Fears are growing that a new form of Creutzfeldt-Jakob disease (CJD - the human form of BSE or mad cow disease) could have spread to humans.

The concern has arisen following a sharp upturn in the number of people dying from sporadic CJD in Switzerland, reports Nature Science Update. Sporadic CJD is a different form of the disease that affects people over the age of 60. Each year between 1997 and 2000, eight to 11 of Switzerland's 6.5 million people developed CJD. In 2001, 19 cases were reported; while seven were reported in the first quarter of 2002. This is around four times higher than the reported incidence anywhere else, including Britain.

Scientists are concerned that BSE has passed into humans and caused sporadic CJD, but it is too early to assess whether this has occurred.

Adriano Aguzzi of the Institute of Neuropathology and National Reference
Center for Human Prion Diseases in Zurich, the researcher who led the study, was quoted as saying: "I'm still hoping the numbers will go down." Epidemiologist Roy Anderson of Imperial College of Science, Technology and Medicine, London, says his "preferred option" is a reporting bias: that an increased awareness of the disease amongst doctors and the public has produced more diagnoses. However, given that other countries undertake intensive CJD surveillance work, this is thought unlikely.

If BSE has caused the sporadic CJD in Switzerland, researchers need to find out how the cattle disease can cause two different forms of the human disease: variant CJD in the UK and elsewhere, and sporadic CJD in Switzerland.

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