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Mad Cow Disease and Variant Creutzfeldt Jakob Disease 1

Mad Cow Disease and Variant Creutzfeldt Jakob Disease

Jason C. Potter

Human Disease 3400 sec. 2

Spring Semester 2012

Lynley Rowan, PhD

5 April 2012


Mad Cow Disease or Bovine Spongiform Encephalopathy (BSE) emerged in United

Kingdom (UK) in the early 1980’s as a result of cattle being fed a prion infected protein meal. It

was only a matter of time before BSE was transmitted to humans and Variant Creutzfeldt Jakob

Disease (vCJD) developed. VCJD is a rare, degenerative brain disease caused by an abnormal

transmissible protein. Manifestations of vCJD include both psychological and neurological

symptoms, with the prognosis being fatal. The infective agent is a mutated prion protein that is

isolated to neural tissue. Since the development of BSE in the 1980’s, and first reported case of

vCJD in 1996, scientists have been perplexed by the uniqueness of the disease and have

continued their research in the hopes of uncovering more effective identification, diagnosis,

prevention and treatment of vCJD (CDC, 2010).

History

Mad Cow disease was first discovered in 1981-1982 in the UK. BSE is related to a

serious disease known as “scrapie” that has been affecting sheep and goats since the mid-18th

century in Europe. BSE is a zoonotic disease that was transmitted to cattle that were fed with

forms of protein meals containing prion. The protein meal contained prions from sheep infected

with scrapie. The protein meal was made of discarded sheep remains containing neural tissue

(Chachra, Narang, & Narang, 1999). Researchers suspect that around the 1980’s changes in the

rendering process of how the protein-rich meal was processed allowed for the infective agent in

carcasses to survive. This caused a contamination of the protein-rich meal, leading to cattle to

becoming infected and creating the BSE epidemic. (Brown, Will, Bradley, Asher, & Detwiler,

2001, pp. 6-7).

Soon after the discovery of BSE, distress arose regarding the risk of transmission to

humans. At this time, the UK and the European Union began taking measures to ensure BSE did


not spread to humans. This consisted of a surveillance unit to monitor any cases in humans,

hoping that transmission to humans could be identified quickly (Brown, Will, Bradley, Asher, &

Detwiler, 2001, p. 8). With time, BSE was eventually spread to humans.

From May to October 1995, the surveillance unit was informed of three cases of classic

Creutzfeldt Jakob Disease (CJD) in humans ages 16, 19, and 29. By December 1995, the

surveillance unit had been notified of 10 alleged cases of classic CJD in individuals younger than

50 years of age. Of these ten individuals, some were found to have familial or sporadic CJD or a

different disease. (Brown, Will, Bradley, Asher, & Detwiler, 2001, p. 9) It was no doubt; cases of

CJD were on the rise, whether or not they were considered truly familial, sporadic or infectious.

Researchers reported, “As of January 1, 1996, the relationship between these cases and BSE

began to excite suspicion but remained tentative because critical information judged necessary to

establish a probable connection was still missing” (Brown, Will, Bradley, Asher, & Detwiler,

2001, p. 9).

In February 1996, another case was reported to the surveillance unit with a similar

clinical presentation to the prior cases reported. This confirmed that the recently reported cases

of CJD were undeniably distinctive. On March 4, analysis of the genetics of six reported cases

revealed there was no genetic cause for the syndrome. The following week, two more cases were

neuropathologically confirmed. A report on the entire ten confirmed cases resulted in the

identification of an unrecognized variant of classic CJD, known as vCJD, arising in individuals

under the age of 45 and most likely due to BSE exposure. The link between BSE and vCJD was

firmly established through laboratory and biological testing comparing the biological

characteristics of the pathogenic agent from cattle infected with BSE and vCJD (Brown, Will,

Bradley, Asher, & Detwiler, 2001, pp. 10-11).


Emergence, Incidence and Prevalence.

