Location: Egg Safety and Quality
Title: Serologic Testing for Salmonella Infections in Poultry Flocks: Limitations and Opportunities Author
Submitted to: American College of Poultry Veterinarians
Publication Type: Proceedings
Publication Acceptance Date: January 28, 2009
Publication Date: March 1, 2009
Citation: Gast, R.K. 2009. Serologic Testing for Salmonella Infections in Poultry Flocks: Limitations and Opportunities. American College of Poultry Veterinarians. pp.168-174. Technical Abstract: Diverse serologic methods have been developed and applied to successfully detect Salmonella infections in poultry with both sensitivity and consistency. However, the field application of serology has been limited by several inherent characteristics of antibody detection tests: (1) infections without a significant systemic phase may never elicit a detectable antibody response, (2) antibody detection demonstrates prior exposure to Salmonella but does not directly indicate whether a flock currently presents an ongoing risk to public health, (3) extensive antigenic cross-reactivity can significantly complicate identifying a particular serotype as the cause of infection, and (4) the diverse environmental sources and reservoirs of Salmonella complicate efforts to control infections in production flocks by identifying infected breeders. Nevertheless, several attributes of antibody tests are distinctly advantageous in comparison to bacteriologic methods such as culturing environmental samples. Serologic assays are easily automated to accommodate large numbers of samples within limited laboratory space and can deliver results very rapidly. The presence of specific antibodies in the yolks of eggs laid by infected hens affords a sample that can be collected with minimal labor, causing no stress to the hens and posing no risk to flock biosecurity. Because antibody titers can persist long after the clearance of active infection, serology is generally of limited value for identifying currently infected flocks in order to prevent their eggs from being released to consumers. However, the persistence of antibody positivity can highly useful for screening to determine whether particular flocks should be subjected to expensive and time-consuming bacteriologic monitoring and for assessing the cost-effectiveness of risk reduction practices.