Salmonella infections are classified as caused either by nonmotile serotypes (S enterica serotype Gallinarum biovar Pullorum for pullorum disease and S enterica serotype Gallinarum biovar Gallinarum for fowl typhoid) or by the many motile paratyphoid Salmonella serotypes. These Salmonella infections have a worldwide distribution.
As a result of a testing and control program in the US through the USDA-administered National Poultry Improvement Plan, the incidence of S Pullorum and S Gallinarum infections has decreased dramatically. Historically, S enterica serotype Arizonae was placed in its own category; however, it is now included with the paratyphoid Salmonella spp. S Arizonae is an egg-transmitted infection affecting primarily young turkeys.
In addition to the infections caused by the nonmotile salmonellae named above, the presence of Salmonella paratyphoid species in poultry is common and has public health importance because of contaminated poultry product consumption.
S Pullorum and S Gallinarum are highly host-adapted to chickens and turkeys. There are > 2,500 non–host-adapted species (paratyphoid) that may be transmitted to almost all animals.
