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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETIC AND BIOLOGICAL DETERMINANTS OF AVIAN TUMOR VIRUS PATHOGENICITY, TRANSMISSION, AND EVOLUTION

Location: Avian Disease and Oncology Laboratory

Title: Current status of Marek’s disease in the United States & worldwide based on a questionnaire survey

Authors
item Dunn, John
item Gimeno, Isabel -

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 13, 2012
Publication Date: January 8, 2013
Citation: Dunn, J.R., Gimeno, I.M. 2013. Current status of Marek’s disease in the United States & worldwide based on a questionnaire survey. Avian Diseases. 57(2):483-490.

Interpretive Summary: A questionnaire was widely distributed in 2011 to estimate the current status of Marek’s disease (MD) and gain a better understanding of current control strategies and future concerns. A total of 112 questionnaires were returned representing 116 countries from sources including national branch secretaries of the World Veterinary Poultry Association, vaccine, breeder, and production companies, as well as MD researchers from various backgrounds. All flock types were listed as having increased MD during the last 10 years in close to 50% of countries by at least one respondent with the majority of these countries located within French-speaking Africa, Eastern Europe, East Asia and South America. Only 18 countries (16%) indicated increasing MD was likely due to higher virulent strains while the presence of other diseases making the bird's immune system weak was a more common explanation. Increased use of Rispens (the most effective vaccine commercially available) was cited as the most likely reason for decreasing MD in 49 countries (42%). In the United States, MD has continued to decrease during the last 10 years, reaching a record low in 2007 (0.0008%) as measured at slaughter. However, recent MD increase in North Carolina and Pennsylvania need to be closely monitored.

Technical Abstract: A questionnaire was widely distributed in 2011 to estimate the global prevalence of Marek’s disease (MD) and gain a better understanding of current control strategies and future concerns. A total of 112 questionnaires were returned representing 116 countries from sources including national branch secretaries of the World Veterinary Poultry Association, vaccine, breeder, and production companies, as well as MD researchers from various backgrounds. Each country listed on a questionnaire was recorded as an individual entry and on average there were 2.0 entries per country (Median 1; Range 1-13). All flock types were listed as having increased MD incidence during the last 10 years in close to 50% of countries by at least one respondent with the majority of these countries located within French-speaking Africa, Eastern Europe, East Asia and South America. Only 18 countries (16%) indicated increasing MD incidence was likely due to higher virulent strains while the presence of other immunosuppressive diseases was a more common explanation. Increased use of CVI988/Rispens was cited as the most likely reason for decreasing MD incidence in 49 countries (42%). In the United States, MD incidence has continued to decrease during the last 10 years, reaching a record low in 2007 (0.0008%) as measured by leukosis condemnation rates in broilers at slaughter. However, recent increase of leukosis condemnations in North Carolina and Pennsylvania need to be closely monitored.

Last Modified: 8/1/2014
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