Both BSE and vCJD are considered epidemic and initially emerged from the UK. The

Center for Disease Control (CDC) (2010) reported:

From 1986 through 2001, more than 98 % of BSE cases worldwide were reported from the UK, where the disease was first described. During this same period, the number of European countries reporting at least one indigenous BSE case increased from 4 through 1993 to 8 through 1998 to18 through 2001. During 2001-2003, three countries outside Europe (Canada, Japan, and Israel) reported their first indigenous BSE cases. Although BSE first appeared in the UK, the total number of annual cases being reported

outside the UK has been raising; the CDC (2010) described an increase of 25 % in 2000 and

more than 55 % in 2003. The CDC (2010) confirmed this increase in BSE outside the UK

reflects the “declining large (more than 183,000 total cases) epidemic of BSE in the UK and the

increasing number of other countries with improved surveillance and higher rates of BSE.”

Despite prevention measures to avoid the spread of BSE to Northern America and Canada, the

first case was identified in Canada in 2003. This created a great amount of concern that BSE may

be occurring in North America. In reaction to the reported case of BSE in Canada, the CDC

(2010) reported the US Department of Agriculture (USDA) implemented extra safeguards “to

minimize the risk for human exposure to BSE and on July 1, 2004, initiated a 12- to 18-month-

long intensive testing program for BSE among cattle at relatively high risk for the disease (e.g.,

non-ambulatory cattle).”

According to CDC (2010), only three cases of vCJD have been reported from the United

States. It is important to note, in spite of where an exposure may have occurred, vCJD is

attributed to the country of the individual’s initial onset of symptoms. To date, there has never

been a reported case of vJCD where the individual did not have a history of exposure in a

country where BSE was occurring. Of the three reported cases in the United States, facts imply


that one of individuals was initially exposed to BSE while residing in the UK and the other

individual while residing Saudi Arabia (CDC, 2010). VCJD was first reported in 1996, and since

then the CDC (2010) reported:

A total of 217 patients with this disease from 11 countries have been identified. As of October 2009, variant CJD cases have been reported from the following countries: 170 from the United Kingdom, 25 from France, 5 from Spain, 4 from Ireland, 3 from the United States, 3 in the Netherlands, 2 in Portugal, 2 in Italy, and one each from Canada, Japan, and Saudi Arabia. Two of the three U.S. cases, two of the four cases from Ireland and the single cases from Canada and Japan were likely exposed to the BSE agent while residing in the United Kingdom.

In regards to the year of onset, the CDC (2010) reported the incidence of vCJD in the UK

peaked in 1999, with 1000 cases per week, and since that time has been declining. In contrast,

the number of reported cases in France has been increasing since the beginning of 2005.

Nevertheless, concern is arising regarding the future incidence of vCJD and pattern of this

epidemic. The CDC (2010) reaffirmed a second wave of cases could possibly occur due to in a

subgroup of the population that may be less susceptible in regard to genetics. As of 2003, the UK

and Portugal reported a BSE incidence rate of “more than 100 indigenous cases per million cattle

more than 24 months of age” (CDC, 2010). The CDC (2010) also reported BSE rates per million

cattle over the age of 24 months in regards to the following countries:

58 for the Republic of Ireland, 46 for Spain, 25 for Switzerland, 12 for France, 11 for Belgium and the Netherlands, 10 for Italy, 9 for Germany, and 7 for Slovakia. The reported rates for Canada, Czech Republic, Denmark, Japan, Poland, and Slovenia were between 0.3 and 6 cases per million.


Below is figure 1 presented by Behgi, et al. (2004), showing the cases of BSE and vCJD in the

UK since 1987:

Figure 1 courtesy of by Behgi, et al. (2004)

The Disease

Etiologic Agent

According to the Journal of Emerging Infectious Diseases, BSE is a zoonotic disease

which becomes fatal to humans eating infected beef. Within weeks of the first reported case of

BSE, concern was raised regarding the risk to humans and the possibility of BSE reaching the

human food chain. BSE is a neurological disease affecting cattle that progressively leads to

death. BSE results from an infective agent called a prion (proteinaceous infectious particles).

