almost all the former and about half of the latter had antibody.4. About two-thirds of the lambs had the same antibody status as their mothers in June and almost all the rest had less antibody than their mothers. Serological evidence suggestive of louping ill without recognizable clinical disease was found in six lambs and a further lamb recovered from clinical disease.5. Revaccination of two-thirds of the flock failed to cause any detectable change in antibody status.6. The epidemiology and pathogenesis are discussed in relation to immunity and infection rates, and to the design of control measures.We are greatly indebted to the late Mr James Murdoch at Dalmellington, Mr John Murdoch at Dalcairnie Farm, and Mr David Murdoch at Knockgray Farm for permission to work on their farms and for all the help they gave us during the study.

scholarly journals Field Efficacy of Steinernema sp. (Rhabditida: Steinernematidae) on the Colorado Potato Beetle Overwintering Generation

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1464
Author(s):  
Maja Čačija ◽  
Renata Bažok ◽  
Majda Kolenc ◽  
Tena Bujas ◽  
Zrinka Drmić ◽  
...  
Keyword(s):  
Colorado Potato Beetle ◽  
First Generation ◽  
Control Measures ◽  
Recommended Dose ◽  
Steinernema Feltiae ◽  
First Year ◽  
Potato Beetle ◽  
Field Efficacy ◽  
Second Year ◽  
Economic Pest

Colorado potato beetle (CPB) is an economic pest of potato that has developed resistance to all classes of chemical insecticides, thus requiring alternative control measures. As a potential solution, entomopathogenic nematodes (EPNs) have proven effective in suppressing this pest, but their efficacy against overwintering generations of CPB in Croatia has not been sufficiently researched. The aim of this two-year (2018–2019) field study was to determine the efficacy of Steinernema feltiae and Steinernema carpocapsae applied to overwintering CPB adults. EPNs were applied at three doses (7.5 mil./10 m2, 5.0 mil./10 m2 (the recommended dose) and 2.5 mil./10 m2) by watering the soil where the adults were overwintering. The first-year results were satisfactory for both EPNs: the efficacy of S. feltiae ranged from 79.03% to 100.00%, while the efficacy of S. carpocapsae ranged from 77.32% to 96.22%. In the second year, the highest efficacy (69.57%) was obtained using the recommended dose of S. feltiae. Although the results are not consistent across the two years of our study and suggest further research, they indicate that EPNs have great potential in controlling overwintering CPB generations to reduce first generation abundance and damage, and also to prevent the spread of new generations to surrounding potato growing areas.

scholarly journals Can Copper Products and Surfaces Reduce the Spread of Infectious Microorganisms and Hospital-Acquired Infections?

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3444
Author(s):  
Joji Abraham ◽  
Kim Dowling ◽  
Singarayer Florentine
Keyword(s):  
Infection Control ◽  
Hospital Admissions ◽  
Copper Alloys ◽  
Well Being ◽  
Mortality Rates ◽  
Pathogen Transmission ◽  
Control Measures ◽  
Traditional Use ◽  
Healthcare Facilities ◽  
Infection Control Measures

Pathogen transfer and infection in the built environment are globally significant events, leading to the spread of disease and an increase in subsequent morbidity and mortality rates. There are numerous strategies followed in healthcare facilities to minimize pathogen transfer, but complete infection control has not, as yet, been achieved. However, based on traditional use in many cultures, the introduction of copper products and surfaces to significantly and positively retard pathogen transmission invites further investigation. For example, many microbes are rendered unviable upon contact exposure to copper or copper alloys, either immediately or within a short time. In addition, many disease-causing bacteria such as E. coli O157:H7, hospital superbugs, and several viruses (including SARS-CoV-2) are also susceptible to exposure to copper surfaces. It is thus suggested that replacing common touch surfaces in healthcare facilities, food industries, and public places (including public transport) with copper or alloys of copper may substantially contribute to limiting transmission. Subsequent hospital admissions and mortality rates will consequently be lowered, with a concomitant saving of lives and considerable levels of resources. This consideration is very significant in times of the COVID-19 pandemic and the upcoming epidemics, as it is becoming clear that all forms of possible infection control measures should be practiced in order to protect community well-being and promote healthy outcomes.

scholarly journals High COVID-19 transmission potential associated with re-opening universities can be mitigated with layered interventions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ellen Brooks-Pollock ◽  
Hannah Christensen ◽  
Adam Trickey ◽  
Gibran Hemani ◽  
Emily Nixon ◽  
...  
Keyword(s):  
Prediction Interval ◽  
Mitigation Strategies ◽  
Control Measures ◽  
Transmission Model ◽  
Model Parameters ◽  
Infection Rates ◽  
First Year Students ◽  
Transmission Potential ◽  
Plausible Model ◽  
Effective Option

