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From: TSS (216-119-143-162.ipset23.wt.net)
Subject: Summary of SEAC’s discussion on the second presumed case of blood transfusion-associated infection with vCJD
Date: August 8, 2004 at 6:29 pm PST

-------- Original Message --------
Subject: Summary of SEAC’s discussion on the second presumed case of blood transfusion-associated infection with vCJD
Date: Sun, 08 Aug 2004 20:31:59 -0500
From: "Terry S. Singeltary Sr."
To: Bovine Spongiform Encephalopathy
CC: cjdvoice@yahoogroups.com


SEAC Statement


7th August 2004

------------------------------------------------------------------------


Summary of SEAC’s discussion on the second presumed case of
blood transfusion-associated infection with vCJD

Background

1. The Department of Health sought advice from the committee on a
presumed second instance of blood transfusion-associated transmission of
the variant Creutzfeldt-Jakob disease (vCJD) agent. The first case of
probable blood transfusion-associated transmission of vCJD1
was considered
by SEAC in February 2004.

2. The National CJD Surveillance Unit (NCJDSU) had investigated this
second patient after death, as the patient was a known recipient of
blood from a donor incubating vCJD. Patient confidentiality and
medico-legal issues surrounding the patient at the time of reporting
required that the issue was considered in the reserved session of the
meeting.

3. The elderly patient died in 2004, showed no clinical signs of vCJD at
the time of death, which was from an unrelated cause. The patient had
received a single unit of non-leucodepleted blood in 1999 that had been
donated by an individual who was confirmed in 2001 as a definite vCJD
case. The donor’s disease onset was in 2000.

4. The NCJDSU had investigated the neuropathology, accumulation of prion
protein and PrPres in autopsied tissues in the case. The PRPN genotype
had also been determined. The following details were reported:

*
No evidence of a spongiform encephalopathy in an examination of
brain material.
*
Immunohistochemical detection of prion protein accumulation in the
spleen and in a cervical lymph node. PrPres was detected by high
sensitivity western blotting in the spleen.
*
No accumulation of prion protein was detected in multiple regions
of the central nervous system, tonsils, appendix, large intestine,
skeletal muscle or thymus.
*
Glycotype profile of PrPres in spleen was the same as has been
found in clinical cases of vCJD.
*
Histological pattern of PrP accumulation in the spleen and the
lymph node is similar to that in two appendixes reported by Hilton
et al (2004)2
.
*
Methionine/valine heterozygosity at codon 129 of PrP gene (PRNP).

5. SEAC was informed that the findings suggested that this might be a
preclinical or subclinical case of iatrogenic vCJD associated with blood
transfusion. However, UK residency of the patient meant that oral
exposure to the BSE agent could not be excluded as a possible cause of
infection. Statistical analysis suggested it was extremely unlikely that
two cases of infection with the vCJD agent would have been detected by
chance in recipients of blood from pre-onset vCJD cases, even if the
prevalence of prion protein accumulation in spleen tissue in the UK
population was substantially larger than suggested by studies on
appendix and tonsil tissue from persons without clinical vCJD.

6. The Department of Health (DH) asked SEAC to assess the data available
on this case, and to advise on the implications this finding may have on
the risk associated with blood, and on any additional concerns for
public health.


Summary of SEAC’s discussion


7. SEAC agreed that the western blot results and glycotype profile
suggested it was unlikely that the infection was preclinical sporadic
CJD (sCJD). The committee noted that a single study by Glatzel et al
(2003) had reported PrPres in the spleen of sCJD clinical cases.
However, the levels of PrPres present in sCJD cases were low and
detected in patients with a lengthy clinical illness from sporadic CJD.

8. The committee agreed that the statistical analysis suggested that the
presence of PrPres in the case was attributable to a vCJD infection
acquired via blood transfusion rather than a primary infection resulting
from a food borne exposure.

9. SEAC agreed that this second patient with apparent vCJD infection
added to the evidence that the vCJD agent can be transmitted by blood.
However the committee noted that in this instance, although vCJD
infection appeared to have been transmitted, it was not known if
clinical vCJD would have developed if the patient had lived longer.

10. SEAC agreed that this case added support to its view on the risk
associated with blood transfusion. The finding was consistent with there
being a substantial risk associated with receipt of non-leucodepleted
blood from a donor incubating vCJD. The extent to which leucodepletion
reduces that risk is not known.

11. The committee agreed that it should be a public health priority for
all recipients of blood (leucodepleted or not) from donors incubating
vCJD to be subject to the kind of careful post-mortem examination that
had been possible in this case. This would help to quantify the nature
and magnitude of the risks of transmission of the vCJD agent through
blood [donated by preclinical cases of vCJD]. The committee re-iterated
the continuing importance of the Transfusion Medicine Epidemiology
Review (TMER) to identify vCJD cases who have been donors and the
recipients of such donations.

12. SEAC noted that the detection of PrPres in lymphoreticular tissues
of vCJD cases and the presence of infection in the spleen of this case
was compatible with the lymphoreticular system being involved in the
early spread of infection before entering the CNS. SEAC agreed that the
detection of prion protein in the spleen but not in the tonsil of the
case has implications for the national anonymous tonsil archive. The
SEAC chair agreed to refer this finding to the DH/MRC steering group
overseeing the archive.

13. SEAC noted that the patient was heterozygous at codon 129 of the
PRNP gene and that this was the first time infection with the vCJD agent
had been reported in an individual not methionine homozygous. This
indicated that genotypes other than the methionine homozygous were
susceptible to infection with the vCJD agent. Uncertainties remain as to
the relative susceptibility of heterozygotes to food borne (or other)
infection or the possible outcomes of infection. The committee agreed
that the similarities between the western blot band analysis and PrPres
glycoprofile seen in this case and in cases of vCJD who were methionine
homozygous was reassuring with respect to the ability to make the
diagnosis of vCJD in those of genotypes other than methionine homozygous.

14. SEAC stated that, in the interests of public health, this case
demonstrates the importance of both in life and in death surveillance of
recipients of blood products derived from blood donations from
individuals subsequently found to be infected with the vCJD agent. The
committee also noted that this case highlighted the importance of
obtaining autopsies in such patients and, more generally, the committee
reiterated the concern that it had expressed previously, that a
mechanism was needed to increase the autopsy rate amongst the UK
population to reduce the possibility that cases of vCJD were being missed.

15. SEAC emphasised the importance of the DH-funded sheep transfusion
study which is designed to investigate the infectivity of different
blood fractions taken from sheep experimentally infected with BSE by
transfusing them into ARQ homozygous sheep. The committee noted that the
two presumed human cases of blood transfusion-associated vCJD infection
indicated the potential infectivity of transfused blood. However,
current technology is unable to quantify the levels of infectivity in
blood and a rapid diagnostic test remained a key research priority.

SEAC
7th August 2004

1.Llewelyn CA, Hewitt PE, Knight RS, Amar K, Cousens S, Mackenzie J,
Will RG. Possible transmission of variant Creutzfeldt-Jakob disease by
blood transfusion. Lancet. 2004 Feb 7;363(9407):417-21.

2. Hilton DA, Ghani AC, Conyers L, Edwards P, McCardle L, Ritchie D,
Penney M, Hegazy D, Ironside JW. Prevalence of lymphoreticular prion
protein accumulation in UK tissue samples. Journal of Pathology: 203
(3).733-739. Published Online: 21 May 2004

http://www.seac.gov.uk/statements/state070804.htm

http://www.seac.gov.uk/statements/statement070804.pdf

TSS





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