Prion diseases are also known as transmissible spongiform encephalopathies (TSEs), affecting

both animals and humans (Brown, Will, Bradley, Asher, & Detwiler, 2001). The CDC (2010)

further explained, “A prion is an abnormal, transmissible agent that is able to induce abnormal

folding of normal cellular prion proteins in the brain, leading to brain damage and the


characteristics signs and symptoms of the disease.” Unlike bacteria, prions do not contain any

DNA or RNA. Of all the pathogens, prions are considered to be the most resistant to

disinfectants. (Engelkirk & Duben-Engelkirk, 2010, p. 52). The exact mechanism by which

prions cause disease is unclear; however, according to Engelkirk & Duben-Engelkirk (2010), “It

is though that normal protein molecules are converted into nonfunctional ones by causing the

normal molecules to change their shape” (p. 52).

Stages and Symptoms

According to Spencer, Knight and Will (2002), individuals affected by vCJD exhibit

psychiatric symptoms in the early stages of the disease. Common psychiatric symptoms include

dysphoria, withdrawal, uneasiness, insomnia and loss of interest. In the early stages of the vCJD,

neurological symptoms are often times not apparent. However, Spencer, et al .,( 2002) found

that of the first 100 reported cases in the UK, neurological symptoms precede psychological

manifestations in 15% of all the cases and both neurological and psychological symptoms are

present in combination in 22% of all cases from the initial onset of vCJD (p. 1479). During the

disease process, no common early neurological symptoms are present; nevertheless, Spencer, et

al., 2002 stated, “A significant portion of patients do exhibit neurological symptoms within 4

months of clinical onset, including poor memory, pain, sensory symptoms, unsteadiness of gait

and dysarthria” (p. 1479). In the last stages of vCJD, patients experience dementia and

eventually slip into a coma. On average, the duration of the illness is approximately 14 months in

most patients (Behgi, et al., 2004).

Unique Characteristics

VCJD is unique in that most physicians in medical school typically learn about classic

CJD, which is unrelated to the ingestion of contaminated beef. According to the CDC (2010),


“Classic CJD is not related to mad cow disease. Classic CJD is also distinct from variant CJD,

another prion disease that is related to BSE.” Thus, the epidemiology of vCJD and classic CJD

are quite different and must be carefully diagnosed to distinguish between the two diseases.

Because vJCD is such a unique and new disease, Henley and Herrman (2004) reaffirmed “its

incubation period is unknown, but it is likely to be years or decade” (p 645). In fact, in the UK

individuals were most likely exposed to BSE-contaminated food in 1984-1986. It is likely the

onset of vCJD was not years later until reported cases in 1994-1996 (Henley & Herrmann, 2004).

Diagnosis

Henley and Herrmann (2004) note that diagnosing vCJD includes several diagnostic

tools; however, one must carefully distinguish between vCJD and classic CJD before a final

diagnosis is made. One of the tests performed in diagnosing vCJD is an electroencephalogram

(EEG), which is used to measure electrical activity in the brain. If vCJD is present, there will be

a lack of sharp wave complexes on EEG; in contrast, if classic CJD is present there will be wave

complexes present (p. 645-647). The CDC also provides definitive criteria for the diagnosis of

vCJD in the United States. For a definitive diagnosis examination of the brain tissue must take

place and the following confirming features must be present:

a. Numerous widespread kuru-type amyloid plaques surrounded by vacuoles in both the cerebellum and cerebrum - florid plaques.

b. Spongiform change and extensive prion protein deposition shown by immunohistochemistry throughout the cerebellum and cerebrum. (Center for Disease Control and Prevention, 2010, 2011)

These definitive features of diagnosing vCJD differ from the diagnosis of classic CJD

where kuru-type amyliod plaques are rare or absent and prion protein is variable in accumulation

rather than extensive as in vCJD (Henley & Herrmann, 2004, p. 647).

