scholarly journals The African swine fever control zone in South Africa and its current relevance

2016 ◽  
Vol 83 (1) ◽  
Author(s):  
Noluvuyo R. Magadla ◽  
Wilna Vosloo ◽  
Livio Heath ◽  
Bruce Gummow
Keyword(s):  
South Africa ◽  
Disease Control ◽  
African Swine Fever ◽  
Control Measures ◽  
Maximum Temperature ◽  
Boundary Line ◽  
Control Line ◽  
Control Zone ◽  
Ornithodoros Moubata ◽  
The Impact

African swine fever (ASF) has been reported in South Africa since the early 20th century. The disease has been controlled and confined to northern South Africa over the past 80 years by means of a well-defined boundary line, with strict control measures and movement restrictions north of this line. In 2012, the first outbreak of ASF outside the ASF control zone since 1996 occurred. The objective of this study was to evaluate the current relevance of the ASF control line as a demarcation line between endemic ASF (north) areas and ASF-free (south) area and to determine whether there was a need to realign its trajectory, given the recent outbreaks of ASF, global climate changes and urban development since the line’s inception. A study of ASF determinants was conducted in an area 20 km north and 20 km south of the ASF control line, in Limpopo, Mpumalanga, North West and Gauteng provinces between May 2008 and September 2012. The study confirmed that warthogs, warthog burrows and the soft tick reservoir, Ornithodoros moubata, are present south of the ASF control line, but no virus or viral DNA was detected in these ticks. There appears to be an increasing trend in the diurnal maximum temperature and a decrease in humidity along the line, but the impact of these changes is uncertain. No discernible changes in minimum temperatures and average rainfall along the disease control line were observed between 1992 and 2014. Even though the reservoirs were found south of the ASF boundary line, the study concluded that there was no need to realign the trajectory of the ASF disease control line, with the exception of Limpopo Province. However, the provincial surveillance programmes for the reservoir, vector and ASF virus south of this line needs to be maintained and intensified as changing farming practices may favour the spread of ASF virus beyond the control line.Keywords: African swine fever; warthog burrow; Ornithodoros moubata;control line

scholarly journals The impact of contact structure on infectious disease control: influenza and antiviral agents

2007 ◽  
Vol 135 (7) ◽  
pp. 1124-1132 ◽  
Author(s):  
H.-P. DUERR ◽  
M. SCHWEHM ◽  
C. C. LEARY ◽  
S. J. De Vlas ◽  
M. EICHNER
Keyword(s):  
Disease Control ◽  
Contact Structure ◽  
Influenza Pandemic ◽  
Antiviral Treatment ◽  
Antiviral Agents ◽  
Emerging Infectious Diseases ◽  
Control Measures ◽  
Variable Degree ◽  
Contact Patterns ◽  
The Impact

SUMMARYPlanning adequate public health responses against emerging infectious diseases requires predictive tools to evaluate the impact of candidate intervention strategies. With current interest in pandemic influenza very high, modelling approaches have suggested antiviral treatment combined with targeted prophylaxis as an effective first-line intervention against an emerging influenza pandemic. To investigate how the effectiveness of such interventions depends on contact structure, we simulate the effects in networks with variable degree distributions. The infection attack rate can increase if the number of contacts per person is heterogeneous, implying the existence of high-degree individuals who are potential super-spreaders. The effectiveness of a socially targeted intervention suffers from heterogeneous contact patterns and depends on whether infection is predominantly transmitted to close or casual contacts. Our findings imply that the various contact networks' degree distributions as well as the allocation of contagiousness between close and casual contacts should be examined to identify appropriate strategies of disease control measures.

scholarly journals Individually Optimal Choices can be Collectively Disastrous in COVID-19 Disease Control

2021 ◽  
Author(s):  
Madison Stoddard ◽  
Debra Van Egeren ◽  
Kaitlyn Johnson ◽  
Smriti Rao ◽  
Josh Furgeson ◽  
...  
Keyword(s):  
Public Health ◽  
Disease Control ◽  
Control Measures ◽  
Disease Spread ◽  
Complete Suppression ◽  
Natural Immunity ◽  
Endemic Disease ◽  
Health Measures ◽  
The Impact

