The prevalence of Fusobacterium necrophorum biovar A in animal faeces.

Only a small proportion of animals tested were found to be excreting Fusobacterium necrophorum biovar A, the causative organism of necrobacillosis, in the faeces (3 of 69 wallabies, 1 of 66 deer, 2 of 81 cattle). The two positive cattle belonged to a single group of calves on a farm with a history of necrobacillosis and the litter underfoot also readily yielded biovar A organisms. All attempts to demonstrate biovar A in litter on other farms and in soil from an area populated by wallabies and deer failed. Ruminal contents from young beef cattle proved a fertile source of F. necrophorum biovar A, 15 of 18 animals giving a positive result. It is suggested that disturbance of the gastrointestinal microflora leads to intestinal multiplication and faecal excretion of the organism, which may then give rise to necrobacillosis of the body surface.