The CDC (2010) also provides criteria for a suspected vCJD diagnosis:


a. Current age or age at death <55 years (a brain autopsy is recommended, however, for all physician-diagnosed CJD cases).

b. Psychiatric symptoms at illness onset and/or persistent painful sensory symptoms (frank pain and/or dysesthesia).

c. Dementia, and development ≥4 months after illness onset of at least two of the following five neurologic signs: poor coordination, myoclonus, chorea, hyperreflexia, or visual signs. (If persistent painful sensory symptoms exist, ≥4 month’s delay in the development of the neurologic signs is not required).

d. A normal or an abnormal EEG, but not the diagnostic EEG changes often seen in classic CJD.

e. Duration of illness of over 6 months. f. Routine investigations of the patient do not suggest an alternative, non-CJD

diagnosis. g. No history of receipt of cadaveric human pituitary growth hormone or a dura

mater graft. h. No history of CJD in a first degree relative or prion protein gene mutation in the

patient. (Center for Disease Control and Prevention, 2010, 2011)

Hennley and Herrman (2004) suggest that physicians should advocate for a brain biopsy

or autopsy in patients that may have vCJD or patients that may have died as a result of the

disease. For physicians and health departments whom may need to perform diagnostic testing—

the CDC funds The National Prion Disease Surveillance Center—providing diagnostic services

free of charge. (p. 648).

The Science

Morphology, Genome and Life Cycle

Understanding the science related to vCJD is linked to the causative agent known as a

prion; an infectious agent that consists of a tiny protein that lacks genes, but can mutate, creating

error in gene expression and failure to fold correctly. A prion protein is typically spiral or helical

in shape. The abnormal form of this protein looks much different, containing many flat, sheet-

like structures. These mutations associated with the disease, affecting the shape of the protein,

are thought to cause the clumping of the protein and in turn the accumulation and damage to the


brain. (Prusiner, 2001). As seen below in Figure 2, brain tissue infected with prions has a spongy

appearance (CDC, 2010).

Figure 2 courtesy of the CDC (2010)

As mentioned, vCJD is caused by ingesting beef containing prion, which eventually

accumulates in the brain leading to death. Diseases affected by prions have long been debated

with uncertainty among scientists; however, recent research conducted by Stanley Prusiner and

Charles Weissmann has confirmed that prion diseases are caused by a toxic form of the prion

protein; this idea is known as the prion hypothesis (Goldberg, 2007, p. 1150).

Golberg (2007) explains:

This protein is able to enter the cells and induce a conformational rearrangement of normal soluble, monomeric cell constituent, the prion protein (PrPc), into a toxic transmissible species (PrPsc). In this pathogenic conformation, the prion is primarily insoluble, is resistant to proteases or detergents. This conformational change and the resulting accumulation of PrPsc ultimately causes severe loss of neurons, glosis, and spongiform appearance (p. 1150).


Below is a simplified diagram (Figure 3) of the prion hypothesis presented by Burthem &

Roberts (2003). Burthen & Roberts explained, “(A and B) Molecules of PrPSc interact directly

with the PrPc causing the structural conversion of the PrPC to form further PrPSc . This

conversion culminates in the formation of polymeric aggregates of PrPSc (C) or in the formation

of further infective material” (p. 223).

Figure 3 courtesy of Burtham & Roberts (2003)

Burthem and Roberts (2003) provide a detailed explanation of the prion hypothesis:

The prion hypothesis requires that, for PrP(Sc)infection to occur, PrP(C)must first be expressed by the host, i.e. there must be a 'pool' of PrP(C)that can be converted to PrP(Sc). Immunological surveillance requires that cells of the immune system encounter and process new proteins entering the body at an early stage after ingestion or inoculation. Moreover, immune cells migrate widely through the body and establish frequent and close contact with other cells. This behavior is essential for the effective immune response to conventional pathogens, but in prion disease this otherwise beneficial process appears to facilitate the propagation and spread of the abnormal protein (p. 122).

