scholarly journals Evaluation du risque de la fièvre catarrhale ovine par les Culicoides introduits via les réseaux de transport et d'échanges commerciaux

Author(s):  
Sebastian Napp ◽  
P. Calistri ◽  
A. Giovannini ◽  
S. Gubbins ◽  
I. Garcia-Bocanegra ◽  
...  

In August 2006, a bluetongue outbreak was detected in the Netherlands. It was caused by bluetongue virus serotype 8 (BTV- 8), a serotype thought to be of sub-Saharan origin. The most obvious mechanisms for BTV introduction, the import of infected hosts or the transport of infected Culicoides on airstreams, seemed unlikely. Therefore, the import of Culicoides along with or independently from the import of animals, plants or other ‘materials’ was considered as one of the possible explanations for the outbreak. In order to assess the likelihood of Culicoides being introduced via transport and trade networks, a quantitative risk assessment model has been constructed.

Author(s):  
Sebastian Napp ◽  
S. Gubbins ◽  
P. Calistri ◽  
Alberto Allepuz ◽  
Anna Alba ◽  
...  

Even though bluetongue virus (BTV) transmission is apparently interrupted during winter, bluetongue outbreaks often reappear in the next season (overwintering). Several mechanisms for BTV overwintering have been proposed, but to date their relative importance remains unclear. In order to assess the probability of BTV overwintering by horizontal transmission in vectors (long-lived Culicoides), ruminants (prolonged viraemia), or a combina­tion of both, a quantitative risk assessment model was developed. Furthermore, the model allowed the role played by the residual number of vectors present during winter to be examined, and the effect of a proportion of Culicoides living inside buildings (endophilic behaviour) to be explored. The model was then applied to a real scenario: overwintering in Germany between 2006 and 2007. The results showed that the limited number of vectors active during winter seemed to allow the transmission of BTV during this period and that this transmission was favoured by the endophilic behaviour of some Culicoides. Even though trans­mission was possible, the likelihood of BTV overwintering by horizontal transmission in vectors, ruminants or in both seemed however too low to explain the observed re-emergence of the disease. Therefore, other overwintering mechanisms that were not considered in the model are likely to have played a significant role in BTV overwintering in Germany between 2006 and 2007.


2013 ◽  
Vol 19 (3) ◽  
pp. 521-527 ◽  
Author(s):  
Song YANG ◽  
Shuqin WU ◽  
Ningqiu LI ◽  
Cunbin SHI ◽  
Guocheng DENG ◽  
...  

2001 ◽  
Vol 127 (2) ◽  
pp. 195-206 ◽  
Author(s):  
E. HARTNETT ◽  
L. KELLY ◽  
D. NEWELL ◽  
M. WOOLDRIDGE ◽  
G. GETTINBY

A quantitative risk assessment model investigating the risk of human infection with campylobacter from the consumption of chicken meat/products is currently being formulated. Here such an approach is used to evaluate the probability that a random bird, selected at slaughter from Great Britain's national poultry flock, will be campylobacter-positive. This is determined from the probability that a flock chosen at random contains at least one colonized bird and the within-flock prevalence of such a flock at slaughter. The model indicates that the probability bird chosen at random being campylobacter-positive at slaughter is 0·53. This probability value has associated uncertainty, the 5th percentile being 0·51 and the 95th percentile 0·55. The model predicts that delaying the age at first exposure to campylobacter can have a significant impact on reducing the probability of a bird being campylobacter-positive at slaughter. However, implementation of current biosecurity methods makes this difficult to achieve.


Author(s):  
Jerico Perez ◽  
David Weir ◽  
Caroline Seguin ◽  
Refaul Ferdous

To the end of 2012, Enbridge Pipelines employed an in-house developed indexed or relative risk assessment algorithm to model its liquid pipeline system. Using this model, Enbridge was able to identify risk control or treatment projects (e.g. valve placement) that could mitigate identified high risk areas. A changing understanding of the threats faced by a liquid pipeline system and their consequences meant that the model changed year over year making it difficult to demonstrate risk reduction accomplished on an annual basis using a relative scoring system. As the development of risk management evolved within the company, the expectations on the model also evolved and significantly increased. For example, questions were being asked such as “what risk is acceptable and what risk is not acceptable?”, “what is the true risk of failure for a given pipe section that considers the likelihood of all threats applicable to the pipeline”, and “is enough being done to reduce these risks to acceptable levels?” To this end, starting in 2012 and continuing through to the end of 2013, Enbridge Pipelines developed a quantitative mainline risk assessment model. This tool quantifies both threat likelihood and consequence and offers advantages over the indexed risk assessment model in the following areas: • Models likely worst case (P90) rupture scenarios • Enables independent evaluation of threats and consequences in order to understand the drivers • Produces risk assessment results in uniform units for all consequence criteria and in terms of frequencies of failure for likelihood • Aggregates likelihood and consequence at varying levels of granularity • Uses the risk appetite of the organization and its quantification allows for the setting of defined high, medium, and low risk targets • Quantifies the amount of risk in dollars/year facilitating cost-benefit analyses of mitigation efforts and risk reduction activities • Grounds risk assessment results on changes in product volume-out and receptor sensitivity • Balances between complexity and utility by using enough information and data granularity to capture all factors that have a meaningful impact on risk Development and implementation of the quantitative mainline risk assessment tool has had a number of challenges and hurdles. This paper provides an overview of the approach used by Enbridge to develop its quantitative mainline risk assessment model and examines the challenges, learnings and successes that have been achieved in its implementation.


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