After 25 years of surveillance, cases of Creutzfeldt-Jakob disease (CJD) are occurring at a rate of approaching two persons per million per population – about double that previously believed.
And yet it is “surprising” that no case of variant CJD, the prion disease transmitted from beef products contaminated with bovine spongiform encephalopathy (BSE), has emerged in Australia, a national CJD meeting has been told.
“It’s unexpected given the immigration, amount of tourism and long-term residential exchange” between Australia and the United Kingdom, neurologist Professor Steven Collins told the 11th Annual National CJD Conference in Melbourne on 24 November,
Residency in the UK and France, where the majority of the 231 cases to date have emerged since the ‘mad cow disease’ scare of 1996, has resulted in vCJD deaths in the US, Canada, Italy, Japan, Portugal, the Netherlands, Spain, Taiwan and Saudi Arabia, said Professor Collins, director of the Australian National CJD Registry (ANCJDR).
Since the registry’s surveillance role was expanded in 1994 to include all forms of CJD – genetic, sporadic as well as medically acquired – rates of detection had increased, he said. This was probably due to more referrals of suspect cases from neurologists, particularly since CJD became a notifiable disease in all states and territories in 2006.
Last year 69 cases of suspected sporadic, acquired and genetic CJD were referred to the ANCJDR, about 40 of them confirmed among the almost 25 million Australian population.
“Better surveillance, better markers, and better detection in the older population group”, were all contributing to the higher rates of disease detection, Professor Collins told the limbic.
Surveillance network systems were now well established with more pre-mortem testing of CSF and MR imaging of the brain, he added.
The ANCJDR was set up in 1993, initially to look for cases of CJD in the more than 2000 Australians treated with human pituitary gonadotrophin for infertility, and human growth hormone for short stature.
It followed the revelation that four Australian women – the only ones in the world – had died of CJD each year between 1988 and 1991 following fertility injection treatment.
Both pituitary hormone recipients and patients who received grafts of dura mater, are regarded as at ‘low risk’ of developing CJD. Five Australians have died of CJD, many more overseas, after grafts of Lyodura brand dura mater.
Patients at risk of developing CJD from medical treatments are morally, although not legally, obligated to disclose their ‘at risk’ status before surgery.
Professor Collins said that while there was still a risk of CJD transmission via surgical instruments from patients who had been on the pituitary hormone program between 1967 and 1985, with 27 years since the last death, the risk was now “unquantifiably low”.
Richard Knight, professor of clinical neurology at the University of Edinburgh told the conference there were currently no cases of variant CJD, anywhere in the world. The most recent cases were reported in 2011, 2013 and 2016.