European surveillance on Creutzfeldt-Jakob disease: a case-control study for medical risk factors

Sporadic Creutzfeldt-Jakob Disease among Physicians, Germany, 1993-2018

sCJD patients were significantly more likely than the general population to be physicians.

We investigated sporadic Creutzfeldt-Jakob disease (sCJD) among physicians in Germany by analyzing occupational information of patients with sCJD recorded by the German CJD Surveillance Unit (1993–2005; 1,250 patients, of whom 4 [0.32%] were physicians) and the National Reference Center for Human Spongiform Encephalopathies (2006–2016; 1,491 patients, of whom 13 [0.87%] were physicians). Among the physicians, we did not identify any neurologists, neurosurgeons, psychiatrists, or pathologists. A cumulative sum test showed an increase in reported physicians over time. Data for 2017–2018 indicated an increased rate of physicians among all notified sCJD cases (5/239 [2.1%]) when we used the total population of Germany as control group. Our data suggest the possibility of an increased risk for sCJD among physicians in Germany. However, we can only speculate about the reasons, and larger multinational studies are needed to replicate the finding and to clarify whether this finding is a general or a country-specific phenomenon.

Co-occurrence of chronic traumatic encephalopathy and prion disease

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with repetitive traumatic brain injury (TBI). CTE is generally found in athletes participating in contact sports and military personnel exposed to explosive blasts but can also affect civilians. Clinically and pathologically, CTE overlaps with post-traumatic stress disorder (PTSD), a term mostly used in a clinical context. The histopathology of CTE is defined by the deposition of hyperphosphorylated tau protein in neurons and astrocytes preferentially with perivascular distribution and at the depths of the cortical sulci. In addition to hyperphosphorylated tau, other pathologic proteins are deposited in CTE, including amyloid β (Aβ), transactive response (TAR) DNA-binding protein 43 kDa (TDP-43) and α-synuclein. However, the coexistence of prion disease in CTE has not been observed. We report three cases of histopathologically validated CTE with co-existing sporadic prion disease. Two were identified in a cohort of 55 pathologically verified cases of CTE submitted to the CTE Center of Boston University. One was identified among brain tissues submitted to the National Prion Disease Pathology Surveillance Center of Case Western Reserve University. The histopathological phenotype and properties of the abnormal, disease-related prion protein (PrPD) of the three CTE cases were examined using lesion profile, immunohistochemistry, electrophoresis and conformational tests. Subjects with sporadic Creutzfeldt-Jakob disease (sCJD) matched for age, PrP genotype and PrPD type were used as controls. The histopathology phenotype and PrPD properties of the three CTE subjects showed no significant differences from their respective sCJD controls suggesting that recurring neurotrauma or coexisting CTE pathology did not detectably impact the prion disease phenotype and PrPD conformational characteristics. Based on the reported incidence of sporadic prion disease, the detection of two cases with sCJD in the CTE Center series of 55 CTE cases by chance alone would be highly unlikely (p = 8.93*10- 6). Nevertheless, examination of a larger cohort of CTE is required to conclusively determine whether the risk of CJD is significantly increased in patients with CTE.

Prion seeding activity and infectivity in skin samples from patients with sporadic Creutzfeldt-Jakob disease

Sporadic Creutzfeldt-Jakob disease (sCJD), the most common human prion disease, is transmissible through iatrogenic routes due to abundant infectious prions [misfolded forms of the prion protein (PrP^Sc)] in the central nervous system (CNS). Some epidemiological studies have associated sCJD risk with non-CNS surgeries. We explored the potential prion seeding activity and infectivity of skin from sCJD patients. Autopsy or biopsy skin samples from 38 patients [21 sCJD, 2 variant CJD (vCJD), and 15 non-CJD] were analyzed by Western blotting and real-time quaking-induced conversion (RT-QuIC) for PrP^Sc Skin samples from two patients were further examined for prion infectivity by bioassay using two lines of humanized transgenic mice. Western blotting revealed dermal PrP^Sc in one of five deceased sCJD patients and one of two vCJD patients. However, the more sensitive RT-QuIC assay detected prion seeding activity in skin from all 23 CJD decedents but not in skin from any non-CJD control individuals (with other neurological conditions or other diseases) during blinded testing. Although sCJD patient skin contained ~10³- to 10⁵-fold lower prion seeding activity than did sCJD patient brain tissue, all 12 mice from two transgenic mouse lines inoculated with sCJD skin homogenates from two sCJD patients succumbed to prion disease within 564 days after inoculation. Our study demonstrates that the skin of sCJD patients contains both prion seeding activity and infectivity, which raises concerns about the potential for iatrogenic sCJD transmission via skin.

Risk of transmission of sporadic Creutzfeldt-Jakob disease by surgical procedures: systematic reviews and quality of evidence

Background: Sporadic Creutzfeldt–Jakob disease (sCJD) is potentially transmissible to humans. Objective: This study aimed to summarise and rate the quality of the evidence of the association between surgery and sCJD. Design and methods: Firstly, we conducted systematic reviews and meta-analyses of case–control studies with major surgical procedures as exposures under study. To assess quality of evidence, we used the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. Secondly, we conducted a systematic review of sCJD case reports after sharing neurosurgical instruments. Results: Thirteen case–control studies met the inclusion criteria for the systematic review of case–control studies. sCJD was positively associated with heart surgery, heart and vascular surgery and eye surgery, negatively associated with tonsillectomy and appendectomy, and not associated with neurosurgery or unspecified major surgery. The overall quality of evidence was rated as very low. A single case–control study with a low risk of bias found a strong association between surgery conducted more than 20 years before disease onset and sCJD. Seven cases were described as potentially transmitted by reused neurosurgical instruments. Conclusion: The association between surgery and sCJD remains uncertain. Measures currently recommended for preventing sCJD transmission should be strongly maintained. Future studies should focus on the potential association between sCJD and surgery undergone a long time previously.

