Animal and Plant Health Inspection Service | Veterinary Services | 1

1. Disease Information

1.1 General Disease and Pathogen Information: Fowl typhoid in chickens and turkeys is 

caused by Salmonella enterica subspecies enterica serovar Gallinarum biovar 

Gallinarum. The disease is often observed in the later growing period and in mature 

stock. It has been reported in chickens, turkeys, quail, guinea fowl, pheasants, 

peafowl, grouse, parrots, sparrows, ostriches, and ring-necked doves. Both vertical 

and horizontal transmission occurs, and birds can become chronic carriers, passing 

the bacteria to their offspring in eggs. Horizontal transmission occurs through 

respiratory and oral routes. Fowl typhoid has been eradicated from commercial poultry 

in many developed countries including the United States and Canada but may persist 

in backyard poultry flocks and game birds.

1.2 Clinical Signs: Clinical signs include acute septicemia which mainly affects mature 

birds and may be particularly severe in commercial laying flocks. Signs may include: 

decreased appetite, depression, dehydration, weight loss, ruffled feathers, and watery 

to mucoid diarrhea. A progressive loss of condition can lead to anemia with pale, 

shrunken combs. Post-mortem lesions include swollen, friable liver, with or without 

necrotic foci, enlarged spleen and kidneys, anemia, and enteritis.

2. Laboratory Criteria

2.1 Agent Isolation and Identification: Samples should not be taken within 2-3 weeks of 

antimicrobial treatment. Swabs or aseptically collected samples from infected tissues 

such as cecal tonsils, liver, gall bladder, and spleen, or intestinal and cloacal contents 

(bagged separately from tissues) should be used for diagnostic testing. Tissues are 

preferable to fecal and environmental samples. More detailed information regarding 

sampling and testing protocols can be found in resources such as the National Poultry 

Improvement Plan (NPIP) program standards. Culture is by selective enrichment and 

plating on selective and non-selective media. Suspect colonies can be identified as 

Salmonella species by polymerase chain reaction (PCR), matrix-assisted laser 

desorption ionization-time of flight (MALDI-TOF), or biochemical testing. Isolates 

identified as Salmonella should be serotyped.

2.2 Agent Characterization: Salmonella ser. Gallinarum var. Gallinarum can be identified 

by serotyping with biochemical testing or whole genome sequencing (WGS).

2.3 Serology: Chicken serum samples can be tested by the rapid whole blood plate 

agglutination test; however, false positives can be seen with ducks and the test is not 

approved for use in turkeys. In the laboratory, serum is tested via the rapid serum plate 

agglutination test, the tube agglutination test, or the microagglutination test. Any 

positive reactors should be confirmed by culture from post-mortem tissues.

Case Definition

Fowl Typhoid (Salmonella enterica subspecies enterica serovar 

Gallinarum biovar Gallinarum)

(Notifiable) April 2022
Animal and Plant Health Inspection Service | Veterinary Services | 2

3. Case Definition and Reporting Criteria

3.1 Suspect Case: growing and mature birds with clinical signs, history, or epidemiology 

consistent with Fowl Typhoid.

3.2 Presumptive Positive Case: a bird with compatible clinical signs AND

3.2.1 positive serum rapid plate agglutination (chickens only); OR

3.2.2 positive tube agglutination; OR

3.2.3 positive microagglutination test.

3.3 Confirmed Positive Case: a bird with compatible clinical signs AND

3.3.1 isolation and identification of Salmonella ser. Gallinarum biovar Gallinarum.