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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 1/6/2015 Publication Date: 7/11/2015 Citation: Dunn, J.R. 2015. Status update on worldwide incidence. Meeting Abstract. American Veterinary Medical Association Annual Convention, July 11-14, 2015, Boston, Massachusetts. Interpretive Summary: Technical Abstract: Avian tumor viruses continue to have major economic impacts in many parts of the world. One of the top concerns facing the poultry industry is the evolutionary trend of Marek’s disease virus (MDV) towards greater virulence. It has been 15 years since a comprehensive set of MDV field strains have been solicited from US poultry companies for pathotyping. In the United States, MD has remained at historical low incidence since reaching a record low in 2007 (0.0008%) as measured by leukosis condemnation rates in broilers at slaughter. Although MD condemnation rates in broilers have been dropping, there has also been increasing use of the highly protective Rispens vaccine in both broiler and layer operations, which may be masking an increase in virulence of circulating MDV field strains. In our 2011 questionnaire, 49 countries (42%) indicated that increased use of Rispens was the most likely reason for decreasing MD. The vast majority of countries (>93%) reported that Rispens vaccination was standard in layers and breeders. During the last 2 years, we solicited samples for virus isolation from broiler and layer flocks located throughout the country for pathotyping and to correlate with vaccination history. The results of this virus characterization will be presented along with results from a new global survey of current incidence. Current status of other avian tumor viruses and related diseases and syndromes will also be presented, including lymphoid leukosis/myeloid leukosis, reticuloendotheliosis, peripheral neuropathy, and hepatitis-splenomegaly syndrome (Hepatitis E virus). |