AbstractControlling COVID-19 transmission in universities poses challenges due to the complex social networks and potential for asymptomatic spread. We developed a stochastic transmission model based on realistic mixing patterns and evaluated alternative mitigation strategies. We predict, for plausible model parameters, that if asymptomatic cases are half as infectious as symptomatic cases, then 15% (98% Prediction Interval: 6–35%) of students could be infected during the first term without additional control measures. First year students are the main drivers of transmission with the highest infection rates, largely due to communal residences. In isolation, reducing face-to-face teaching is the most effective intervention considered, however layering multiple interventions could reduce infection rates by 75%. Fortnightly or more frequent mass testing is required to impact transmission and was not the most effective option considered. Our findings suggest that additional outbreak control measures should be considered for university settings.

Effect of selenium supplementation on survival, liveweight and wool weight of young sheep on Kangaroo Island, South Australia

1979 ◽  
Vol 19 (101) ◽  
pp. 689 ◽  
Author(s):  
SK Walker ◽  
GP Hall ◽  
DH Smith ◽  
RW Ponzoni ◽  
GJ Judson
Keyword(s):  
Total Dose ◽  
Whole Blood ◽  
Sodium Selenite ◽  
South Australia ◽  
Selenium Concentration ◽  
Mortality Rates ◽  
Selenium Supplementation ◽  
First Year ◽  
Weaning Weight ◽  
Fleece Weight

The responses in liveweight, wool weight and survival, to selenium supplementation, were studied in young sheep from weaning to yearling age. The experiment was conducted over three years. In the first year, one sodium selenite supplementation rate was used (total dose 46.5 mg). During the following two years two supplementation rates were administered (total doses 46.5 mg and 93 mg). Mean concentrations of selenium in whole blood in unsupplemented sheep varied from 0.19-0.56 pmol l-l and from 0.20-0.44 pmol l-1 in the two years in which concentrations were measured. Supplementation, which commenced at lamb marking, increased the selenium concentration in sheep at weaning and thereafter. Selenium supplementation improved the break-of-season weight (P < 0.01) and yearling weight (P < 0.01 ) but not weaning weight (0.05 < P < 0.1 ). Hogget fleece weight was improved (P < 0.01 ) and mortality reduced (P < 0.01) by selenium supplementation. There was a treatment x year interaction in mortality rates (P < 0.01 ). There were no significant differences between the two supplementation rates

Larger Numbers Needed

PEDIATRICS ◽  
1987 ◽  
Vol 80 (5) ◽  
pp. 764-764
Author(s):  
THOMAS E. WISWELL
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Urinary Tract Infections ◽  
First Year ◽  
Infection Rates ◽  
Symptomatic Urinary Tract Infection ◽  
Tract Infections ◽  
First Year Of Life

In Reply.— Dr Altschul presents data on urinary tract infections during infancy and reports infection rates substantially lower than those we have previously reported.1,2 He then makes several conclusions based on these differences. His data indicate that the maximum infection rates would be 0.11% among girls and 0.02% and 0.12% among circumcised and uncircumcised boys, respectively. In contrast, from a population of 422,328 infants, we found the overall incidence of symptomatic urinary tract infection during the first year of life to be 0.57% in girls, 0.11% in circumcised boys, and 1.12% in uncircumcised boys.

Description of a simulation model for the population dynamics of Eimeria acervulina infection in broilers

Parasitology ◽  
1994 ◽  
Vol 108 (5) ◽  
pp. 503-512 ◽  
Author(s):  
A. M. Henken ◽  
H. W. Ploeger ◽  
E. A. M. Graat ◽  
T. E. Carpenter
Keyword(s):  
Population Dynamics ◽  
Simulation Model ◽  
Difference Equations ◽  
Life Stages ◽  
Eimeria Acervulina ◽  
Growing Period ◽  
Equilibrium Level ◽  
Equilibrium Number

SummaryA simulation model for the population dynamics of Eimeria acervulina infection in broilers is presented. The model describes the development of the numbers of parasites in the various life-stages during the growing period of broilers and the empty house period between grow-outs. The model includes assumptions with respect to development of immunity to E. acervulina infection and effects of application of anticoccidial drugs. The model consists of a set of difference equations that are solved numerically at 1 h intervals. Under constant conditions, an equilibrium level was reached after a few grow-outs during which infection always peaked around the 21st day in the growing period. Within a growing period, infection peaked earlier (later) than the 21st day in case initial numbers of sporulated oocysts were higher (lower) than the equilibrium number.

scholarly journals Retrospective Study on Personal Protective Equipment During Pandemic Link to Outbreak of Carbpenem-Resistant Enterobacteriace

