Transcript Slide 1

Zoonotic Influenza & Highly
Pathogenic Avian Influenza
(HPAI) in Poultry
Photo: Tim Uyeki, CDC
Learning Objectives
• Describe inter-species transmission of avian
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influenza virus
Describe characteristics of HPAI vs. LPAI
List avian influenza control measures in poultry
populations
Describe measures to mitigate risk for poultry
and outbreak response workers
3 Categories of Influenza in Humans
• Seasonal (Human)
• Avian (Zoonotic)
• Pandemic
Pandemic Potential
Hemagglutinin
Antigenic drift and shift
 Annual epidemics
 Large changes- rare
sporadic pandemics
Neuraminidase
M2
PB1
PB2
PA
HA
NP
NA
MA
NS
M1
Matrix
An influenza virus does not have to be
HPAI to have pandemic potential.
Many Species Affected by Influenza A
H1, H2, H3
H5N1
Commercial,
LBMs
Others
Genetic
Reservoirs
Intermixing
H10
H1-12
H14-15
H1-2, 4-7,
H9-13, 15-16
Other Aquatic
Birds?
H1, H3
H3, H7
H1, H3, H4, H7, H13
Two Groups of Influenza in Poultry
• Low pathogenic AI (LPAI)
 Most common influenza virus infection in birds
 Mild clinical and inapparent infections
 Any subtype (H1 to H16)
• Highly pathogenic AI (HPAI)
 Causes severe illness in poultry and often death
 Some H5 or H7 virus strains
 LPAI H5 or H7 can mutate into HPAI H5 or H7 subtypes
Most AI viruses are not a public health problem
Avian Influenza in Other Species
Domestic and wild birds
• Ducks, geese, sparrows, poultry, pets
• May be asymptomatic & infect other
birds
Mammals
• Humans, cats, dogs, pigs, horses, marine
mammals, ferrets, minks, stone marten
• Infection via exposure to infected birds
Avian Influenza in Cats and Dogs
Domestic cats, tigers, leopards, dogs
• H5N1 from ingesting infected poultry
• For HPAI H5N1 areas, FAO recommends:
Keep cats from infected birds
Keep cats indoors on commercial poultry
operations
Monitor cats for infection
Advises AGAINST killing cats to control virus
Role in spreading H5N1 is unknown
Highly Pathogenic Avian H5 and H7
Subtypes Can Cause Human Infection
• Transmission
Contact with infected sick or dead birds
Contact with contaminated poultry or bird products
Rare human-to-human transmission (HPAI H5N1)
• Human disease
Usually due to infection with HPAI
Severity varies by virus strain
LPAI infections documented
Usually mild symptoms
Examples: H7 and H9 viruses
LPAI Strains Can Mutate
into HPAI
• Wild birds introduce LPAI to domestic flocks
LPAI can rapidly evolve into HPAI
HPAI causes poultry epizootics
• Mutations observed with some H5 and H7
subtypes
Most H5 and H7 are LPAI, do not mutate
Need rapid detection and aggressive intervention
Can lead to pandemics
May take years to clear from a geographic area
Poultry Outbreaks:
Notifiable Avian Influenza (NAI)
World Animal Health Organization
“Avian influenza in its notifiable form (NAI) is defined as an
infection in POULTRY caused by any influenza A virus of the
H5 or H7 subtypes or by any AI virus with an intravenous
pathogenicity index (IVPI) greater than 1.2 (or as an alternative
at least 75% mortality) as described below. NAI viruses can be
divided into highly pathogenic notifiable avian influenza
(HPNAI) and low pathogenicity notifiable avian influenza
(LPNAI)”
LPAI Infection in Birds
• Natural hosts: waterfowl, gulls, shorebirds
Usually exhibit no signs of illness
• LPAI in non-reservoir species
Domesticated unvaccinated fowl easily infected
No outward disease or only mild infection
Non-specific signs (respiratory, ruffled feathers, reduced
egg production)
Easy to miss!
