Performing Department
POPULATION HEALTH & REPRODUCTION
Non Technical Summary
Trichinellosis is a zoonotic disease caused by one of the most widely distributed parasite groups in the world, Trichinella. At least eight species have been identified in humans and a wide range of animals including pigs, horses, wild game, birds, fish and even reptiles. The epidemiology of Trichinella can be broken down into two cycles. The domestic cycle refers to the cycle of transmission involving human settlements whereas the sylvatic cycle consists of the transmission of Trichinella among wildlife, primarily carnivorous and omnivorous scavenger species. In California, human, black bear and wild pig population growth, coupled with increased urban development has created an expanding ecological niche for parasite transmission resulting from the overlap of the domestic and wildlife cycles. The public, wildlife officials, and hunters have expressed concern over lack of information for risk of infection from wildlife meat. Our goal is to investigate the overall prevalence of Trichinella in free-ranging black bears and wild pigs in California. We aim to determine and map the prevalence of Trichinella by detecting larval DNA in black bear and feral pig tissue samples. We propose to collect survey data on hunter meat handling behavior and ultimately develop a model to evaluate risk of human infection from wildlife meat. The results of this study will help to gain an understanding of the contemporary epidemiology of Trichinella and thus 1) supply information to inform the public whether or not Trichinella is a key risk for consumption of wildlife meat; and 2) provide California agencies with the data and analyses necessary to better monitor and control the agricultural and public health aspects of the parasite.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Human food borne outbreaks associated with the consumption of wildlife meat infected with disease-causing parasites such as Trichinella continue to occur due to a lack of contemporary data and decreased public awareness. The overall goal of the proposed integrated project is to conduct research, outreach, extension and education that together will provide a science-based approach and the necessary training to reduce and prevent the occurrence of human trichinellosis in the United States. Conducting this integrated project will have a direct, immediate, and positive impact on improving the food safety information and practices for consumers of wildlife meat and provide both lay and technical guidance materials for controlling agricultural and public health aspects of the parasite. Many questions remain about the risks associated with the consumption of wildlife meat given their status as important ant reservoirs of Trichinella sp. in the environment. The research, outreach, extension and educational activities we propose in this project will together fill critical knowledge gaps about the food safety risks posed by wildlife and provide much needed information on effective management practices to reduce and prevent the occurrence of human trichinellosis. The results of this study will help to gain an understanding of the contemporary epidemiology and current public awareness of Trichinella and thus 1) supply information and educational workshops and lay publications to inform the public whether or not Trichinella is a key risk for consumption of wildlife meat; 2) provide California agencies with the data and analyses necessary to better monitor, control and prevent the agricultural and public health aspects of the parasite; 3) adapt newly-published state-of the art RT-PCR Trichinella-detection techniques for use at UC Davis and share them with diagnostic labs including the California Animal Health and Food Safety (CAHFS) Laboratory System for use in Trichinella surveillance; 4) develop epidemiologic models to assess risks to hunters and other wildlife meat consumers of Trichinella given various public health action scenarios.
Project Methods
Prevalence of Trichinella sp. will be estimated by determining the presence of larval DNA in the skeletal muscle tissue of black bears and wild pigs. In cooperation with the California Department of Fish and Game and USDA Wildlife Services tissue samples will be collected opportunistically, primarily from hunter-killed and depredation carcasses over a period of two full hunting seasons, between August 2011- December 2014. The CDFG requires that any person who takes a bear must present the skull to a Department office/officer within 10 days of taking. It is not required for wild pig hunters to present carcasses to Department officials, thus field stations will be established at various locations throughout the state corresponding to hunting density for wild pig sample collection. Upon presentation of the skull or carcass, 10 gram samples will be removed from the base of the tongue by trained Department officials using a series of tissue biopsy punches. Based on 2010 hunter take reports we predict that a total of approximately 2000 individuals from each species will be taken per season16. Assuming a 25% compliance rate we will collect 500 black bear samples and 500 wild pig samples (total of 1000) each season. Over the scope of the project we will collect 2000 samples. DNA samples will be extracted and analyzed using RT-PCR, a recently published technique for Trichinella diagnostics capable of detecting and identifying all species and genotypes of Trichinella. This technique is fast and highly sensitive, which will allow for the detection of infections as low as 1 larva per 100 grams of tissue. Using logistic regression, we will compare the odds of Trichinella between each animal species, with covariates such as season, location, and host factors screened for their association (P greater than or equal to 0.05) with this parasite.A standardized questionnaire will be developed, approved by the UC Davis Institutional Review Board, and distributed to successful hunters upon presentation of the carcass to Department of Fish and Game wardens or offices. The questionnaire will consist of the following sections: a) demographic information, such as location of the hunt, date killed, proximity to human establishment; b) intended uses, for example, recreation, consumption ; c) meat handling practices, including meat preparation and storage; d) current hunter education, knowledge and beliefs. Starting in 2012 and continuing through June of 2015, we will conduct a series of workshops in conjunction with CDFG officials to increase the awareness of the potential risks of the trichinellosis for consumers of wildlife meat. These workshops will cover the results of Aims 1 and 2 and provide hunters with recommendations for the most effective prevention strategies. Workshops will consist of a panel of experts including our investigators, CDFG officials, and food safety professionals. We also intend to publish the results of our study in lay publications aimed at high risk groups such as California Hunting Digest and the CDFG magazine, Outdoor California.