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25 August 1998
The Ministry of Agriculture and Forestry’s Invermay Animal Health Laboratory is alerting farmers in Otago and Southland to an emerging disease in pregnant ewes which in the last few weeks has caused abortions in hundreds of ewes and many ewe deaths.
The disease is a type of salmonellosis caused by Salmonella Brandenburg. It causes ewes in late pregnancy to become very dull and fevered, they abort and occasionally they develop severe diarrhoea. If the ewes are not treated immediately with broad spectrum antibiotics they die.
Salmonellosis has been around for many years causing severe diarrhoea and deaths, but until now the type of Salmonella involved has usually been Salmonella Typhimurium or Salmonella Hindmarsh.
Salmonella Brandenburg appears to be new to Otago/Southland. In 1997 the organism caused a number of big abortion outbreaks in Canterbury, and this season again in the same area more outbreaks have been reported.
In Otago and Southland in the last few weeks the disease has occurred in clusters of adjacent farms in South Otago and in central and southern Southland. There have been heavy losses on some farms, with dozens of ewes aborting and many subsequently dying.
The source of infection in the current outbreaks is not known. However it is likely that anything that takes mud and faeces from paddock to paddock, like gumboots and vehicle tyres, may help spread infection.
Farmers whose ewes show signs of this disease should contact their veterinarian immediately, because early treatment and management changes may help keep losses to a minimum.
Invermay vets and veterinary practitioners are currently gathering information about outbreaks, and they are seeking information from farmers using questionnaires. It is important to have as much information about the disease as possible so that control methods can be developed.
As with all types of salmonellosis, Salmonella Brandenburg may pose a risk to human health. When dealing with sheep which could be infected, good standards of hygiene are needed to minimise the risk of spread of infection to people as well as to other animals.
More information from:
Marjorie Orr, Invermay Animal Health Laboratory
Phone 03 489 3809. Fax 03 489 7988