Aetiology
The disease is caused by Borrelia anserina or Borrelia gallinarum, a highly mortile helical bacterium which stains well with romanosky and aniline stains. The organism is present in the blood and all organs particularly in the liver, spleen and bone marrow.
Host/age/distribution
The bacterium Borrelia anserine infects chickens, turkey, geese, ducks, pheasants, grouse and canaries. It affects all ages and is worldwide in distribution.
Transmission
It is transmitted by arthropods such as Argas persicus and occasionally by infected faeces. The bacterium is poorly resistant outside the host although may be carried by Argas persicus for 430 days.
Morbidity and mortality
Morbidity and mortality up to 100%.
Clinical signs
Depression
Cyanosis of the comb and wattle
Ruffled feathers
Elevation in body temperature which results in thirst and dehydration.
Rapid weight loss
Often greenish diarrhea with excessive urates
Weakness and continuous paralysis
Decreased egg production may be seen in both systemic and intestinal forms.
Post-mortem lesions
Marked splenomegaly with marble-like appearance.
Liver enlarged and mottled with necrosis of various sizes and marginal infarction haemorrhages.
Swollen kidneys
Bile coloured mucoid enteritis.
The ticks are discovered adhering to the skin when the plumage is removed.
Diagnosis
Tentative diagnosis is based on characteristic clinical signs and post-mortem lesions while positive diagnosis is by recognizing the spirochaetes in giemsa stained smears.
Treatment
Penicillin, tylosin, tetracycline are effective for treatment.
Prevention
Control vectors.
Vaccination are available but acquired immunity is short and revaccination is necessary.