AVIAN INFLUENZA
An Animal Health Perspective
Dr. Thomas J. Holt
State Veterinarian/Director
FDACS, Division of Animal Industry
Etiology
• Orthomyxoviridae
• Envelope
• Glycoprotein projections/surface antigens
• Hemagglutinin (HA) and neuraminidase (NA)
• 15 hemagglutinin and 9 neuraminidase antigens
• A Type designation (A - only, B or C only present in
humans)
• Primary reservoir is wild birds, especially water fowl
• H5, H7 strains of primary concern
2
Avian Influenza
• Incubation Period 3-14 days
• Highly contagious (100%)
• Low-Path - low mortality, recover in 3
weeks
• High-Path - >95% mortality within 24
hours
3
Disease in Poultry
• Low pathogenic strains
– mild to severe respiratory symptoms
– egg production may drop by up to 45% and take 2—4
weeks to recover
• High pathogenic strains
– severe respiratory distress, diarrhea, nervous signs
– watery eyes and sinuses
– cyanosis of the combs, wattle and shanks
– swelling of the head
4
Gross Lesions
Swollen head, edema
Paint brush hemorrhage
Excess mucous, hemorrhage
5
Why Control Low-Path H5/H7 AI?
• Significant carcass condemnations
• Significant egg production losses
• Inter-state and international trade embargoes
• Mutation to High Path
• Potential Zoonotic Disease
6
Infection and Depopulation Spatial Patterns
March 12 through June 24, 2002
7
Virginia: All Turkey and Chicken Flocks
As of April 18, 2002
Turkey or
Chicken Flock
8
2002 VA AI Outbreak H7N2
March 7-12
Index Case Confirmation
Voluntary Company Depopulation
On-Site Burial
March 28
20 Positive Flocks
State/Company Control Measures
Controlled Slaughter Permitted
9
2002 VA AI Outbreak H7N2
April 12
60 Positives Flocks
30 Flocks Pending Depopulation
24 hr. State Destruction Orders
USDA Assistance Requested
April 14
Initial Deployment of Task Force
April 18
Full Assistance of Task Force
10
Virginia: Infected Flocks (89)
As of April 18, 2002
11
2002 VA AI Outbreak H7N2
April 25 Barrel or Dead Bird Surveillance
12 Flocks Positive In Initial Round
May 8
West Virginia Flock Positive
Intensive Surveillance
No Additional Cases
July 2
Last Positive Case Found to Date
Continue Enhanced Surveillance
12
2002 VA AI Outbreak
197 Positive Farms/ 1000 Farms
20%
4.7 million birds/ 56 million birds
8.4%
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15
Types of farms affected
No. of farms affected …………………………...………. 197
Turkeys (78%):
Turkey breeders ……………………………………… 28
Commercial turkeys (meat) ……………………125
Chickens (22%):
Broilers (chickens) ……………..........................13
Broiler breeders (chickens) ………….………..29
Layers (chickens) ………………………………….…… 2
No positives found in area backyard
flocks or wild waterfowl.
16
Weekly Epidemic Curve
Avian Influenza, Virginia 3-3-02 to 7-15-02
26
24
22
20
18
16
14
12
10
8
6
4
2
0
3/3-3/9
3/24-3/30
4/14-4/20
5/5-5/11
5/26-6/1 6/9-6/15
Week of Diagnosis
6/30-7/6
17
18
Incident Command Post
19
VIRGINIA AVIAN INFLUENZA
TASK FORCE
Personnel
Total Personnel by Organization: 766
4/16/02 - 8/23/02
APHIS: 469
DHHS:
168
USFS:
61
State:
24
DODVC: 22
Contract: 22
20
Virginia AI Task Force
Mission: To control low path AI
1. Identify and eliminate foci of
infection
2. Prevent spread of disease
Priorities:
1. Safety of Incident Personnel
and Involved Public
2. Adherence of Strict Biosecurity
Measures by Incident Personnel
21
Three Focus Areas
• Surveillance
• Eliminate foci of infection
• Biosecurity
22
Laboratory Diagnosis
•
•
•
•
Viral isolation
AGID
ELISA
Battery of specific antigens to identify its
serologic identity (HA and NA type).
• Sera from infected chickens usually yield positive
antibody tests as early as 3 or 4 days after first
signs of disease.
