March
For an overview of all updates made to the Communicable Disease Control Manual, refer to Updates to the Communicable Disease Control Manual – Health New Zealand | Te Whatu Ora
June
Creutzfeldt-Jakob Disease (CJD) is one of the transmissible spongiform encephalopathies that affect humans. Sporadic CJD, accounting for 85–90% of CJD, occurs at an incidence of 1–2 per million per year.
Other transmissible spongiform encephalopathies include kuru (once common amongst the Fore people of Papua New Guinea), and hereditary forms such as Gerstmann-Straussler-Scheinker syndrome and fatal familial insomnia. CJD is subdivided into sporadic (previously known as classic), familial, iatrogenic and variant forms. The variant form of CJD (vCJD) is linked epidemiologically and through laboratory studies to bovine spongiform encephalopathy (BSE) in cattle.
All spongiform encephalopathies are caused by proteinaceous infectious particles (termed ‘prions’) that undergo conformational change, leading to cellular death and inducing a similar conformational change in other proteins around them.
Arises spontaneously.
Based on the small number of vCJD cases, the incubation period for foodborne transmission is approximately 13 years.
Not applicable (arises spontaneously).
Variant CJD is most likely to have been caused by consumption of food products contaminated by BSE-infected cattle.
Infection is passed on as a result of medical treatment or invasive medical intervention through exposure to infectious material from a case. Most cases of iCJD have been transmitted through cadaveric dural grafts or treatment with human pituitary hormones; two cases have been transmitted through corneal transplantation, contaminated neurosurgical instruments or from EEG depth electrodes. Each acquired form involves the inoculation, implantation or transplantation of infectious material.
For sporadic, familial and iatrogenic cases of CJD, only the tissues of the central nervous system, including the brain, dura mater, spinal cord ganglia, CSF (low risk), posterior eye and the olfactory tract, appear to be infective. Blood transmission has not been demonstrated for sporadic CJD, but has been implicated in several cases of variant CJD.
For variant CJD, abnormal prion protein has also been detected in various lymphoid tissues, including tonsils, spleen, gastrointestinal lymphoid tissues (for example, Peyers patches of the appendix and rectum), lymph nodes, thymus and adrenal gland. Some vCJD cases have been linked to blood transfusions, and it is thought that vCJD can be transmitted by blood components from people who are asymptomatic but later develop the disease.
There have been no isolations of infective material from human faeces, saliva, tears, vaginal secretions, semen or milk.
Cases are increasingly likely to be infective during the last 40 percent of the incubation period or longer (that is, approximately eight years before the onset of symptoms for sporadic CJD). Central nervous system tissue is infective throughout symptomatic illness.
Case classification follows the international consensus diagnostic criteria used by the National CJD Research & Surveillance Unit (UK) refer to the following.
Cases are classified based on a combination of clinical features, investigative findings (cerebral magnetic resonance imaging (MRI), electroencephalogram (EEG), cerebrospinal fluid (CSF) real-time quaking-induced conversion (RT-QuIC) or 14-3-3 protein), and, when available, definitively brain histopathology.
The New Zealand Creutzfeldt-Jakob Disease Surveillance Registry (external link) classifies cases according to these criteria; some cases may remain unclassified if sufficient information is unavailable.
Creutzfeldt-Jakob Disease is a rapidly progressive and universally fatal neurodegenerative disease.
Several subtypes exist, distinguished by causative mechanism and clinical features. However, these clinical differences are not reliably distinguishable in practice — for example, sporadic, genetic, and iatrogenic forms can appear clinically identical.
Sporadic CJD (sCJD)
Familial CJD (fCJD)
Variant CJD (vCJD)
Iatrogenic CJD (iCJD)
There are no epidemiological criteria for CJD.
Requires at least one of the following.
In addition, to the laboratory definitive evidence internationally used consensus criteria must be met. This includes:
Refer to:
Refer to Appendix 4: Direct laboratory notification of communicable diseases flowcharts for the direct laboratory notification process for Creutzfeldt-Jakob Disease and other spongiform encephalopathies.
Testing may be carried out for the following reasons.
Health practitioners should notify:
Notification to the New Zealand Creutzfeldt-Jakob Disease Surveillance Registry (external link) requires completion of a questionnaire to allow case classification and assessment of risk factors for transmissible disease.
Laboratory confirmation for CJD requires detection of any of the following.
Refer to Laboratory criteria and case classifications for confirmed and probable case definitions.
| Test | Sample | Timing of sample collection |
| RT-QulC or 14-3-3 assays |
|
On clinical presentation |
Testing is performed by the Florey Institute in Melbourne, Australia which supports diagnostic services for Aotearoa New Zealand.