Quality evaluation for the surveillance system of human prion diseases in China based on the data from 2010 to 2016

The surveillance of CJD or human prion diseases (PrDs) has been conducted for 10 y in China. To evaluate the quality of China CJD surveillance system, the collections of the clinical and epidemiological information, the sampling, the clinical examinations and laboratory tests and follow-up survey were separately analyzed based on the data from 2010 to 2015. The obtaining rates of clinical-information table, epidemiological-information table, sample inspection sheet and medical record of the referring patients from reporting units to the center of CJD surveillance maintained or reached at very high levels, being close to 100% in the past 3 y. 93.82%, 85.23%, 96.21% and 94.70% of the reported cases had the data of MRI, EEG, CSF 14-3-3 and PRNP sequencing, respectively. Follow-up surveys were conducted in about 50% cases in 2010 and 2011, 93.39% cases in 2012 and 100% cases in the last 3 y. High obtaining rates of the clinical and epidemiological data, high conducting rates of the relevant clinical examinations and laboratory tests, high performing rates of follow-up survey for every referring case reflect a good implemental capacity in China CJD surveillance system, which supplies solid basis for recognition and diagnosis of human prion diseases and guarantees good quality of China CJD surveillance system.

Prions: Beyond a Single Protein

Since the term protein was first coined in 1838 and protein was discovered to be the essential component of fibrin and albumin, all cellular proteins were presumed to play beneficial roles in plants and mammals. However, in 1967, Griffith proposed that proteins could be infectious pathogens and postulated their involvement in scrapie, a universally fatal transmissible spongiform encephalopathy in goats and sheep. Nevertheless, this novel hypothesis had not been evidenced until 1982, when Prusiner and coworkers purified infectious particles from scrapie-infected hamster brains and demonstrated that they consisted of a specific protein that he called a "prion." Unprecedentedly, the infectious prion pathogen is actually derived from its endogenous cellular form in the central nervous system. Unlike other infectious agents, such as bacteria, viruses, and fungi, prions do not contain genetic materials such as DNA or RNA. The unique traits and genetic information of prions are believed to be encoded within the conformational structure and posttranslational modifications of the proteins. Remarkably, prion-like behavior has been recently observed in other cellular proteins-not only in pathogenic roles but also serving physiological functions. The significance of these fascinating developments in prion biology is far beyond the scope of a single cellular protein and its related disease.

Clinical update of Jakob-Creutzfeldt disease

PURPOSE OF REVIEW

The present review discusses recent clinical data on diagnosis, new forms, and treatment of human prion diseases, and briefly summarizes research suggesting prion-like mechanisms in other neurodegenerative diseases.

RECENT FINDINGS

When proper sequences are performed, MRI has high diagnostic utility in prion disease, but there are issues with interpretation of images. The spectrum of MRI's utility for diagnosis and understanding human prion disease is still being explored. Two recent diffusion tensor imaging studies quantified changes in the gray and white matter in sporadic Jakob-Creutzfeldt disease, with unexpected results. The diagnostic utility of cerebrospinal fluid biomarkers has been controversial. A few studies showed that amplification methods can detect prions in either cerebrospinal fluid, olfactory epithelium, blood and/or urine in various human prion diseases. Additional cases of variably protease-sensitive prionopathy have led to a broader understanding of this novel sporadic prion disease. A few new mutations causing genetic prion disease, one with a very atypical presentation, have been identified. Although recent human prion disease treatment trials did not show benefit, they have improved our understanding, and led to better quantification, of the progression of these disorders. Lastly, we briefly summarize the increasing evidence that many nonprion neurodegenerative proteinopathies might spread in the brain by a prion-like mechanism.

SUMMARY

New prion detection methods appear promising, but need to be replicated with larger sample sizes. Identification of novel forms of human prion disease might better elucidate the full spectrum of prion diseases and expand our understanding of their pathogenesis.

Is Surgery a Risk Factor for Creutzfeldt-Jakob Disease? Outcome Variation by Control Choice and Exposure Assessments

Objective.

To determine whether methodological differences explain divergent results in case-control studies examining surgery as a risk factor for Creutzfeldt-Jakob disease (CJD).

Methods.

After case-control studies were systematically identified using PubMed, we performed a homogeneity analysis and applied models to effect sizes (odds ratio [OR] with 95% confidence interval [CI]) using 2 parameters: type of control subject used and consistency of data ascertainment. The hospitals and communities were located in Europe, Japan, and Australia. Patients were CJD case subjects and age- and sex-matched control subjects in the hospital or community. Because of the natural history of the disease, CJD subjects are not considered reliable sources of information for these studies. Therefore, individuals who are considered close to the subjects and who have knowledge of their medical history, including spouses and relatives, are necessarily identified as proxy informants for the surgical record of the case subjects.

Results.

Overall, the effect sizes lacked homogeneity (P<.0001). Three studies that used control subjects from the community revealed a significantly elevated risk of CJD for patients who underwent surgery (OR, 1.82; 95% CI, 1.41-2.35 [P<.0001 ]), whereas 3 investigations that used control subjects from the hospital revealed a significantly reduced risk (OR, 0.69; 95% CI, 0.52-0.90 [P = .0069]). Two studies that used proxy informants to acquire information about case subjects and control subjects (consistent ascertainment) found that the risk of CJD was significantly lower in those subjects who underwent surgery (OR, 0.65; 95% CI, 0.48-0.87 [P = .0043]). Conversely, 4 studies in which proxy informants acted only on behalf of case subjects (inconsistent data ascertainment) found a significant positive association between surgery and CJD (OR, 1.67; 95% CI, 1.32-2.12 [P<.0001 ]). Both models fit the data very well, leaving no remaining variance in effect sizes to explain.

Conclusion.

Variation in the type of control subjects used and in exposure assessment in case-control studies may partially explain conflicting data regarding the association between surgery and CJD. However, there was almost complete confounding of these 2 parameters, making interpretation more difficult. Planning of future investigations must carefully consider these design elements.

