Salmonella bacteria is a frequent cause of foodborne illness in Canada. Salmonella organisms are spread among birds by two routes: horizontal and vertical transmission.

Salmonella Enteritidis is the only one serotype that we know about that infects the hen’s ovaries and can be transmitted to the inside of the egg – this is called vertical transmission. Salmonella Heidelberg (SH)is a Provincially reportable disease because there has been one report published that indicates a possibility that SH is also transmitted from the ovaries to the egg.

Salmonella bacteria can move because they have flagellum (long tails). An egg shell has more than 17,000 tiny pours on its surface; if an egg is placed on a Salmonella-infected environment, or is soiled with manure or debris from the environment, the bacterium may move through the egg pores and infect not only the shell, but the egg contents – this is called horizontal transmission. Sources of Salmonella contamination for the egg include manure from carrier hens, feed, unclean equipment, human or other animals (rodents and insects). Most Salmonella stereotypes are horizontally transmitted. Salmonella Typhimirium DT104 horizontally transmitted and is a Provincially reportable disease because it is resistant to antibiotics and poses a significant human health risk.