SEARCH VEGSOURCE:

 

 

Follow Ups | Post Followup | Back to Discussion Board | VegSource
See spam or
inappropriate posts?
Please let us know.
  




From: TSS ()
Subject: EVALUATION CRITERIA FOR ANTE MORTEM DIAGNOSTIC TESTS FOR SUBCLINICAL vCJD
Date: September 14, 2006 at 2:25 pm PST

##################### Bovine Spongiform Encephalopathy #####################

1

© SEAC 2006

SEAC 94/2

EVALUATION CRITERIA FOR ANTE MORTEM DIAGNOSTIC TESTS FOR SUBCLINICAL vCJD

ISSUE

1. The UK blood services are preparing a systematic process to evaluate rapid ante

mortem diagnostic tests for subclinical vCJD. The Department of Health (DH) has

requested SEAC advice on general principles to consider for evaluation of such

tests, which could be used by the blood services to develop an evaluation

strategy. Ante mortem diagnostic tests for subclinical vCJD could also be used to

inform on the prevalence of vCJD in the population and be used in the analysis of

potential therapies.

BACKGROUND

2. Three cases of probable human transmission of prion infection from a blood

donor who later developed vCJD have been reported, providing compelling

evidence that vCJD infection can be transmitted via blood transfusion1,2,3. Blood

donor exclusion criteria and other precautionary safety measures have been

introduced since 1998 to reduce the number of potential iatrogenic cases of

vCJD. However, the development of an accurate and sensitive ante mortem

blood test to identify asymptomatic individuals infected with vCJD could

substantially reduce the potential for transmission of vCJD via blood transfusion

and other medical interventions. It could be clinically valuable in confirming the

diagnosis of symptomatic cases and monitoring the effect of potential therapies.

In addition, such a test could provide an important tool to ascertain better the

prevalence of vCJD infections.

3. There are ethical and practical issues associated with ante mortem testing for

subclinical vCJD. These have been discussed and comparisons made with

testing for other blood borne diseases in Duncan et al4 (Annex 1). Ethical

1 Peden et al. (2004) Preclinical vCJD after blood transfusion in a PRNP codon 129 heterozygous patient.

Lancet 364, 527-529.

2 Llewelyn et al. (2004) Possible transmission of variant Creutzfeldt-Jakob disease by blood transfusion Lancet.

363, 411-412.

3 http://www.hpa.org.uk/hpa/news/articles/press_releases/2006/060209_cjd.htm

4 Duncan et al.(2005) Ethical considerations in presymptomatic testing for variant CJD. J.Med Ethics 31, 625-30

2

© SEAC 2006

considerations of ante mortem testing for subclinical vCJD have also recently

been considered in detail by the Health Protection Agency. A report on this

consideration is expected to be released in Autumn 2006 as well as a wider

consultation of the recommendations. A report of the consultation is expected in

spring 2007.

4. There are a number of rapid post mortem tests validated by the European Food

Safety Authority (EFSA) for transmissible spongiform encephalopathies (TSEs) in

animals5. A number of commercial organisations have recently claimed to have

developed ante mortem tests that can be used on blood or other easily

accessible biological material for the identification of asymptomatic individuals

infected with vCJD. However, in the absence of a defined standardised system to

evaluate and compare the effectiveness of these diagnostic tests, none has

undergone formal independent evaluation and validation.

Previous scientific committee considerations

5. SEAC has not discussed the evaluation criteria for diagnostic tests for subclicial

vCJD. However, this issue has been discussed in recent reports from the World

Health Organisation (WHO)6 and the European Commissionís Scientific

Committee on Emerging and Newly Identified Health Risks (SCENIHR)7. SEAC

provided a response to the SCENIHR report consultation in February 2006. This

issue has also been considered by a number of advisory groups to DH and an

overview will be provided at SEAC 94.

WHO report

6. The WHO report states that:

The development of reliable diagnostic procedures to detect asymptomatic

subjects during the long periods of incubation of CJD and vCJD is of vital

importance. However, test methods must be appropriately validated, and

validation requires that appropriate blood reference materials be developed,

characterized and made available both to qualified test developers and to

regulatory authorities.

5 Raeber & Oesch (2006). Diagnostics for TSE agents. Dev.Biol. 123:313-23 and EFSA scientific reports on the

evaluation of BSE/TSE tests. http://www.efsa.europa.eu/en/science/tse_assessments/bse_tse.html

6 World Health Organisation (2006) Guidelines on tissue infectivity distribution in transmissible spongiform

encephalopathies. http://www.who.int./bloodproducts/TSEREPORT-LoRes.pdf

7 Scientific Committee on Emerging and Newly Identified Health Risks (2006) Opinion on the safety of humanderived

products with regard to vCJD.

http://ec.europa.eu/health/ph_risk/committees/04_scenihr/scenihr_cons_02_en.htm

3

© SEAC 2006

Attempts to develop, optimize and validate tests to detect infectivity in blood in

experimental and natural TSEs, including BSE in ruminants and vCJD in humans,

are now in progress. These very important efforts should be encouraged and

supported, both financially and by providing test developers with TSE reference

materials and panels of replicate coded and randomized samples, including

reference materials of human origin when available.

