Synonyms
Salmonellosis, Infectious leukemia
Aetiology
Fowl typhoid is caused by the bacteria S. gallinarum related to the causative agent S. pullorum. S gallinarum is a non motile gram negative rod shaped organism. The two salmonella organisms are antigenicaaly similar and can be differentiated by a sugar fermentation test were S. gallinarum ferments maltose and dulcitol whereas S. pullorum does not.
Age/host range
Affects all ages of birds but the disease is more significant in growing and adult chickens which are most commonly affected than turkeys, game birds, quail, pheasants, guinea fowls, sparrows, parrots and canaries.
Transmission
-Transmission is mainly horizontally by contamination of feed and water by excreta ofcarriers or infected birds.
-Transovarian transmission (vertical)
-Formites
Clinical Signs
Morbidity is 10-100%; mortality is from 10-90% and increased in stressed or immunocompromised flocks and may be up to 100%.
Clinical signs include;
Acute form such as
Sudden death without premonitoring signs, dejection, ruffled feathers, sudden drop in feed consumption and watery to mucoid greenish-yellow diarrhea.
Surviving birds enter a chronic stage in which there’s anaemia(pale and shrunken combs), drop in egg production, decreased fertility and diminished hatchability and reluctance to move.
Post-mortem lesions
In acute form
Severely congested, enlarged bronzed-greenish tinted liver with small necrotic foci, enlarged and congested kidneys and spleen, enteritis of anterior small intestine, brownish colour of the lungs and whitish nodules on the cardiac muscles.
In chronic form
The ovaries are affected by inflammatory and degenerative changes; misshapen, discoloured cystic or nodular ova among a normal appearing ovules and egg yolk peritonitis.
Diagnosis
Tentative diagnosis is based on characteristic clinical signs and post-mortem lesions. Positive diagnosis is by isolation and recognition of the causative organism. Tube and rapid plate agglutination tests have been the standard serological test for many years.
Differential diagnosis
Pasteurellosis, pullorum disease and coli-septicaemia
Treatment
Furazolidone, amoxicillin and quinozaline, tetracyclines, fluoroquinolones are used.
Prevention
Dipping contaminated eggs in antibiotic solution containing 400ppm and 800ppm of gentamycin is helpful in controlling S. gallinarum in eggs.
Vaccines for fowl typhoid have been used both live(usually based on the Houghton 9R strain) and bacterins can be used at 9-10th week of age.