The neuropathology of traumatic brain injury

Traumatic brain injury, a leading cause of mortality and morbidity, is divided into three grades of severity: mild, moderate, and severe, based on the Glasgow Coma Scale, the loss of consciousness, and the development of post-traumatic amnesia. Although mild traumatic brain injury, including concussion and subconcussion, is by far the most common, it is also the most difficult to diagnose and the least well understood. Proper recognition, management, and treatment of acute concussion and mild traumatic brain injury are the fundamentals of an emerging clinical discipline. It is also becoming increasingly clear that some mild traumatic brain injuries have persistent, and sometimes progressive, long-term debilitating effects. Evidence indicates that a single traumatic brain injury can precipitate or accelerate multiple age-related neurodegenerations, increase the risk of developing Alzheimer's disease, Parkinson's disease, and motor neuron disease, and that repetitive mild traumatic brain injuries can provoke the development of a tauopathy, chronic traumatic encephalopathy. Clinically, chronic traumatic encephalopathy is associated with behavioral changes, executive dysfunction, memory loss, and cognitive impairments that begin insidiously and progress slowly over decades. Pathologically, chronic traumatic encephalopathy produces atrophy of the frontal and temporal lobes, thalamus, and hypothalamus, septal abnormalities, and abnormal deposits of hyperphosphorylated tau (τ) as neurofibrillary tangles and disordered neurites throughout the brain. The incidence and prevalence of chronic traumatic encephalopathy and the genetic risk factors critical to its development are currently unknown. Chronic traumatic encephalopathy frequently occurs as a sole diagnosis, but may be associated with other neurodegenerative disorders, including Alzheimer's disease, Lewy body disease, and motor neuron disease. Currently, chronic traumatic encephalopathy can be diagnosed only at autopsy; however, promising efforts to develop imaging, spinal fluid, and peripheral blood biomarkers are underway to diagnose and monitor the course of disease in living subjects.

Clinical Overlap between Jakob-Creutzfeldt Disease and Lewy Body Disease

Objective:

Sporadic Jakob-Creutzfeldt disease (sCJD) and dementia with Lewy bodies (DLB) have overlapping clinical symptoms that can lead to their misdiagnosis. We delineated the clinical overlap between sCJD and DLB, and assessed the value of magnetic resonance imaging (MRI) to differentiate between them.

Methods:

Medical records, MRI, electroencephalogram (EEG) and cerebrospinal fluid (CSF) were reviewed from 56 sCJD and 30 DLB subjects.

Results:

46% of sCJD subjects met probable DLB criteria and 40% of DLB subjects met probable CJD criteria. A greater proportion of sCJD subjects had cerebellar signs (66% vs. 10%, p<0.001), myoclonus (64% vs. 30%, p=0.002), and visual symptoms (other than hallucinations) (61% vs. 7%, p<0.001), whereas more DLB subjects had hallucinations (70% vs. 39%, p=0.007) and fluctuations (57% vs. 23%, p=0.002). Cortical and/or basal ganglia MRI diffusion weighted imaging hyperintensities consistent with sCJD were seen in 96% of sCJD subjects but in none with DLB. Logistic regression in sCJD revealed that those meeting probable DLB criteria were more likely to have occipital lobe involvement on MRI (OR 1.4, p=0.058, model p=0.022). Parietal lobe involvement on MRI was a predictor of “Other Focal Cortical signs” (OR 1.9, p=0.021). EEG and CSF assessments lacked sensitivity for sCJD as 48% of sCJD patients had a negative EEG; 67% of the 36 sCJD patents with a CSF evaluation had a negative or inconclusive 14-3-3 result. Too few DLB patients had EEG or CSF to assess their utility.

Conclusion:

Sporadic CJD and DLB have significant symptom overlap. MRI helps differentiate these diseases and is related to the signs/symptoms observed in sCJD.

The role of neuroimaging in evaluating patients affected by Creutzfeldt-Jakob disease: a systematic review of the literature

Diagnosis of Creutzfeldt-Jakob disease during life can be challenging since the huge variability of the symptoms which can be observed, especially in its early stages, may simulate other common forms of dementia. In latest years, noninvasive techniques such as magnetic resonance, positron emission tomography, and single-photon emission tomography have been evaluated to help clinical neurologists to provide a definite diagnosis. We here provide a systematic review of the current knowledge of neuroimaging in CJD in order to establish the actual state of the art.

Ocular Tonometry and Sporadic Creutzfeldt - Jakob Disease (sCJD): A Confirmatory Case-Control Study

AIMS

To evaluate the hypothesis that sporadic Creutzfeldt-Jakob disease (sCJD) may be transmitted through ocular tonometry.

BACKGROUND

The infectious agent of sCJD may be present in the cornea prior to clinical symptoms. Cornea infectiousness has been documented by cornea transplants in guinea pigs and humans. sCJD is resistant to complete inactivity by conventional sterilization techniques. Thus contact tonometry equipment is not disinfected sufficiently to kill sCJD. We previously hypothesized that contact tonometry is a sCJD risk factor.

STUDY DESIGN

Population-based case-control study.

PLACE AND DURATION OF STUDY

Department of Neurology, School of Medicine, Loma Linda University, Loma Linda, CA, USA; 4 years.

METHODOLOGY

An 11-state case-control study of pathologically confirmed definite sCJD cases, individually matched controls, and a sample of control surrogates was conducted. Ocular tonometry histories were obtained from case-surrogates, controls, and a sample of control-surrogates.

RESULTS

The odds ratio (OR) for ever vs never having had an ocular tonometry test was statistically significant for matched and unmatched analyses for 15 through 3 years prior to disease onset, using both control self-responses and control surrogates: ORs were ∞ and 19.4 with 1-sided P-values <0.0001 and 0.003 and ORs=∞ and 11.1 with 1-sided P-values <0.003 and 0.02, respectively. ORs increased as the number of tonometry tests increased during this age period: trend test, 2-sided P-value < 0.0001. For ≥5 vs <5 tonometry tests, the OR was 5.8 (unmatched) and 3.7 (matched), 2-sided P-value<0.00005. Respondents generally could not specify the type of tonometry. There was no indication of increased tonometry testing among cases within 2 years of disease onset.

