001119 Link Between Beef and CJD Remains Unproven

London - There is still no proof that past consumption of beef is a risk factor for variant CJD, thought to be a human form of 'mad cow' disease, according to a study by the National CJD Surveillance Unit in Edinburgh.

In the study, the 51 people who died of vCJD in the UK by the end of 1999 were compared with healthy people of the same age. The researchers also failed to show an increased risk of vCJD associated with past surgery, previous blood transfusion or occupation.

However, the study is limited in its ability to prove such associations because of the “small number of cases and controls,” the surveillance unit said in its annual report.

It added: “For some putative risk factors, such as blood transfusion or surgery, it will be many years before an accurate assessment of risk can be made because of the likely prolonged incubation periods.”

Analysis by the surveillance unit did however indicate that the risk of vCJD may be higher in northern England and Scotland than in the south.

Almost all vCJD cases and unaffected people were reported to have eaten beef, sausages, burgers and meat pies, according to the report. Although the people with vCJD ate beef more often than unaffected people, this was not statistically significant.

The study also analyzed the frequency of consumption of three food items that may have contained mechanically-recovered meat--burgers, meat pies and sausages. Mechanically-recovered meat is flesh collected from animal carcasses using high-powered water jets. The study found widespread consumption of these food items in both cases and unaffected people but no significant difference between them.

The study found that 61% of the cases and 70% of unaffected people had had operations. Examination of specific operations such as tonsillectomy or appendectomy also failed to show any significant differences between the two groups.

Fourteen people with vCJD reported working in the catering industry compared with five unaffected people, however this was not a statistically significant difference. Four people with vCJD worked in the meat industry and three in medicine or medical-related professions compared with two and three unaffected people, respectively. Overall, people began to experience the symptoms of vCJD at about age 28 and the median age of death was 29. The two youngest people with vCJD were 14 years old when they began to experience symptoms and the oldest person was 53.

The risk of vCJD appears to be higher in northern UK--about 2.57 cases per million people--compared with the south, which has 1.3 cases per million people.

However, the finding “should be treated with caution” given “the small numbers of cases on which this finding is based,” the report said.

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