Introduction
Disease caused by one of the two poultry-adapted strains of Salmonella bacteria, Salmonella Gallinarum. This can cause
mortality in birds of any age. Broiler parents and brown-shell egg layers are
especially susceptible. Chickens are most commonly affected but it also infects
turkeys, game birds, guinea fowls, sparrows, parrots, canaries and bullfinches.
Infections still occur worldwide in non-commercial poultry but are rare in most
commercial systems now.
Morbidity is 10-100%; mortality is increased in stressed or
immunocompromised flocks and may be up to 100%. The route of infection is oral
or via the navel/yolk. Transmission may be transovarian or horizontal by
faecal-oral contamination, egg eating etc, even in adults. The bacterium is
fairly resistant to normal climate, surviving months, but is susceptible to
normal disinfectants.
Signs
·
Dejection.
·
Ruffled feathers.
·
Inappetance.
·
Thirst.
·
Yellow diarrhoea.
·
Reluctance to move.
Post-mortem lesions
·
Bronzed enlarged liver with small necrotic foci,
and/or congestion.
·
Engorgement of kidneys and spleen.
·
Anaemia.
·
Enteritis of anterior small intestine.
Diagnosis
Isolation
and identification. In clinical cases direct plating on Brilliant Green,
McConkey and non-selective agar is advisable. Enrichment procedures usually
rely on selenite broth followed by plating on selective media. Tube and rapid
plate agglutination tests have been the standard serological tests for many
years but have only been validated for chickens. LPS-based Elisa assays have
been developed but not widely applied commercially. Differentiate from
Pasteurellosis, pullorum disease and coli-septicaemia.
Treatment
Amoxycillin, potentiated
sulponamide, tetracylines, fluoroquinolones.
Biosecurity, clean chicks. As with other salmonellae, recovered birds
are resistant to the effects of infection but may remain carriers. Vaccines for
fowl typhoid have been used in some areas, both live (usually based on the
Houghton 9R strain) and bacterins.
Introduction
Disease
caused by one of the two poultry-adapted strains of Salmonella bacteria, Salmonella
Pullorum, this usually only causes mortality in birds up to 3 weeks of age.
Occasionally it can cause losses in adult birds, usually brown-shell egg
layers. It affects chickens most commonly, but also infects turkeys, game
birds, guinea fowls, sparrows, parrots, ring doves, ostriches and peafowl. It
still occurs worldwide in non-commercial poultry but is now rare in most
commercial systems.
Morbidity is 10-80%; mortality is increased in stressed or
immunocompromised flocks and may be up to 100%. The route of infection is oral
or via the navel/yolk. Transmission may be transovarian or horizontal mainly in
young birds and may sometimes be associated with cannibalism. The bacterium is
fairly resistant to normal climate, surviving months but is susceptible to
normal disinfectants.
Signs
·
Inappetance.
·
Depression.
·
Ruffled feathers.
·
Closed eyes.
·
White diarrhoea.
·
Vent pasting.
·
Gasping.
·
Lameness.
Post-mortem lesions
·
Grey nodules in lungs, liver, gizzard wall and
heart.
·
Intestinal or caecal inflammation.
·
Splenomegaly.
·
Caecal cores.
·
Urate crystals in ureters.
Diagnosis
Isolation
and identification. In clinical cases direct plating on Brilliant Green,
McConkey and non-selective agar is advisable. Enrichment procedures usually
rely on selenite broth followed by plating on selective media.
Differentiate from Typhoid,
Paratyphoid, paracolon, other enterobacteria, chilling and omphalitis
Treatment
Amoxycillin, poteniated
sulponamide, tetracylines, fluoroquinolones.
Prevention
Eradication from breeder flocks. As with other salmonellae, recovered
birds are resistant to the effects of infection but may remain carriers.
Vaccines are not normally used as they interfere with serological testing and
elimination of carriers.
Introduction
Salmonella Enteritidis and S.Typhimurium are
presented separately from other sero-types of Salmonella because, on the one hand, these bacteria are often
specifically cited in zoonosis control legislation, and, secondly, because
there are differences in the epidemiology as compared to other salmonellae.
These are the predominant sero-types associated with human disease in most
countries.
Salmonella Enteritidis, especially phage type 4, has become much more common in both poultry and humans since the early 80s. The
prevalence of S.Typhimurium has
remained relatively stable though the spread of the highly antibiotic-resistant
strain DT104 in various farmed species gives some reason for concern.
Infections in chickens, turkeys and ducks cause problems worldwide with
morbidity of 0-90% and a low to moderate mortality. Many infected birds are
culled and others are rejected at slaughter. The route of infection is oral;
many species are intestinal carriers and infection may be carried by faeces,
fomites and on eggshells.
Vertical
transmission may be either by shell contamination or internal transovarian
contamination of yolk. Feed and feed raw material contamination is less common
than for other sero-types. 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 and other bacterial infections.
Signs
·
Dejection.
·
Ruffled feathers.
·
Closed eyes.
·
Diarrhoea.
·
Vent pasting.
·
Lost appetite and thirst.
·
Stunting in older birds.
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.
·
Perihepatitis.
·
Misshapen ovules in the ovaries in S.E. infection
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 such as E. coli. S.Enteritidis causes cross-reactions
which may be detected with S.Pullorum
serum agglutination tests. It is possible to detect reactions with specific
antigens in agglutination tests but competitive and direct Elisa tests are more
commonly used today.
Treatment
Sulphonamides, neomycin, tetracyclines, amoxycillin, fluoroquinolones in
accordance with the sensitivity. 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. Early depletion of infected breeding stock is required in
some countries such as those of the European Union. 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 increasingly being used for S. Enteritidis and S. Typhimurium
infection; both inactivated (bacterins) and attenuated live organisms.
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VETERINARY CARE