Historical Article— Pullorum Disease: Evolution of the Eradication Strategy K. A. Schat, AE K. V. Nagaraja, BD and Y. M. Saif C A Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853 B College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108 C Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691 D Deceased July 22, 2020 Received 4 March 2021; Accepted 18 March 2021; Published ahead of print 19 March 2021 SUMMARY. The history of pullorum disease is closely intertwined with the history of avian health research and that of the poultry industry. The seriousness of the disease galvanized the attention and brought together, for the first time, the pioneers of poultry health research to work cooperatively on different aspects of the disease. Control of the disease made it possible for intensive poultry production to develop as the basis for the modern poultry industry. During the early 1900s, bacillary white diarrhea (BWD) was a devastating disease of young chickens threatening the developing poultry industry. Dr. Leo F. Rettger isolated and described the bacterial pathogen, Salmonella enterica serotype Pullorum, for the first time in 1900. BWD was renamed pullorum disease in 1929. In subsequent years, Rettger and coworkers were able to reproduce the disease and fulfill Koch’s postulates. Rettger et al. also showed that Salmonella Pullorum was vertically transmitted, which was the first time that a pathogen was shown to be vertically transmitted. The development of serologic tests was of crucial importance because it led to the development of effective eradication methods to identify carrier birds and to exclude these birds from the breeder flocks. The negative impact of pullorum disease on the poultry industry ultimately was one of the major reasons that the National Poultry Improvement Plan (NPIP) was developed by scientists, the poultry industry, and the United States Department of Agriculture (USDA). Needless to say, the work of the pioneering researchers formed the basis for the control of the disease. The NPIP started in 1935, with 34 states participating in testing 4 million birds representing 58.2% of the birds hatched. The program rapidly expanded to 47 states by 1948 and tested more than 30 million birds. In 1967, all commercial chicken hatcheries participating in the NPIP were 100% free of pullorum and typhoid disease caused by Salmonella enterica serotype Gallinarum. This historical overview of pullorum disease describes in some detail the progress made, especially during the early years, toward controlling this disease using methodologies that were often very basic but nonetheless effective. One has to admire the ingenuity and persistence of the early researchers leading to their achievements considering the research tools that were available at the time. RESUMEN. Art´ ıculo hist ´ orico—Pulorosis: Evoluci´ on de las estrategias de erradicaci´ on La historia de la pulorosis esta ´ estrechamente relacionada con la historia de la investigaci´ on en salud aviar y de la industria av´ ıcola. La severidad de la enfermedad despert´ o la atenci´ on y reuni´ o, por primera vez a los pioneros de la investigaci´ on en salud av´ ıcola para trabajar de manera cooperativa en diferentes aspectos de la enfermedad. El control de la enfermedad hizo posible que la producci´ on av´ ıcola intensiva se desarrollara como base de la industria av´ ıcola moderna. A principios de la d´ ecada de los 1900, la diarrea blanca bacilar (con las siglas en ingl´ es BWD) era una enfermedad devastadora de pollos j´ ovenes que amenazaba la industria av´ ıcola en desarrollo. El Dr. Leo F. Rettger aisl´ o y describi´ o el pat´ ogeno bacteriano, Salmonella enterica serotipo Pullorum, por primera vez en 1900. La diarrea blanca bacilar pas´ o a llamarse pulorosis (pullorum disease) en 1929. En los a ˜ nos siguientes, Rettger y sus colaboradores pudieron reproducir la enfermedad y cumplir los postulados de Koch. Rettger y col. tambi´ en mostraron que Salmonella Pullorum se transmit´ ıa verticalmente, y fue la primera vez que se demostr´ o que un pat´ ogeno se transmit´ ıa verticalmente. El desarrollo de pruebas serol´ ogicas fue de crucial importancia porque condujo al desarrollo de m´ etodos de erradicaci´ on efectivos para identificar aves portadoras y eliminar a estas aves de las parvadas reproductoras. El impacto negativo de la pulorosis en la industria av´ ıcola fue, en ´ ultima instancia, una de las principales razones por las que los cient´ ıficos, la industria av´ ıcola y el Departamento de Agricultura de los Estados Unidos (USDA) desarrollaron el Plan Nacional de Mejoramiento Av´ ıcola (NPIP). Es importante decir que el trabajo de los investigadores pioneros form´ o la base para el control de la enfermedad. El Plan Nacional de Mejoramiento Av´ ıcola comenz´ o en a ˜ no 1935, con 34 estados participando en el ana ´lisis de 4 millones de aves que representaban el 58.2% de las aves producidas. El programa se expandi´ o ra ´pidamente a 47 estados en 1948 y evalu´ o a ma ´s de 30 millones de aves. En 1967, todas las plantas incubadoras de pollos comerciales que participaban en el Plan Nacional de Mejoramiento Av´ ıcola estaban 100% libres de pulorosis y tifoidea aviar causada por Salmonella enterica serotipo Gallinarum. Esta rese˜ na hist´ orica de la pulorosis describe con cierto detalle el progreso realizado, especialmente durante los primeros a˜ nos, hacia el control de esta enfermedad utilizando metodolog´ ıas que a menudo eran muy ba ´sicas no obstante efectivas. Es admirable el ingenio y la persistencia de los primeros investigadores que los llevaron a sus logros considerando las herramientas de investigaci´ on que estaban disponibles en ese momento. Key words: history, pullorum disease, Salmonella Pullorum, white bacillary diarrhea Abbreviations: BWD ¼ bacillary white diarrhea; KSAC ¼ Kansas State Agricultural College; NECAD ¼ Northeastern Conference on Avian Diseases; NCLWBWD ¼ Northeastern Conference of Laboratory Workers in Bacillary White Diarrhea; NPIP ¼ National Poultry Improvement Plan; R.O.P. ¼ Record of Performance; PT ¼ pullorum typhoid; WPIA ¼ Washington Poultry Improvement Association E Corresponding author. E-mail: kas24@cornell.edu AVIAN DISEASES 65:227–236, 2021 227 Downloaded from http://meridian.allenpress.com/avian-diseases/article-pdf/65/2/227/2852247/i0005-2086-65-2-227.pdf by AAAP Member Access user on 13 July 2021