A

B

C


As discussed, the causative agent in vCLD is a prion; however, Belay (1999) discussed a

specific variation in the sequence of genes has been confirmed. The most significant

polymorphism leads to the formation of two different protein forms. The first form has an amino

acid called methionone at the 129th amino acid in the protein sequence, and the second form has

an amino acid called valine in the same position (p. 298). Belay (1999) also addressed several

studies that have shown the polymorphism at codon 129 has a significant impact in determining

the susceptibility of the host and the disease expression of familial, iatrogenic (infectious), or

sporadic CJD (p. 298). Individuals that developed the vCJD had a double-methionine form of the

prion protein, but no other mutations. This implies that this particular variation in the gene

somehow influences an individual’s susceptibility to vCJD (Prusiner, 2001). In fact, Brown et

al., (2001) concluded, “The encoding alternatives methionine (met) and valine (Val), are

distributed in the approximate proportions of 50% Met/Val, 40% Met/Met, and 10 % Val/Val.”

In 2001, it was reported that all 76 vCJD patients tested have been homozygous for methionine,

and apparently single infecting strains of BSE may not be able to replicate in any other human

genotype (p. 10). In 2005, Ludman & Turner reported that “ to date in all clinical cases of

variant CJD have occurred in methionine 128 homozygous individuals; it seems likely that

valine homozygous and methionine/valine heterozygous individuals are more resistant to

infection, or if infected, to the development of clinical variant CJD” (p. 16).

Transmission

Bovine to Human.

Research has positively confirmed the transmission of vCJD is directly related to the

biological features of the pathological agent isolated from BSE infected cattle. The source of the

infection appears to have been from beef products contaminated by nervous system tissue


containing prions (Brown et al., 2001, p. 10). Brown et al., (2001) explained how contamination

originally could have occurred:

Cerebral vascular emboli from cranial stunning instruments used to immobilize cattle before killing by exsanguination; contact of muscle with brain or spinal cord tissue by saws or other tools used during slaughter; inclusion of paraspinal ganglia in cuts of meat containing vertebral tissues; and perhaps most importantly the presence of residual spinal cord and parasprinal ganglia tissue in the paste of mechanically recovered meat that could legally be added to cooked meat products such as meat pies, beef sausages, and various canned meat preparations (p. 10). According to the CDC (2011), BSE may have originally resulted due to feeding cattle

meat and bone meal that contained products from a randomly occurring case of BSE or scrapie

from possible contaminated sheep products. The CDC (2011) stated, “There is strong evidence

and general agreement that the outbreak was then amplified and spread throughout the United

Kingdom cattle industry by feeding rendered, prion-infected, bovine meat and bone meal to

young calves.” The CDC (2011) confirmed there is solid epidemiologic and laboratory data for a

connecting link between vCJD that was first reported from the United Kingdom in 1996, and the

epidemic of BSE. A unique characteristic of vCJD is the long incubation period. The CDC

(2011) reported similar incubation periods for human forms of prion diseases and the time frame

of initial exposure to BSE and the clinical manifestations of the disease.

Blood Products.

VCJD may also be transmitted through blood products such as transfusions and using

blood products from an infected person with vCJD. Turner & Ludman (2008) addressed the

topic of vCJD by blood transfusion and discussed the direct link of vCJD and blood donation.