SCENIHR report

7. In considering the available data on ante mortem tests for subclinical vCJD,

SCENIHR concluded that:

Important advances in test methodologies for prion detection have been made in

recent years, and the application of these advances in the diagnosis of vCJD has,

in particular, been fruitful. However, no diagnostic system has yet emerged with

the high level of sensitivity and specificity required for routine screening of blood

or urine. It is essential that confirmatory assays are available, and all ethical

implications are considered and carefully taken into account before implementing

testing. Independent validation of any new methodology should be mandatory

prior to implementation, and it is recommended to adopt the EU procedure used

for the BSE testing. For validation carefully controlled vCJD reference materials

should be used. However, the availability of blood from individuals at increased

risk of vCJD or diagnosed with vCJD is very limited. Therefore, ethical collection

of such valuable material should be considered a priority. Special strategies are

then needed to evaluate potential blood tests in order to conserve material.

Collection of urine should be considered which could be tested when more

sensitive tests for abnormal prion protein suitable for testing urine become

available. The issue of false positives needs careful consideration, as even

minute percentages of these may actually involve a large number of individuals.

The ethical issues of informing an individual of test results, without providing any

certainty as to the likelihood of progression to clinical disease, should be

considered seriously.

Diagnostic Tests

SNIP...FULL TEXT 32 PAGES ;

http://www.seac.gov.uk/papers/94-2.pdf

RECALLS AND FIELD CORRECTIONS: BIOLOGICS -- CLASS II
______________________________
PRODUCT
Source Plasma, Recall # B-1708-6
CODE
Units: MI180733, MI180927, MI181625, MI181780, MI182337, MI182519, MI183140,
MI183311, MI183955, MI185006, MI185278, MI185822, MI186081, MI186855,
MI187183, MI187903, MI188273, MI188695, MI189257, MI189553, MI190136,
MI190473, MI191073, MI191395, MI191972, MI192303, MI193473, MI194343,
04MINA0377, 04MINA0801, 05MINA7147, 05MINA7451, 05MINA8094, 05MINA8504,
05MINA9548, 05MINA9883, 05MINB0489, 05MINB0875, 05MINB1469, 05MINB1874,
05MINB3116, 05MINB7192, 05MINB7529, 05MINB8246, 05MINB8612, 05MINB9236,
05MINB9366, 05MINB9475, 05MINB9641, 05MINC0031, 05MINC0237, 05MINC0336,
05MINC0894, 05MINC0964, 05MINC1138, 05MINC1619, 05MINC1750, 05MINC1907,
05MINC1977, 05MINC2375, 05MINC2774, 05MINC3113, 05MINC3484, 05MINC4277,
05MINC4623, 05MINC5623, 05MINC5914, 05MINC7545, 05MINC7870, 05MINC8355,
05MINC8689, 05MINC9437, 05MINC9775, 05MIND0067, 05MIND0393, 05MIND0892,
05MIND0951, 05MIND1836, 05MIND2183 and 05MIND2962
RECALLING FIRM/MANUFACTURER
BioLife Plasma Services L.P., Muncie, IN, by facsimile on November 22, 2005.
Firm initiated recall is complete.
REASON
Blood products, collected from unsuitable donors based on risk factors for
Creutzfeldt-Jakob Disease (CJD), were distributed.
VOLUME OF PRODUCT IN COMMERCE
80 units
DISTRIBUTION
CA, NC, and MD

______________________________

PRODUCT
a) Red Blood Cells, Leukocytes Reduced, Recall # B-1714-6;
b) Fresh Frozen Plasma, Recall # B-1715-6;
c) Platelets, Recall # B-1716-6
CODE
a), b), and c) Unit: 2443732
RECALLING FIRM/MANUFACTURER
South Texas Blood and Tissue Center, San Antonio, TX, by letters dated
November 11, 2003 and December 18, 2003. Firm initiated recall is complete.
REASON
Blood products, collected from a donor who was at increased risk for new
variant Creutzfeldt-Jakob Disease (nvCJD), were distributed.
VOLUME OF PRODUCT IN COMMERCE
3 units
DISTRIBUTION
TX and WI

END OF ENFORCEMENT REPORT FOR SEPTEMBER 13, 2006

###

http://www.fda.gov/bbs/topics/enforce/2006/ENF00969.html

PRODUCT
Fresh Frozen Plasma, Recall # B-1751-6
CODE
Unit: 4936623
RECALLING FIRM/MANUFACTURER
Gulf Coast Regional Blood Center, Houston, TX, by facsimile dated September
16, 2005. Firm initiated recall is complete.
REASON
Blood product, which was collected from an unsuitable donor based on risk
factors for variant Creutzfeldt-Jakob Disease (vCJD), was distributed.
VOLUME OF PRODUCT IN COMMERCE
1 unit
DISTRIBUTION
TX

END OF ENFORCEMENT REPORT FOR SEPTEMBER 6, 2006

###

http://www.fda.gov/bbs/topics/enforce/2006/ENF00968.html

USA mad cow blood for humans are a dime a dozen, the come out just
about every week ;


http://disc.server.com/discussion.cgi?disc=167318;article=2971;title=CJD%20WATCH


http://disc.server.com/discussion.cgi?disc=167318;article=2972;title=CJD%20WATCH

14 September 2006 - The agenda and meeting papers for the 94th SEAC meeting on Thursday 21st September have been published.

http://www.seac.gov.uk/agenda/agen210906.htm

TSS

#################### https://lists.aegee.org/bse-l.html ####################




Follow Ups:



Post a Followup

Name:
E-mail: (optional)
Subject:

Comments:

Optional Link URL:
Link Title:
Optional Image URL: