Spirochaetosis :

• Avian intestinal spirochaetosis ( AIS ) is an acute , febrile, septicaemia, bacterial disease that affects a wide range of birds.
• It is characterised by chronic diarrhoea in diseased birds, and subsequently results in faecal staining of egg and wet litter.
• It results from colonization of caeca and rectum by one or more species of anaerobic spirochaetal bacteria .
• Also called Tick fever or Tick paralysis.

Etiology :

              Borrelia anserina

Transmission :

• It is transmitted by arthropods eg : Argas persicus ( tick) and occasionally by infected faeces.
• Diseases are more prevalent where poultry ticks are found .
• Directly between birds by faecal-oral route

                        Fig : Argas persicus

Host range :

• Mainly affect poultry and turkey
• Also occur in geese,ducks,pheasants,sparrow and crow

Effect on bird varies :

• Weight of infection
• Other factors
• Diet ( quality of wheat /other feed )
• Management of related factors ( onset of egg laying ,moulting , floor housing , overcrowding , and other stresses)
• Genetics and concurrent infection with other disease agents.

Signs :

• Depression
• Anorexia
• Cyanosis of comb and wattle
• Thirst
• Often diarrhoea ( greenish) with excessive urates
• Weakness and progessive paralysis
• Drop in egg production in both systemic and intestinal forms
• High fever
• Jaundice
• Inco-ordination / paralysis of legs and wings.

Postmortem lesions :

• Marked splenomegaly with mottling
• Spleen mottled with ecchymotic hemorrhage
• Liver enlarged with small haemorrhage
• Necrotic foci
• Mucoid enteritis ( green- catarrhal enteritis)
• Hemorrhage in proventriculus
• Presence of tick in skin
• Kidney may be enlarged and pale

Microscopic lesions :

• Spirochaetes may be visible in caecal lumen or colonizing the epithelium
• Penetration between and below caecal epithelial cells oe caecal epithelial cell erosion/ necrosis has been described .

• Necrosis of hepatocytes
• Necrosis and depletion of lymphoid tissue in spleen and hemosiderosis
• Catarrhal enteritis
• Perivascu;lar gliosis in brain
• Hemorrhagic dermatitis
• Organism can be seen in liver section by silver stain

Diagnosis :

• History
• Clinical signs and symptoms
• Postmortem lesions
• Isolation and direct demonstration of intestinal spirochaetosis
• PCR testing
• Serological test [ Agar- gel diffusion ]
• Detection of spirochaetal antibody in yolks of eggs laid by infected hens
• Hematology
• Presence of tick infestation