Title: Avian Influenza David J' Henzler, D'V'M', Ph'D' Public Health Veterinarian West Virginia Dept of Hea
1Avian InfluenzaDavid J. Henzler, D.V.M.,
Ph.D.Public Health VeterinarianWest Virginia
Dept of Health and Human ResourcesBureau of
Public Health
- Presented at West Virginia University,
Department of Community Medicine, Public Health
Grand Rounds - October 11, 2006
2Outline
- Interaction of influenza viruses among different
hosts - Become familiar with the clinical morbidity and
mortality of LPAI and HPAI viruses - Learn survival times of AIV in the environment
- Understand global progression of the Eurasian
HPAI - Recognize the ecology of influenza viruses
- Whats in the future ???
3Acknowledgements
- Dr. Loretta Haddy, WVDHHR, Director Division of
Surveillance and Disease Control - Dennis Senne, USDA, NVSL, Ames, Iowa
- Dr. Tony Joannis, National Veterinary Laboratory,
Jos, Nigeria
4The Influenza Virus
- Orthomyxovirus
- Small-medium size, enveloped
- RNA
- Negative sense
- Single stranded
- 8 segments, codes 10 proteins
- Major surface proteins
- Hemagglutinin (H1-H16)
- Neuraminidase (N1-N9)
- 144 potential combinations
- Virulence varies (LPAI, HPAI)
5Type A Influenza Surface Antigens
Hemagglutinin (H) Subtypes
1 2 3 4 5 6 7 8 9 10 11 12
13 14 15 16
Human
Equine
Swine
Avian
Neuraminidase (N) Subtypes
1 2 3 4 5 6 7 8 9
Human
Equine
Swine
Avian
6H3
Ecology of Influenza
Genetic Reservoirs
H3, H7
H1, H2, H3
Intermixing
H5N1
Commercial, LBMs Others
H10
H1-12 H14-15
H1-2, 4-7, H9-13, 15-16
Other Aquatic Birds?
H1, H3, H4, H7, H13
H1, H3
Modified from D. Swayne
7AI Viruses Change Frequently
- Antigenic Drift mutations in H gene cause minor
antigenic changes to H protein - Continuous process
- Limits protective immunity, virulence shift
- Antigenic Shift Replacement of H or N
- Emergence of novel (pandemic) strains
- Genetic reassortment (human and animal viruses)
- Recombination
- Insertion of large chunk of extraneous RNA near
the HA cleavage site virulence shift
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9Asian H5N1 Bird FluWhere Did it Come From?
- 1996 HP H5N1 isolated from geese in Guangdong
Province, China
- 1997 - Hong Kong
- 18 human cases, 6 deaths
- 1.5 M birds depopulated
D. Swayne
10Cumulative Number of Confirmed Human Cases of
Avian Influenza A/(H5N1) Reported to WHO 3
October 2006
Total number of cases includes number of
deaths.WHO reports only laboratory-confirmed
cases.
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13Clinicopathologic Forms of AI
Highly Pathogenic (HPAI)
Low Pathogenicity (LPAI)
Localized infection no, mild disease (any
subtype)
- Acute, systemic
- disease
- High mortality
- H5 H7 subtypes
H5 and H7 subtypes are notifiable
International reporting
14AI Factors Influencing Pathogenicity
- Only H5 or H7 subtypes (most are LPAI)
- Polygenic
- HA plays dominant role
- Multiple basic amino acids at
- HA cleavage site
- Glycosylation sites near HA cleavage site
- Recombination - insertion of extraneous RNA near
HA cleavage site
15Pathogenesis of AI
Replication at point of entry
LP strains
HP strains
HA cleaved
HA cleaved
by furin, PC6 (ubiquitous)
by trypsin (localized)
Viremia
Respiratory / Intestinal
replication
Systemic infection
Multiple dibasic
Few dibasic
amino acids
amino acids
(B-X-X-R/)
(B-X-B-R/)
16HPAI outbreaks in poultry since 1959
- 25 outbreaks, 11 (H5), 14 (H7)
A/chicken/Scotland/59 (H5N1) A/turkey/England/63
(H7N3) A/turkey/Ontario/7732/66
(H5N9) A/chicken/Victoria/76 (H7N7) A/chicken/Germ
any/79 (H7N7) A/turkey/England/199/79
(H7N7) A/chicken/Pennsylvania/1370/83
(H5N2) A/turkey/Ireland/1378/83
(H5N8) A/chicken/Victoria/85 (H7N7) A/turkey/Engla
nd/50-92/91 (H5N1) A/chicken/Victoria/1/92
(H7N3) A/chicken/Queensland/667-6/94 (H7N3)
A/chicken/Mexico/8623-607/94 (H5N2) A/chicken/Paki
stan/447/94 (H7N3) A/chicken/NSW/97
(H7N4) A/chicken/Hong Kong/97 (H5N1) A/chicken/Ita
ly/330/97 (H5N2) A/turkey/Italy/99
(H7N1) A/chicken/Chile/2002 (H7N3) A/chicken/Nethe
rlands/2003 (H7N7) A/chicken/SE Asia/2003
(H5N1) A/chicken/USA-Texas/2004
