Avian Influenza
Symptoms in Birds
Texas A&M University
College of Veterinary Medicine
Clinical Symptoms
of Avian Influenza
This presentation is about
Avian Influenza as it affects birds
2006
Avian Influenza
Avian Influenza
A contagious viral infection and/or disease of many avian
species including poultry, wild and exotic birds, ratites,
shore birds and migratory waterfowl.
The highly pathogenic form of the disease is
characterized by severe depression, decrease in egg
production, high mortality, edema, hemorrhage, and
frank necrosis.
All H5 and H7 infections are reportable to the World
Organization for Animal Health (OIE).
Dennis Senne 2005
2006
Avian Influenza
Avian Influenza
Low pathogenic avian influenza (LPAI)
– Associated with mild illness in poultry
– Can evolve into highly pathogenic viruses
– Associated with poultry outbreaks worldwide
High pathogenic avian influenza (HPAI)
– Causes high mortality in domestic poultry
– Subtypes H5 and H7
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Avian Influenza
H5N1 virus
electron micrograph of avian influenza H5N1 virus
2006
Avian Influenza
Host Range
•Exotic Birds
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Avian Influenza
•Domestic Poultry
Peri-domestic species
Occasional isolations
of avian influenza virus
from starlings and
house sparrows (in
contact with infected
poultry)
Replication of some
avian influenza virus in
these species
(experimental)
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Avian Influenza
Natural Reservoirs of
Influenza A Viruses
Wild aquatic birds
Majority are represented
by two Orders:
1. Anseriformes (ducks,
geese, and swans)
Dennis Senne 2005
2006
Avian Influenza
Natural Reservoirs of
Influenza A Viruses
2.Charadriiformes (gulls,
terns, and shorebirds)
Usually show no
clinical disease
Dennis Senne 2005
2006
Avian Influenza
The Muscovy Ducks
Natural Reservoir
http://www.domestic-waterfowl.co.uk/mozzie.htm
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Avian Influenza
How are these viruses transmitted
and maintained in these species?
Transmission: Fecal/Oral route
Heavy fecal shedding by infected ducks
Long term persistence in water
Isolation of AIVs from surface water
Maintenance: Bird to bird
Persistence in environment
2006
Avian Influenza
Clinical Signs
Incubation period 3-5 days
Severe depression
Decreased food and water consumption
Drastic decline in egg production
Many birds affected
2006
Avian Influenza
Turkeys with Avian Influenza
cvm.umn.edu
Many birds are depressed and huddling
2006
Avian Influenza
Clinical Signs
Dehydration
Huddling
Subcutaneous swelling of the head and
neck area
Nasal and oral cavity discharge
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Avian Influenza
Note swollen head, and discharges.
Wattle is cyanotic and necrotic.
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Avian Influenza
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Avian Influenza
Clinical Signs
Huddling
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Avian Influenza
Clinical Signs
Ruffled feathers
Swollen, cyanotic (blue) combs and
wattles
Conjunctivitis with respiratory signs
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Avian Influenza
Ruffled feathers
Respiratory Symptoms
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Avian Influenza
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Avian Influenza
Swollen blue, cyanotic combs and wattles
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Avian Influenza
Swollen blue, cyanotic combs and wattles
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Avian Influenza
Clinical Signs
Edema/necrosis of
comb/wattle
Cyanosis
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Avian Influenza
HPAI - Cyanotic comb of an infected chicken
on the left compared to a normal chicken on the right.
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Avian Influenza
Clinical Signs
Subcutaneous
hemorrhage
of shanks
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Avian Influenza
Subcutaneous hemorrhage of shanks
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Avian Influenza
Hemorrhage of the shanks and hocks
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Avian Influenza
Clinical Signs
Neurological signs (Nervous signs) Similar
to Exotic Newcastle Disease
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Avian Influenza
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Avian Influenza
Neurological signs
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Avian Influenza
Neurological signs
Cyanosis
Ruffled feathers
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Avian Influenza
Neurological signs
Hemorrhages on shanks
Ruffled feathers
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Avian Influenza
Clinical Signs
Coughing
Sneezing
Diarrhea
Sudden death
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Avian Influenza
Clinical Signs
I. Capua
D. Halvorson
Huddling
Sinusitis
Respiratory signs
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Avian Influenza
D. Halvorson
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Avian Influenza
Clinical Signs
Sudden onset and high mortality
Birds found dead
2006
Avian Influenza
Dennis Senne, 2005
Post Mortem Lesions
Lesions may be absent
with sudden death
2006
Avian Influenza
http://www.avian-influenza-disinfectant.com/avian_influenza.htm
Lesions
Head and neck edema
Swollen and cyanotic combs and wattles
Petechial hemorrhages on internal
membrane surfaces
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Avian Influenza
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Avian Influenza
Lesions
Excessive mucous exudate in the lumen
of the trachea, or severe hemorrhagic
tracheitis
Petechiae on the inside of the sternum,
on the serosa and abdominal fat,
serosal surfaces and in the body cavity
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Avian Influenza
Lesions
HPAI - Opened swollen wattle.
