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Epidemiology Bulletin VIRGINIA EPIDEMIOLOGY BULLETIN Robert B. Stroube, M.D., M.P.H., Health Commissioner Christopher Novak, M.D., M.P.H., Editor Suzanne R. Jenkins, V.M.D., M.P.H., Acting State Epidemiologist Vickie L. O’Dell, Layout Editor January 2005 Volume 105, No. 1 Transmissible Spongiform Encephalopathies (TSEs) A little over one year ago, on Decem- of diseases known as transmissible ber 25, 2003, the US Department of Agri- spongiform encephalopathies (TSEs). This a b culture (USDA) confirmed the diagnosis article is part of the Virginia Department of bovine spongiform encephalopathy of Health’s efforts to improve surveillance (BSE, or “mad cow disease”) in a single for TSEs in Virginia to better understand 1 dairy cow in Washington state. As a re- the disease as well as to detect any conversion sult, the USDA expanded and intensified changes in disease patterns. its national testing program for BSE. From June 1, 2004, to January 2, 2005, 167,476 Overview of TSEs alpha-helices beta-sheets cattle were tested. Not a single positive TSEs are a group of relatively rare pro- 2 animal was found. gressive neurodegenerative disorders that In May 2004, the New Jersey Depart- affect both humans and animals. They are Figure 1. (a) A healthy cellular ment of Health and Senior Services distinguished by long incubation periods, prion protein contains only alpha- (NJDHSS) and the Centers for Disease characteristic spongiform changes of the helices. (b) The pathogenic isoform Control and Prevention (CDC) reported brain associated with neuronal loss, and with alpha-helical structures on a suspected cluster of Creutzfeldt- the lack of a detectable immune or inflam- converted to beta-sheets.6 Jakob disease (CJD) cases (including one matory response. Unconventional agents Virginia resident) reportedly linked to the termed prions (or proteinacious infectious Garden State Racetrack in Cherry Hill, • Chronic Wasting Disease (CWD) in particles), abnormal isoforms of a normal deer and elk; New Jersey. Although there was public cellular protein encoded by a gene on chro- • Exotic ungulate encephalopathy concern that these deaths might have re- mosome 20, are considered the etiologic (EUE) in nyala and greater kudu; sulted from the consumption of meat con- agent by most scientists.4 An alternative taminated with the agent that causes BSE, hypothesis, the virino model, proposes that • Transmissible Mink Encephalopathy the study did not find a significantly el- the agent consists of a small nucleic acid, (TME) in mink; and evated number of cases of CJD or a and that this molecule is protected by the • Feline Spongiform Encephalopathy common etiology for the cases of CJD host prion protein. A third theory proposes (FSE) in cats. 3 that were identified. that TSEs are caused by conventional vi- While there is no evidence of contact However, incidents like these reinforce ruses. However, to date no infection-spe- or aerosol transmission for most prion dis- the need for healthcare providers to be cific nucleic acid has been detected in eases, they are infectious under some cir- aware of the previously low-profile group cases of TSE.5 cumstances, such as direct central ner- Known TSEs include: vous system inoculation or consuming con- Creutzfeldt-Jakob disease (CJD), taminated tissue. Prions are also charac- In This Issue: • New Variant CJD (vCJD), Kuru, terized by extreme resistance to conven- Transmissible Spongiform Gerstmann-Straüssler-Scheinker tional inactivation procedures including ir- Encephalopathies ........................... 1 radiation, boiling, dry heat, and chemicals Index to Volume 104 ....................... 5 (GSS), and Fatal Familial Insomnia (FFI) in humans; (formalin, alcohols). And while prion in- Office of Chief Medical Officer fectivity in purified samples is diminished • Scrapie in sheep and goats; 2004 Report .................................... 6 by prolonged digestion with proteases, Virginia Joins NEDSS ..................... 7 • Bovine Spongiform Encephalopathy prion inactivation requires 1N NaOH, 4M Flu Corner ....................................... 7 (BSE) in cattle; guanidinium hydrochloride or isocyanate, tion (e.g., aphasia, 1979 through 1994, CJD was recorded as apraxia, dyslexia, dys- the cause of 3,642 deaths. The average graphia, agnosia, left- age at death was 67 years. Approximately right disorientation, uni- 98% of the deaths were among persons lateral neglect) may 45 years of age or older, and 80% of the occur.10 CJD deaths were among persons 60 years Myoclonus, often of age or older (Figure 4).4 provoked by sensory The average annual age-adjusted death stimuli, usually appears rate during the study period was 0.95 within the first six deaths per million persons in the US. This months of symptom is consistent with published estimates of onset. Cerebellar dis- the crude incidence worldwide of one case Figure 2. EEG typical of CJD, with diffuse one-hertz turbances occur and per million persons. The age-adjusted death triphasic waves.7 