• Real time reverse transcriptase polymerase chain
reaction (rT-RT-PCR)
23
Avian Influenza Tests
Virus Level
AGID
Directigen
RT-PCR
Virus Isolation
0
7
14
21
Days Post-Infection (Flock)
28
24
AI Surveillance
Pre-Outbreak
During
Outbreak
Post-Outbreak
Breeders or
Layers
NPIP required
Ab
testing
Ab At Slaughter
Weekly Ag
Bi-weekly Ab
Pre-Slaughter
Ag/Ab
Ab every 4-6
weeks
Pre-Slaughter
Ag/Ab
Breeder
Replacements
NPIP required
Ab
testing
Weekly Ag
Pre-movement
Ag/Ab
Monthly Ab
Pre-movement
Ag/Ab
Ab At Slaughter
Weekly Ag
Pre-Slaughter
Ag/Ab
Pre-Slaughter
Ag/Ab
None
Weekly Ag
Pre-Slaughter
Ag
Ab/Ag At
Slaughter
Turkey
Growout
Broilers
25
Barrel
Surveillance
26
27
Elimination of Foci of Infection
•
•
•
•
•
•
Rapid humane euthanasia of infected flocks
Rapid removal of carcasses
Disposal – a major challenge
Closing of Houses followed by testing
Cleaning and Disinfection of houses
Implementation of Biosecurity Measures
28
Carcass Disposal Methods
– On Farm Burial
– Incineration
– Landfill
– Composting
29
Biosecurity
30
31
Incident Command System
• Incident Command Staff
• Planning
• Administration and Finance
• Logistics
• Operations
32
Incident Commanders
33
Forest Service
34
Army
35
Department of Health and
Human Services
36
Incident Command System Daily
Meeting
0700
Surveillance Personnel (All)
0800
Daily Briefing (All w/o Surveillance)
1300
Chiefs Meeting
(Commanders and Chiefs)
1800
Planning Meeting (Planning)
1830
Plans Approval Meeting
(Commanders and Chiefs)
37
Planning Meeting
38
Morning Briefing
39
Supply
40
Training
Training
41
Surveillance
42
Epidemiological Assessments Proved
Critical in Success
• Surveillance Design for
Commercial Flocks
• Surveillance of Backyard Flocks
• Surveillance of Wildbirds
• Case Control Study
• GIS Mapping and Spatial Analysis
43
44
45
AI Case Control Study
Preliminary Results
Epidemiology Section
Analysis team:
Jennifer McQuiston
Lindsey Garber
46
Risk Factors Assessed:
Premises Characteristics
- Security
- Nearby lake/pond
Farm Management
- litter source
- dead bird disposal
Biosecurity
- Visitor log
- Showers
- Disinfectant Footbaths
Presence of Other Birds and Animals (wild, domestic)
Recent Visitors
Recent Travel
47
Case Control Study
Assessment of Risk Factors
Variable
Odds Ratio
P Value
Use of Renderer
7.3
<0.001
Older Birds
>10 weeks
>4
<0.001
Use of Non Family Caretakers
2.1
0.04
Family Member Working Offsite
2.0
0.03
Wild Mammals on Site
1.9
0.04
48
Epidemiological Considerations
• The source of this outbreak was never established.
• The same strain of H7N2 has been seen in other small
outbreaks in eastern states and live bird markets in the
Northeast over a number of years.
• A case-control study found flocks 7 times more likely to
be infected if transporting dead birds to a rendering
facility.
• No evidence was found of airborne spread or spread
associated with depopulation or disposal.
• Disease was spread primarily by movement of people and
equipment in a densely populated poultry rearing area.
49
Lessons Learned
 The H7N2 strain that has circulated among Live Bird
Markets of the Northeast and their supply and distribution
channels continues to represent a serious threat to
commercial poultry.
 Control measures need to be taken to lessen the spread of
this virus and further protect commercial flocks.
 Rendering practices need to be reexamined with respect to
the risk of disease spread.
 During an outbreak biosecurity measures at the farm and
plant level must be strengthened to prevent disease spread
by people and equipment.
50
Reasons for Success
• Lessons Learned from the Past
• Industry Involvement and Commitment
• Cooperation Between Virginia, West
Virginia, USDA and all of the Cooperators
• Improved Technologies (Rapid Diagnosis
and Computer Support)
• Rapid and Coordinated Response
51
AI Vaccination: Poultry
• Non H5/H7 AI vaccines routinely used
in some areas
• H5/H7 vaccines traditionally not used
because of trade restrictions
• Usage of H5/H7 vaccines requires
USDA and State Approval
52
AI Vaccination: Poultry
• 2003 Connecticut H7N2 Outbreak
Controlled and Eradicated utilizing
H7N3 vaccine, intense biosecurity, and
controlled slaughter
53
AI Vaccination: Human
• Animal Health responders must be
included in targeted human vaccination
in zoonotic outbreak involving poultry.
• Poultry workers in outbreak area of any
zoonotic AI should also be included as
priority for vaccination.
54
Commercial Poultry
in Florida
55
Added Animal Health Concerns
with Zoonotic AI
• Farm workers may introduce disease to
poultry
• Birds may serve as reservoir with on-going
human and bird exposure
• Personal safety of Animal Task Force
Workers and Poultry Caretakers
56
Added Animal Health Concerns
with Zoonotic AI
• Humane care and euthanasia of birds
• Carcass Disposal, Biosecurity, and
Environmental Safeguards
• Rapid Detection and Prevention of Spread
57
Florida Department of Agriculture and Consumer Services
Charles Bronson, Commissioner
AVIAN INFLUENZA
An Animal Health Perspective
Presented by:
Dr. Thomas J. Holt
State Veterinarian/Director
Division of Animal Industry
Phone: 850-410-0900
Email: holtt@doacs.state.fl.us