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Atypical scrapie/Nor 98

October 2009

Finding atypical scrapie (or Nor 98) in a sheep in New Zealand was only a matter of time. Nor 98 (it was first identified in Norway in 1998) is a brain condition of sheep and goats that is thought to be natural and spontaneous in occurrence, so any country that looks for it is very likely to eventually find it. There are no known food safety concerns and Nor 98 has not been shown to be able to pass from animal to animal. Nor 98 is quite different to ‘classical’ scrapie and is likely to have been in sheep for decades or even hundreds of years, and simply never recognised. Nor 98 has in fact been described as a “scientific curiosity”.

Why then, if it’s not going to do any harm to human or animal, was it being looked for? New Zealand is classified as free from classical scrapie (which is infectious between sheep) and that means our sheep brains can be used as negative controls in the development of rapid tests for the detection of classical scrapie and other transmissible spongiform encephalopathies (TSEs). To be used in this way, the brain tissue needs to be confirmed to actually be negative before it can be used. During the testing to do this, one brain from a shipment of 200 tested positive for Nor 98.

That hasn’t affected our position as being free of classical scrapie. We simply join the many other countries that have looked hard enough to find Nor 98. Cases have been reported from Norway, Sweden, Finland, the UK, Germany, France, Portugal, Belgium, the Netherlands, Ireland, Denmark, United States, Canada and Falkland Islands.

Last year, after examining member country submissions and investigating rigorous scientific research, the World Organisation for Animal Health (OIE) decided that Nor 98 should not be listed in its Terrestrial Animal Health Code. The Code sets out trade recommendations or restrictions for listed diseases or conditions, and the OIE determined there was no need for such recommendations around Nor 98.

This story parallels in many ways the story of science itself, particularly when biological systems (and food is a product of biology) are involved. The wonderful complexity and possibility of nature means that we need to look long and hard in many places in order to find those one in a thousand occurrences.

The bigger question for a food safety authority is where we should be addressing our limited resources. In the case of the Nor 98 finding, discovery was through testing that was done to confirm the suitability as a control in a laboratory. Would we (or our colleagues in MAF Biosecurity New Zealand) be applauded for spending a great deal of money looking for Nor 98 here when we know that it does not harm people or other animals? Or are we better serving New Zealanders and exporters (and the millions of consumers overseas eating New Zealand foods) by focusing on identifying real hazards and controlling the risks that they present?

Our answer has always been the latter. The discovery of Nor 98 in a sheep here is expected and of academic scientific interest. Our focus is staying on the more important work of ensuring food is safe and suitable for consumption although we continually monitor emerging science. Doing that means consumers are protected and our food products can have fair access to international markets.