Prion diseases are not infectious in the usual way. For example, they are not spread by airborne droplets like colds and flu, or by sexual contact like HIV.
The evidence suggests there is no risk of developing CJD from ordinary (even intimate) contact with someone with the condition. No special precautions are required. However, it is sensible for anyone who might be exposed to the blood of a CJD patient (usually medical staff) to wear gloves, as is routine in the management of any illness..
There are four types of CJD - sporadic, genetic (inherited), iatrogenic and variant. The accuracy of a clinical diagnosis varies depending on the form of the disease. However, in most cases, a very reliable clinical diagnosis is possible. An absolutely definite diagnosis is generally only possible after death when a post mortem has been performed.
A clinical diagnosis rests on the presence of typical symptoms and signs, the exclusion (by tests) of other possible illnesses and may be supported by certain specific test results.
In genetic CJD, testing for the genetic mutation can be undertaken (usually on a blood sample).
Iatrogenic CJD is diagnosed on the basis of symptoms developing in someone with a relevant past exposure, for example, in those given human growth hormone.
In sporadic CJD, the EEG (electroencephalogram), CSF (cerebrospinal fluid) tests and MR (Magnetic Resonance) brain imaging are often very helpful.
The diagnosis of variant CJD may be very difficult, but MR brain scanning, a prion protein blood test and tonsil biopsy may be helpful.
There is no current evidence that there is a significant risk of blood transfusion transmission of forms of CJD other than variant CJD.
As of October 2015, there have been 4 instances of probable transfusion transmitted vCJD infection. In 3 of these, the recipients developed vCJD between around 5 and 8 years following transfusion of red blood cells from donors who went on to develop vCJD (but who were not clinically ill at the time iof donating). In the remaining case, the recipient died of another disease but was found to have subclinical (asymptomatic) infection with vCJD.
All these implicated transfusions took place between 1996 and 1999 with no further transfusion-related incidents having been identified as of October 2015. These transfusions were all of ‘non-leucodepleted’ blood. Leucodepletion (reduction of white blood cell content in donations) was instituted as a universal blood transfusion measure in the UK in 1999. It is believed that leucodepletion reduces the risk of vCJD transfusion-transmission.
There has been one single reported case of probable transmission of vCJD infection via a blood product. Blood products are treatments derived from blood and, in this instance, it concerned a product called ‘Factor VIII’ used to treat haemophilia (a blood clotting disorder).
People who have received a blood transfusion since 1980 are not now allowed to donate blood as a further precautionary measure against the possible risk of vCJD being transmitted by blood and blood products
The risk of contracting vCJD from blood transfusion or treatment with blood products cannot be dismissed but it appears to very low. Various protective measures are in place (such as universal leucodepletion) and the situation is being carefully monitored by a collaborative study between the Blood Transfusion Services and the National CJD Research and Surveillance Unit. As of October 2015, there is no routine blood test in use that enables donations to be screened for vCJD infection. It should be emphasised that blood transfusions may be very important or even life-saving treatments in certain clinical situations.
For further blood information, there is a question and answer article, written by the National Blood Service, in issue 13 of the CJD Support Network newsletter. See the newsletter downloads.
The risk of contracting CJD from organ transplants is uncertain. A woman later shown to have been suffering from sporadic CJD did recently provide material for three eye operations. Unfortunately, a transplant usually has to be done before a full post mortem has taken place, so this risk cannot be completely eliminated. In the vast majority of cases, the benefit of having the transplant far outweighs the risk of contracting CJD from a donor. There is no proven case of transmission of CJD via organ transplant surgery since…
Neurological examination and electroencephalogram (EEG) testing of people in the later stages of CJD indicate that they lose awareness of their condition as the disease progresses. Obviously this saves them - but not their families - much mental suffering.
In the early stages, however, patients with CJD can develop anxiety, agitation and fear, which can be very distressing; sometimes this is associated with visual hallucinations.
Post mortem examination is not compulsory when CJD is suspected - the doctor will need the permission of the next of kin. In some specific instances, the matter may be referred to the coroner (in England & Wales) or the Procurator Fiscal (in Scotland).
It often helps the family if they can have an absolutely definite cause of death, which at present is only possible after post mortem. The findings may also help research into the disease.
In the UK, all cases of suspected CJD are reported to the National CJD Surveillance Unit in Edinburgh and to the National Prion Clinic in London. The number of cases of sporadic CJD in the UK has increased since 1970, when organised records were begun. In 1970-71 there were 21 deaths from sporadic CJD and in 2002 there were 67 deaths from sporadic CJD. Most of the increase has occurred since 1990 and in the over 70 age group.
There has been a similar increase in numbers in other countries where CJD surveillance is undertaken; it is not specific to the UK.
At least some of this increase is due to greater awareness of CJD among the medical profession and the availability of better diagnostic tests but some might represent a genuine increase in the incidence of the disease.
As of October 2015 there are no known living vCJD patients in the world, a total of 177 reported UK cases, with no reports of definite or probable cases in the UK since 2013.
It is widely accepted that vCJD originated from dietary contamination with infected material from BSE (Bovine Spongiform Encephalopathy) affected cattle. It is notable that, in the UK, no-one born after 1989 has so far ben diagnosed with vCJD; specific measures were put into action in 1989 to protect human diet.
There are good reasons for believing that the incubation period for dietary-related vCJD could be very long and certain genetic factors can influence this. Therefore, the possibility of further cases cannot be excluded, although analysis suggests that, if there are further cases, the number will be relatively small.
In the majority of cases, theses two illnesses look very different and there should be no confusion. There is clinical similarity between some cases of CJD and some cases of Alzheimer’s Disease but careful clinical assessment and investigations (such as brain MR imaging and CSF tests) generally allow accurate differentiation of these illnesses.
At present there is no way of protecting people from the sporadic or familial forms of CJD. Iatrogenic CJD is guarded against by destroying surgical instruments that have been used on people with CJD, and by not using their organs for transplant.
In relation to dietary-related variant CJD, BSE in cattle is being monitored and controlled and there are various measures to protect the human food chain from BSE contamination.
There is however remaining concern about secondary transmission of vCJD from individuals who might have subclinical (asymptomatic) BSE/vCJD infection-especially via blood transfusion. However, there are measures in place to reduce any risk and the risk appears to be very low. This is discussed in the blood section above.
Genetic forms of CJD can, of course, be inherited but this may be from either the mother or the father.
The risk of transmission of disease, as an infection, from a mother affected by CJD to a child in the womb, during delivery or via breast-feeding, appears to be extremely low, if it is a risk at all. It is, on the basis of present knowledge, just a theoretical risk with no reported instance of this in humans, despite the fact that children have been born to ill mothers (with CJD and with a related illness called Kuru).
There is no cure, at present, for CJD, although scientists are researching into the causes of and potential treatments for the disease. However, there are a number of drugs already available which can relieve symptoms and make the patient more comfortable.
Equally important are general support and care for both the person and their family. Social services should be involved at an early stage to advise on benefits, day centres, respite and long term care. Speech and occupational therapists can help with specific problems, while the district nurse may provide more general nursing care and advice.
What happens on admission to hospital varies. Much depends on the type of hospital, the patient and, of course, the views of the family. Following admission there will be an investigation and tests to establish the diagnosis and general supportive nursing care.
Specialist nurses are employed by both the National Prion Clinic and the National CJD Research & Surveillance Unit; they can give advice and support to families and other health professionals.