1a.Objectives (from AD-416):
Explore and develop opportunities for control based on data identifying and characterizing routes of infection of Salmonella in the lymph nodes of cattle. Salmonella vaccine and chlorate will be evaluated to determine effectiveness in eliminating Salmonella from the lymph nodes following oral and dermal inoculation of dairy cattle.
1b.Approach (from AD-416):
Three studies will be conducted using dairy calves purchased and transported to our laboratory in College Station, TX. The first study will examine the duration and distribution of infection of Salmonella in several lymph nodes in calves receiving an SRP Salmonella vaccine. The second study will examine routes of exposure (oral or dermal) on Salmonella uptake and distribution by the lymph nodes. The final study will examine the effectiveness of sodium chlorate in eliminating Salmonella from the lymph nodes of previously infected calves.
The goal of this project is to establish if Salmonella is acquired by the peripheral lymph nodes following intradermal exposure and to evaluate the efficacy of a Salmonella vaccine in preventing uptake by these nodes following both oral and intradermal Salmonella exposure. In FY 2013, project work established that Salmonella-positive lymph nodes could be produced following both oral and transdermal exposure; however, the transdermal route of infection is more reliable and predictable. A potential Salmonella vaccine was tested, and while it was not completely effective, it did show merit in reducing the prevalence of Salmonella-infected lymph nodes. A full-scale study of the vaccine in a commercial feedlot is currently underway. As work by this project continues, important new knowledge will be gained on approaches to prevent Salmonella-infected lymph nodes in cattle from being a significant source of Salmonella food poisoning in humans.