Abstract Background: The word ‘pandemic’ conjures dystopian images of bodies stacked in the streets and societies on the brink of collapse. Despite this frightening picture, denialism and noncompliance with public health measures are common in the historical record, for example during the 1918 Influenza pandemic or the 2015 Ebola epidemic. The unique characteristics of SARS-CoV-2—its high basic reproduction number (R0), time-limited natural immunity and considerable potential for asymptomatic spread—exacerbate the public health repercussions of noncompliance with interventions (such as vaccines and masks) to limit disease transmission. Our work explores the rationality and impact of noncompliance with COVID-19 disease control measures. Methods: In this work, we used game theory to explore when noncompliance confers a perceived benefit to individuals. We then used epidemiological modeling to predict the impact of noncompliance on control of COVID-19, demonstrating that the presence of a noncompliant subpopulation prevents suppression of disease spread. Results: Our modeling demonstrating that noncompliance is a Nash equilibrium under a broad set of conditions, and that the existence of a noncompliant population can result in extensive endemic disease in the long-term after a return to pre-pandemic social and economic activity. Endemic disease poses a threat for both compliant and noncompliant individuals; all community members are protected if complete suppression is achieved, which is only possible with a high degree of compliance. For interventions that are highly effective at preventing disease spread, however, the consequences of noncompliance are borne disproportionately by noncompliant individuals. Conclusions: In sum, our work demonstrates the limits of free-market approaches to compliance with disease control measures during a pandemic. The act of noncompliance with disease intervention measures creates a negative externality, rendering COVID-19 disease control ineffective in the short term and making complete suppression impossible in the long term. Our work underscores the importance of developing effective strategies for prophylaxis through public health measures aimed at complete suppression and the need to focus on compliance at a population level.

MODELING CHOLERA TRANSMISSION UNDER DISEASE CONTROL MEASURES

2020 ◽  
pp. 1-26
Author(s):  
MARGARET BROWN ◽  
MIKO JIANG ◽  
CHAYU YANG ◽  
JIN WANG
Keyword(s):  
Disease Control ◽  
Disease Transmission ◽  
Control Measures ◽  
Transmission Dynamics ◽  
Threshold Dynamics ◽  
Education Programs ◽  
Multiple Control ◽  
Indirect Transmission ◽  
Transmission Pathways ◽  
The Impact

We present a new mathematical model to investigate the transmission dynamics of cholera under disease control measures that include education programs and water sanitation. The model incorporates the impact of education programs into the disease transmission rates and that of water sanitation into the environmental pathogen dynamics. We conduct a detailed analysis to the autonomous system of the model and establish the local and global stabilities of its equilibria that characterize the threshold dynamics of cholera. We then perform an optimal control study on the general model with time-dependent controls and explore effective approaches to implement the education programs and water sanitation while balancing their costs. Our analysis and simulation highlight the complex interaction among the direct and indirect transmission pathways of the disease, the intrinsic growth of the environmental pathogen and the impact of multiple control measures, and their roles in collectively shaping the transmission dynamics of cholera.

Control of Simultaneous Outbreaks of Carbapenemase-Producing Enterobacteriaceae and Extensively Drug-ResistantAcinetobacter baumanniiInfection in an Intensive Care Unit Using Interventions Promoted in the Centers for Disease Control and Prevention 2012 Carbapenemase-Resistant Enterobacteriaceae Toolkit

2014 ◽  
Vol 35 (7) ◽  
pp. 810-817 ◽  
Author(s):  
Kyle B. Enfield ◽  
Nujhat N. Huq ◽  
Megan F. Gosseling ◽  
Darla J. Low ◽  
Kevin C. Hazen ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Infection Control ◽  
Disease Control ◽  
Control Measures ◽  
Surgical Trauma ◽  
Infection Control Measures ◽  
Resistance Plasmids ◽  
Centers For Disease Control ◽  
The Impact

ObjectiveWe describe the efficacy of enhanced infection control measures, including those recommended in the Centers for Disease Control and Prevention’s 2012 carbapenem-resistant Enterobacteriaceae (CRE) toolkit, to control concurrent outbreaks of carbapenemase-producing Enterobacteriaceae (CPE) and extensively drug-resistantAcinetobacter baumannii(XDR-AB).DesignBefore-after intervention study.SettingFifteen-bed surgical trauma intensive care unit (ICU).MethodsWe investigated the impact of enhanced infection control measures in response to clusters of CPE and XDR-AB infections in an ICU from April 2009 to March 2010. Polymerase chain reaction was used to detect the presence ofblaKPCand resistance plasmids in CRE. Pulsed-field gel electrophoresis was performed to assess XDR-AB clonality. Enhanced infection-control measures were implemented in response to ongoing transmission of CPE and a new outbreak of XDR-AB. Efficacy was evaluated by comparing the incidence rate (IR) of CPE and XDR-AB before and after the implementation of these measures.ResultsThe IR of CPE for the 12 months before the implementation of enhanced measures was 7.77 cases per 1,000 patient-days, whereas the IR of XDR-AB for the 3 months before implementation was 6.79 cases per 1,000 patient-days. All examined CPE shared endemicblaKPCresistance plasmids, and 6 of the 7 XDR-AB isolates were clonal. Following institution of enhanced infection control measures, the CPE IR decreased to 1.22 cases per 1,000 patient-days (P= .001), and no more cases of XDR-AB were identified.ConclusionsUse of infection control measures described in the Centers for Disease Control and Prevention’s 2012 CRE toolkit was associated with a reduction in the IR of CPE and an interruption in XDR-AB transmission.