Turner and Ludman (2008) reported that, “Eighteen patients with vCJD have, or have has

previously, been blood donors, from whom a total of 66 recipients have been identified, 26 of

whom are still alive. Of those who have died, four cases of transmission of vCJD prions have


been identified” (p .15) In December 2003, the first case of vCJD linked to a blood transfusion

was indentified. The individual that became infected with vJCD developed the disease 6 years

after receiving a blood transfusion. The blood donor developed signs and symptoms of vJCD 3

years after donating (Turner & Ludman, 2008, p. 15). This data clearly shows that individuals in

the incubation period of vCJD can transmit the disease to another individual through blood

transfusion. No specific immunological reaction related to prion infection has been indentified

nor has specific DNA been found related to the transmission of vCJD. Thus, typical serological

and biological tests in donors have not been possible (Ludlam & Turner, 2005, p. 18).

Iatrogenic.

Transmission from human to human through direct contact has not been confirmed;

however, individuals can be infected with vCJD through iatrogenic transmission. Ludlan &

Turner (2008) reported iatrogenic transmission has been well documented. The transmission

occurs through direct inoculation of the Central Nervous System (CNS) through contaminated

neurosurgical instruments, intracerebral electrodes, dura matter and corneal grafts. Iatrogenic

transmission has also occurred by pituitary growth hormone and gonadotrophins taken from

cadavers and administered to patients by intramuscular injection (Turner & Ludman, 2008, p.

15). Despite technological advanced sterilization techniques, it is possible for vCJD to be

transmitted to another patient. Campbell (2006) reported that stainless steel instruments used in

neurosurgery can transmit vCJD to another patient even if the instrument is thoroughly sterilized

with formaldehyde. It is recommended that only disposable instruments be used in neurological

surgery and tonsil removal to prevent the transmission of vCJD from one patient to another.

According to Ludman & Turner (2005), patients with vCJD have shown evidence of irregular

prion accumulation in follicular dendritic cells and peripheral lymphoid tissue, including the


tonsils (p. 17). Another concern has been brought up regarding dental surgery involving

removal of an infected root. Since formaldehyde is ineffective in disinfecting instruments, it has

been recommended that dental surgeons use 4% hypochlorine (p.93). Campbell (2006) reiterated

the possibility of direct transmission from human to human through the use of infected surgical

instruments, “The fear is there may be a bank of human carriers passing on the infection to

others” (p. 93).

Port of Entry.

Clinical presentation and specific signs and symptoms of vCJD can vary depending on

the route of infection. CNS transmission is likely to have a shorter incubation period. According

to Ludlam & Turner (2005), the incubation period is roughly two years and the infected

individual develops rapid dementia. Peripherally transmitted cases usually have a longer

incubation period, ranging from 13-15 years and symptoms include ataxia and sensory

disturbances (Ludlam & Turner, 2005, p. 15). Tan, Williams, Khan, Champion & Nielson (1999)

discussed four categories related to certain organs containing more infectious prions than others:

Direct administration into the central nervous system is the most infectious route, followed by administration in to the blood vessels, and intraperitoneal, intramuscular, and subcutaneous exposure. Oral ingestion is less efficient than the parenteral routes. Finally, the dose of infectious material is an important determinant of transmissibility (p. 2333).

Fate of Victim

According to Ludman & Turner (2005), after transmission of the disease, the fate of the

victim infected with vCJD is a poor prognosis that eventually leads to death. Ludman and Turner

(2005) stated in the end stages of the disease patients develop progressive dementia and

myoclonus “with an average clinical course to death of 6 months—2 years” (p. 15).


Vulnerability and Risk

As reported by the CDC (2010), almost all cases of vCJD have been in persons under the

age of 55, with the median age at death being 28. Ludlam & Turner (2005) also reported the

median age of death has not changed over the first 10 years of the outbreak; this suggests there

may be an age related susceptibility or exposure (p. 17). Reasoning for this specific age

distribution is not fully understood at this time; however, the CDC (2010) suggested that through

the oral route of exposure, older adults are less susceptible to vCJD than young adults and

children. Concern has also been raised that some individuals in the population may be

genetically susceptible to vCJD. The CDC (2010) discussed this concern, presented in the

following quote:

In 2004, a prevalence study of asymptomatic vCJD infections in the UK identified three positive appendices out of a sample of 12,674 surgically removed tonsils and appendices that were satisfactory for analysis. Genetic studies completed on two of the appendices regarded as positive for vCJD revealed that both had a different polymorphism at codon 129 of the prion protein gene than any of the patients with clinical vCJD tested to date, indicating that more people are genetically susceptible to vCJD infection, although not necessarily to the disease, than had been previously determined. The CDC (2010)confirmed the current risk for acquiring vCJD from eating BSE-

contaminated beef products in countries with a possible increase risk of BSE cannot be exactly

determined. The CDC (2010) stated if current public health measures are being implemented,

the risk of being infected with vCJD due to eating contaminated beef is extremely small;

nonetheless, the risk is not zero. The CDC (2010) reported, “A rough estimate of this risk for the

UK in the recent past, for example, was about 1 case per 10 billion servings.”

Individuals receiving blood transfusion are at risk of being infected with vCJD from the

blood of a donor that may still be in the incubation period. Individuals that received blood from

donors in the UK that were subsequently diagnosed with vCJD are considered high risk for


developing vCJD. These individuals are contacted on a regular basis and offered special follow

up care and counseling. In 2004, in the UK, all patients with hemophilia were sent letters stating

whether or not they had received plasma-derived clotting concentrates between the years of1980-

2001. (Ludlam &Turner, 2008, p. 15, 21). As of 2003, one of case of vCJD in a 62-year old UK

man is thought to have been as a result from a blood transfusion contaminated with the vCJD

infectious agent. Just a year later, another case in the UK was reported that was very suspicious,

likely being transmitted by a blood transfusion. Due to the reported cases of possible

transmission through a blood transfusion, the UK quickly implemented specific safeguards. A

ban was placed on all persons receiving blood transfusions after 1980 in the UK from donating

blood in the future. In January 2002, in order to reduce the risk of bloodborne transmission of

vCJD, the USDA released guidance, which included a geography-based donor deferral policy

(CDC, 2010).

Ludlam &Turner (2008) discussed the potential risk posed to patients undergoing

invasive medical procedures such as neural, tonsil, or oral surgery for an infected root. The risk

increases in these types of surgeries when considering patient to patient transmission due to

surgical instruments that may be harvesting the infective agent associated with vCJD. (15-17).

Prevention

In regards to prevention, the CDC (2010) recommended:

To reduce any risk of acquiring vCJD from food, travelers to Europe or other areas with indigenous cases of BSE may consider either avoiding beef and beef products altogether or selecting beef or beef products, such as solid pieces of muscle meat (rather than brains or beef products like burgers and sausages), that might have a reduced opportunity for contamination with tissues that may harbor the BSE agent. Milk and milk products from cows are not believed to pose any risk for transmitting the BSE agent. In order to prevent BSE from entering the U.S., harsh restrictions were implemented by

the USDA in June of 1997, becoming effective in October 1997. This included restrictions on the


importing of live cattle, sheep and goats, and certain ruminant products where BSE had been

identified. Later, this restriction was extended to all European countries. This feed ban is

enforced by the FDA through inspections and feed testing programs. In October 2009, the FDA

issued a regulation creating an enhanced BSE-related feed ban in the U.S. This feed ban helped

to synchronize feed control measures in the US and Canada. In July of 2007, an enhanced BSE-

related feed ban was put into effect in Canada in order to quickly eliminate the spread of BSE in

Canada. (CDC, 2010).

To help with prevention measures in relation to vCJD, the CDC continues to monitor

trends and the current incidence in the U.S. through several surveillance methods. The CDC has

placed more attention on the national surveillance of classic CJD in order to more effectively

detect vCJD. This is accomplished through autopsies on patients with possible prion diseases.