corticospinal tract in- rate of male patients was slightly higher volvement (such as than that of female patients, and most sodium hypochlorite (2% free chlorine con- extensor plantar reflexes, clonus, and hy- (95.2%) deaths were among whites.4 centration), or steam autoclaving at 132°C perreflexia) appear. Signs of basal gan- for 4.5 hours.8 glia involvement, such as hypokinesia, dys- Virginia CJD Epidemiology tonic posturing, Creutzfeldt-Jakob CJD is currently a reportable condi- cogwheel rigidity, tion in Virginia only if the ill person is less Disease (CJD) tremor, and than 55 years of age; therefore data on choreoathetoid The prototype TSE in hu- this condition are very limited. However, movements, may mans, Creutzfeldt-Jakob dis- a review of death certificate data in 2004 develop. In the fi- ease (CJD), is a rapidly fatal found a total of 72 cases of CJD from nal stage the pa- dementing illness that occurs 1986-2003 (annual range: 0 to 10 cases). tient loses all worldwide. Although 10% This suggests an overall incidence of CJD mental and physi- of cases are due to autoso- of 0.62 per million persons over the 18 cal functions. The mal dominant inheritance Figure 3. Spongiform changes in CJD year period. Among the five regions in Vir- patient may lapse (familial CJD), most cases (>90%) oc- ginia, the Northern region had the lowest into a coma and usually dies from an in- cur unpredictably in the population (spo- incidence (0.29/1,000,000 persons/year), fection, such as aspiration pneumonia, radic CJD). Less than 1% of cases are while the Eastern region had the highest precipitated by the bedridden, unconscious the result of iatrogenic transmission (0.96/1,000,000 persons/year). The rates state.10 (e.g., associated with receipt of con- in the 35 health districts (using 2002 popu- Neuropathologic evaluation, particu- taminated human pituitary growth hor- lations) varied from 0/1,000,000 persons/ larly by immunohistochemistry or West- mone, human pituitary gonadotrophin, year to 2.47/1,000,000 persons/year (Fig- ern blot, is currently the most definitive dura mater grafts or corneal tissue, or ure 5). However, due to the very small method to diagnose human prion diseases. exposure to contaminated neurosurgi- numbers of cases of CJD that were re- In terms of treatment, although some cal equipment).4,9 However, all six of medications can help the cases linked to the use of contami- relieve jerking move- nated equipment occurred before the ments and unsteadi- implementation of sterilization proce- Figure 4. Creutzfeldt-Jakob disease deaths and death ness (e.g., clonaze- 4 dures currently used in health care fa- rates by age group, United States, 1979 through 1994. pam) and the pos- cilities. No such cases have been re- sible benefits of ported since 1976.9 quinacrine are un- The incubation period of CJD can range der evaluation, from one year to more than 30 years.10 there is no cure for Prodromal symptoms may include head- TSEs and they are in- ache, anorexia, behavioral changes, and variably fatal.6,8 depression.7 Initial neurologic signs can include progressive memory loss over US CJD weeks to months, as well as vertigo, Epidemiology blurred vision, visual field defects, or diplo- pia. Mental deficits rapidly lead to global In 1996, Holman dementia, as well as self-neglect, apathy, et al. examined or irritability. Some patients complain of trends in the inci- easy fatigability, somnolence, or insomnia. dence of CJD in the Other abnormalities of higher cortical func- United States. From 2 January 2005 ported, these rates are considered un- Table 1: Clinical and pathologic characteristics distinguishing stable. classic Creutzfeldt-Jakob disease (CJD) from variant CJD (vCJD) The average age at death of CJD cases in Virginia from 1986 through 2003 CDharacteristic CDJ vCJ was 70 years (range: 42-94 years). More Msedian age at death 6s8 yr 28 yr cases occurred in females (64%) than males. The disease predominantly oc- Msedian duration of illness 4s-5 month 13-14 month curred in whites (89%) with 8% of cases Clinical signs and Dementia; early Prominent psychiatric/behavioral in blacks and 1% of cases in Asians. symptoms neurologic signs symptoms; painful dysesthesias; Therefore, the overall pattern of CJD in delayed neurologic signs Virginia appears comparable to the US Periodic sharp waves on Otften present Absen pattern. electroencephalogram One limitation to our understanding of 'dPulvinar sign' on MRI* N%ot reporte Present in >75 CJD in Virginia and the US is that sur- veillance mainly uses death certificate Presence of 'florid plaques' Rsare or absent Present in large number on neuropathology data. However, it is very likely that some cases do not get recorded. CJD is an un- Immunohistochemical Variable Marked accumulation of PrPres** common disease and physicians who are analysis of brain tissue accumulation not familiar with the signs and symptoms Presence of agent in Ndot readily detected Readily detecte may mistake it for other conditions.
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