Society For Risk Analysis Annual Meeting 2013

Session Schedule & Abstracts

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Common abbreviations

Zoonotic Diseases: Risk & Characterization of Human Illness

Room: Key Ballroom 4   8:30 AM - 10:00 AM

Chair(s): Sarah Taft

Sponsored by MRASG

T1-D.1  08:30  Use of an Administrative Database to Characterize Babesiosis Occurrence in the United States, 2006-2008. Walderhaug MO*, Menis M, Anderson SA; U.S. FDA CBER

Abstract: Babesiosis is a zoonotic disease caused by several species of protozoan parasite of the genus Babesia. This illness is typically spread to humans by tick bite. The symptoms of babesiosis range in severity from asymptomatic to high fever with hemolytic anemia. Symptoms are more likely to be severe for cases where the infected person is very young, very old, or immunocompromised. Blood units containing babesiosis that were collected from asymptomatic blood donors represent a threat to blood recipients, and there is no approved screening test at present. To assess the risk of transfusion transmitted babesiosis, we undertook an analysis to estimate the number of potential carriers of babesiosis that could be donating. Babesiosis became a nationally notifiable disease in 2011, however before 2011, the illness was sporadically reported to the CDC. We performed a nationwide study of the diagnosis of babesiosis in the inpatient, outpatient, skilled nursing facility, and carrier standard analytical Medicare enrollment files for calendar years 2006 to 2008. Our findings show that estimates of state-specific rates from our study are up to ten times higher than nationally reported rates at the time. Babesiosis rates were highest in the Northeastern states of the U.S. The rates of babesiosis in males over 65 years in age were significantly higher than rates in females which may reflect higher exposures to ticks in Babesia-endemic areas by males partaking in outdoor activities. Accurate estimates of the rates of asymptomatic cases of babesiosis in blood donors is an important factor in estimating the benefits and risks of screening blood donors for carriers of babesiosis. The use of these results in a general population risk assessment is limited in that the database used provides data on the elderly but not on the general population. Large administrative databases may have some limitations, but they may also be useful sources of health information for risk assessments.

T1-D.2  08:50  Modelling the species jump: spatially ranking influenza A virus ability to cross species barrier and infect humans. Hill AA*, Kosmider RD, Dewe T, Kelly L, De Nardi M, Havelaar A, Von Dobscheutz S, Stevens K, Staerk K; Animal Health and Veterinary Laboratories Agency, Royal Veterinary College, Istituto Zooprofilattico Sperimentale delle Venezie

Abstract: One of the most notorious group of zoonotic pathogens are Influenza A viruses. Historically, avian influenza viruses have been of primary concern as they were responsible for the pandemics in 1918 (“Spanish flu”), 1967 (Hong Kong) and 2009 (“Swine flu”).The latter outbreak has challenged the ethos of Influenza A pandemic preparedness and highlights the importance of taking a broader approach to the problem. The European Food Safety Authority (EFSA) has commissioned an Article 36 research project to develop a more formal approach to the identification of animal influenza A strains that have the potential to make the species jump into humans. We propose a prototype risk assessment framework to spatially rank Influenza A viruses circulating in animal populations for their potential to jump the species barriers to humans. We use a modified version of the classical epidemiological risk equation to estimate the risk of at least one human infection (given an infected livestock population) within a 5km2 area. The output will be a list of ranked animal viruses that could have the potential to infect humans in certain areas of the globe and, hence, may have pandemic potential. The intention is for the model to be eventually used regularly to prioritise research/surveillance for animal influenzas in higher risk areas of the globe. We will present initial spatial ranking results of the framework model for historic strains (validation) and hypothetical strains to illustrate the important issues and drivers of the model.

T1-D.3  09:10  Zoonotic diseases from companion animals: risk of salmonellosis associated with pet food. Lambertini E*, Buchanan RL, Narrod C, Pradhan AK; University of Maryland, Joint Institute for Food Safety and Applied Nutrition

Abstract: Recent Salmonella outbreaks associated with dry pet food highlight the importance of these foods as vehicles for zoonotic pathogens. The need to characterize the risk profile of this class of products is currently not supported by data. Moreover, the relative impact of industry practices and household behavior in mitigating risk is unknown. This study aims to: 1) model the microbial ecology of Salmonella in the dry pet food production chain, 2) estimate pet and human exposure to Salmonella through pet food, and 3) assess the impact of mitigation strategies on human illness risk. Data on Salmonella contamination levels in pet food ingredients, production parameters, bacterial ecology on food and surfaces, and transfer by contact were obtained through a systematic literature review and from industry data. A probabilistic quantitative microbial risk assessment model was developed to estimate exposure of pets and their owners to Salmonella in pet food, and the associated illness risk. Model outcomes highlight that human illness risk due to handling pet food is minimal if contamination occurs before the heated extrusion step (10-15 CFU/Kg of food at the point of exposure, even with initial 1015 CFU/Kg in the protein meal ingredient). Risk increases significantly if contamination occurs in coating fat, with mean probability of illness per exposure Pill 1/1000 at mean Salmonella levels of 107 CFU/Kg fat. In this case, an additional post-coating 3-Log CFU reduction is needed to limit Pill to 10-6 (mean of 0.03 CFU/Kg in finished product). Recontamination after extrusion and coating, e.g. via dust or condensate, can lead to even higher risk (Pill 1/100 with mean Salmonella levels of 0.4 CFU/Kg in intermediate product). In this scenario, hand washing after handling food would reduce the Pill only by 30%. The developed risk model provides a tool to estimate health impacts under a range of production and household handling scenarios. Model results provide a basis for improvements in production processes, risk communication to consumers, and regulatory action.

T1-D.4  09:30  Modelling the risks of introduction of ticks infected with Crimean-Congo haemorrhagic fever virus into GB. England M, Brouwer A, Gale P*; AHVLA

Abstract: Crimean-Congo haemorrhagic fever virus (CCHFV) is a tick-borne zoonosis. Recently, large outbreaks of CCHFV have occurred in new foci in south-east Europe and the Balkans, most notably in Turkey. Migratory birds have previously been suggested as a factor in the spread of CCHFV into Europe but here for the first time we present data for international horse movements as a potential risk factor in the spread of CCHFV-infected ticks. The numbers of CCHFV-infected unfed adult ticks in GB that could potentially bite and infect a human from these two pathways were predicted and compared. CCHFV has never been detected in GB and no infected ticks have been reported on birds or horses in GB. GB does not have competent Hyalomma spp. tick vectors for CCHFV and transmission within GB is only a theoretical possibility assumed here. A spatial analysis of GB under current climatic and land cover conditions predicted the areas of GB where imported Hyalomma spp. ticks could survive to the next life stage following detachment from imported horses or migratory birds. Hyalomma spp. ticks would enter GB on birds as nymphs and on horses as fed and mated adults. A total of 143 CCHFV-infected unfed adult Hyalomma spp. ticks was predicted to be present in GB as a result of importations on horses between 1st April and 31st July each year under current habitat conditions. For the same time period, a total of 11 CCHFV-infected Hyalomma spp. adult ticks was predicted to be present in GB as a result of importations on migratory birds. Although a greater number of CCHFV-infected ticks were imported into GB on migratory birds each year than on horses, the ability of each female to lay an average of 6,500 eggs following detachment in GB led to an overall greater number of CCHFV-infected ticks that could bite a human from the horse pathway than from the bird pathway.Empirical data would be required to justify these predictions.

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