>In message <p05010408b6ebca11ee8e@[216.254.77.128]>, Doug Henwood
><dhenwood at panix.com> writes
>>
>>James, do you still think there's no risk to humans from mad cow disease?
>
>Well, yes, this was recently confirmed by some Cambridge scientists here
>in a TV report. Bovine Spongiform Encephalitis and Creutzfeld Jakob
>Disease are, as far as anyone can tell, not directly related.
Best tell the Centers for Disease Control, which says <http://www.cdc.gov/ncidod/diseases/cjd/bse_cjd.htm>:
>Since 1996, evidence has been increasing for a causal relationship
>between ongoing outbreaks in Europe of a disease in cattle, called
>bovine spongiform encephalopathy (BSE, or "mad cow disease"), and a
>disease in humans, called new variant Creutzfeldt-Jakob disease
>(nvCJD). Both disorders are invariably fatal brain diseases with
>unusually long incubation periods measured in years, and are caused
>by an unconventional transmissible agent.
>
>Although there is strong evidence that the agent responsible for
>these human cases is the same agent responsible for the BSE
>outbreaks in cattle, the specific foods that may be associated with
>the transmission of this agent from cattle to humans are unknown.
>However, bioassays have identified the presence of the BSE agent in
>the brain, spinal cord, retina, dorsal root ganglia (nervous tissue
>located near the backbone), and the bone marrow of cattle
>experimentally infected with this agent by the oral route.
and at <http://www.cdc.gov/ncidod/diseases/cjd/bse_cjd_qa.htm>
>[Q] What is the new variant form of CJD that the experts in the
>United Kingdom believe might be related to the BSE outbreak in
>cattle?
>
>[A] In contrast to the classic form of CJD, the new variant form in
>the United Kingdom predominantly affects younger persons (median age
>at death: 27.5 years as of October 2000), has atypical clinical
>features, with prominent psychiatric or sensory symptoms at the time
>of clinical presentation and delayed onset of neurologic
>abnormalities, including ataxia within weeks or months, dementia and
>myoclonus late in the illness, a duration of illness of at least 6
>months, and a diffusely abnormal non-diagnostic electroencephalogram.
>
>The characteristic neuropathologic profile of new variant CJD
>includes, in both the cerebellum and cerebrum, numerous kuru-type
>amyloid plaques surrounded by vacuoles and prion protein (PrP)
>accumulation at high concentration indicated by immunohistochemical
>analysis.
>
>Recently published data show an increasing trend for the epidemic of
>new variant CJD in the United Kingdom. A listing of monthly updated
>numbers of new variant CJD cases in the United Kingdom is available
>at: http://www.doh.gov.uk/cjd/cjd_stat.htm.
>
>
>[Q] Is there evidence directly linking this newly recognized variant
>of CJD to BSE exposure?
>
>[A] There is strong epidemiologic and laboratory evidence for a
>causal association between new variant CJD and BSE. The absence of
>confirmed cases of new variant CJD in other geographic areas free of
>BSE supports a causal association.
>
>In addition, the interval between the most likely period for the
>initial extended exposure of the population to potentially
>BSE-contaminated food (1984-1986) and onset of initial new variant
>CJD cases (1994-1996) is consistent with known incubation periods
>for CJD.
>
>An experimental study reported in June 1996 showed that three
>cynomologus macaque monkeys inoculated with brain tissue obtained
>from cattle with BSE had clinical and neuropathological features
>strikingly similar to those of new variant CJD (Nature
>1996;381:743-4).
>
>A study published in 1996 indicated that a Western blot analysis of
>infecting prions obtained from 10 new variant CJD patients and
>BSE-infected animals had similar molecular characteristics that were
>distinct from prions obtained from patients with other types of CJD
>(Nature 1996;383:685-90).
>
>Interim results of an ongoing experimental study involving
>inoculation of a panel of inbred mice with the agents causing BSE
>and new variant CJD substantially increased the strength of the
>scientific evidence for a causal association between new variant CJD
>and BSE (Nature 1997;389:498-501).
>
>Two additional groups of inbred mice and a group of cross-bred mice
>inoculated with brain homogenates from new variant CJD cases were
>also reported to have had latency periods and lesion profiles
>consistent with the BSE pattern (Bruce, pers. comm. 2000).
>
>The latency period, neuropathology, and disease-causing PrP isoforms
>in transgenic mice expressing bovine PrP that were inoculated with
>new variant CJD, BSE, and scrapie brain extracts provided additional
>evidence supporting the link between BSE and new variant CJD (Proc
>Natl Acad Sci 1999;96:15137-42).