(H5N2) A/chicken/Canada-BC/2004
(H7N3) A/Ostrich/South Africa/2004 (H5N2)
Largest outbreak in last 50 years
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18Serological Epidemiology (serum)
- 34 of 47 flocks had serum evaluated by AGID
- 24 flocks had antibodies present in gt 50 of
birds (71) - 10 flocks had antibodies present
in lt 50 of birds (29) - Multiple serum antibody measurements were taken
in 17 flocks of which 11 flocks (64.7) had
decreasing serum antibody - 5 (45.5) of these 11 flocks had rapid and steep
decreasing antibody over four to five months
19Serological Epidemiology (egg yolk)
- Egg samples were collected from nine flocks -
three of theses flocks had multiple egg
collections which allowed for some assessment of
antibody response as monitored by AGID on egg
yolks - In a period of six weeks measurable antibody
decreased rapidly from 97, 93 and 76
respectively to 10, 20 and 12 - In two of three flocks no detectable antibody was
present from a sample of 30 eggs each at 11 weeks
from initial detection of yolk antibody
20Serological Epidemiology(serum and egg yolk)
- This H7N2 (MPAI) virus did not result in full
conversion of birds when sampled for antibody-
many of which experienced declining antibodies on
a flock basis - These data also suggest eggs can be used as a
monitor for a flocks AI status but for a limited
period relatively early in infection - Eggs may not have detectable antibodies in the
first weeks following infection with (MPAI)
21Wild-Caught and Experimental Mouse Studies
- 141 wild House mice, Mus musculus, trapped from
eighteen poultry houses in the early stages of AI
infection and were not involved as biological
vectors of the H7N2 (MPAI) virus - Experimental studies with two strains of H7N2
(MPAI) isolates in influenza susceptible mice did
replicate in the respiratory tract and produce
infrequent mild lesions evident on histopathology - H5N1(HPAI) isolated from poultry and humans in
Hong Kong did replicate to high titers in
influenza resistant mice resulting in clinical
signs, and severe lesions in the respiratory
tract and death
22Traditional Depopulation Methods Spread the
Virus
- In the process of traditional depopulation
methods much organic debris including feathers,
dust, and other organic material became airborne - New farms located within 1 to 1 ¼ miles were
diagnosed with AI within a few days of
depopulating infected flocks with (MPAI) - The pattern of spread became predictable and six
premises were thought to be infected with these
methods prior to trial field experiments of
allowing birds to remain in production
23Depopulation Methods
24Surveillance and Control Measures Applied to
Flocks Remaining in Production
- Quarantine, strict biosecurity, and controlled
marketing of products - Nest run eggs were held in farm coolers during
early stages of infection and then sent to
further processing (breakers) via dedicated
trucks on dedicated days and a closed loop of egg
handling and transport materials - Surveillance mortality cultures, serum and egg
yolk antibody, environmental culture and sentinel
hen serology
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26Extent of OutbreakPennsylvania 2001-02 Broilers
- Nine broiler flocks affected (172,518 birds)
- Influenza isolated from seven flocks (142,816
birds) - Includes two broiler breeders (15,939 birds)
- Index case (12/4/01), others through 1/3/02
- Spread over two county area containing 3.5
million poultry - Five of seven cases within one-mile area, one
case 17 miles away and separated by two mountain
ranges
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29Hemorrhagic trachea with caseous plugs
Hemorrhagic wet edematous lungs
30FLOCK A
Fig. 1. Daily mortalities () of hens and
roosters in broiler breeder flock A before
(12/01/01), during and after the clinical phase
of avian influenza H7N2 infection.
31FLOCKS A B
Fig. 3. Daily egg production () in two broiler
breeder flocks A and B before (12/01/01), during
and after the clinical phase of avian influenza
H7N2 infection.
