Emerging Infections/CJD |
Published on: 10 July 2008 |
Creutzfeldt-Jakob disease (CJD) biannual update (2009/1)
This six-monthly report provides an update on reports of incidents of potential iatrogenic (healthcare-acquired) exposure to CJD via surgery, and on the National Anonymous Tonsil Archive. Data are correct as of 1 July 2009.
For numbers of CJD case reports, readers should consult data provided by the national CJD Surveillance Unit (NCJDSU), Edinburgh [1]. The latest yearly analysis of vCJD reports (onsets and deaths) is also available from the NCJDSU website [2].
Reports of incidents of potential iatrogenic exposure to CJD via surgery:
1 January 2000 to 30 June 2008
There were a total of 371 incidents reported during this period (table 1). Fifteen surgical incidents were reported between 1 July 2008 and 30 June 2008 (ie since the previous update report [3]). A surgical incident occurs when a patient undergoes surgery but is only identified as having CJD or being at risk of CJD at a later date. This means that the ACDP TSE Working Group infection control guidelines would not have been followed. The surgery carried out on an index patient with, or at risk of CJD, may result in contamination of the instruments with abnormal prion protein. Table 1 shows the number of CJD surgical incidents reported to the CJD Incidents Panel from January 2000 to 30 June 2009 by the diagnosis of the index patient. Incidents are included in this table once they are closed (ie final advice has been issued). This is because information (such as initial diagnosis) may change during the course of the investigation.
Table 1. Closed CJD Surgical Incidents (n=371) reported to the CJD Incidents Panel, by diagnosis of index patient: 1 January 2000 to 30 June 2009
Incident type |
2000 |
2001 |
2002 |
2003 |
2004 |
2005 |
2006 |
2007 |
2008 |
First half 2009 |
Total |
1. Sporadic (possible, probable or definite) |
7 |
19 |
22 |
23 |
16 |
17 |
29 |
16 |
17 |
4 |
170(46%) |
2. vCJD (possible, probable or definite) |
6 |
14 |
22 |
5 |
4 |
1 |
2 |
|
|
|
54(15%) |
3. Familial including 'at risk' familial |
|
2 |
2 |
7 |
1 |
3 |
6 |
|
2 |
|
23(6%) |
4. 'At risk' vCJD blood component recipient |
|
|
|
|
4 |
10 |
6 |
1 |
|
|
21(6%) |
5. 'At risk' - vCJD plasma product recipient |
|
1 |
2 |
|
10 |
17 |
7 |
8 |
6 |
|
51(14%) |
6. 'At risk' - other |
|
|
2 |
2 |
1 |
2 |
4 |
|
|
|
11(3%) |
7. CJD type unclear/ CJD unlikely |
1 |
1 |
|
4 |
|
1 |
2 |
|
|
|
9(2%) |
8. Not CJD |
2 |
1 |
4 |
7 |
7 |
1 |
|
|
2 |
|
24(6%) |
9.Other |
|
|
1 |
1 |
1 |
2 |
1 |
|
|
|
6(2%) |
10. No longer considered 'at-risk' |
|
|
1 |
|
|
|
|
1 |
|
|
2(1%) |
Total |
16 |
38 |
56 |
49 |
44 |
54 |
57 |
26 |
27 |
4 |
371(100%) |
Investigation of surgical incidents may result in advice to remove surgical instruments from clinical use (to quarantine, destroy, or donate for research). Such advice is generally only given for instruments considered to be potentially contaminated with the CJD agent that have not undergone a certain number of cycles of use and decontamination since their use on an index patient. Hospitals are asked to consider sending any instruments to be permanently removed from use to the Surgical Instrument Store (held by the Health Protection Agency, Porton Down) for research. Since 2000, there have been 44 incidents, only one more over the year, in which the Panel advised that instruments should be permanently removed from use.
