In cooperation with public health and animal health agencies, the Research Team from The New England Journal of Medicine conducted multistate investigations involving patient interviews, trace-back investigations, and environmental testing at a mail-order hatchery linked to the outbreak in order to identify the source of infections and prevent additional illnesses. A case was defined as an infection with the outbreak strain between 2004 and 2011.

From 2004 through 2011, the team identified 316 cases in 43 states. The median age of the patient was 4 years. Interviews were completed with 156 patients (or their caretakers) (49 per cent), and 36 of these patients (23 per cent) were hospitalized. Among the 145 patients for whom information was available, 80 (55 per cent) had bloody diarrhea. Information on contact with live young poultry was available for 159 patients, and 122 of these patients (77 per cent) reported having such contact. A mail-order hatchery in the western United States was identified in 81 per cent of the trace-back investigations, and the outbreak strain was isolated from samples collected at the hatchery. After interventions at the hatchery, the number of human infections declined, but transmission continued.

The Research Team identified a prolonged multistate outbreak of salmonellosis, predominantly affecting young children and associated with contact with live young poultry from a mail-order hatchery. Interventions performed at the hatchery reduced, but did not eliminate, associated human infections, demonstrating the difficulty of eliminating salmonella transmission from live poultry.

Presented in part at the Council of State and Territorial Epidemiologists Annual Conference, Atlantic City, NJ, 24-28 June 2007; at the American Veterinary Medical Association Convention, St. Louis, 16-19 July 2011; and at the US Animal Health Association Conferences, Reno, NV, October 18–23, 2007, and San Diego, CA, 7–14 October 2009.

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

NOTE: The Research Team consisted of Nicholas H. Gaffga, M.D., M.P.H., Casey Barton Behravesh, D.V.M., Dr.P.H., Paul J. Ettestad, D.V.M., Chad B. Smelser, M.D., Andrew R. Rhorer, M.S., Alicia B. Cronquist, R.N., M.P.H., Nicole A. Comstock, M.S.P.H., Sally A. Bidol, M.P.H., Nehal J. Patel, M.P.H., Peter Gerner-Smidt, M.D., D.Med.Sci., William E. Keene, Ph.D., M.P.H., Thomas M. Gomez, D.V.M., Brett A. Hopkins, D.V.M., Ph.D., Mark J. Sotir, Ph.D., M.P.H., and Frederick J. Angulo, D.V.M., Ph.D.