Salmonella infections are classified as nonmotile serotypes ( S enterica Pullorum and S enterica Gallinarum) and the many motile paratyphoidSalmonella. These Salmonella infections have a worldwide distribution. As a result of the institution of a testing and control program in the USA through the USDA-administered National Poultry Improvement Plan, the incidence of S enterica Pullorum or S enterica Gallinarum infection has decreased dramatically. Historically, S enterica Arizonae was placed in its own category, but it is now included with the paratyphoid Salmonella. S enterica Arizonae is an egg-transmitted disease primarily of young turkeys. In addition to the above nonmotile salmonellae, Salmonella paratyphoid infections in poultry are relatively common and have public health significance because of contaminated poultry product consumption.
S enterica Pullorum and S enterica Gallinarum are highly host-adapted to chickens and turkeys. There are >2,500 nonhost-adapted species (paratyphoid) that may be transmitted to almost all animals.