The Panel may advise contacting and informing some patients of their possible exposure to CJD in a surgical incident. Such advice is generally only given for patients who have definitely been exposed to potentially contaminated instruments which have been used on risk tissues in certain index patients. The Panel may advise that some of these patients should be considered "at-risk of CJD for public health purposes" and asked to take certain precautions (ie, not to donate blood or other tissues and to inform their medical and dental carers prior to any invasive procedures) in order to reduce the risk of transmitting the CJD agent further. There have been 20 incidents which resulted in patients being categorised as at risk. This has not changed since the last report (data as at June 2008). Previously we were unable to report the number at risk for one of the incidents due to an ongoing, local investigation. This investigation has now concluded and the below table reflects this, with an additional 30 patients being categorised as at risk. The Panel has to date categorised 94 patients as "at-risk", 15 of whom died before notification. Three patients have not been notified due to local, clinical decisions.
Diagnosis of index patient |
Procedure on index patient |
Number of Incidents | Alive 'at-risk' |
Died before notification |
Total |
||
Notified |
Not notified |
Total |
|||||
Sporadic CJD |
Brain biopsy |
2 |
20 |
1 |
21 |
7 |
28 |
|
Cataract surgery |
12 |
19 |
|
19 |
4 |
23 |
vCJD |
Appendectomy |
1 |
|
2 |
2 |
|
2 |
|
Cataract surgery |
1* |
1 |
|
1 |
|
1 |
'At risk' vCJD |
Endoscopy & GI surgery |
4 |
8 |
30** |
38 |
4 |
40 |
Total |
|
20 |
4 8 |
33 |
81 |
1 5 |
94 |
National anonymous tonsil archive for studies of detectable abnormal prion protein
The National Anonymous Tonsil Archive (NATA) continues to receive approximately 300 tonsil pairs per week (figure 1). The archive had received a total of 75,905 tonsil pairs up to the end of June 2009 from hospitals in England and Scotland. A further 3,000 tonsil pairs have been received from the Medical Research Council Prion Unit at the Institute for Neurology, National Hospital for Neurology and Neurosurgery. Therefore the total number of tonsil pairs in the archive was 78,905. The number of collection forms that were completed but no tonsil tissue collected was 2,298 (1,494 due to patient objection and 804 due to clinical pathology being requested).
Out of the 100 NHS Hospital Trusts that perform over 200 tonsillectomies per year in England, 91 have been recruited and are currently sending tonsil pairs to NATA on a regular basis. There are 120 hospitals sites within these trusts taking part in NATA. At present, approximately 50,000 tonsillectomies are performed annually in England. Figure 2 shows the number of tonsil pairs received from each Strategic Health Authority.
Figure 1. Number of tonsil pairs collected for NATA quarterly: Q1 2004 Q2 2009
Testing of homogenates of the tonsil tissue from the archive began at the end of January 2007. Two enzyme immunoassays (EIAs) are being used for the initial screening of the homogenates for the presence of abnormal prion protein. These EIAs allow the identification of any tonsils that need to be investigated further by the more specific tests of Western blotting (WB) and immunohistochemistry (IHC) [5].
References
1. The National Creutzfeldt-Jakob Disease Surveillance Unit, The University of Edinburgh. CJD statistics. CJD figures. Edinburgh: NCJDSU, 3 May 2005. Available at: http://www.cjd.ed.ac.uk/figures.htm.
2.The National Creutzfeldt-Jakob Disease Surveillance Unit, The University of Edinburgh. Incidence of variant Creutzfeldt-Jakob Disease Onsets and Deaths in the UK January 1994 March 2005.Edinburgh: NCJDSU, 14 April 2005. Available at: http://www.cjd.ed.ac.uk/vcjdqdec06.htm.
3. HPA. Creutzfeldt-Jakob disease update report. Health Protection Report [serial online] 2009; 2(50): Emerging Infections/CJD. Available at: http://www.hpa.org.uk/hpr/archives/2008/hpr5008.pdf.
4. HPA CJD Incidents Panel [online]. London: HPA. Available at:
http://www.hpa.org.uk/web/HPAweb&Page&HPAwebAutoListName/Page/1204031511121
5. Spongiform Encephalopathy Advisory Committee. Combining evidence from tissue surveys to estimate the prevalence of subclinical vCJD. SEAC, 2008. Available at: http://www.seac.gov.uk/papers/paper100-2.pdf