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Avian Influenza
Hemorrhages and edema
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Avian Influenza
Edema
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Avian Influenza
Petechial hemorrhages on
internal membrane surfaces
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Avian Influenza
Lesions
Hemorrhages of the trachea
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Avian Influenza
Hemorrhages of the trachea
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Avian Influenza
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Avian Influenza
Lung hemorrhage and edema
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Avian Influenza
Note hemorrhages and edema around the heart
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Avian Influenza
Lesions
Hemorrhages on the mucosal surface of
the proventriculus, particularly at the
juncture with the gizzard
Hemorrhages and erosions of the gizzard
lining
Hemorrhagic foci on the lymphoid tissues
in the intestinal mucosa
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Avian Influenza
Hemorrhages of the intestine
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Avian Influenza
Hemorrhages on the
mucosal surface of the
proventriculus, particularly
at the juncture with
the gizzard
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Avian Influenza
Hemorrhage in intestinal
serosa, mucosa
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Avian Influenza
Hemorrhagic foci on the lymphoid
tissues in the intestinal mucosa
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Avian Influenza
Lesions
Severe congestion of the musculature
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Avian Influenza
Lesions
Severe kidney congestion, sometimes
with urate deposits in the tubules
Hemorrhages and degeneration of the
ovary
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Avian Influenza
Differential Diagnosis
Clinically indistinguishable from virulent
Newcastle Disease
Suspect with:
Sudden death
Drop in egg production
Facial edema, cyanotic combs and
wattles
Petechial hemorrhages
2006
Avian Influenza
Differential Diagnosis
Velogenic Newcastle disease
Acute fowl cholera
Respiratory diseases, especially infectious
laryngotracheitis, Avian pneumovirus,
Infectious bronchitis
Chlamydia
Mycoplasma
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Avian Influenza
Differential diagnosis
Water deprivation
Heat exhaustion
Toxins – food or water borne
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Avian Influenza
Disease Summary
Avian influenza is a contagious viral disease
of birds characterized by respiratory signs,
depression and reduced feed and water
intake. In egg laying birds there is a
decline in egg production and quality.
There are two pathotypes of Avian
Influenza virus: the most common is low
pathogenic AI (LPAI) and the other is
highly pathogenic AI (HPAI).
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Avian Influenza
Disease Summary
The most virulent form (HPAI) was once called
fowl plague. At the 1981 International
Symposium on Avian Influenza, the term fowl
plague was replaced with the term "highly
virulent" influenza virus infection. The Avian
Influenza epidemic of 1983-1984 required yet
new terms to describe relative pathogenicity of
different isolates of the same serotype
(nonpathogenic, low-pathogenic, highly
pathogenic).
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Avian Influenza
Disease Summary
Avian Influenza outbreaks have occurred
throughout the world. LPAI is common in large
turkey-producing areas, particularly where semiconfinement or range-rearing is still widely
practiced. Outbreaks are more sporadic in other
areas of the United States. AI can occur in most,
if not all, species of birds. In the United States,
most outbreaks have been in turkeys. A few
outbreaks have occurred in chickens. Humans,
horses, pigs, and some wildlife species may be
infected with influenza viruses, and a cycle
between birds and swine exists.
2006
Avian Influenza
Disease Summary
A chicken outbreak of LPAI in 1983 mutated into
HPAI in 1983-1984 resulting in a federal-state
eradication program that required the
depopulation of 17 million birds. Similar
outbreaks of LPAI in Mexico in 1992 and Italy in
1999 also mutated into HPAI causing severe
losses.
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Avian Influenza
Disease Summary
Influenza viruses vary widely in pathogenicity and
ability to spread among birds. Two pathotypes
are recognized: LPAI and HPAI. These
pathotype designations are derived from
laboratory inoculation of 8 susceptible chickens;
LPAI isolates cause death in 0 to 5 of 8 chickens
and HPAI isolates cause death in 6 or more.
Although most H5 and H7 isolates are low path
viruses, so far all HPAI outbreaks have been due
to H5 or H7 viruses.
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Avian Influenza
Special thanks to the staff at
Plum Island Animal Diagnostic Center,
Dr Corrie Brown and Dr John El-Attrache
for the use of images from their presentations.
Also, thanks to the Pohler family and to
Elisabeth Bush for allowing me to
photograph their birds.
SUZANNE BURNHAM
2006
Avian Influenza