scholarly journals Dynamical analysis of the spread of African swine fever with the live pig price in China

2021 ◽  
Vol 18 (6) ◽  
pp. 8123-8148
Author(s):  
Yihao Huang ◽  
◽  
Jing Li ◽  
Juan Zhang ◽  
Zhen Jin ◽  
...  
Keyword(s):  
Supply And Demand ◽  
African Swine Fever ◽  
Control Measures ◽  
Basic Reproductive Number ◽  
Dynamical Analysis ◽  
Critical Conditions ◽  
Reproductive Number ◽  
Price Function ◽  
The Government ◽  
The Impact

<abstract><p>Pork makes up the highest proportion of household expenditure on meat in China and supply and demand have been basically stable in the past decade. However, the catastrophic outbreak of African swine fever (ASF) in August 2018 disrupted the balance and reduced the national herd by half within six months. The consequence was a gross lack of supply to the market and consumer demand was unable to be met. Accordingly, live pig prices rose sharply from 2019. In order to assess the influence of ASF on the price of the live pigs, we use a price function to characterize the relationship between price of the live pigs and the nation's pig stock, and then establish a time delay ASF epidemic dynamical model with the price function. By analyzing the dynamical behaviors of the model, we calculate the basic reproductive number, discuss the stability of equilibrium, and obtain the critical conditions for Hopf bifurcation. The model reasonableness is confirmed by carrying out data fitting and parameter estimation based on price data of the live pigs, the pig stock data and the outbreak data of ASF. By performing sensitivity analysis, we intuitively show the impact of ASF on the price of live pigs and the pig stocks, and assess the key factors affecting the outbreak of ASF. The conclusion is drawn that, with the control measures adopted by related government department in China, the basic reproductive number ($ R_0 = 0.6005 $) means that the ASF epidemic has been controlled. Moreover, the price of the live pig increases linearly with $ R_0 $, while the effect of the number of infected pigs on the subsequent price is non-linear related. Our findings suggest that society and the government should pay more attention to the prevention of animal disease epidemics.</p></abstract>

scholarly journals An entry risk assessment of African horse sickness virus into the controlled area of South Africa through the legal movement of equids

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0252117
Author(s):  
John D. Grewar ◽  
Johann L. Kotze ◽  
Beverly J. Parker ◽  
Lesley S. van Helden ◽  
Camilla T. Weyer
Keyword(s):  
South Africa ◽  
Census Data ◽  
Movement Control ◽  
Control Measures ◽  
Western Cape ◽  
African Horse Sickness ◽  
Annual Probability ◽  
Local Municipality ◽  
Important Health ◽  
The Impact

South Africa is endemic for African horse sickness (AHS), an important health and trade-sensitive disease of equids. The country is zoned with movement control measures facilitating an AHS-free controlled area in the south-west. Our objective was to quantitatively establish the risk of entry of AHS virus into the AHS controlled area through the legal movement of horses. Outcomes were subcategorised to evaluate movement pathway, temporal, and spatial differences in risk. A ‘no-control’ scenario allowed for evaluation of the impact of control measures. Using 2019 movement and AHS case data, and country-wide census data, a stochastic model was developed establishing local municipality level entry risk of AHSV at monthly intervals. These were aggregated to annual probability of entry. Sensitivity analysis evaluated model variables on their impact on the conditional means of the probability of entry. The median monthly probability of entry of AHSV into the controlled area of South Africa ranged from 0.75% (June) to 5.73% (February), with the annual median probability of entry estimated at 20.21% (95% CI: 15.89%-28.89%). The annual risk of AHSV entry compared well with the annual probability of introduction of AHS into the controlled area, which is ~10% based on the last 20 years of outbreak data. Direct non-quarantine movements made up most movements and accounted for most of the risk of entry. Spatial analysis showed that, even though reported case totals were zero throughout 2019 in the Western Cape, horses originating from this province still pose a risk that should not be ignored. Control measures decrease risk by a factor of 2.8 on an annual basis. Not only do the outcomes of this study inform domestic control, they can also be used for scientifically justified trade decision making, since in-country movement control forms a key component of export protocols.

