Fowl Typhoid

Etiology and Epidemiology:

The causal agent is Salmonella gallinarum . The incidence of fowl typhoid is low in the USA and Canada, but much higher in other countries. Although S gallinarum is egg-transmitted and produces lesions in chicks and poults similar to those produced by S pullorum , there is a much greater tendency to spread among growing or mature flocks. Mortality in young birds is similar to S pullorum infection but may be higher in older birds.

Clinical Findings and Lesions:

Clinical signs and lesions in young birds are similar to those of infection with S pullorum . The older bird may be pale, dehydrated, and have diarrhea. Lesions in the older bird may include a swollen, friable, and often bile-stained liver, with or without necrotic foci, enlarged spleen and kidneys, anemia, and enteritis.

Diagnosis:

Diagnosis should be confirmed by isolation and identification and serotyping of S gallinarum (NPIP testing procedure).

Treatment and Control:

Treatment and control are as for pullorum disease (see above). There are no federally licensed vaccines in the USA. In other countries, vaccines (killed or modified live) made from a rough strain of S gallinarum (9R) have been useful in controlling mortality. More recently, vaccines derived from outer membrane proteins, mutant strains, and a virulence-plasmid-cured derivative of S gallinarum have shown promise in protecting birds against challenge. The standard serologic tests for pullorum disease are equally effective in detecting fowl typhoid.
Reference :- Merck Veterinary Manual
 
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