CONCLUSIONS

The a priori hypothesis was supported. Contact tonometry, preferred by ophthalmologists, may be capable of transmitting sCJD. Consideration should be given to using disposable instrument covers after each use. The use the disposable covers or non-contact tonometry is preferable in the absence of effective disinfectant processes at this time.

Ethics in prion disease

This paper is intended to discuss some of the scientific and ethical issues that are created by increased research efforts towards earlier diagnosis, as well as to treatment of, human prion diseases (and related dementias), including the resulting consequences for individuals, their families, and society. Most patients with prion disease currently are diagnosed when they are about 2/3 of the way through their disease course (Geschwind et al., 2010a; Paterson et al., 2012b), when the disease has progressed so far that even treatments that stop the disease process would probably have little benefit. Although there are currently no treatments available for prion diseases, we and others have realized that we must diagnose patients earlier and with greater accuracy so that future treatments have hope of success. As approximately 15% of prion diseases have a autosomal dominant genetic etiology, this further adds to the complexity of ethical issues, particularly regarding when to conduct genetic testing, release of genetic results, and when or if to implement experimental therapies. Human prion diseases are both infectious and transmissible; great care is required to balance the needs of the family and individual with both public health needs and strained hospital budgets. It is essential to proactively examine and address the ethical issues involved, as well as to define and in turn provide best standards of care.

Analyses of the survival time and the influencing factors of chinese patients with prion diseases based on the surveillance data from 2008-2011

Background

Prion diseases are kinds of progressive, incurable neurodegenerative disorders. So far, survival time of the patients with these diseases in China is unclear.

Methods

Based upon the surveillance data from Chinese Creutzfeldt-Jakob disease (CJD) surveillance network from January 2008 to December 2011, a retrospective follow-up survey was performed. The survival times of Chinese patients with prion diseases and the possible influencing factors were analyzed.

Results

Median survival time of 121 deceased patients was 7.1 months, while those for sporadic CJD (sCJD), familial CJD (fCJD) and fatal familial insomnia (FFI) cases were 6.1, 3.1 and 8.2 months, respectively. 74.0% of sCJD patients, 100% of fCJD cases and 91.7% FFI cases died within one year. The general socio-demographic factors, abnormalities in clinical examinations, clinical manifestations, and social factors did not significantly influence the survival times of Chinese prion patients.

Conclusions

Survival time of Chinese patients with prion diseases was comparable with that of many Western countries, but obviously shorter than that of Japan. Patients with acute onset and rapid progression had significantly short survival times.

Impact of leucocyte depletion and prion reduction filters on TSE blood borne transmission

The identification in the UK of 4 v-CJD infected patients thought to be due to the use of transfused Red Blood Cell units prepared from blood of donors incubating v-CJD raised major concerns in transfusion medicine. The demonstration of leucocyte associated infectivity using various animal models of TSE infection led to the implementation of systematic leuco-depletion (LD) of Red Blood cells concentrates (RBCs) in a number of countries. In the same models, plasma also demonstrated a significant level of infectivity which raised questions on the impact of LD on the v-CJD transmission risk. The recent development of filters combining LD and the capture of non-leucocyte associated prion infectivity meant a comparison of the benefits of LD alone versus LD/prion-reduction filters (LD/PR) on blood-borne TSE transmission could be made. Due to the similarity of blood/plasma volumes to human transfusion medicine an experimental TSE sheep model was used to characterize the abilities of whole blood, RBCs, plasma and buffy-coat to transmit the disease through the transfusion route. The impact of a standard RBCs LD filter and of two different RBCs LD/PR prototype filters on the disease transmission was then measured. Homologous recipients transfused with whole-blood, buffy-coat and RBCs developed the disease with 100% efficiency. Conversely, plasma, when intravenously administered resulted in an inconstant infection of the recipients and no disease transmission was observed in sheep that received cryo-precipitated fraction or supernatant obtained from infectious plasma. Despite their high efficacy, LD and LD/PR filtration of the Red Blood Cells concentrate did not provide absolute protection from infection. These results support the view that leuco-depletion strongly mitigates the v-CJD blood borne transmission risk and provide information about the relative benefits of prion reduction filters.

Sensitivity to biases of case-control studies on medical procedures, particularly surgery and blood transfusion, and risk of Creutzfeldt-Jakob disease

BACKGROUND

Evidence of risk of Creutzfeldt-Jakob disease (CJD) associated with medical procedures, including surgery and blood transfusion, is limited by susceptibility to bias in epidemiological studies.

METHODS

Sensitivity to bias was explored using a central-birth-cohort model using data from 18 case-control studies obtained after a review of 494 reports on medical procedures and risk of CJD, systematic for the period January 1, 1989 to December 31, 2011.

RESULTS

The validity of the findings in these studies may have been undermined by: recall; control selection; exposure assessment in life-time periods of different duration, out of time-at-risk of effect, or asymmetry in case/control data; and confounding by concomitant blood transfusion at the time of surgery. For sporadic CJD (sCJD), a history of surgery or blood transfusion was associated with risk in some, but not all, recent studies at a ≥10 year lag time, when controls were longitudinally sampled. Space-time aggregation of surgical events was not seen. Surgery at early clinical onset might be overrepresented among cases. Neither surgical history nor blood transfusion unlabelled for donor status, dental treatments or endoscopic examinations were linked to variant CJD (vCJD).

CONCLUSIONS

These results indicate the need for further research. Common challenges within these studies include access to and content of past medical/dental treatment records for diseases with long incubation periods.

Nosocomial transmission of sporadic Creutzfeldt-Jakob disease: results from a risk-based assessment of surgical interventions

OBJECTIVES

Evidence of surgical transmission of sporadic Creutzfeldt-Jakob disease (sCJD) remains debatable in part due to misclassification of exposure levels. In a registry-based case-control study, the authors applied a risk-based classification of surgical interventions to determine the association between a history of surgery and sCJD.