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33PA Overall Surveillance
1985 85,000 tests 2004 211,000
tests 2005 240,000 tests (estimate) AI
Monitored Flock Program 390 flocks Tested
Flocks Several hundred Meat Bird Surveillance
20 flock at slaughter Layers 12 to 30
eggs/flock/month Diagnostic Cases Dealer and
truck or crate wash facilities
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36Molecular Diagnostics
- Real Time RT-PCR (RRT-PCR)
- Smart Cycler System Cepheid, Sunnyvale, CA
- Results in 2.5 hr
- Matrix assay detects all subtypes
- Can differentiate H5 and H7 subtypes
37Cases of non- H5 or H7 AI
- 2004 19 cases (2 commercial layer complexes
(H2N2) - Frequently in muscovey ducks
- Duck flock with H4,N4,N2 antibodies (raccoon
captured on premise also with H4N2 antibodies) - 2005 21 cases (H4N2 from environmental sample
on dealer premise) H6N8 guineas and H11N9
environments in Northeast LBM (11/15/2005)-
depopulation of 535 birds
3821 Base Insertion in BC LPAI
- February 2004 in two-aged broiler breeder farm in
Frazer Valley, BC a 21 base AA insertion sequence
at hemagglutinin cleavage site over 3-wk period
HPAI - Resulting 17 million poultry depopulated
- Open air tissue grinding/composting after
depopulation procedures to another operation 12
days post
39Frazer Valley HPAI cont.
- Phylogenetic epidemiology of index case LPAI
(H7N3) to A/TU/Ontario/2000 (H7N3) - Lack of comprehensive AIV monitoring program in
Canada may have resulted in failure to detect
circulating virus - Bowes, VA, Ricthie SJ, Byrne S et al, Avian Dis.
48928-934, 2004
40Risk Factors Spread of AI H7N2 in 2002 VA
Outbreak
- Rendered Poultry Carcasses (Corrected OR of 7.3)
- Birds over 1019 wks (OR 4.9)
- Non-family caretakers (OR 2.1)
- Observation of wildlife (OR 1.9)
- McQuiston JH, Garber LP, Porter-Spalding, BA et
al, JAVMA, Vol 226, No. 5, March 1, 2005
41Stability of Hong Kong H5N1 Virus
in Feces at Environmental Temperatures
5
Wet Feces
(4 C)
4
3
Virus Titer (log 10)
2
Wet Feces
Wet Feces
(35 C)
(25 C)
1
Dry Feces
(25 C)
0
0
1
2
3
4
5
8
17
21
28
40
Days at Condition
Source Shortridge et al. 1998
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43HPAI H5 Experimentally Recovered from Chicken Meat
- 2 LPAI and 2 HPAI viruses intranasally inoculated
in 3-4 wk chickens - HPAI (H5N1) Korea 2003 and (H5N2) PA 1983 virus
detected in blood, bone marrow, breast and thigh
meat - Korea virus infected breast meat caused resulted
in AI infection and death - David E. Swayne and Joan R. Beck, Avian Dis.
4981-85, 2005
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46Highway or Flyway? Wild Bird Species Infected
with H5N1
Bar headed goose
Whooper swan
Greater black-headed gull
Grey heron
Brown-headed gull
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48Danube River/ Black Sea
?
49Index Case Nigeria, Africa February 8, 2006
50Poultry worker should put on face mask also motor
bike should be located further from .. THE
BUILDING (Biosecurity Measure)
51Keep sick birds away from feed mill (Biosecurity
may track virus on bottom of shoes and feed bags
to healthy poultry)
52Chickens in Kaduna State
53Hemorrhage in intestines (can also be END,
Coccidiosis, other)
54Chickens in Kaduna State
55Coloration and swelling
56Blue/purple coloration of leg shanks. Also swollen
57Ovarian follicles may be hemorrhagic
58Ostriches also infected
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60Human Influenza Pandemics
Antigenic Shift
1918 H1N1
1957 H2N2
1968 H3N2
- 1918-19 Spanish Flu (H1N1)
- - 20-50 million deaths worldwide - 500,000 U.S.
deaths - 1957-58 Asian Flu (H2N2)
- - 2-4 million deaths worldwide
- - 70,000 U.S. deaths
- 1968-69 Hong Kong Flu (H3N2) - 1 million deaths
worldwide -34,000 U.S. deaths
61Closing Thoughts
- International perspective visible (WHO)
- Poultry/birds are primarily infected (humans are
sentinels) - Extremely limited human-to-human transmission
- Antiviral therapy
- LHD planning
- Development of human vaccines
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64David J. Henzler, D.V.M., Ph.D. State Public
Health Veterinarian Bureau for Public
Health Division of Surveillance Disease
Control Infectious Disease Epidemiology
Program 350 Capitol St., Room 125 Charleston, WV
25301 Phone (304) 558-5358 E-mail
davidhenzler_at_wvdhhr.org
Snake River Hells Canyon, Idaho