In response to Rick Welsh's query about links between
Kruetzfeld-Jakob disease and BSE-infected animal bits spread on
plants as fertilizer.
The Armed Forces Institute of Pathology reports:
2. Is CJD infectious?
Creutzfeldt-Jakob disease refers to the familial, sporadic and
iatrogenic form of human prion disease most commonly occuring as
a spongiform encephalopathy. The sporadic disease occurs in an
incidence of approximately 1 in 1,000,000. Human to human
transmission has not been shown to "naturally" occur except in
the unusual circumstances of Kuru (transmission through very
unusual rituals among the Fore tribe in New Guinea) and
iatrogenic transmission. Except for these instances, transmission
through the gastrointestinal tract, respiratory tract and direct
contact have not been shown to occur.
3. What precautions can I take?
This information is a general guidline for health workers. The
prion particle is not particularly infectious. Direct CNS
inoculation is usually required for transmission. Skin, GI tract,
and respiratory tract are poor routes of infectivity. In
comparison, the hepatitis virus and HIV virus are many fold more
"infectious". The usual health precautions for infectious
diseases should be taken i.e. gloves, gown, disposable booties
and mask. Other guidelines are disposal of contaminated material
after autoclaving. In the laboratory setting a 1% NaOH wipe is
used to neutralize the prion protein on working surfaces and
instruments. Liquid waste is brought to a concentration of 1N
NaOH (approximately 600 cc of 6N NaOH per gallon of liquid waste)
and autoclaved at 132 degrees centigrade for 5 hours. Instruments
and dry waste are autoclaved similarly for 4.5 hours. These
procedures may be harsh on instruments and required containers
and containment bags that can withstand these procedures. On
non-autoclaveable surfaces, 1% NaOH followed by washdown with
bleach has been used.
6. How is CJD transmitted?
The only known cases of CJD transmission from one human to
another have occurred through prolonged ("years") direct
contact of "neural" tissue from one patient to another.
Examples are growth hormone pituitary extracts, dura mater
grafts (all from a single manufacturer), isolated cases of
transmission by corneal graft, and tissue on implanted
electroencephalogram electrodes. Surgical instruments used
on a CJD infected patient may have accidentally inoculated
other patients, however no proof of such an event exists.
There have been 30 cases of CJD in health care workers,
however no occupation link has been established. These cases
are very rare.
*However,* here is what the World Health Organization reported in
its press release from a 4/3/96 press conference in Geneva:
Bovine Spongiform Encephalopathy:
1. No part of any animal which has shown signs of TSE should enter any
food chain, human or animal. All countries must ensure the slaughter
and safe disposal of TSE-affected animals so that TSE infectivity
cannot enter any food chain. All countries should review their
rendering procedures to ensure that they effectively inactivate TSE
2. All countries should establish continuous surveillance and
compulsory notification for BSE according to recommendations
established by the Office International des Epizooties in Paris. In
the absence of surveillance data, the BSE status of a country must be
considered as unknown.
3. Countries where BSE exists in native cattle should not permit
tissues that are likely to contain the BSE agent to enter any food
chain, human or animal.
It might be worth asking Stanley Prusiner (UC-San Francisco) and
Karen Hsiao (U. Minnesota) Rick's question directly.
Hey, Gail Feenstra and the UC-Davis crew, wouldn't Prusiner make a
great keynoter/presenter for next year's AFHVS conference?
I'm sending prion links separately.
Michele Gale-Sinex, communications manager
Center for Integrated Ag Systems
UW-Madison College of Ag and Life Sciences
Voice: (608) 262-8018 FAX: (608) 265-3020
In the towers of steel, belief goes on
and on, in this heartland, in this heartland