DESIGN

Case-control study, allowing for detailed analysis according to time since exposure.

SETTING

National populations of Denmark and Sweden.

PARTICIPANTS

From national registries of Denmark and Sweden, the authors included 167 definite and probable sCJD cases with onset during the period 1987-2003, 835 age-, sex- and residence-matched controls and 2224 unmatched. Surgical procedures were categorised by anatomical structure and presumed risk of transmission level. The authors used logistic regression to determine the odds ratio (OR) for sCJD by surgical interventions in specified time-windows before disease-onset.

RESULTS

From comparisons with matched controls, procedures involving retina and optic nerve were associated with an increased risk at a latency of ≥1 year OR (95% CI) 5.53 (1.08 to 28.0). At latencies of 10 to 19 years, interventions on peripheral nerves 4.41 (1.17 to 16.6) and skeletal muscle 1.58 (1.01 to 2.48) were directly associated. Interventions on blood vessels 4.54 (1.01 to 20.0), peritoneum 2.38 (1.14 to 4.96) and skeletal muscle 2.04 (1.06 to 3.92), interventions conducted by vaginal approach 2.26 (1.14 to 4.47) and a pooled category of lower-risk procedures 2.81 (1.62 to 4.88) had an increased risk after ≥20 years. Similar results were found when comparing with unmatched controls.

INTERPRETATION

This observation is in concordance with animal models of prion neuroinvasion and is likely to represent a causal relation of surgery with a non-negligible proportion of sCJD cases.

The risk of iatrogenic Creutzfeldt-Jakob disease through medical and surgical procedures

There have been more than 400 patients who contracted Creutzfeldt-Jakob disease (CJD) via a medical procedure, that is, through the use of neurosurgical instruments, intracerebral electroencephalographic electrodes (EEG), human pituitary hormone, dura mater grafts, corneal transplant, and blood transfusion. The number of new patients with iatrogenic CJD has decreased; however, cases of variant CJD that was transmitted via blood transfusion have been reported since 2004. Clearly, iatrogenic transmission of CJD remains a serious problem. Recently, we investigated medical procedures (any surgery, neurosurgery, ophthalmic surgery, and blood transfusion) performed on patients registered by the CJD Surveillance Committee in Japan during a recent 9-year period. In a case-control study comprising 753 sporadic CJD (sCJD) patients and 210 control subjects, we found no evidence that prion disease was transmitted via the investigated medical procedures before onset of sCJD. In a review of previously reported case-control studies, blood transfusion was never shown to be a significant risk factor for CJD; our study yielded the same result. Some case-control studies reported that surgery was a significant risk factor for sCJD. However, when surgical procedures were categorized by type of surgery, the results were conflicting, which suggests that there is little possibility of prion transmission via surgical procedures. In our study, 4.5% of sCJD patients underwent surgery after onset of sCJD, including neurosurgeries in 0.8% and ophthalmic surgeries in 1.9%. The fact that some patients underwent surgery, including neurosurgery, even after the onset of sCJD indicates that we cannot exclude the possibility of prion transmission via medical procedures. We must remain vigilant against prion diseases to reduce the risk of iatrogenesis.

Medical procedures and risk for sporadic Creutzfeldt-Jakob disease, Japan, 1999-2008

Surgery or blood transfusion had little effect on the incidence of sCJD.

To elucidate the association between medical procedures and sporadic Creutzfeldt-Jakob disease (sCJD), we analyzed medical procedures (any surgical procedure, neurosurgery, ophthalmic surgery, and blood transfusion) for patients registered by the CJD Surveillance Committee in Japan during 1999–2008. We conducted an age-stratified case–control study with 753 sCJD patients and 210 controls and a study of patients who underwent neurosurgical or ophthalmic surgical procedures at the same hospital. Although the control group was relatively small, no evidence was found that prion disease was transmitted through the investigated medical procedures before onset of sCJD. After onset of sCJD, 4.5% of the sCJD patients underwent operations, including neurosurgical for 0.8% and ophthalmic for 1.9%; no special precautions against transmission of prion diseases were taken. Fortunately, we have not identified patients with prion disease attributed to these operations. Our findings indicate that surgical procedures or blood transfusion had little effect on the incidence of sCJD.

A case-control study of sporadic Creutzfeldt-Jakob disease in Switzerland: analysis of potential risk factors with regard to an increased CJD incidence in the years 2001-2004

Background

In 2001, the observed annual mortality from Creutzfeldt-Jakob disease (CJD) in Switzerland increased from less than 1.5 to 2.6 per million inhabitants. An underlying cause could not be identified.

Methods

To analyse potential risk factors for sCJD in Switzerland, close relatives of 69 sCJD-patients and 224 frequency age-matched controls were interviewed in a case-control study using a standardised questionnaire. 135 potential risk factors including socio-demographics, medical history, occupation and diet were analysed by logistic regression adjusting for age, sex and education.

Results

sCJD patients were more likely to have travelled abroad, worked at an animal laboratory, undergone invasive dental treatment, orthopaedic surgery, ophthalmologic surgery after 1980, regular GP visits, taken medication regularly, and consumed kidney. No differences between patients and controls were found for residency, family history, and exposure to environmental and other dietary factors.

Conclusion

Although some factors were significantly more frequent among sCJD-cases, this study did not reveal specific explanations for the increased incidence of deaths due to sporadic CJD observed in Switzerland since 2001. Results have to be interpreted with caution due to multiple testing and possible recall bias in association with a long incubation period. The most plausible reason for the increase in Swiss sCJD cases after 2000 is an improved case ascertainment. Therefore, underreporting of cases might well have occurred before the year 2001, and the "real" yearly incidence of sCJD might not be lower than, but rather above 2 per million inhabitants.

