• If you are having problems logging in please use the Contact Us in the lower right hand corner of the forum page for assistance.

Factors determining the potential for vCJD via surgical inst

flounder

Well-known member
Subject: Factors determining the potential for vCJD via surgical instruments
Date: August 2, 2006 at 6:39 am PST
Factors determining the potential for

onward transmission of variant

Creutzfeldt–Jakob disease via

surgical instruments

Tini Garske1,*, Hester J. T. Ward2, Paul Clarke1, Robert G. Will2

and Azra C. Ghani1

1Department of Epidemiology and Population Health,

London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK

2National Creutzfeldt–Jakob Disease Surveillance Unit, Western General Hospital,

Edinburgh EH4 2XU, UK

While the number of variant Creutzfeldt–Jakob disease (vCJD) cases continues to decline,

concern has been raised that transmission could occur directly from one person to another

through routes including the transfer of blood and shared use of surgical instruments. Here

we firstly present data on the surgical procedures undertaken on vCJD patients prior to onset

of clinical symptoms, which supports the hypothesis that cases via this route are possible. We

then apply a mathematical framework to assess the potential for self-sustaining epidemics via

surgical procedures. Data from hospital episode statistics on the rates of high- and mediumrisk

procedures in the UK were used to estimate model parameters, and sensitivity to other

unknown parameters about surgically transmitted vCJD was assessed. Our results

demonstrate that a key uncertainty determining the scale of an epidemic and whether it is

self-sustaining is the number of times a single instrument is re-used, alongside the infectivity

of contaminated instruments and the effectiveness of cleaning. A survey into the frequency of

re-use of surgical instruments would help reduce these uncertainties.

Keywords: variant Creutzfeldt–Jakob disease; self-sustaining epidemic;

mathematical model; epidemiology

1. INTRODUCTION

To date it is believed that the majority of clinical cases

of variant Creutzfeldt–Jakob disease (vCJD) in the UK

have been caused by consumption of Bovine spongiform

encephalopathy (BSE)-infected beef (Bruce et al. 1997;

Hill et al. 1997; Scott et al. 1999). Despite high

estimates of the number of BSE-infected cattle that

entered the food supply (in the order of 3–4 million

animals (Donnelly et al. 2002)), the number of cases of

vCJD has remained low with 161 cases to the end of

2005, and the annual incidence steadily decreasing since

2000. Estimates for the total scale of the epidemic

through this route have reduced over time and now lie

in the low hundreds (Clarke & Ghani 2005).

A survey of appendix and tonsil tissues (Hilton et al.

2004) estimated a much higher prevalence of infection in

the population than suggested by the clinical cases. This

finding is best explained by the hypothesis that a large

proportion (84.4%) of infections are sub-clinical (i.e. will

never go on to develop symptoms within their lifetime;

Clarke & Ghani 2005). Evidence for a sub-clinical vCJD

state has been found in animal studies (Hill et al. 2000;

Hill & Collinge 2003; Bishop et al. 2006). Infection is

detectable throughout the CNS and lymphatic system in

patients with clinical vCJD (Wadsworth et al. 2001). In

addition, the abnormal formof the prion protein (PrPSc)

has been detected in the spleen of a patient who died

from other causes (Peden et al. 2004) and in the

appendix of a vCJD case removed 3 years prior to

their death (Hilton et al. 1998). Given that infectious

PrPSc is detectable in patients showing no clinical

symptoms, it is possible that it could be transmitted

through surgical procedures. Surgical instruments are

decontaminated routinely before use on another patient.

However, research suggests that PrP binds strongly to

stainless steel and that current sterilisation procedures

are unlikely to be effective because of the high

temperatures required to deactivate PrPSc (Flechsig

et al. 2001; Yan et al. 2004). Furthermore, a survey of

decontamination practices has shown that past practices

fell short of the expected standard in many hospitals

(Estates 2000). Although steps have been taken to

improve the situation (Estates 2001), it is likely that the

reality of decontamination is still less than perfect and

hence that residual infectivity will remain.

J. R. Soc. Interface

doi:10.1098/rsif.2006.0142

Published online

*Author for correspondence ([email protected]).

Received 22 May 2006

Accepted 21 June 2006 1 q 2006 The Royal Society


snip....

full text ;


http://www.journals.royalsoc.ac.uk/media/7hxdahxwvm0wxxrrvbfk/contributions/8/0/v/8/80v81437446nu2m5.pdf


NOT TO FORGET THE SPORADIC CJDs ;


Transmission of Creutzfeldt-Jakob disease to a chimpanzee by electrodes contaminated during neurosurgery.

Gibbs CJ Jr, Asher DM, Kobrine A, Amyx HL, Sulima MP, Gajdusek DC.

Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.

Stereotactic multicontact electrodes used to probe the cerebral cortex of a middle aged woman with progressive dementia were previously implicated in the accidental transmission of Creutzfeldt-Jakob disease (CJD) to two younger patients. The diagnoses of CJD have been confirmed for all three cases. More than two years after their last use in humans, after three cleanings and repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were implanted in the cortex of a chimpanzee. Eighteen months later the animal became ill with CJD. This finding serves to re-emphasise the potential danger posed by reuse of instruments contaminated with the agents of spongiform encephalopathies, even after scrupulous attempts to clean them.

