1. Avian Influenza –epidemiology and clinical features
Economic issue
Import/export issue
Zoonotic issue
Food safety issue
David A. Halvorson, D.V.M.
University of Minnesota
References: 1. Diseases of Poultry, 11th ed, Chap 5 2.
Economic issue
Zoonotic issue
Food safety issue
Import/export issue

2. Avian Influenza - the virus
Subtypes - surface proteins
Pathotypes - low and high path types
LPAI and HPAI
So far all HPAI viruses have been H5 or H7
“notifiable AI”
Susceptible to environment
Survives in cold moist conditions
Requires dense population of susceptible hosts
High mutation rate and constantly changing
H&N have little to do with pathogenicity, but… like a coat and pants, same number doesn’t mean same virus
Pathotypes independent of H&N, but… Cleavage site LP require host proteases, HP cleave on their own.
All AI bad for turkeys
Mutation rate means change
Segmented genome means change

3. Definitions? Bird flu / avian influenza
Any infection with an avian influenza virus
Or is it High Path H5N1 as found in East Asia?
What will the media call it if we get any avian influenza virus?
What will the press call it if we find H5?

4. What are the risks? Risk of introduction of AI into poultry flocks
Risk of spread within farm
Risk of spread from or to others
Risk of failure to detect
Risk of H5 or H7
Risk of High Path H5 or H7
Risk of human infection
Risk of pandemic
Risk of detection
Risk of reaction

5. The risk of introduction of Avian Influenza to your farm
Waterfowl and wild bird reservoir
Live poultry market reservoir
Swine
Reservoir requires susceptibles
waterfowl most important for turkeys
live markets more linked to chicken AI East coast for sure and probably to the CA outbreak in layers
swine a reservoir for turkey breeders (endemic in swine) this week BC quarantined turkeys with H3N2 swine
Commercial poultry cannot be allowed to become a reservoir, where has that happened?

6. major waterfowl brooding area
all 16 hemagglutinins and 9 neuraminidases
high rates of infection in juveniles
Recall turkey production MO and Ark and VA and NC
Only CA and MN have high turkey numbers and high waterfowl numbers of the top 6 turkey states
Photo: Patricia Sheley

7. Free Flying Floating Flu Factories
Enteric infection
10 billion per day
Free Flying Floating Flu Factories

8. “I wish viruses were the size of ping pong balls so people could see them.”
Dr Mahesh Kumar, poultry veterinarian, St Cloud, Minnesota

9. If AI viruses occupied one cubic inch
86,943 square miles in Minnesota
3.49 X 1014 square inches in Minnesota
One million ducks each excreting ten billion viruses per day (1016)
1016/3.49X1014 =
The whole state would be covered to 29 inches deep with virus from ducks in one day.
In 100 days it would be about 250 feet deep

10. Insert sentinel intro Sentinel duck study
Describe what was done, placement, weekly monitoring, including virus isolation etc.
Duck smiles as he gets swabbed (other end) Cloaca definition?
Lead into nest slide
Sentinel duck study

11. Years and percent positive
Vs weeks
Ducks lead into next slide

12. Vertical axis years and percent pos; horizontal axis is weeks
Turx

13. Note gazillion serotypes, also note H5N1
Lead into ducks and turks together (couldn’t do this today)

14. Lead into results

15. Sites and percent vs weeks
Paynesville H4N6, H3N6, H4N5, H12N5, H10N5, H4N2 and only H3N6 and H4N6 in turkeys
Svea H4N8 and H6N8 and no virus detected in turkeys
Some viruses infected turkeys and some did not. Also temporal effect.
Leads into next slide showing Svea and Paynesville

16. Svea – positive in August
Characteristics of pond and temporal isolation rate and duck activity
Lead into 4 year summary
Paynesville – positive in September

17. 4 years ducks and turx with weeks, then water temp
35 days at 40 F
7 days at 70 F
Red arrow shows where we began isolating virus from water

18. Mean environmental temp and detection of H5 in aquatic and terrestrial birds – east asia
Lead into Silver Lake winter

19. Describe sentinel ducks placed at Silver Lake in Rochester, MN late December of 84 and monitored 85
Results – note subtype.
Lead into MN history
Photo: Josh Halvorson

20. Over 60% of migrating NA birds use the Mississippi flyway

21. Minnesota history is primarily in turkeys and all low path AI
major turkey producing state
same geographic area as wild waterfowl
contact between range or semi-confined turkeys and wild birds
20 years ago as much as 10% of turkeys raised in Minnesota were raised on range.
Economic decision related to seasonal demand for holiday turkeys
Today - nil

