New Zealand

Salmonella

SALMONELLOSIS (Enteric form)

  • Salmonellosis is a bacterial disease that is characterised by outbreaks of severe diarrhoea and death.
  • In sheep there are two forms of the disease seen. The enteric form and the reproductive form. The enteric form is caused by Salmonella hindmarsh, Salmonella typhimurium and Salmonella bovis-morbificans. The reproductive form is caused by Salmonella Brandenburg, although on rare occasion S. Brandenburg can also cause an enteric disease in non-pregnant sheep.
  • Generally the enteric form is seen between December to June, probably due to the increased stress associated with mob stocking and rotational or intensive grazing.
  • Carrier animals are regarded as the source of any outbreak but clinical disease only occurs as a result of some stress factor, such as:
    • A sudden change in nutrition to poor feed.
    • Holding stock in yards over long periods (>24 hrs)
    • Transport over long distances
    • Holding sheep at high stocking rates
  • The normal clinical presentation is to suddenly find a few ewes dead every few days when mobs are shifted. The mortality rate is usually about 1% but can exceed 5% on rare occasions. Many ewes will show no signs prior to death but some will be observed with a karki coloured diarrhoea that adheres to the wool on the hocks and crutch.
  • Post mortem examination reveals severe inflammation of the abomasum and the intestines with enlargement of the mesenteric lymph nodes. Confirmation can be made by culture of the gut contents.
  • Salmonella is a zoonotic disease, therefore care must be taken when handling both the sick and dead animals in order to prevent human infections.

SALMONELLOSIS (Reproductive form)

Link to Salmonella Brandenberg

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