Surgery and risk of sporadic Creutzfeldt-Jakob disease in Denmark and Sweden: registry-based case-control studies

BACKGROUND

Epidemiologic evidence of surgical transmission of sporadic Creutzfeldt-Jakob disease (sCJD) remains controversial.

METHODS

From Danish and Swedish registries we selected 167 definite and probable sCJD cases (with onset between 1987 and 2003) and 3,059 controls (835 age-, sex-, and residence-matched, and 2,224 unmatched). Independent of case/control status, surgical histories were obtained from National Hospital Discharge Registries. Surgical procedures were categorized by body system group and lag time to onset of sCJD. Exposure frequencies were compared using logistic regression.

RESULTS

A history of any major surgery, conducted >/=20 years before sCJD onset, was more common in cases than both matched (OR = 2.44, 95% CI = 1.46-4.07) and unmatched controls (OR = 2.25, 95% CI = 1.48-3.44). This observation was corroborated by a linear increase in risk per surgical discharge (OR = 1.57, 95% CI = 1.13-2.18; OR = 1.50, 95% CI = 1.18-1.91). Surgery of various body systems, including peripheral vessels, digestive system and spleen, and female genital organs, was significantly associated with increased sCJD risk.

CONCLUSIONS

A variety of major surgical procedures constitute a risk factor for sCJD following an incubation period of many years. A considerable number of sCJD cases may originate from health care-related accidental transmission.

Risk factors for sporadic Creutzfeldt-Jakob disease

OBJECTIVE

Although surgical transmission of Creutzfeldt-Jakob disease (CJD) has been demonstrated, these iatrogenic cases account for only a small proportion of all CJD cases. The majority are sporadic CJD (sCJD) cases of unknown cause. This study investigated whether some cases classified as sCJD might have an unrecognized iatrogenic basis through surgical or other medical procedures

METHODS

This study compared medical risk factors from 431 sCJD cases referred 1998 to 2006 with 454 population control subjects. Possible geographic and temporal links between neurological and gynecological operations in 857 sCJD cases referred from 1990 to 2006 were investigated

RESULTS

A reported history of ever having undergone surgery was associated with increased risk for sCJD (odds ratio, 2.0; 95% confidence interval, 1.3-2.1; p = 0.003). Increased risk was not associated with surgical categories chosen a priori but was confined to the residual category "other surgery," in which the increase in risk appeared most marked for three subcategories: skin stitches, nose/throat operations, and removal of growths/cysts/moles. No convincing evidence was found of links (same hospital, within 2 years) between cases undergoing neurosurgery or gynecological surgery

INTERPRETATION

It is unlikely that a high proportion of UK sCJD cases are the result of transmission during surgery, but we cannot exclude the possibility that such transmission occurs occasionally. A study based on accurate surgical histories obtained from medical records is required to determine whether the increased risk associated with reported surgical history reflects a causal association or recall bias.

Tonometer disinfection practice in the United Kingdom: A national survey

PURPOSE

To assess current tonometer disinfection practice in the UK, and compare with published recommendations.

METHODS

Every ophthalmology unit with training recognition in the UK was contacted (n=155). A senior nurse at each institution completed a telephone questionnaire regarding local tonometer disinfection practice.

RESULTS

The response rate was 100%. Thirty-five units (23%) reported exclusive use of disposable tonometer heads and were excluded from further analysis. One hundred and twenty units (77%) used either reusable or a combination of reusable and disposable tonometer heads. Where reusable heads were used, 80 units (67%) immersed them in a chlorine-based solution such as sodium hypochlorite or sodium dichloroisocyanurate. Others used isopropyl alcohol (18 units), hydrogen peroxide (12 units), chloramine (5 units), chlorhexidine (4 units) and peracetic acid (1 unit). Where a chlorine-based agent was used, the concentration of available chlorine ranged from 125 to 30 000 p.p.m., with 50 units (63%) using a concentration of less than 5 000 p.p.m. (i.e., inadequate based on published recommendations). Where the tonometer head was immersed in disinfectant between patients (n=101), 29 units (29%) provided just one tonometer head per practitioner, making adequate soak time between patients unlikely. Every unit replenished the disinfectant at least daily, deemed sufficient for most agents. However, hydrogen peroxide solutions should be replenished twice daily, which did not take place in nine units.

CONCLUSION

This survey reveals disparity between current tonometer disinfection practice and published international recommendations, with some institutions using practices that may render patients susceptible to transmissible infection.

Blood transfusion and spread of variant Creutzfeldt-Jakob disease

The effect of reducing vCJD transmission by excluding potential blood donors who have received a blood transfusion can be quantified and depends on the absolute number of cases observed or expected.

Variant Creutzfeldt-Jakob disease (vCJD) may be transmissible by blood. To prevent secondary transmission through blood components, several countries have started to exclude as donors persons who have received a blood transfusion. We investigated the effectiveness of this measure by using a dynamic age-structured model. It is the first such model based on epidemiologic data: 1) blood donor activities, 2) a case-control study on CJD, 3) age distribution of recipients, and 4) death of recipients of blood transfusions. The model predicts that an infection like vCJD, which has been introduced into the population by the alimentary route, could not become endemic by transfusion alone and that <1% of cases would be avoided by excluding from blood donation those persons who have received a transfusion.

Classification of surgical procedures for epidemiologic assessment of sporadic Creutzfeldt-Jakob disease transmission by surgery

BACKGROUND

In this preparatory phase of a case-control study, we propose and evaluate a new tool for classifying surgical procedures (SPs) in categories useful for epidemiologic research on surgical transmission of sporadic Creutzfeldt-Jakob disease (sCJD).

METHODS

All SPs reported to the Swedish National Hospital Discharge Registry in the period 1974-2002, and undergone by 212 Swedish patients with registered diagnosis of CJD at death, hospital discharge or notification, in the period 1987-2002, 1060 age-, sex- and residence-matched controls and 1340 randomly chosen population controls, were reclassified into one of six categories of hypothetical transmission risk level. For that purpose the following two attributes were used: non-disposable instruments involved; and highest assigned ad-hoc risk level for four tissues or anatomical structures contacting such instruments.