22. Year Flocks Sub-types
(3) H1N1, H4N8, H6N1, H6N2, H6N8, H9N2
H4N1, H6N1, H6N2, H9N2, H10N7
H4N2, H4N6, H4N8, H7N3, H10N7
H5N2, H6N8, H10N7
H1N1, H3N2, H4N2, H4N8, H5N2, H6N1, H6N2, H6N8, H6N?, H9N2, H?N2
H5N?
H1N1, H2N3, H4N6, H6N8, H8N4
H1N1, H2N7, H4N2, H4N6, H4N8, H5N2, H5N6, H6N8, H7N3
H1N1, H4N3, H4N6, H4N8, H6N5, H9N9
H1N1, H3N8, H5N2, H5N8, H7N7, H9N5
258 (1) H2N2, H4N6, H5N6, H7N9, H8N4, H9N2
H1N1, H4N3, H4N8, H9N2, H10N7
H1N1, H6N2, H10N7, H13N2
H1N1, H4N2, H4N6, H4N8, H5N2, H5N3, H6N1, H6N2, H6N8, H7N3
H1N1, H4N2, H6N8, H7N3
H1N1, H4N6, H5N9, H9N2
H5N2, H6N?, H7N1
H1N1, H6N8, H9N2, H10N7
H2N2, H9N2, H?N2
1 (1) H1N1, (H5N2 pheasant)
H1N1, H6N1
H1N1
H1N1
H1N1, H9N9, H10N7
H1N1, H1H3N1N2, H?N?
H1N1, H1N2, H3N2,
H1N1, H3N1, H3N2, H3N?,
1974 – H5N1
28 Years of Avian Influenza Introductions in Poultry in Minnesota ( )
David A. Halvorson, DVM
University of MN
Dale C. Lauer, DVM
MN Board of Animal Health
Comments from Dale C. Lauer DVM, BAH:
This table shows all the subtypes of AI viruses, all low path, that have been identified..note the many H5 and H7’s.
1 - Range turkey production which has ceased for the most part 10 years ago, used to be our biggest risk. The biggest risk for influenza introductions now is the swine industry.
cases of AI in Minnesota in all had a H1N1 or H3N2 (we suspect swine) component, no other H types.
Provided by Dr. Michelle Powell

23. Minnesota History – all LPAI
110 introductions of avian influenza, 1100 turkey flocks, 1 commercial layer flock, 1 broiler flock, 3 gamebird farms
Is the decline after 1998 due to a decline in duck numbers?
25 years of using range turkeys for monitoring AI in the environment reveals 20 out of110 introductions were H5 or H7 in contrast to low level detection in waterfowl
Approx 2500 flocks raised in MN each year
One gamebird farm went under, one could have and one survived
All AI outbreaks in poultry in MN have been associated with wild bird or swine reservoir – no LBM
H3 very common in waterfowl but was rare in turkeys

24. Notifiable avian influenza – how likely?
Mich and CAlif were turkeys with no known association with LBMs, Ohio hatching eggs associated with Calif.
Rest associated with LBMs
H5 or H7 LPAI Oct 1, 2001 to Sept 30, 2002

25. AI in the Live Poultry Markets
Low pathogenicity H7N2 AI (LPAI) has been isolated frequently from live poultry markets in the North East since 1994.
Approximately 150 markets in NY, NJ and New England
Approximately 25 million birds marketed annually
LPMs also present in TX, CA, FL, MN and probably other States
Chicken outbreaks more associated with LBMs

26. State control programs require marketing of AI negative birds.
AI Epidemiology –
Live Bird Markets
State control programs require
marketing of AI negative birds.
Courtesy of Dr. Ernie Zirkle

27. Minnesota LPMs

28. H5/7 AI in Commercial Flocks Linked to Live Poultry Marketing Systems
LPAI: (H7N2)
: PA (47 flocks, 2.5 M birds)
2001: CT (1 flock, 16,000 birds)
: PA (7 flocks)
2002: VA, WV, NC (210 flocks, 4.7 M birds)
2003: CT (4 flocks, 4.5 M layers)
2004: DE, MD (3 flocks, about 500,000 birds)
2004: TX (H7N3; 2 flocks)
HPAI: (H5N2)
2004: TX (1 flock)

29. North American history of HPAI
1925 and 29 “fowl plague” NE US
A/chicken/Pennsylvania/83 H5N2
1994-? A/chicken/Puebla/94 H5N2
2004 A/chicken/Texas/04 H5N2
2004 A/chicken/British Columbia/04 H7N3

31. How does the virus travel from the reservoir to poultry flocks?
Waterfowl infect other wild birds and seed down the environment
Direct contact between poultry & wild birds
Indirect, anything traveling from contaminated environment to poultry & water itself
Live poultry markets
Indirect contact with crates, etc
Swine
Indirect contact with manure or people associated with swine
Birds that share waterfowl and poultry habitats
Waterfowl environment itself
Lead into contaminated crates

33. Once influenza is introduced, how does it spread from flock to flock & farm to farm?
Unclean bird-moving equipment or personnel
Partial flock removal
Moving actively infected birds
Manure movement
Dead bird disposal
Egg packing material
Crews & personnel
Lead into next slide McCapes et al
How about airborne transmission?

34. Lead into

35. Review: Reservoirs and Prevention
Waterfowl and other birds
Live bird markets
Moved by people

36. What does LPAI do to birds?
Low pathogenic AI is a problem in turkeys, broilers and egg laying birds
The subtype does not matter

37. Clinical signs
Huddling
Sinusitis
Eyes closed
Quiet

38. Clinical signs
Depression

39. LPAI in egg layers

40. Clinical signs
Depression

41. Clinical signs
Sinusitis

42. Clinical signs
Swollen infraorbital sinus
Nasal discharge
Watery eye

43. Clinical signs
Note density

44. Lesions Caseous exudate in the sinuses
Photo courtesy of Dr. Ilaria Capua

45. Lesions
Inflammation of air sacs
Air sac walls thicken
Exudate present

47. Fibrinous exudate in air sacs, pericardial sac, or the peritoneum

48. Economic loss to turkey growers due to LPAI in 1995
Utah Minnesota
mortality $374,000 $2,182,000
condemnation$793,000 $1,204,000
rescheduling $750,000 $2,000,000
vaccination $119, $140,000
medication $683,000
TOTAL $2,034,000 $6,209,000

49. Economic loss ($) due to avian influenza in Minnesota

50. Control: Biosecurity AI is preventable
Avoid wild birds and live bird markets
Structure the farm to reduce risk
Operate as if your economic survival depended on it
Movement of birds, manure, people and equipment

51. Questions?
Photo: Brent Halvorson