Salmonella diarizonae in sheep
Report no: 2008: 40
Salmonella diarizonae is a subspecies of Salmonella that has been demonstrated to be endemic in sheep in various regions of Norway. The Norwegian Food Safety Authority has asked The Norwegian Scientific Committee on Food Safety (VKM) to assess this microbe’s potential and actual significance regarding both human and animal health. VKM concludes that the impact of this bacterial subspecies on human health in Norway is marginal.
It has also been questioned whether the contention that Norway’s domestic animal population is almost Salmonella-free can be defended when S. diarizonae is demonstrated relatively frequently in sheep in some regions.
The spread of S. diarizonae in sheep in Britain from the 1970s up to 2000 shows that it is important to implement preventive measures in order to impede the dissemination of this infection to new areas in Norway.
This can be done by first establishing which large population units (e.g. counties) are free of the bacteria, and ensure that the bacteria is not then introduced to these areas by purchasing live animals from an infected area and/or by use of a communal/shared ram for mating purposes from an infected area.
It would be very difficult, and extremely expensive, to attempt to combat the infection in large population units which are already thoroughly infected. The variant (S. diarizonae 61.k:1,5, (7)) which has been detected in sheep is very rarely demonstrated as a cause for human infections, including in those areas in which the endemic prevalence in sheep is high. It therefore appears that the impact of this bacterial subspecies on human health in Norway is marginal.
The VKM Panel on Biological hazard was responsible for this risk assessment.