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New variant Creutzfeldt-Jakob disease: the epidemic that never was

BMJ 2001; 323 doi: https://doi.org/10.1136/bmj.323.7317.858 (Published 13 October 2001) Cite this as: BMJ 2001;323:858

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what are the consequences of heavy petting?

vCJD deaths have been documented since 1995, predominantly in the
younger age group. Most cases are presumed to link to BSE and result from
the consumption of beef, or beef products, containing the infective prion.
The BSE prion has attracted unequalled horror billing publicity during
this period: indestructible, infective in minute quantities, threatening
most UK meat eaters in the late 1980s with a latent and incurable disease.

Studies undertaken on the basis of the above assumption, and in
anticipation of a vCJD epidemic, have cast some doubt on previous claims.
Venter argues that the causal link between the BSE prion and vCJD is
itself suspect (1). Regional rates of vCJD have shown no clear association
with BSE incidence or variations in diet (2). Prospective surveillance of
children for vCJD has identified few new cases, and death rates from vCJD
have fallen in recent years (3,4). Whereas predicted death rates are based
upon incomplete understanding of the efficiency of prion transmission to
the human population, an alternative transmission mechanism may indicate
that the at-risk population is much smaller than originally predicted.

Spongiform encephalopathy, transmissible through animal contact, is
evident in American deer and elk. Experiments successfully demonstrating
prion transfer and replication across species, increase the likelihood of
vCJD developing from animals other than the bovine species. In terms of
BSE prion content, the quality of beef eaten by the UK population may
formerly have been poor but meat consumed by domestic pets must have been
a lot worse. Furthermore, some domestic /working dogs would have had
direct access to the carcasses of BSE cattle and scrapie infected sheep.
How many of our domestic pets developed spongiform encephalopathy from
eating BSE prion infected meat? vCJD is difficult to diagnose; the
progress of spongiform encephalopathy may be less easily recognisable in
cats and dogs, appearing late in life when symptoms are characteristic of
old age. Domestic pets present a possible route for transfer of an
infective prion to the human population. How many of the vCJD victims
could have been described as 'animals mad' ? (5).

In recognition of a potential hazard, the CJD Surveillance Unit case
registry records animal contact for each vCJD victim. This documentation
may be inadequate, however, as risk is more likely to relate to extreme
behaviour rather than normal animal contact. Children may perceive less
health risk in petting than adults. Our social interaction with domestic
animals has increased markedly over past years, presenting new risks (6)
without adequate public health control or investigation. With specific
reference to vCJD, we should not have to wait two decades or more to
realise that we may not understand the transmission mechanism.

1.Venters GA. New variant Creutzfeldt-Jacob disease: the epidemic
that never was. BMJ 2001;323:858-861.

2.Cousens S, Smith PG, Ward H, Everington D, Knight RSG et al.
Geographical distribution of variant Creutzfeldt-Jacob disease in Great
Britain, 1994-2000. The Lancet 2001;357:1002-1007.

3.Verity, CM, Nicholl A, Will RG, Devereux G, Stellitano L. Variant
Creutzfeldt-Jacob disease in UK children: a national surveillance study.
The Lancet 2000; 356: 1224-1227.

4.Department of Health monthly Creutzfeldt –Jacob disease statistics.
www.doh.gov.uk/cjd/stats/jan03.htm

5.Devine D. Tragic degeneration of a model girl. Western Mail 2001; 28th
April.

6.Tenkate TD, Stafford RJ. Risk factors for Campylobacter infection in
infants and young children: a matched case-control study. Epidemiology
Infection 2001; 127: 399-404.

Competing interests:  
None declared

Competing interests: No competing interests

07 January 2003
W. Robert Williams
senior lecturer
School of Care Sciences, University of Glamorgan, Pontypridd CF37 1DL