RESULTS

A total of 1170 different SP codes were reclassified as follows: 3.1% in the high-risk, 59.1% in the lower-risk, 24.4% in the lowest-risk, and 2.1% in the no-risk groups, with 11.3% procedures negatively defined by rubric as "other than..." being assigned to two spurious diluted-high and diluted-lower risk categories. The high-risk group mainly comprised neurosurgical (53%) and ophthalmic (39%) procedures. Sensitivity of neurosurgery and of ophthalmic surgery excluding neurosurgery, for the high- and diluted-high risk vs. other categories was 46% and 84%, while specificity was 98% and 95%, respectively. Sensitivity analysis based on these indices revealed that non-significant odds ratio effects of 1.4 and 1.3 for neurosurgery and ophthalmic surgery corresponded to statistically significant values of 5.1 after reclassification.

CONCLUSIONS

This classification might contribute to quantify effects masked by use of body-system SP-categories in case-control studies on sCJD transmission by surgery.

Tissue Safety in View of CJD and Variant CJD

Epidemiological studies on human transmissible spongiform encephalopathies (Creutzfeldt-Jakob Disease, CJD) have shown that the agent could be transmitted by highly infectious tissues like brain, spinal cord or retina and medicinal products derived from these tissues (i.e. human growth hormone, dura mater). A few cases of transmission of CJD by neurosurgical instruments have been reported. The transmission of the agent of variant CJD, which is suspected to be transmitted by BSE-contaminated food, by blood transfusion implies that in contrast to the agent of classical CJD this agent can also be transmitted by organs and tissues other than nerve tissues. Health authorities have implemented guidelines to reduce the risk of transmission of human and animal TSE by human and veterinary medicinal products. The high resistance of TSE agents against physical or chemical treatment hamper the development of highly efficient inactivation steps in the production of medicinal products. Donor selection is considered as an efficient measure to reduce the risk of TSE transmission. However, the development of rapid, sensitive and specific diagnostic test systems is urgently required to test blood, organs and tissue of donors.

Tissue classification for the epidemiological assessment of surgical transmission of sporadic Creutzfeldt-Jakob disease. A proposal on hypothetical risk levels

Background

Epidemiological studies on the potential role of surgery in Creutzfeldt-Jakob Disease transmission have disclosed associations with history of specific surgical interventions or reported negative results.

Methods

Within the context of a case-control study designed to address surgical risk of sporadic Creutzfeldt-Jakob Disease in Nordic European countries (EUROSURGYCJD Project), a strategy was adopted to categorise reported surgical procedures in terms of potential risk of Creutzfeldt-Jakob Disease acquisition. We took into account elements of biological plausibility, either clinically or experimentally demonstrated, such as tissue infectivity, PrP expression content or successful route of infection.

Results

We propose a classification of exposed tissues and anatomic structures, drawn up on the basis of their specific putative role as entry site for prion transmission through contact with surgical instruments that are not fully decontaminated.

Conclusions

This classification can serve as a reference, both in our study and in further epidemiological research, for categorisation of surgical procedures in terms of risk level of Creutzfeldt-Jakob Disease acquisition.

Prion disease: possible implications for oral health care

BACKGROUND

Prion diseases are a group of rare fatal neurodegenerative disorders in humans and animals that are histopathologically characterized by spongiform change within the central nervous system.

TYPES OF STUDIES REVIEWED

The author reviewed all available case reports and any studies of the oral aspects of prion diseases published in peer-reviewed journals and available via PubMed. He then outlined the risk of nosocomial transmission of prions in dental health care.

RESULTS

Sporadic Creutzfeldt-Jakob disease, or sCJD, is the most common of the acquired human prion disorders, and it typically affects elderly people and leads to rapid death. In contrast, variant CJD, or vCJD, has affected young adults from Europe, giving rise to a slow onset disorder comprising both psychiatric and neurological upset. Oral neurological manifestations are rare and seem to occur only in people with vCJD; there are no oral mucosal or gingival manifestations of prion disease. Prions can be detected in the oral tissues--usually the gingivae and dental pulp--of animals experimentally infected with prions. In contrast, prions have not been detected in the pulpal tissue of people with sCJD, and there are no data of pulpal infection in vCJD. There also are no data suggesting that prions are transmitted easily in the dental setting, but there remains the rare risk of such transmission if appropriate infection control measures are not adhered to.

CLINICAL IMPLICATIONS

Few people in the United States and worldwide have prion disease. Oral manifestations are rare. Evidence suggests that the risk of transmission and acquisition of a prion infection as a result of dental treatment is rare, if appropriate infection control measures are maintained.

Prion (PrPres) allotypes profiling: a new perspectives from mass spectrometry

Biochemical methods employed for PrPres allotypes profiling are reviewed and compared with the latest mass spectrometric approaches. Emphasis is put on the advantages offered by a recently proposed electrospray strategy.

[The use of disposable instruments of a high performance polymer for tonsillectomy and adenoidectomy]

Cases of the new variant Creutzfeldt-Jakob disease (vCJD) in human beings have to be anticipated in Germany. In subclinical vCJD, the accumulation of prions in lymphoid tissue has been identified prior to their manifestation in cerebral tissue. The remarkable resistance of prions to standard methods of sterilisation questions the safety of reusing metallic surgical instruments. The transmission of vCJD via such reusable surgical instruments in tonsillectomies and adenoidectomies cannot be excluded. In this study, 96 tonsillectomies and adenoidectomies were performed with disposable instruments made of a high performance polymer (Aesculap, Tuttlingen). No increase in the number of intra- or postoperative complications was evident. These disposable instruments may represent an alternative to reusable metallic surgical instruments in potentially infected patients or in patients desiring the use of disposable instruments during their operation for safety reasons.