Real-Time Quaking-Induced Conversion (RT-QuIC) is a highly sensitive and specific assay used to detect abnormal prion proteins in cerebrospinal fluid. It works by amplifying misfolded prion proteins through a shaking-induced reaction, allowing for early and accurate detection. A positive result supports diagnosis of prion disease in individual with compatible clinical symptoms. RT-QuIC is now considered the most reliable non-invasive test for ante-mortem diagnosis of sporadic CJD.
14-3-3 protein in cerebrospinal fluid is a marker for acute neuronal injury. Elevated levels support diagnosis of CJD in individuals with compatible clinical illness and neurological findings. 14-3-3 protein testing is still used but has lower specificity and may yield false positives in other neurological condition.
Prion protein (PrP) detection in brain tissue confirms post-mortem detection of misfolded PrP is the gold standard for definitive diagnosis. Detection of PrP in brain tissue remains essential for surveillance classification as definite CJD.
‘Suspected CJD’ is notifiable, and attending medical practitioners must immediately report suspected cases directly to the New Zealand CJD register (external link), at cjd.registry@otago.ac.nz, at the Department of Medicine, University of Otago, Dunedin School of Medicine.
Notification to the CJD register requires completion of a questionnaire to allow case classification and assessment of risk factors for transmissible disease.
Medical practitioners must also inform their local medical officer of health. Any cases suspected of being iatrogenic or variant CJD must also be notified to the director of public health.
See Appendix 5: Escalation pathways for more information
There is no reason to defer, deny or in any way discourage the admission of a person with CJD into any health care setting. Based on current knowledge, isolation of patients is not necessary; they can be nursed in the open ward system using standard precautions. Private room nursing care is not required for infection control, but may be appropriate for compassionate reasons.
In regard to invasive medical interventions, people with confirmed or suspected CJD are the highest-risk patients. They must be managed according to infection control policies using specific precautions (see documents referred to in ‘other control measures (external link)’, below). Cases must not donate blood or organs.
Supportive.
Provided by the clinician or by a psychologist. Referral to the Genetic Health Service may be made to counsel regarding familial risk.
For infection control purposes, individuals with confirmed or suspected CJD are the highest-risk patients. Intermediate precautionary measures and counselling are also important for people who are identified as having been exposed to CJD or as being at risk of CJD (for example, have a family history).
| Symptomatic cases | As per case classification. |
| Asymptomatic individuals at risk from familial forms of CJD linked to genetic mutations |
Individuals who have been shown by specific genetic testing to be at significant risk of developing CJD or other prion disease. Individuals who have a blood relative known to have a genetic mutation indicative of familial CJD. Individuals who currently have, or have had two or more blood relatives affected by CJD or other prion disease. |
| Asymptomatic individuals identified as potentially at risk due to iatrogenic exposures |
Recipients of hormone derived from human pituitary glands, for example, growth hormone, gonadotrophin. (In New Zealand, the human pituitary hormone programme ceased in 1985.) Individuals who have received a graft of dura mater. (In October 1988 the New Zealand Department of Health, now Ministry of Health, recommended that commercially produced dura mater not be used.) Cases who have been contacted as potentially at risk, including individuals considered to be:
|
Source: Adapted from UK Advisory Committee on Dangerous Pathogens (ACDP) 2007.
Note:
Individuals at risk of disease must not donate blood or organs. They must notify their health care providers of their risk of developing prion disease as this has implications for lumbar puncture, endoscopy and surgical procedures and for transport and laboratory processing of samples.
The donation of heart valves and skin is not permitted if a person has visited or lived in the United Kingdom (England, Scotland, Isle of Man and the Channel Islands), Republic of Ireland (Eire) or France between 01 January 1980 and 31 December 1996 for more than six months. Donation of other organs, and blood is allowed.
The CJD registry and local medical officers of health will liaise regarding any potential case clusters.
Comprehensive advice on case care, occupational exposure, laboratory safety, decontamination of instruments and surfaces, waste disposal and post-mortem care can be found in control guidance documents published by both the Australian Department of Health and Ageing and the United Kingdom’s Department of Health. These documents are the basis of New Zealand’s national policy approach recommended by the Ministry of Health. They can be located at the following websites.
[1] For description see Alison Green. ‘RT-QuIC: a new test for sporadic CJD (external link).’ Practical Neurology, Volume 19 (2019), pp.49-55.