Resembles other diseases
Anticipated in some regions
HPAI Infection in Birds
• Natural host: wild birds and waterfowl
Usually asymptomatic
Severe, fatal disease in some wild bird species
• Domestic ducks
Can be infected but appear healthy
In contact with humans and domestic poultry
Transmit virus via feces and respiratory secretions
HPAI Symptoms in Poultry
HPAI lethal in poultry
• Facial edema; swollen &
cyanotic combs, wattles; drastic
decline in egg production
• Internal hemorrhaging in 48
hours
• Mortality nears 100%
• Difficult to miss - severe disease
and sudden onset
Transmission Between Birds
• Viral shedding – main transmission routes
Feces (most common in poultry)
Respiratory secretions
• Contact between infected & healthy birds
• Indirect contact
Contamination
Unwashed egg shells
Airborne transmission
Improper carcass disposal
Geographic Spread of Virus
• Movement of birds
Migratory and free-ranging birds
Legal poultry trade
Illegal poultry trade
• Movement of equipment
Vehicles, tractors, buckets
• Movement of people
Hands, hair, clothing, shoes
Investigators must practice biosecurity!
Review Question #1
Is LPAI or HPAI more common
among poultry?
Answer: LPAI
Review Question #2
Why is HPAI infection among
poultry important to public health?
Answer: HPAI has been transmitted to
humans and has the greatest know
potential to develop into a pandemic
Avian Influenza on Poultry Farms
Prevention and Control
Prevention and Control
• Increased disease surveillance in high risk areas
• Increased biosecurity on poultry farms
• Control of movement of birds and fomites
• Rapid, humane destruction of infected and at-risk
birds and proper disposal of carcasses
• Vaccination of at-risk poultry in some circumstances
• Timely updating of vaccines for poultry to keep up
with antigenic changes of circulating strains
AI Surveillance Tools:
Active Surveillance
• Test at poultry slaughter/processing sites
Trachael or cloacal swabs
Serum, eggs
• Test birds at live bird markets
• Test exhibition, pet and fighting birds
• Import and export testing
• Door-to-door interviews with poultry owners
AI Surveillance Tools:
Passive Surveillance
• Increase sick and dead bird investigations
• Investigate poultry clinical case reports
• Investigate flocks with production drops
• Investigate flocks with respiratory disease
Diagnosis of
Avian Influenza in Poultry
Detection
• Antibody, antigen, virus or RNA
Rapid tests
• Screen for infection of flock
Biosecurity Via Bioexclusion
• Keep poultry indoors
• Prevent new bird contact
• Clean/disinfect between
flocks
• Control traffic onto farm
FAO Sector Systems
For analytical purposes four main production systems
(sectors) have been characterized by FAO and OIE:
• Sector 1: Industrial Integrated System
• Sector 2: Commercial Production System
• Sector 3: Small-Scale Commercial Production System
• Sector 4: The Village or Backyard System
www.fao.org
Biosecurity: Sectors 1 & 2
Large Commercial Poultry Operations
• High level biosecurity
• Birds/products
marketed
commercially
Biosecurity: Sector 3
Small Commercial Poultry Operations
• Birds/products may enter
live bird markets
• Birds/products marketed
commercially and/or
distributed locally
• Low to minimal or
moderate biosecurity
Biosecurity: Sector 4
Backyard Poultry
• Birds/products
consumed locally
• Minimal-tononexistent
biosecurity
Biocontainment on Infected Farms
• Depopulate
• Movement control
 On and off farm
• Test birds
• Close and disinfect bird markets and swap
meets
Destruction and Disposal of Birds in
Affected Area
• Humanely kill birds within 24 hours of diagnosis
Carbon dioxide, dislocate neck, other methods
Keep accurate records
Dispose per EPA guidelines
• Communication and security
• Clean & disinfect
• 21 day hiatus after inspection
• Enhanced active/passive surveillance
Compensation
• Reimbursement for loss of birds
• Encourages
Voluntary reporting of sick/dead birds
‘Stamping Out’ efforts
• Payment
Monetary
In-kind payment (restocking, supplies)
Vaccination for Poultry with Inactivated
Whole Avian Influenza Virus
• Advantages
 Can be effective against circulating H5 subtype
Reduces viral shedding
• Disadvantages
Possible subclinical infection
Vaccinated poultry can still shed virus
Administered by injection
May limit exportation
Involves veterinary authorities
• Recombinant vaccines under development
Seasonal Influenza Vaccine
for Humans Exposed to H5N1
Vaccinate poultry workers and health workers,
but keep in mind:
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In tropics and subtropics, human influenza
epidemic all year
 Timing and vaccine composition challenging
Vaccine does not protect against H5N1, but
against reassortment
At least two week delay for protection
www.who.int
Occupational Exposure
to Sick Poultry
• HPAI & LPAI viruses can spread to humans
• Rare, but preventive measures critical
Biosafety measures
Personal protective equipment
• Surveillance of exposed workers
• Annual seasonal influenza vaccination
• Co-infection with avian and human influenza
A viruses could lead to reassortment
Personal Protective Equipment
(PPE)
• Impermeable gloves
• Goggles
• Respirators
Fit testing
• Protective clothing
• Boots or protective foot covers
• Biosafety and biocontainment
Photo: Tim Uyeki, CDC
Public Health and
Animal Health Integration
• Communicate and share data between animal and
human surveillance networks improves the ability
to:
Characterize risk
Prevent disease spread
Enhance control efforts
• Joint participation
AI surveillance, response and control group
Development of guidelines and action plans
• Cross-notification of results
Establish official channels of communication
Review Question #3
Why has seasonal influenza
vaccination been recommended in
poultry workers responding to H5N1
outbreaks in poultry?