PMID: 8006664 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8006664&dopt=Abstract

TSS
 

TimH

Well-known member
flounder said:
Subject: Factors determining the potential for vCJD via surgical instruments
Date: August 2, 2006 at 6:39 am PST
Factors determining the potential for

onward transmission of variant

Creutzfeldt–Jakob disease via

surgical instruments

Tini Garske1,*, Hester J. T. Ward2, Paul Clarke1, Robert G. Will2

and Azra C. Ghani1

1Department of Epidemiology and Population Health,

London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK

2National Creutzfeldt–Jakob Disease Surveillance Unit, Western General Hospital,

Edinburgh EH4 2XU, UK

While the number of variant Creutzfeldt–Jakob disease (vCJD) cases continues to decline,
concern has been raised that transmission could occur directly from one person to another

through routes including the transfer of blood and shared use of surgical instruments. Here

we firstly present data on the surgical procedures undertaken on vCJD patients prior to onset

of clinical symptoms, which supports the hypothesis that cases via this route are possible. We

then apply a mathematical framework to assess the potential for self-sustaining epidemics via

surgical procedures. Data from hospital episode statistics on the rates of high- and mediumrisk

procedures in the UK were used to estimate model parameters, and sensitivity to other

unknown parameters about surgically transmitted vCJD was assessed. Our results

demonstrate that a key uncertainty determining the scale of an epidemic and whether it is

self-sustaining is the number of times a single instrument is re-used, alongside the infectivity

of contaminated instruments and the effectiveness of cleaning. A survey into the frequency of

re-use of surgical instruments would help reduce these uncertainties.

Keywords: variant Creutzfeldt–Jakob disease; self-sustaining epidemic;

mathematical model; epidemiology

1. INTRODUCTION

To date it is believed that the majority of clinical cases

of variant Creutzfeldt–Jakob disease (vCJD) in the UK

have been caused by consumption of Bovine spongiform

encephalopathy (BSE)-infected beef (Bruce et al. 1997;

Hill et al. 1997; Scott et al. 1999). Despite high

estimates of the number of BSE-infected cattle that

entered the food supply (in the order of 3–4 million

animals (Donnelly et al. 2002)), the number of cases of

vCJD has remained low with 161 cases to the end of

2005, and the annual incidence steadily decreasing since

2000. Estimates for the total scale of the epidemic

through this route have reduced over time and now lie

in the low hundreds (Clarke & Ghani 2005).

A survey of appendix and tonsil tissues (Hilton et al.

2004) estimated a much higher prevalence of infection in

the population than suggested by the clinical cases. This

finding is best explained by the hypothesis that a large

proportion (84.4%) of infections are sub-clinical (i.e. will

never go on to develop symptoms within their lifetime;

Clarke & Ghani 2005). Evidence for a sub-clinical vCJD

state has been found in animal studies (Hill et al. 2000;

Hill & Collinge 2003; Bishop et al. 2006). Infection is

detectable throughout the CNS and lymphatic system in

patients with clinical vCJD (Wadsworth et al. 2001). In

addition, the abnormal formof the prion protein (PrPSc)

has been detected in the spleen of a patient who died

from other causes (Peden et al. 2004) and in the

appendix of a vCJD case removed 3 years prior to

their death (Hilton et al. 1998). Given that infectious

PrPSc is detectable in patients showing no clinical

symptoms, it is possible that it could be transmitted

through surgical procedures. Surgical instruments are

decontaminated routinely before use on another patient.

However, research suggests that PrP binds strongly to

stainless steel and that current sterilisation procedures

are unlikely to be effective because of the high

temperatures required to deactivate PrPSc (Flechsig

et al. 2001; Yan et al. 2004). Furthermore, a survey of

decontamination practices has shown that past practices

fell short of the expected standard in many hospitals

(Estates 2000). Although steps have been taken to

improve the situation (Estates 2001), it is likely that the

reality of decontamination is still less than perfect and

hence that residual infectivity will remain.

J. R. Soc. Interface

doi:10.1098/rsif.2006.0142

Published online

*Author for correspondence ([email protected]).

Received 22 May 2006

Accepted 21 June 2006 1 q 2006 The Royal Society


snip....

full text ;


http://www.journals.royalsoc.ac.uk/media/7hxdahxwvm0wxxrrvbfk/contributions/8/0/v/8/80v81437446nu2m5.pdf


NOT TO FORGET THE SPORADIC CJDs ;


Transmission of Creutzfeldt-Jakob disease to a chimpanzee by electrodes contaminated during neurosurgery.

Gibbs CJ Jr, Asher DM, Kobrine A, Amyx HL, Sulima MP, Gajdusek DC.

Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.

Stereotactic multicontact electrodes used to probe the cerebral cortex of a middle aged woman with progressive dementia were previously implicated in the accidental transmission of Creutzfeldt-Jakob disease (CJD) to two younger patients. The diagnoses of CJD have been confirmed for all three cases. More than two years after their last use in humans, after three cleanings and repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were implanted in the cortex of a chimpanzee. Eighteen months later the animal became ill with CJD. This finding serves to re-emphasise the potential danger posed by reuse of instruments contaminated with the agents of spongiform encephalopathies, even after scrupulous attempts to clean them.

PMID: 8006664 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8006664&dopt=Abstract

TSS

:D :D :D If I could be so BOLD as to point out the mere suggestions and theoretical possibilities........... :D

after three cleanings and repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were implanted in the cortex of a chimpanzee. Eighteen months later the animal became ill with CJD. This finding serves to re-emphasise the potential danger posed by reuse of instruments contaminated with the agents of spongiform encephalopathies, even after scrupulous attempts to clean them.

But ..... but ...... but......... Ron Arnold says that a quick dip in a mild acid solution("strong enough to dissolve the outer skin of an orange") is sufficient to destroy prions on his urine sampling gear....... :D :D :D :D :D :D :D :D
 
Top