(Mortality from dementia in occupations at risk of exposure to bovine spongiform encephalopathy: analysis of death registrations)
(Commentary: Uncertainty over length of incubation tempers optimism)
In a study to ascertain whether transmissible spongiform encephalopathy has had any effect on people working in animal husbandry and slaughter, researchers in this week's BMJ find that there has been no increase in certified deaths from Creutzfeldt-Jakob disease or other dementias in this group during the period 1979-96.
Paul Aylin from Imperial College of Medicine and colleagues scrutinized people aged 20-74 years who died in England and Wales between 1979-96 and for whom the occupation information recorded at death included butcher and abattoir worker, farmer and farm worker or veterinarian. They found that those few deaths (four farmers/farm workers) that were certified as due to Creutzfeldt-Jakob disease were not higher than might be expected by chance.
However, in an accompanying commentary Dr Annick Alprovitch writes that these results should be interpreted with caution when using them to predict future deaths from the disease. She says that the incubation period of Creutzfeldt-Jakob is unknown and could be anything from two to more than 30 years. She concludes that despite Aylin et al's optimistic findings, this uncertainty re-emphasises the need to continue epidemiological surveillance of Creutzfeldt-Jakob disease in Europe.
Dr Paul Aylin, Senior Clinical Lecturer, Department of Epidemiology and Public Health, Imperial College of Medicine at St Mary's, London email@example.com
Dr Annick Alprovitch, Head of Unit, Institut National de la Sant et de la Recherche Mdicale, Research Unit 360, Epidemiologie des Maladies Neurologiques, Hpital la Salptrire, Paris, France
Contact: Jill Shepherd
BMJ-British Medical Journal