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Last updated: 19 February 2010, Volume 4 No 7 (PDF file,187 KB)

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Creutzfeldt-Jakob disease (CJD) biannual update (2010/1)

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 26 January 2010.

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:
2000 to 31 December 2009

Since the previous update report [3], 19 surgical incidents were reported – between 1 July and 31 December 2009 – bringing the total number reported since 2000 to 407 (table 1). 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 31st December 2009 by the diagnosis of the index patient. Information about the CJD Incidents Panel can be found on the HPA website [4].

Table 1. Closed CJD Surgical Incidents (n=407) 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	24	16	18	31	17	21	11	186(46%)
2. vCJD (possible, probable or definite)	6	14	22	5	4	1	2	–	1	1	56(14%)
3. Familial including 'at risk' familial	–	2	2	7	1	3	7	–	2	2	26(6%)
4. 'At risk' vCJD blood component recipient	–	–	–	–	4	10	6	1	–	–	21(5%)
5. 'At risk' - vCJD plasma product recipient	–	1	2	–	10	18	9	8	6	8	62(15%)
6. 'At risk' - other	–	–	2	2	1	2	4	–	–	1	12(3%)
7. CJD type unclear/ CJD unlikely	1	1		4	1	1	2	–	–	–	10(2%)
8. Not CJD	2	1	4	7	7	1	1	–	3	–	26(6%)
9.Other	–	–	1	1	1	2	1	–	–	–	6(1%)
10. No longer considered 'at-risk'	–	–	1	–	–	–	–	1	–	–	2(0%)
Total	16	38	56	50	45	56	63	27	33	23	407(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 46 incidents in which instruments were 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. Since 2000, 22 incidents have given rise to such advice. There are currently nine incidents in which 77 patients have been categorised as ‘at-risk' by the Panel, according to the current risk assessment. Seven of these patients died before notification. A total of 31 patients are currently notified of their ‘at-risk' status. Notifications are pending for another 31 patients. Three patients have not been notified due to local, clinical decisions.

The Panel has revised its advice on endoscopy and anterior eye patients. This has led to patients being denotified in 2006 and 2009. This resulted in reclassification of 38 patients from the ‘at-risk' category; 32 in anterior eye surgery, two in invasive endoscopy.

Table 2. Panel advice to inform patients that they are ‘at-risk' of CJD/vCJD: 1 January 2000 to 30 June 2009

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	2	28
vCJD	Appendectomy	1	–	2*	2	–	2
	Endoscopy and GI surgery	2†	3	1 **	4	1	5
'At risk' vCJD	Endoscopy and GI surgery	4	8	30**	38	4	42
Total	–	9	31	34	65	7	77

*Local decision not to notify.
† The index patient in one of these incidents was a haemophiliac plasma product recipient with evidence of vCJD infection.
** Notification pending.

National anonymous tonsil archive for studies of detectable abnormal prion protein

The National Anonymous Tonsil Archive (NATA) continues to receive approximately 250 tonsil pairs per week (figure 1). The archive had received a total of 81,604 tonsil pairs up to the end of December 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 84,604. The number of collection forms that were completed but no tonsil tissue collected was 2,395 (1,565 due to patient objection and 830 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 – Q4 2009

Just over 5,000 tonsillectomies are performed in Scotland each year. The project in Scotland, where there are 14 hospitals that each carry out more than 200 tonsillectomies per year, is being coordinated by Health Protection Scotland. All fourteen of these hospitals have been recruited and are collecting tonsils for NATA. The tonsil tissue is being transported to the Health Protection Agency in Colindale for inclusion in the archive. Figure 3 shows all hospitals in England and Scotland currently recruited in the study.

Figure 2. Tonsils pairs collected by Strategic Health Authority, January 2004 - December 2009

Figure 3. NHS Trusts and Scottish Hospitals currently collecting and sending tonsil tissue to the archive December 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. 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 - December 2006. Edinburgh: NCJDSU, 2 February 2007. Available at: http://www.cjd.ed.ac.uk/vcjdqdec06.htm.

3. HPA. Biannual CJD update (2009/1). Health Protection Report [serial online] 2009; 3(27): Emerging Infections/CJD. Available at: http://www.hpa.org.uk/hpr/archives/2009/hpr2709.pdf.

4. HPA. CJD Incidents Panel [online]. London: HPA, 2010. 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. London: SEAC, 2008. Available at: http://www.seac.gov.uk/papers/paper100-2.pdf.