Mortality trend from sporadic Creutzfeldt-Jakob disease (CJD) in Italy, 1993-2000

The objective was to identify any possible cases of variant Creutzfeldt-Jakob disease (CJD) in Italy, and to estimate the trends in mortality from sporadic CJD for 1993-2000. CJD cases were ascertained through direct notification to the Registry; 382 definite or probable sporadic CJD patients, but no cases of variant CJD were identified. The average yearly mortality rate was 1.04 cases per million inhabitants, with an increase in deaths in the 60-69 and > or =70 year age groups. Survival was shorter in male respect to female and in patients with an age at onset > or =65 years. CJD cases were uneven distributed among different regions in the period 1993-1995, but not herein after. The rise in mortality from sporadic CJD in Italy likely reflects increased awareness and better diagnosis during the years. However, continuous notification and postmortem examination of all suspected cases are recommended for optimal surveillance.

Retention of corneal epithelial cells following Goldmann tonometry: implications for CJD risk

AIMS

To assess the adequacy of current decontamination methods for the Goldmann tonometer in the context of variant Creutzfeldt-Jakob disease (vCJD).

METHODS

Reusable Goldmann tonometer prisms were used to perform applanation tonometry on different groups of patients. Following tonometry, retained materials were collected from the tonometer prism head and examined using cytological methods. The used tonometers were subjected to a series of conditions to evaluate their effect on the residual cell numbers found on the tonometer heads. These included wiping alone and wiping or washing followed by disinfection of the tonometer prism. The effect on cell counts of drying the prism overnight was studied, as well as drying overnight and then wiping and disinfecting. All disinfections were performed with sodium hypochlorite (0.05% w/v).

RESULTS

The cytology specimens of 69 patients were studied. Patients using eye drops regularly desquamated significantly more corneal epithelial cells with Goldmann tonometry than patients not using regular eye drops. The mean number of cells was 156 (range 0-470) for patients using eye drops and 14 (4-57) for patients not using eye drops (p = 0.004). Wiping or washing the tonometer head reduced the cell number significantly but neither method completely eliminated cells. The two methods were not significantly different (p=0.3). Drying left a large number of cells (23-320 cells).

CONCLUSIONS

Retained corneal epithelial cells, following the standard decontamination routine of tonometer prisms, may represent potential prion infectivity. Manual cleaning was the most important step in reducing epithelial cell retention.

Transmissible spongiform encephalopathy update and implications for blood safety

At this time, the accumulated evidence does not support the implementation of measures targeted against the risk of transfusion transmission of sporadic, familial, or iatrogenic CJD. Evolving information about vCJD, however, suggests that policy makers need to consider implementing measures to protect against exposure to vCJD, if such measures themselves do not lead to decreased blood safety. Surveillance of human TSEs and investigation of the risk of transfusion transmission must continue in order to provide further refinements in blood safety policy.

The risk of transmission of variant Creutzfeldt–Jakob disease via contact lenses and ophthalmic devices

This review collated the available information regarding the risk of transmission of variant Creutzfeldt-Jakob disease (vCJD) via contact lenses and other ophthalmic devices. The topics examined include: the emerging background science of the unconventional infective agent, the prion, particularly those factors affecting transmission; the estimates of the number of undiagnosed infective individuals; and evidence of infectivity in the external eye. Despite many uncertainties in the literature, we conclude that cross-infection is theoretically possible. An assessment of the extensive search for a complete inactivation procedure resulted in the recommendation of the use of sodium hypochlorite (NaOCl), which does not appear to distort rigid lenses. Further tests are required for other devices.

Creutzfeldt-Jakob disease cluster in an Australian rural city

Through the Australian National Creutzfeldt-Jakob Disease Registry, 6 pathologically confirmed sporadic cases were recognized over a 13-year period in persons who had been long-term residents of a moderate-sized rural city, whereas the expected number was 0.923. An extensive investigation could not find any point-source or case-to-case transmission links. This occurrence is highly statistically significant (p = 0.0027) when viewed in isolation and remains significant (p < 0.02) when only the cases that arose after the cluster was recognized were taken into account. However, a more conservative statistical analysis suggests that such a grouping could have arisen by chance in at least one population group of this size when the whole country is taken into consideration.

The epidemiology of variant Creutzfeldt-Jakob disease in Europe

Variant Creutzfeldt-Jakob disease is one of a family of neurodegenerative diseases, first diagnosed in 1996. Scientific evidence strongly supports the hypothesis that it is acquired through consumption of bovine spongiform encephalopathy-infected meat. The majority of cases have been diagnosed in the UK in young individuals, with an excess of cases in the north and a significant cluster of cases in Leicestershire. Many uncertainties in its biology and epidemiology, in particular the length of the incubation period, make predictions of any future epidemic difficult. Studies are currently under way to obtain more precise estimates of the prevalence of asymptomatic infection through testing tonsil and appendix tissues for the abnormal prion protein.

Prion diseases: epidemiology in man

Prion disease in man was first described as Creutzfeldt-Jacob disease (CJD) in the 1920s. CJD may have three different origins: sporadic, familial, due to mutations in the prion gene, or infectious, due to iatrogenic exposure to infectious brain material. As an example of the latter, kuru, in Papua New Guinea, was a variant of CJD transmitted by cannibalism. Between 1957 and 1982 more than 2500 died of kuru. Sporadic CJD is the most common form of CJD and occurs with an incidence of around one per million in most parts of the world. Familial CJD accounts for approximately 10% of all European cases of CJD, and is associated with inherited mutations of the prion protein gene, caused by one of the 24 single amino acid substitutions or insertions of octapeptide repeats. CJD caused by infections involves either iatrogenic cases of CJD, resulting from exposure to infectious brain, pituitary or ocular tissue, or from ingestion of infected food items. As of today, a few hundred iatrogenic cases of CJD have been diagnosed worldwide, the majority due to transmission by cadaveric pituitary HCG. So far, 111 cases of vCJD have been diagnosed caused by BSE-contaminated food. The size of the epidemic is still unclear and worst-case scenarios indicate that we may expect many thousands of cases in the future.