L O N D O N, Aug. 3, 2000 -- The number of people contracting the human form of mad cow disease has increased by about 23 percent a year in Britain since 1994, new research has found.
The findings, published this week in The Lancet medical journal, are part of scientists’ effort to determine the scope of variant Creutzfeldt-Jakob Disease, a fatal brain-wasting disease.
They are struggling to make accurate predictions about how large the epidemic will be or when it will reach its peak because they don’t know the incubation period of the disease. It could lay dormant for 20 years without being detected.
Diagnosis of the Deceased
The disease, which experts think comes from eating beef contaminated with the cattle ailment bovine spongiform encephalopathy, can only be confirmed by examining the brains of victims after they have died.
The scientists have had to establish the onset of the infection by asking the victims’ relatives when symptoms first occurred.
Experts don’t know exactly how long it takes between becoming infected and getting symptoms, and the lag between becoming sick and dying has varied.
The study, by scientists at the London School of Hygiene and Tropical Medicine and the National CJD Surveillance Unit, also found that deaths from variant CJD have risen by about a third each year since 1994, slightly faster than the increase in the onset of the disease. Researchers don’t know why deaths are rising faster than the incidence.
As of June 30, a total of 75 confirmed or suspected cases have been documented. Sixty-nine of those people have died.
Canadians Could Catch Mad Cow
The research said 14 people have died of the disease in the first six months of this year, compared with 18 deaths for the whole of 1998.
“Although absolute numbers remain low, there appears to be a real increase in the incidence … in the U.K., which is a cause for concern,” said Dr. Hester Ward of the surveillance unit, based in Edinburgh, Scotland.
“Until it is known whether this increasing trend is maintained over time, it is difficult to predict future numbers of cases,” she said.
The disease first surfaced in the mid-1990s, a decade after a vet discovered Britain’s first BSE-infected cattle herd.
Since the British outbreak, which affected some 180,000 cattle, about 200 cases have been found in Portugal and smaller numbers in Ireland, Belgium, Luxembourg, the Netherlands, France, Denmark and Switzerland.
A European Union report concluded Tuesday that cases of mad cow disease are unlikely to occur in the United States and Canada, but cannot be ruled out.
Last month, U.S. Agriculture Secretary Dan Glickman ordered the slaughter of 376 sheep originating from Belgium on suspicion they may have a mad cow-type disease.