One factor that makes Salmonellacontrol so difficult is its many potential sources. Salmonellais a very common bacterium in the intestinal tracts of many types of animals and can be easily transmitted to other animals. Salmonellacan be introduced into a poultry flock by rodents, insects, dogs, cats, people, feed ingredients, other birds and many other sources. Some types of Salmonellacan also be transmitted through eggs to the next generation of chickens or turkeys.
A second factor that complicates Salmonella control is that there are so many types. Salmonellais a very large family of bacteria with tremendous variation within the group. As one type of Salmonellais eliminated from a poultry production system, it is commonly replaced by a different type of Salmonellathat gets inadvertently introduced into the system. Effective vaccination to prevent Salmonellain poultry flocks is difficult because each type of Salmonellain a poultry flock must be targeted by a vaccine specific for that type of Salmonella.