1. Viroids & Prions

2. Viroids Small, circular RNA molecules without a protein coat
Infect plants
Potato famine in Ireland??
Viroids are usually transmitted by seed or pollen. Infected plants can show distorted growth.

3. Prions (short for proteinaceous infectious particle)
Prions are “infectious proteins”
They are normal body proteins that get converted into an alternate configuration by contact with other prion proteins (a misfolded protein)
They have no DNA or RNA
The main protein involved in human and mammalian prion diseases is called “PrP” (prion protein)

4. Prion Disease
Most prion diseases are found in the central nervous system and are capable of spreading to the peripheral nervous system thus infecting meat and muscle
The abnormal prion protein infects the host animal by promoting conversion of normal cellular prion protein to the abnormal prion form.
The build-up of the abnormal protein in the brain is associated with widespread neurodegeneration.

5. “Very Bad Protein- Prion”
“Good Protein”
“Very Bad Protein- Prion”
Infectious proteins convert normal proteins

6. Prion Diseases Prions form insoluble deposits in the brain
Causes neurons to rapidly degenerate.

7. Prion Diseases of Animals:
The post mortem appearance of the brain has large vacuoles in the cortex and cerebellum. Specific examples include:
Scrapie: sheep, goats
CWD (chronic wasting disease): muledeer, elk, white tailed deer, moose
BSE (bovine spongiform encephalopathy): cows

8. Normal Brain Tissue- Diseased Brain Tissue
Holes in the brain are BAD….very BAD.
Normal Brain Tissue- Diseased Brain Tissue

9. Scrapie:
A fatal disease that affects the nervous systems of sheep and goats.
It is related to bovine spongiform encephalopathy (BSE or "mad cow disease")
It does not appear to be transmissible to humans.
The name scrapie is derived from one of the symptoms of the condition, wherein affected animals will compulsively scrape off their fleece against rocks, trees or fences.
The disease apparently causes an uncontrollable itching sensation in the animals. Other symptoms include excessive lip-smacking, strange gaits, and convulsive collapse.

11. Chronic Wasting Disease:
Chronic Wasting Disease (CWD) is a transmissible neurological disease of deer and elk that produces small lesions in brains of infected animals.
It is characterized by loss of body condition, behavioral abnormalities and death.
Chronic Wasting Disease:

12. Where has it been found? CWD is known to infect wild deer and elk in Colorado, Illinois, Kansas, Nebraska, New Mexico, New York, South Dakota, Utah, Wisconsin, West Virginia, Wyoming, Alberta and Saskatchewan. It has been diagnosed in captive herds in Colorado, Nebraska, South Dakota, Montana, Oklahoma, Kansas, Minnesota, New York, Wisconsin, Wyoming, Alberta and Saskatchewan. CWD has not been found in Pennsylvania.

13. How are these Prion diseases spread?
The origin and mode of transmission of the prions causing CWD is unknown, but recent research indicates that prions can be excreted by deer and elk, and is transmitted by eating grass growing in contaminated soil.
Based on epidemiology, transmission of CWD is thought to be lateral or from animal to animal; although maternal transmission may occur, it appears to be relatively unimportant in maintaining epidemics.
Research has recently shown that an infected deer's saliva is able to spread the CWD prions.
(go to chronic wasting disease alliance web page to view short video)

14. BSE or Mad Cow Disease moo. moo.
Bovine spongiform encephalopathy (BSE or commonly mad cow disease) is a fatal, neurodegenerative disease of cattle.
The disease is transmissible to humans.
Transmission of BSE occurs when healthy animals consume tainted tissues from others with the disease.

15. How is that possible?
We are HERBIVORES!

16. Just ask the idiots in the United Kingdom
Just ask the idiots in the United Kingdom! There was a HUGE outbreak of Mad Cow in the late 1980’s MILLION of us had to be killed to prevent spreading the infection!

17. Well, it seems the BRITS were forcing us to be cannibals
Well, it seems the BRITS were forcing us to be cannibals! When a sick cow died, they ground it up and fed it to us! That is how the disease was spreading!

18. How is that possible?...
A British inquiry into BSE concluded that the epidemic was caused by cattle, who are normally herbivores, being fed the remains of other cattle in the form of meat and bone meal (MBM), which caused the infectious agent to spread

19. Hmmmmm…Here’s an idea! Let’s take sick “downer” cows and then turn them into “yummy cow pellets” and then feed these pellets to other cows! What’s the worst that could happen?
Downers

20. Mad Cow Epidemic in Britain:
In the United Kingdom, the country most affected, more than 179,000 cattle were infected and 4.4 million slaughtered during the eradication program.
by October 2009, BSE has killed 166 people in Britain, and 44 elsewhere with the number expected to rise because of the disease's long incubation period

21. How were humans getting “Mad Cow?”
For many of the British, direct evidence exists that they had consumed tainted beef, and this is assumed to be the mechanism by which all affected individuals contracted it (cooking the meat does not destroy the prion)
Disease incidence also appears to correlate with slaughtering practices that led to the mixture of nervous system tissue with of hamburger and other beef.
The human disease was designated variant Creutzfeldt-Jakob disease
(show YOU TUBE Clip of Indian Dude and British Family)
How were humans getting “Mad Cow?”

22. Symptoms: Degeneration of physical and mental abilities, and ultimately death

24. U.S. Food and Drug Admin:
The Harvard risk assessment study, released in November 2009, determined that the chances of BSE entering the United States and posing a risk to consumers and the agricultural industry are "extremely low."
Further, in the unlikely event that BSE would appear in U.S. cattle herds, the government's "multiple firewall" system would keep the disease from spreading so that it would eventually die out, according to the study. This firewall consists of a feed ban, import controls, and a surveillance program.

25. BSE in North America
As of January 2005, five BSE-infected cattle have been identified in North America. The first was in 1993, involving an animal born in Britain.
The second was reported in Canada on May 20, It occurred in a single older cow that may have contracted the disease from contaminated feed in earlier years. The animal had been destroyed and declared unfit for consumption prior to being diagnosed. The United States issued a temporary ban on all Canadian beef.
On December 23, 2003, the first case of BSE in the United States was found in a single Holstein cow in Washington State. Agriculture Secretary Ann Veneman called the discovery "a clear indication that our surveillance and detection program is working." However, the United States tested only 20,526 cows in 2003 out of the roughly 35 million slaughtered.
The government plans to double the number of cattle tested in 2004, and has banned the use of "downer cows" for human consumption..

27. Prion Diseases of Man: CJD: Creutzfeld-Jacob Disease *
GSS: Gerstmann-Straussler-Scheinker syndrome
FFI: Fatal Familial Insomnia
Kuru *
Alpers Syndrome (children)
These diseases affect the structure of brain tissue and are all fatal and untreatable

29. Kuru:
Kuru is the condition which first brought prion diseases to prominence in the 1950s.
Found in geographically isolated tribes in the Fore highlands of New Guinea. Established that ingesting brain tissue of dead relatives for religious reasons was likely to be the route of transmission.
They ground up the brain into a pale grey soup, heated it and ate it.

31. (I personally think that is a mighty fine tip.)
Clinically, the disease resembles CJD. It is speculated that at some point in the past a tribe member developed CJD, and as brain tissue is highly infectious this allowed the disease to spread (mainly to woman and children).
Afflicted tribes were encouraged to stop eating dead relatives.
(I personally think that is a mighty fine tip.)
Show YOUTUBE Kuru Video