scholarly journals A050 THE IMPACT OF COVID-19 AND DISEASE CONTROL MEASURES ON PEDIATRIC FOOD ALLERGY PARENTS/CAREGIVERS AND PATIENTS

2020 ◽  
Vol 125 (5) ◽  
pp. S10
Author(s):  
C. Warren ◽  
S. Chinthrajah ◽  
P. Newmark ◽  
L. Herbert ◽  
S. Fox ◽  
...  
Keyword(s):  
Food Allergy ◽  
Disease Control ◽  
Control Measures ◽  
The Impact

Diseases under conservation tillage systems

1996 ◽  
Vol 76 (4) ◽  
pp. 635-639 ◽  
Author(s):  
K. L. Bailey
Keyword(s):  
Disease Control ◽  
Crop Rotation ◽  
Conservation Tillage ◽  
Control Measures ◽  
Residue Management ◽  
Reduced Tillage ◽  
Published Data ◽  
Common Disease ◽  
Oilseed Crops ◽  
The Impact

The primary focus of this paper is on the effects of tillage and residue management on some diseases of cereal and oilseed crops in western Canada. In this region, reduced tillage lowers the impact of some root diseases but increases the impact of foliar diseases on cereals. Published data showing evidence of the effect of reduced tillage on diseases of oilseed crops is scarce. Diseases that were less economically important under higher tillage regimes may become more important with reduced tillage, but location and local environment largely influence which diseases will be present. Crop rotation is a key factor in residue management for disease control. Disease and yield loss were higher with monoculture than with more diverse rotations. Some crops may pose a greater risk to succeeding susceptible crops that share common disease problems, such as Sclerotinia on peas and canola. A well-balanced rotation should be at least 4 yr long with 50% of the interval devoted to cereals and the remainder divided among pulses, flax, other oilseed crops, or forages. The risk of most diseases may be lowered by understanding and managing the interactions between pathogens and crop residue through modifying local environmental conditions, crop rotation, limited tillage, and antagonistic mycoflora. Single disease control measures may be inadequate with reduced tillage; a holistic approach to crop systems and plant health management may provide the solution to disease problems. Key words: Zero tillage, conventional tillage, crop rotation, disease control, cereals, oilseeds

scholarly journals This time is different: model-based evaluation of the implications of SARS-CoV-2 infection kinetics for disease control

2020 ◽  
Author(s):  
Kaitlyn E Johnson ◽  
Madison Stoddard ◽  
Ryan P Nolan ◽  
Douglas E White ◽  
Natasha Hochberg ◽  
...  
Keyword(s):  
Disease Control ◽  
Control Strategies ◽  
Control Measures ◽  
Testing Strategies ◽  
Health Strategy ◽  
Quantitative Understanding ◽  
Dependent Model ◽  
Primary Basis ◽  
The Impact ◽  
Kinetics Of

As the ongoing COVID-19 pandemic passes from an acute to a chronic situation, countries and territories are grappling with the issue of how to reopen safely. The unique kinetics of infectivity of SARS-CoV-2, with its significant presymptomatic transmission, presents an unprecedented challenge to our intuitions. In this context, a generalizable quantitative understanding of the impact of SARS-CoV-2 infectivity on disease control strategies is vital. We used a previously published time-dependent model of SARS-CoV-2 infectivity (He et al., 2020) to parameterize an epidemiological model of transmission, which was then used to explore the effect of various disease control measures. Our analysis suggests that using symptom-based isolation alone as a control strategy is ineffective in limiting the spread of COVID-19, in contrast to its effectiveness in other diseases, such as SARS and influenza. Additionally, timeliness of testing and tracing strategies to reduce time to isolation, along with widespread adoption of measures to limit transmission are critical for any containment strategy. Our findings suggest that for symptom-based isolation and testing strategies to be effective, reduced transmission is required, reinforcing the importance of measures to limit transmission. From a public health strategy perspective, our findings lend support to the idea that symptomatic isolation should not form the primary basis for COVID-19 disease control.

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