Abstracts Accepted for Session 1: Optimizing Agriculture Systems/Disposition of Final Products

Optimizing Carcass Management Implementation Using Sensitivity Analyses from Risk Assessment

Lori P. Miller

USDA APHIS, Riverdale, Maryland

The purpose of this presentation is to discuss how to choose the most effective carcass management options for livestock or poultry operations using sensitivity data resulting from a series of risk assessments recently published by the US Environmental Protection Agency in collaboration with USDA and the US Department of Homeland Security. The risk assessments evaluated exposure pathways to human, animal and environmental receptors from various carcass management options for carcasses resulting from natural disasters and biological, chemical or radiological incidents.

The models used to perform the assessments assumed baseline data of 50 tons of carcass material under other baseline conditions. The models were then rerun varying certain parameters to evaluate sensitivity of those parameters to the overall exposure magnitude. For example, one analysis found that if 100 infected cattle carcasses were piled as close as 200 feet to an uninfected herd, there would not likely be an outbreak in that herd; however, if 10,000 cattle carcasses were piled, they would have to be 2000 feet away in order to protect the uninfected herd.

The presentation will examine the various sensitivity analyses in the risk assessments, and apply them to typical scenarios to demonstrate conditions which are likely to be protective of human, animal and environmental health.

Presentation: session 1.1

Animal Movement in Tunisia Using Social Network Analysis

Kalthoum Sana *, Cherni Jamel,Baccar Mohamed Naceur, Coste Caroline, Squarzoni Cécile

Mahrajène, TU

Understanding animal movement is essential foran effective surveillance of emergent and remerging diseases in Tunisia. In this context, characterisation of animal movement using social network analysis method can provide useful data to adjust surveillance strategies and control program. To identify localitieswith high vulnerability to infection or high potential risk of transmitting the disease,investigations on animal movement in cattle, sheep and goat markets were conducted to collect data on source, target, species, gender and numbers of animals. Degree and Betweenesswere calculatedfor each node. A total of 14,757 movements were detected during the period of study in 106 livestock markets. Result shows that animal movements occur throughout the whole country with a concentration in the central (West and East) and the north (West and East)governorates. The network was a directed free-scale graph with 947nodes,3173 arcs and a density of 0.004. Highest degree and Betweenesswere 75 and 90872 respectively. This study revealed the presence of “super-spreaders” of diseases such as Sidibouzid, Moknine, Mateur, bousselem, Nabeul …Those localities are key players in the initial spread of diseases. Information provided by social network analysis were useful to map risk of introduction and the spread of diseases and help decision makers in preparedness, surveillance (check point) and control of an epidemic. to evaluate the vulnerability of animal movement network to the spread of a specific disease.to reduce risk of the spread of diseases by.

Presentation: session 1.2

Application of Diagnostic Tests to Inform the Choice of Disposal Option for Diseases Where Animals Can Recover

Sasidhar Malladi, Peter Bonney, Amos Ssematimba, Kaitlyn St. Charles, Marie Culhane, Tim Goldsmith, David A. Halvorson, Carol J. Cardona

Fort Collins, Colorado

Early depopulation and disposal have been recognized as key factors in the control of animal disease outbreaks. Diseases where the animals can eventually recover, however, represent a unique circumstance with additional considerations with regards to the timing of depopulation and the disposal option choice. In this case, the prevalence of infectious animals would be lower at later stages of disease spread in the population where most of the animals would have recovered. The potential risk of disease spread associated with off-site disposal would also be correspondingly lower during the later stages of infection given the lower prevalence of actively shedding animals. We discuss how the prevalence of infectious and recovered animals varies over time and the significance for off-site disposal based on an example scenario of LPAI infection in a broiler breeder flock. We used stochastic simulation models to predict the prevalence of infectious and recovered birds over time in an LPAI infected broiler breeder flock. We then simulated detection via various diagnostic testing options including serological testing of 15 samples using the Agar Gel Immunodiffusion (AGID) assay, RRT-PCR testing using pooled samples of 11 swabs each, and combinations of RRT-PCR and serological tests. The simulation models were used to predict the range of time to detect LPAI post exposure and the prevalence of infectious birds at the time of detection under various active surveillance models. We then used the simulation model results to show the benefit of additional diagnostic testing in reducing uncertainty in the outcome variables and providing confidence that the number of infectious birds at the time of movement to disposal is acceptable. Our results indicate that a combination of RRT-PCR and serological tests provides the most information regarding the prevalence of infectious birds and the additional number of days required for the flock stop shedding. Finally, we discuss how the concepts and approach illustrated through the LPAI example may be generalized to other diseases where the animal populations would eventually recover.

Presentation: session 1.3

Vapor Phase Perioxide for Decontamination in Agriculture

Dusan Pavlik, Helena Maresova, Andrea Palyzova, Marek Kuzma

Institute of Microbiology, Prague, Czech Republic

The spread of infections in agriculture, whether due to bioterrorism or as a consequence of the natural occurrence of pathogens in the environment, is a serious social-economic problem. The hazards are not local infections but their spreading by contaminated agricultural equipment, working clothes or business channels in the distribution of goods and products, but also through other ways. Another significant danger is the periodic uninterrupted vector of spreading of microorganisms by the agricultural activity itself, i.e.: feeding-excreta-fertilizer-grow-agricultural product-feed. In addition, this is complicated by the fact that microorganisms can obtain during this process a resistance either by selective pressure or through the interspecific transmission. To prevent the spread of infection, both preventative measures such as vaccination, the use of pathogen-resistant crop strains, etc., must be carried out, but in case of an outbreak of infection, it is crucial to decontaminate the source of the infection, as well as the material and equipment that occurred at the outbreak. Also, in the case of a systematic cycle of microorganisms, this cycle must be interrupted. As a method of choice for decontamination in large areas, application of gaseous decontamination agents appears a very promising. There are a number of gaseous decontamination agents, such as formaldehyde, which is carcinogenic or ethylene oxide, which is flammable and forms an explosive mixture with air. In connection with decontamination of large areas, chlorine dioxide is the most commonly mentioned, but it has a relatively high toxicity. However, the decontamination agent for large areas should not only be highly efficient but should be easy to deploy, inexpensive, compatible with construction materials, harmless, with long shelf-time and odorless. Perhaps the best fulfills these requirements vapors of hydrogen peroxide (VHP). Therefore, we focused on testing of VHP for agriculture applications. The efficiency of the process is influenced by various parameters like concentration of VHP in the target area, humidity, the length of the process, morphology of the surface and its composition and also by the presence of other contamination. The decontamination effectiveness was evaluated on an antibiotic-resistant microbial community from a swine farm environment. It was used on artificial test coupons stained by the suspension of microorganisms but it was also applied on various surfaces, like painted steel, wood, plasterboard, concrete, etc. The tested materials were further soiled by blood, dust, or bovine serum albumin, grease etc. to follow the effect of surface contamination. The test equipment was specially designed to follow the effect of geometry of the decontaminated area to assess the influence of pollution localization in the room and to model different levels of availability of pollution by hydrogen peroxide. Moreover, it was also tested the influence of a combination of hydrogen peroxide with additives. It was also evaluated the level of damage of various materials, which represented the common room construction materials. The results indicate that VHP is the very promising agent for decontamination in agriculture and can be easily deployed in case of emergency or applied on a daily basis.

Presentation: session 1.4