Answer: Vaccination of poultry workers with
seasonal influenza vaccine may minimize the
risk of co-infection and genetic reassortment of
human and avian influenza viruses in humans.
Review Question #4
What are the benefits and drawbacks of
vaccines in the prevention and control
of HPAI in poultry?
Answer: They can limit spread of infection,
but may also prevent the implementation of
control measures when needed.
Limiting the Spread of Avian
Influenza A (H5N1)
Prevention of H5N1
Limit animal infections
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Improve farm biosecurity
Cull sick/exposed animals
Disinfect premises
Vaccinate poultry
Limit human infections
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Use PPE around sick animals and humans
Antiviral prophylaxis in at-risk individuals
Isolate and treat human cases
Educate the public
Develop preparedness and response plans
Public Health Response
to AI H5N1 in Birds
• Identify infection source
Eliminate risky exposures
Involve veterinary collaboration
• Identify contacts of human and animal cases
Actively monitor temperature & illness for 7-10
days
If ill, refer to physician
Do not test for H5N1 unless ill
• Give antiviral prophylaxis if indicated
Antiviral Chemoprophylaxis for
Human H5N1 Infections
CDC recommendations:
Pre-exposure for persons involved in killing or
disposing of infected poultry
Post-exposure for persons in close contact to
infected birds within the previous 10 days
WHO. Rapid advance guidelines for pharmacological management of H5N1. 2006
Antiviral Chemoprophylaxis for H5N1:
WHO Recommendations
Who is at low risk?
Those who:
Cull non-infected or likely non-infected animals
Handle sick animals while using appropriate PPE
Decontaminate environments while using
appropriate PPE
Antiviral chemoprophylaxis is generally not
recommended for low-risk persons
Antiviral Chemoprophylaxis for H5N1:
WHO Recommendations, continued
Who is at moderate risk?
Those who:
Handle sick animals or decontaminate without
appropriate PPE
Are unprotected & have exposure to infected birds or to
birds implicated in human cases
Chemoprophylaxis for a week after last exposure
WHO recommends oseltamivir for
chemoprophylaxis of high-risk groups
Antivirals Not Used in Animals
• Human use only
• Use in poultry threatens effectiveness for
treatment of human AI:
“WHO, FAO and OIE urge Member States not to use
antiviral drugs in animals in order to preserve the efficacy
of these drugs for the treatment of influenza infections in
humans.”
http://www.who.int/foodsafety/micro/avian_antiviral/en/index.html (November 2005)
Summary
• Isolate domestic birds from wild birds
• Practice good biosecurity in all flocks
• Need adequate surveillance systems
• Early detection and rapid response
• Response is a joint effort between both animal
and public health authorities
Resources
• Animal Health
World Organization for Animal Health: www.oie.int
UN Food and Agriculture Organization:
www.fao.org
USDA Avian Influenza website
http://www.usda.gov/wps/portal/usdahome?navid=AVIAN
_INFLUENZA&navtype=SU
• Human Health
World Health Organization: www.who.int/en/
US Centers for Disease Control: www.cdc.gov
Glossary for Lectora
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pathogenicity
highly-pathogenic avian influenza (HPAI) versus lowpathogenic avian influenza (LPAI)
zoonotic
mutagenic
epizootic
OIE
Depopulation
notifiable avian influenza
IVPI
Glossary, continued
• HPNAI
• LPNAI
• viral shedding
• fomites
• biosecurity
• PPE
• recombinant vaccines