DISEASE E&E (Disease Emergence 2)

Question 1

Human demographics/behaviour:

Answer 1

-how we interact with animals
Ex. bush meat trade and Ebola virus

Question 2

Monkeypox outbreak US 2003:

Answer 2

-various reservoir hosts (rope squirrels, tree squirrels, poached rats, dormice, various monkeys)
-human-human transmission was limited (‘stuttering chains’)

Question 3

How did monkeypox get into US?

Answer 3

-having contact with infected prairie dogs purchased as pets
>touching sick animal
>receiving a bite or scratch
>cleaning cage or touching bedding of sick animal

Question 4

What was the source of monkeypox?

Answer 4

-shipment of animals from Ghana
-stored in close proximity to prairie dogs

Question 5

Examples of how people conceal animals, trying to get them into the country:

Answer 5

-ceramic garden gnomes
-hollow books
-computer hardware
-prosthetic leg
-behind or among legal cargo

Question 6

What are the most potent factors that drive disease emergence?

Answer 6

-human activities

Question 7

International travel:

Answer 7

-swifter movement of people, animals, and pathogens over large distances
-transportation of vectors
-9/11 caused a delayed outbreak and prolonged influenza season
-human migrants
-intensification of animal and plant trade

Question 8

FMD 2001 UK outbreak:

Answer 8

-first discovered at a pig slaughter plant
-farmer was probably feeding illegal food waste (ex. restaurant waste)
>restaurant was probably getting illegal meat from Asia
-sheep on the farm also got infected
-went to sheep market, where it spread even more
-2-3 weeks before they found the first case

Question 9

Ecology of food production:

Answer 9

-done on a global basis
-networks and pathways within these systems are not well described
-we have a very limited understanding of the complexities of these systems
Ex. one pen of 300 at a feed lot would have at least 100 farms

Question 10

Prior to BSE:

Answer 10

-several TSE’s (transmissible spongiform encephalopathies) were known in humans
>CJD
>Kuru

Question 11

Kuru:

Answer 11

-seen in tribe in New Guinea
-“to tremble with cold”
-the disease was infectious and probably spread through cannibalistic practices

Question 12

What is special about TSEs?

Answer 12

-prions (proteinaceous infectious particles)

Question 13

Natural uninfectious prion proteins:(PrPc)

Answer 13

-is found in cells of normal animals
>function is unclear

Question 14

Infectious prion protein (PrPsc):

Answer 14

-folded into a different shape
*change in 3D shape of protein makes it incredibly stable

Question 15

What happened in UK (BSE)?

Answer 15

-first known cases were on a dairy farm then found on more
-meat and bone meal (MBM) hypothesis

Question 16

Meat and bone meal (MBM) hypothesis:

Answer 16

-all cases had been fed MBM
-explained breed and geographic differences
>guernsey: high incidence (feed mill used MBM)
>jersey: low incidence (feed mill did not use MBM)
-risk of exposure to calves was 30x

Question 17

3 theories for origins of BSE?

Answer 17

1. Originated from a scrapie-like agent from sheep
2. Caused by spontaneous genetic mutation of the PRP gene of cattle
3. Originated from another mammalian species with a TSE, who’s carcass was rendered and incorporated into MBM

Question 18

Why was feeding of MBM so widespread?

Answer 18

-freely available
-was needed: no other easily available cost-effective source of protein feed in the UK
-commonly included as a protein source in calf starter rations

Question 19

MBM freely available:

Answer 19

-massive reduction in UK sheep flock
-there was no market for cull sheep beyond rendering

Question 20

BSE infected cows goes to slaughter or dies on farm:

Answer 20

-infective material
-brain
-spinal cord
-tonsils
-eyes
-small intestine
*food contamination
*rendering plant

Question 21

BSE infected cow cycle:

Answer 21

1. Infected cow
2. Dies or sent to slaughter
3. Food contamination OR
4. Rendering plant
5. Meat and bone meal
6. Feed mill
7. Fed to ruminants

Question 22

British epidemic steps to try stop it (BSE):

Answer 22

1. First verified case
2. Feed ban introduced
3. SBO ban
4. Mammalian MBM ban
5. Feed security assured

Question 23

SBO ban:

Answer 23

-specified bovine offal
-can’t use other parts besides the skeletal muscles

Question 24

2 ways BSE spread:

Answer 24

1. Ship cattle
2. Shipment/movement of MBM around the world

Question 25

How did BSE get to North America?

Answer 25

-did not import MBM from UK, most of it came from USA
-Saler cow was imported from UK, and many others from UK and Ireland
>CFIA culls
>some were already dead and went to rendering plants

Question 26

Measures to stop BSE in Canada:

Answer 26

1. Ruminants MBM ban to ruminants
2. SRM removal (food contamination)
3. SRM removal (rendering plant)

Question 27

SRM removal:

Answer 27

*specified risk material
-infective material
-brain
-spinal cord
-tonsils
-eyes
-small intestine

Question 28

MBM movement:

Answer 28

-simply a commodity
-traded and moved across borders
-commodity brokers look for opportunities to buy and sell it
-once it moves to another country, it quickly loses it’s identity of origin

Question 29

Microbial adaptation and change:

Answer 29

-emergence of antimicrobial resistant bacteria as a result of human usage of antimicrobial drugs in both humans, horses and pigs
-antigenic ‘drift’ of various influenza viruses

Question 30

Breakdowns or deficiencies in public health infrastructure:

Answer 30

-though as an important factor in developing countries, but can still happen in North America
Ex. Cholera outbreak in Haiti after earthquake
>outbreak of Cryptosporidium in North Battleford, SK
>mumps outbreak in university students in Canada (lack of vaccination of specific cohort of children)

Question 31

Outbreak of Cryptosporidium in North Battleford, SK:

Answer 31

-2001
-50 people hospitalized
-waste water treatment plant was upstream from the surface water treatment plant
>sedimentation failure in water treatment plant
>Doctor noticed the increased cases of diarrhea

Question 32

Walkerton, ON, 2000 (surface runoff with E.coli and campylobacter jejuni):

Answer 32

-entered a well supplying drinking water
-bacteria was from cattle manure spread (best management practices were in place)
-the well was chlorinated less than the amount required
>manually monitored: employees just made fictitious entries
-2300 cases of gastroenteritis, 7 deaths