Perceived Risk of Bovine Spongiform Encephalopathy and Dietary Behavior

The German BSE crisis in early 2001 can be considered as a natural experiment with strong behavioral consequences. The present study investigated psychological and other factors associated with reduced meat consumption compared to the first months of the previous year. As expected, all types of meat, with the exception of poultry and game, were eaten less often. The effect was strongest in beef, where almost half of the sample reported reduced meat consumption. As predicted by the health belief model, perceived threat was associated with subjective vulnerability. It was not, however, strongly associated with perceived seriousness of BSE, probably due to the ubiquitous public discussion of the topic. Reduced beef consumption has three to four times more frequent in the event of subjective threat.

The risk of transmitting prion disease by blood or plasma products

Various experimental studies have shown infectivity in blood in relation to bovine spongiform encephalitis (BSE) and variant Creutzfeldt-Jakob disease (vCJD). Human to human transmission vCJD infection has been reported via transfusion of non-leukocyte-reduced red cells and, probably, via factor VIII concentrates. A number of precautionary measures are in place but uncertainties remain, especially concerning the number of BSE-infected people in the population. Additional measures such as prion filtration need consideration.

Variant Creutzfeldt-Jakob Disease: implications for the health care system

The recognition of the first cases of variant Creutzfeldt-Jakob Disease in the United Kingdom (UK) in 1996 and the realisation that this new disease represented the human form of the cattle disease BSE has prompted a considerable investment in research, particularly in the UK, Europe and the United States (US). Much has been learnt about this disease but much is still unknown. Infectivity is not destroyed by conventional sterilisation and disinfection treatment methods. This, combined with the widespread distribution throughout the lymphoid system as well as the central nervous system, raises the spectre of transmission through both surgical and ophthalmological procedures. Reports in 2004 of two likely transfusion-transmitted cases of vCJD suggest the probability of infection through blood transfusion and tissue transplantation. The risk of hospital-based and community-based transmission has not been quantified. To complicate matters even further, there is no suitable ante-mortem screening test or effective treatment for this fatal disease. The incubation period prior to onset of clinical disease is many years and there is good evidence for the existence of subclinical infection and infectivity during this stage. The extent of under-diagnosis and misdiagnosis is probably significant, adding to the risk of human-to-human transmission.

Variant CJD: the present position and future possibilities

Variant Creutzfeldt-Jakob disease (CJD) is one of the transmissible spongiform encephalopathies (TSEs), or prion diseases, and is thought to be due to transmission of BSE from cattle to man via diet. These are characterized by the tissue deposition of an abnormal isoform of the normal cellular prion protein, a progressive, fatal neurological course and having the potential for infectivity. Infectivity is difficult to inactivate, and instances of iatrogenic CJD have been reported. The involvement of the tonsil, appendix and other lymphoid tissue in variant CJD has increased concerns about possible human-to-human spread.

Diagnostic challenges in Creutzfeldt-Jakob disease: case report

Sporadic Creutzfeldt-Jakob disease (CJD) is the most common prion disease. The diagnosis can be confirmed only by histological examination of brain tissue obtained at biopsy or at autopsy. Because of the transmissible nature of the disease, autopsy or brain biopsy cannot be performed at many institutions, which poses numerous challenges in confirming the diagnosis. We report the case of a patient with CJD in which autopsy to confirm the diagnosis was performed after overcoming numerous obstacles and advocating with hospital leadership. This case illustrates the numerous challenges that exist in achieving a definitive diagnosis of CJD and in postmortem disposition of the body, and we provide recommendations to clinicians who face similar challenges.

Clinical features of variant Creutzfeldt-Jakob disease

Since 1996, over one hundred cases of variant Creutzfeldt-Jakob disease have appeared, mostly in the United Kingdom. In this review, we summarise the major clinical features of this progressive neurodegenerative condition and compare them with those of sporadic Creutzfeldt-Jakob disease. We emphasise the young age (median 26 years) at presentation and the dominant psychiatric/behavioural features, particularly depression. Sensory symptoms are present initially in half the cases and florid psychiatric symptoms, such as delusions or hallucinations, are also common. Given these symptoms, many patients present in clinical practice initially to a psychiatrist but are referred to neurologists when neurological signs become apparent. Although the definitive diagnosis remains neuropathological, a confident pre-mortem diagnosis is now possible when the 'pulvinar sign' is seen on magnetic resonance imaging studies.

Emerging viral infections

The past decade has witnessed the emergence of several significant viral pathogens and the further evolution of additional viral pathogens. Transmitted by a variety of differing routes, these organisms have presented substantial intellectual challenges to medicine of the 20th and 21st centuries. As perhaps the benchmark pathogen of the past decade, HIV has provided medicine and society with a most formidable opponent, and one that has yet to be fully conquered. Nonetheless, a variety of additional viral pathogens have also perplexed medicine over the past 10-15 years.

Universal leukocyte reduction

Leukocyte reduction of blood components, in the United States, is generally reserved for conditions in which a clinical indication has been documented. There is no evidence that either Creutzfeldt-Jakob disease or variant Creutzfeldt-Jakob disease are transmitted by transfusion in humans or that leukocyte reduction of blood components could reduce their transmission. A number of adverse outcomes following transfusion are alleged to be the result of white blood cells. At this point in time, there are insufficient clinical data to justify the universal leukocyte reduction of blood components.

[Transfusion safety: emergent or hypothetical risks]

Three categories of emerging risks are studied: 1) A new variant of Creutzfeld-Jakob disease, different from its sporadic form; limited to the British isles (48 of 51 cases), it affects younger patients, and has a higher duration with a predominance of psychiatric symptoms. Environmental risk factors include a previous stay in the British isles and oral transmission via contaminated food. No link has been made evident between blood component (BC) transfusion and occurrence of the disease. A potential risk exists if its agent is found in blood and peripheral lymphoid tissues and if buffy coat from infected animals has been inoculated intracerebrally. Since 1993, prevention measures have been taken: exclusion of donors with a potential risk as well as transfused donors, systematic leukocyte reduction and implementation of disease surveillance. Excluding donors after a several month-stay in the British Isles is being discussed. 2) Novel hepatitis viruses. Hepatitis G virus (HGV) has been detected in 2-4% of blood donors. Ten percent of patients with chronic non-A-E hepatitis are HGV RNA positive. The incidence of HGV infection is higher than expected from PCR studies. HGV has a high prevalence in the world. Novel DNA non-enveloped virus (TTV) has a normal distribution. Its prevalence varies from 2 to 80%, depending on the country. Although it has not been shown to be aggressive for the liver, prolonged follow-up is required. 3) Human herpes virus 8 (HHV8) is associated with Kaposi's sarcoma in 80% of cases. Its prevalence (0-20%) varies depending on the country. Kaposi's sarcoma has never been reported after BC transfusion. PCR-based viral DNA searches have yielded negative results in 19 poly-transfused subjects. Continuous monitoring is required for recipients at risk (e.g., immunosuppressed). In response to a possible health risk, emerging risks govern the "Precaution Principle", so difficult to implement.