2021 ◽  
Vol 1 (S1) ◽  
pp. s9-s10
Author(s):  
Kenisha Evans ◽  
Jennifer LeRose ◽  
Angela Beatriz Cruz ◽  
Lavina Jabbo ◽  
Teena Chopra
Keyword(s):  
Retrospective Study ◽  
Infection Control ◽  
Personal Protective Equipment ◽  
Horizontal Transmission ◽  
Control Measures ◽  
Protective Equipment ◽  
Local Health ◽  
Infection Rates ◽  
Infection Control Measures ◽  
The Impact

Background: In 2019, according to the Centers for Disease Control and Prevention, carbapenem-resistant Enterobacteriaceae (CRE), had cost the lives of >35,000 patients, particularly the most virulent plasmid-mediated New Delhi metallo-β-lactamase (NDM). Although healthcare systems normally have strict surveillance and infection control measures for CRE, the rapid emergence of novel SAR-CoV-2 and COVID-19 led to a shortage of personal protective equipment (PPE) and medical supplies. As a result, routine infection practices, such as contact precautions, were violated. Studies have shown this depletion and shift in resources compromised the control of infections such CRE leading to rising horizontal transmission. Method: A retrospective study was conducted at a tertiary healthcare system in Detroit, Michigan, to determine the impact of PPE shortages during the COVID-19 pandemic on NDM infection rates. The following periods were established during 2020 based on PPE availability: (1) pre-PPE shortage (January–June), (2) PPE shortage (July–October), and (3) post-PPE shortage (November–December). Rates of NDM per 10,000 patient days were compared between periods using the Wilcoxon signed rank-sum test. Isolates were confirmed resistant by NDM by molecular typing performed by the Michigan State Health Department. Patient characteristics were gathered by medical chart review and patient interviews by telephone. Results: Overall, the average rate of NDM infections was 1.82 ±1.5 per 10,000 patient days. Rates during the PPE shortage were significantly higher, averaging 3.6 ±1.1 cases per 10,000 patient days (P = .02). During this time, several infections occurred within patients on the same unit and/or patients with same treating team, suggesting possible horizontal transmission. Once PPE stock was replenished and isolation practices were reinstated, NDM infection rates decreased to 0.77 ±1.1 per 10,000 patient days. Conclusion: Control of CRE requires strategic planning with active surveillance, antimicrobial constructs, and infection control measures. The study illustrates that in times of crisis, such as the COVID-19 pandemic, the burden of effective infection control requires much more multidisciplinary efforts to prevent unintentional lapses in patient safety. A swift response by the state and local health departments at a tertiary-care healthcare center conveyed a positive mitigation of the highest clinical threats and decreased horizontal transmission of disease.Funding: NoDisclosures: None

scholarly journals Random-Walk, Agent-Level Pandemic Simulation (RAW-ALPS) for Analyzing Effects of Different Lockdown Measures

2021 ◽  
Vol 7 ◽  
Author(s):  
Anuj Srivastava
Keyword(s):  
Random Walk ◽  
Simulation Model ◽  
Random Walks ◽  
Stochastic Simulation ◽  
Preventive Measures ◽  
Infection Rates ◽  
Physical Proximity ◽  
Stochastic Simulation Model ◽  
Restrictive Measures ◽  
Effective Use

This article develops an agent-level stochastic simulation model, termed RAW-ALPS, for simulating the spread of an epidemic in a community. The mechanism of transmission is agent-to-agent contact, using parameters reported for the COVID-19 pandemic. When unconstrained, the agents follow independent random walks and catch infections due to physical proximity with infected agents. Under lockdown, an infected agent can only infect a coinhabitant, leading to a reduction in the spread. The main goal of the RAW-ALPS simulation is to help quantify the effects of preventive measures—timing and durations of lockdowns—on infections, fatalities, and recoveries. The model helps measure changes in infection rates and casualties due to the imposition and maintenance of restrictive measures. It considers three types of lockdowns: 1) whole population (except the essential workers), 2) only the infected agents, and 3) only the symptomatic agents. The results show that the most effective use of lockdown measures is when all infected agents, including both symptomatic and asymptomatic, are quarantined, while the uninfected agents are allowed to move freely. This result calls for regular and extensive testing of a population to isolate and restrict all infected agents.

A simple simulation model for complex coacervates

Soft Matter ◽  
2021 ◽  
Author(s):  
Sai Vineeth Bobbili ◽  
Scott Milner
Keyword(s):  
Phase Diagram ◽  
Aqueous Solution ◽  
Phase Separation ◽  
Simulation Model ◽  
Simple Simulation ◽  
The Impact ◽  
Oppositely Charged

When oppositely charged polyelectrolytes mix in an aqueous solution, associative phase separation gives rise to coacervates. Experiments reveal the phase diagram for such coacervates, and determine the impact of charge...

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