Parsons - Scrapie + BSE

Transmissible Spongiform Encephalopathies (TSE’s) is a family of diseases that affect multiple species and derives its name for its common histological pathology in brain parenchyma resulting from:

–Multiple vacuoles in neurons

what is the appearance of the brain parenchyma with scrapie?

–multiple vacuoles

–reactive astrocytes

–gliosis

The earliest reported example of a Transmissible Spongiform Encephalopathies was

–Scrapie described in sheep in 1732

scrapie is the name in which animals

goats and sheep

what is scrapie names in humans?

–Creutzfeldt-Jakob disease (CJD)

Kuru

Gerstmann-Straussier Syndrome (GSS)

Fatal Familial Insomia (FFI)

Alpers Syndrome

The infective agent underlying Transmissible Spongiform Encephalopathies has been a controversial topic over the years but is now believe to be a

•a prion which is a normal protein in the brain that is coded by the PrP gene

becomes a misbehaving protein

Scrapie is a transmissible spongiform encephalopathy that causes a neurodegenerative disease in sheep and goats.  Scrapie

–Has its highest incidence in Suffolk sheep

–Can present with intense incessant pruritus or “mad itch”

–In sheep has a low flock morbidity (20-40%) and high mortality (100%), but rarely affects goats.

–All choices are correct

all correct

what are the clinical signs of scrapie?

•behavioral changes

•muscle tremors

•intense incessant pruritus****

•incoordination & ataxia

•death

who & signalment

2.5 - 4.5 y

Suffolk »»

goats get it from infected sheep (rare)

Rule-outs on a differential diagnosis list for Scrapie include:

•Contagious Ecthyma/Sore Mouth/Orf

•Ovine Progressive Pneumonia (OPP)

•Scabies (mange) and lice

•Caseous lymphadenitis

•Scabies (mange) and lice

diagnosis

–Hard to perform antemortem

–animal inoculation is not practical

•expensive and time consuming

what are the rule outs

-Scabies (mange), lice

–viral encephalitides

–neurotoxins

pregnancy toxemia

Scrapie is a reportable disease in Pennsylvania as there is an active national eradication program for the disease.  Integral to this control program is susceptibility testing that is

–Based on an ante-mortem biopsy of the animals nictitating membrane

–Based on a PCR assay on blood cells to check codon 171 of PrP gene

–Based on a post-mortem immuno-staining of brain tissue

–Based on antibiotic susceptibility testing of bacterial cultures

–Based on a PCR assay on blood cells to check codon 171 of PrP gene

how long does the flock infected with scrapie have to be monitored for?

42 mos

what are new developments used to control scrapie?

Q/Q (glutamine) – susceptible

Bovine spongiform encephalopathy (BSE) or “Mad Cow Disease” causes a neurodegenerative disease cattle.  BSE clinical signs include:

–Excessive anger specifically directed at people

–Increased milk production

–Signalment of being a British dairy cow between 3 and 5 years of age

Positive withers test

Signalment of being a British dairy cow between 3 and 5 years of age

signalment of BSE

3-5 y/o

BSE clin signs

•Alteration of nervousness, aggression, mental status apprehension

•Alteration of tremor, ataxia, falling, posture & movement paresis

•Alteration of   head shyness, hyperaesthia sensation to touch & sound

•General Signs: Deceased milk production, Loss of body condition despite continued appetite

BSE emerged in the mid 1980’s as a disease of British dairy cattle.  Critical to the control of this disease epidemic by the late 1990’s was

–The development of an effective vaccine in 1992

–Implementation of a specific ruminant offal (SRO) ban by the United Kingdom in 1988

–Culling and destruction of all cattle in the United Kingdom over the age of 30 months in 1996

–The announcement of the first case of  new-variant CJD in humans in 1996

–Implementation of a specific ruminant offal (SRO) ban by the United Kingdom in 1988

BSE - Impact on British Cattle Industry

•ruminant-derived protein removed from cattle feedstuffs

•red meat consumption in Europe initially fell 20-40%

•British beef industry devastated

–most cases have been reported in dairy cattle

•~ 50% of diary cattle culled and destroyed at the expense of the European Union

–models predicted this will not expedite eradication

remains a political rather than veterinary issue

New-variant CJD emerged as a novel human TSE characterized on post-mortem by “florid” plaques in neurons, neuropathology reminiscent of Kuru.   Clinical signs of nv-CJD differed from classical CJD such that:

–nvCJD patients were younger (29 vs 65 years)

–nvCJD patients had a longer course of disease (12 vs. 4 months)

–nvCJD patients presenting complaints were psychiatric problems & ataxia vs. progressive dementia & myoclonus

–All choices are correct

all correct

v-CJD

•younger age of patient

–median 29 vs.. mean of 65 for CJD

•longer course of disease

–median 12 mon vs. 4 mon for CJD

•lack typical EEG of CJD

•presenting complaint differs

–psychiatric problems & ataxia vs. progressive dementia & myoclonus

•neuropathology reminiscent of Kuru

–“florid” plaques

There are less than 200 deaths associated with nvCJD despite estimates of over 80 million Brits being at risk during the outbreak.   The unfortunate few that suffered nvCJD all had in common that they were:

–All homozygous for methionine codon 129 of prion protein gene

–All were vegetarians

–All lived near large dairy farms in northern Yorkshire county

–All were frequent visitors to McDonalds

–All homozygous for methionine codon 129 of prion protein gene