Fowl typhoid and pullorum disease.

Fowl typhoid (FT) and pullorum disease (PD) are septicaemic diseases, primarily of chickens and turkeys, caused by Gram negative bacteria, Salmonella Gallinarum and S. Pullorum, respectively. Clinical signs in chicks and poults include anorexia, diarrhoea, dehydration, weakness and high mortality. In mature fowl, FT and PD are manifested by decreased egg production, fertility, hatchability and anorexia, and increased mortality. Gross and microscopic lesions due to FT and PD in chicks and poults include hepatitis, splenitis, typhlitis, omphalitis, myocarditis, ventriculitis, pneumonia, synovitis, peritonitis and ophthalmitis. In mature fowl, lesions include oophoritis, salpingitis, orchitis, peritonitis and perihepatitis. Transovarian infection resulting in infection of the egg and subsequently the chick or poult is one of the most important modes of transmission of these two diseases. Salmonella Gallinarum and S. Pullorum can be isolated by use of selective and non-selective media. Salmonella Pullorum produces rapid decarboxylation of ornithine whereas S. Gallinarum does not, an important biochemical difference between the two bacteria. Both FT and PD can be detected serologically by use of a macroscopic tube agglutination test, rapid serum test, stained antigen whole blood test or microagglutination test. Both diseases can be controlled and eradicated by use of serological testing and elimination of positive birds. Vaccines may be used to control the disease and antibiotics for the treatment of FT and PD. Although FT and PD are widely distributed throughout the world, the diseases have been eradicated from commercial poultry in developed countries such as the United States of America, Canada and most countries of Western Europe. Both S. Gallinarum and S. Pullorum are highly adapted to the host species, and therefore are of little public health significance. © OIE, 2000