Medical investigators trying to demonstrate a link between so-called mad cow disease and a similar condition in humans point to a small village in Leicestershire, England as proof.
Don't hold your breath. For now, the only thing demonstrated by the strange occurrences in this village is that mad cow disease and what is perceived as its human counterpart remain mystery diseases with no clearly established link.
What investigators know for sure is that something odd has been occurring in and around the quaint community of Queniborough. During the 1990s, five people living in or near the town contracted what appeared to be a new variant form of Creutzfeldt-Jakob disease that has been repeatedly linked with bovine spongiform encephalopathy, the technical name for mad cow disease.
Two of the victims, a young man and woman, even lived a couple of hundred yards from each other on the same street, played together as children, attended the same school and ate the same school lunches.
The two cases, coupled with the deaths of three others of similar age in close proximity, simply were too coincidental for investigators to ignore.
They point to these strange occurrences as evidence that of some kind of environmental culprit is behind this new variant Creutzfeldt-Jakob disease, most likely eating beef from cattle infected with BSE.
The young ages of these victims, investigators say, also support their claims that they are dealing with an entirely new form of CJD linked with BSE. Previous cases of CJD involving older people have not been associated with the cattle disease.
Several theories have been formulated to account for the spike in CJD cases, known as the Queniborough cluster. For a time, investigators cited school lunches of minced meat and sausage as likely sources since these were produced from the old-fashioned slaughtering methods rather than the more advanced meat recovery methods prescribed as a safeguard against infection. A polio vaccine made from calf fetus serum was also closely scrutinized.
Finally, in March 2001, investigators with the Leicestershire Health Authority concluded that the most likely sources of infection were local butcher shops using older methods of meat extraction that may have increased the likelihood that meat cuts were tainted with spine and brain tissue.
Still, the evidence remains inconclusive. The health authority report states that only four out of five CJD victims within the Queniborough area may have been exposed to possibly tainted meat, leaving one unaccounted for.
Further complicating matters is the fact that the inquiry uncovered no evidence of butchers using meat extraction methods considered illegal under British law. Also, the data used by the researchers to reach their conclusion was partly based on anecdotal accounts of family members, drawn from memories stretching back as far as 20 years.
The investigators even conceded that “on a national basis” the unusual cluster around Quenibourgh “is unlikely to explain how all of the people who developed the disease were exposed to the BSE agent.”
One other factor continues to baffle investigators. With almost 200,000 cows testing for mad cow, why hasn't a similar spike in variant CJD occurred in humans?
The bottom line: evidence linking BSE with humans is compelling but still inclusive. Yes, there are plenty of reasons to suspect a link between mad cow disease and CJD in humans but no smoking gun — not yet, at least.
(Jean Weese is an Alabama Cooperative Extension System food scientist and Auburn University associate professor of nutrition and food science)