Introduction
Salmonellae bacteria other than the species specific sero-types S. Pullorum, S. Gallinarum, and also other than S. Enteritidis and S. Typhimurium (which are considered separately), are capable of causing enteritis and septicaemia in young birds. Sero-types vary, but S. Derby, S. Newport, S. Montevideo, S. Anatum, S. Bredeney are among the more common isolates. Even if these infections do not cause clinical disease, their presence may be significant with respect to carcase contamination as a potential source of human food poisoning. They infect chickens, turkeys and ducks worldwide.
Morbidity is 0-90% and mortality is usually low. The route of infection is oral and transmission may be vertical as a result of shell contamination. Regardless of the initial source of the infection, it may become established on certain farms, in the environment or in rodent populations. Many species are intestinal carriers and infection is spread by faeces, fomites and feed (especially protein supplements but also poorly stored grain). Certain sero-types are prone to remain resident in particular installations (e.g. S. Senftenberg in hatcheries). The bacteria are often persistent in the environment, especially in dry dusty areas, but are susceptible to disinfectants that are suitable for the particular contaminated surfaces and conditions, applied at sufficient concentrations. Temperatures of around 80°C are effective in eliminating low to moderate infection if applied for 1-2 minutes. This approach is often used in the heat treatment of feed. Predisposing factors include nutritional deficiencies, chilling, inadequate water, other bacterial infections and ornithosis (in ducks).
Signs
- Signs are generally mild compared to host-specific salmonellae, or absent.
- Dejection.
- Ruffled feathers.
- Closed eyes.
- Diarrhoea.
- Vent pasting.
- Loss of appetite and thirst.
Post-mortem lesions
- In acute disease there may be few lesions.
- Dehydration.
- Enteritis.
- Focal necrotic intestinal lesions.
- Foci in liver.
- Unabsorbed yolk.
- Cheesy cores in caecae.
- Pericarditis.
Diagnosis
Isolation and identification. In clinical cases direct plating on Brilliant Green and McConkey agar may be adequate. Enrichment media such as buffered peptone followed by selective broth or semi-solid media (e.g. Rappaport-Vassiliadis) followed by plating on two selective media will greatly increase sensitivity. However this has the potential to reveal the presence of salmonellae that are irrelevant to the clinical problem under investigation. Differentiate from Pullorum/Typhoid, other enterobacteria.
Treatment
Sulphonamides, neomycin, tetracyclines, amoxycillin, fluoroquinolones. Good management. Chemotherapy can prolong carrier status in some circumstances.
Prevention
Uninfected breeders, clean nests, fumigate eggs, all-in/all-out production, good feed, competitive exclusion, care in avoiding damage to natural flora, elimination of resident infections in hatcheries, mills, breeding and grow-out farms. Routine monitoring of breeding flocks, hatcheries and feed mills is required for effective control. Infection results in a strong immune response manifest by progressive reduction in excretion of the organism and reduced disease and excretion on subsequent challenge.
Vaccines are not generally used for this group of infections.