This has helped to increase the ability to detect more vCJD cases (CDC, 2010). The CDC also

continues to investigate possible deaths from iatrogenic CJD and vCJD reported by health care

professionals. Most importantly, “in 1996-97, CDC established, in collaboration with the

American Association of Neuropathologists, the National Prion Disease Pathology Surveillance

Center at Case Western Reserve University, which performs special diagnostic tests for prion

diseases, including post-mortem tests that can detect vCJD.” (CDC, 2010).

Treatment

The CDC stated (2010), “As of September 2004, treatment of prion diseases remains

supportive; no specific therapy has been shown to stop the progression of these diseases.”

Becoming infected with vCJD is fatal to the patient. In a study conducted by Vries, Sque, Bryan

& Abu-Saad (2003), the need for palliative care and development of educational initiatives is

addressed. They concluded that caring for patients with vCJD is very a stressful experience in all


stages of the illness. Patient’s affected by vCJD are often times admitted to psychiatric units,

where they eventually die. Vries, Sque, Bryan & Abu-Saad (2003) argued it is more appropriate

for patients affected by vCJD to be cared for by health care professionals in hospice

environments. Consequently, there should be planning initiated by the healthcare team for

patients affected by illnesses such as vCJD that are terminal and involve dementia (p. 518).

Global Economy

With the outbreak of BSE in the 1990’s and eventual transmission to humans, both the

UK and the U.S. have created measures in response to the crisis. According to the CDC (2010),

the department of Health and Human Services (HHS) in 2001 began to create a department-wide

action plan. This plan helped to outline steps to improve the scientific understanding and

research in regards the BSE and other TESs. The CDC (2010) presented the department-wide

action plan:

Surveillance for human disease is primarily the responsibility of CDC. Protection is primarily the responsibility of the Food and Drug Administration (FDA). Research is primarily the responsibility of the National Institutes of Health (NIH). Oversight is primarily the responsibility of the Office of the Secretary of DHHS. In is no question, both BSE and vCJD have had significant impact on the global

economy. In fact, Campbell (2006) stated, “The BSE crisis has cost the UK government more

than 4 billion pounds alone in compensation to farmers and caused much disquiet in agriculture”

(p.94). Due to the slaughtering of thousands of cattle; ban on importing ruminant products from

all European countries; and severe restrictions that were placed on the importation of cattle,

sheep, and goats; the global market has suffered greatly.

Campbell (2006) also discussed the controversy of scientist being criticized for initially

telling the public the transmission of BSE to humans was only a distant possibility. Campbell

(2006) stated, “There is no doubt that the reputation of scientists has been badly affected by the


BSA saga and we know that the story is not at an end. The experience with BSE has increased

the resistance of the public to biotechnology in general” (p. 94). Campbell (2006) also addressed

the concern journalists have with scientist when they pose the question “is it safe to eat beef?”

and they do not receive a direct yes or no, but would rather speak about risk factors.

Beghi, et, al (2004) reaffirmed the reality that the future effect on the global economy in

relation to BSE and vCJD is unknown at this time due to the long and ill-defined incubation

period of prion diseases. Thus, we do not know the beginning and the end of the human outbreak

of BSE and the effects it may have on our future economy.

The epidemic of Mad Cow Disease that spread throughout the UK in the 1980’s raised

concern worldwide. With humans coming in contact with contaminated beef, vCJD developed as

a result. Scientists continue to conduct further research to fully understand the impact of a prion

disease such a vCJD. The research is focused on finding a more effective way of identifying

potential carriers early on, and preventing transmission that can occur through blood transfusions

and invasive medical procedures. In addition to research taking place, government agencies in

the UK and U.S. are continually implementing preventative measures to stop infected beef

products from reaching humans. Due to the uniqueness of this disease and the long incubation

period, scientists, researchers, and government agencies fear there could be a large portion of the

population carrying the disease and unknowingly spreading it to others, creating a second wave

of the BSE outbreak.


References

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