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National Trichinae Research Project By Lawrence E. Miller, DVM, MS, MPM
The National Pork Producers Council and USDA’s Agricultural Research Service, Animal and Plant Health Inspection Service and Food Safety and Inspection Service are involved in a collaborative effort in the Northeastern U.S. to address an animal production issue of both domestic and international market concern. The issue is that of the continued presence of Trichinella spiralis in the U.S. pork supply, and the effort is entitled the National Trichinae Research Project (NTRP).
The continued presence of trichinae in U.S. swine has a significant impact on pork sales both domestically and abroad. Unlike many of our trading partners that inspect every swine carcass for the presence of trichinae, in the U.S. we assume every carcass is potentially infected and therefore thoroughly cook all pork to inactivate the parasite. American consumers are very aware of the need to properly cook pork. As a result, pork is routinely overcooked to remove the potential parasite, which diminishes the flavor and versatility of the product.
Internationally, the U.S. is the lowest cost pork producer in the world, yet we remain a net importer of pork products. One barrier to expanding U.S. pork export markets is international concern over the presence of trichinae in the U.S. swine herd. Clearly elimination of this parasite could have a profound effect on American pork sales and could therefore be of great benefit to U.S. producers.
The NTRP has two goals. The first goal is to evaluate the utility of an ELISA serologic test for determining herd trichinae status at the farm level. To date, line speeds, labor requirements, and cost have prevented the individual examination of all swine carcasses for trichinae in U.S. slaughter plants. Periodic serologic screening of herds, and evaluation of premises to ensure the absence of trichinae risk factors, may ultimately prove to be an effective method for assuring trichinae-safe status of U.S. pork. In addition, as more is learned about test accuracy, a national trichinae prevalence study using serum samples collected for pseudorabies and brucellosis screening may ultimately be undertaken.
The second goal of the NTRP is to identify risk factors for herd trichinae infection. Much has been said concerning the use of the Hazard Analysis Critical Control Point approach at the farm level for biological pathogens of animal or human health concern. Presently, trichinae is one of the few biological entities where the critical control points are believed to be known. Trichinae positive status is generally associated with inadequately cooked waste-food feeding, poor rodent control, feeding of wildlife carcasses or severe cannibalism. An important component of the NTRP will be to verify the primary risk factors for trichinae. Once risk factors are confirmed, the next phase of the project will focus on risk removal from positive herds, development of negative herds, and subsequently tracking herds over time to ensure that negative status can be maintained.
As mentioned previously, the NTRP is a cooperative effort involving the National Pork Producers Council, Agricultural Research Service, Animal and Plant Health Inspection Service, and Food Safety and Inspection Service, along with State Veterinarian and Pork Producer Association offices in participating states. The project was initiated in January, 1995, in Ohio, New Jersey, and the New England area. In Ohio and New Jersey, pseudorabies and brucellosis samples collected at slaughter will be analyzed for trichinae at the State Diagnostic Laboratories using a commercially available ELISA kit. In New Jersey and New England, a case-control study to identify operation risk factors for trichinae will be conducted, with samples being collected from three different types of swine operations: licensed waste feeders, non-licensed waste feeders (no meat products) and grain feeding operations. Producer participation in the program is completely voluntary. In all three areas, a risk factor questionnaire and on-farm evaluation will be conducted on trichinae-positive operations. In addition, producers will have the option of participating in a trichinae clean-up and tracking segment of the study. Analysis of slaughter serum samples from Ohio and New Jersey will be useful for estimating herd trichinae prevalence in the Northeastern U.S. Herd trichinae status is kept confidential throughout the course of the project. To date, producers have been enthusiastic regarding project goals and direction.
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