Avian Influenza: Outbreak in Spring 2015 and Preparing for Fall - - PowerPoint PPT Presentation

Avian Influenza:

Outbreak in Spring 2015 and Preparing for Fall

James A. Roth, DVM, PhD Center for Food Security and Public Health College of Veterinary Medicine Iowa State University

Topics for Today

• Understanding key properties of influenza

viruses

• How did the H5N2 virus get to Iowa?
• Characteristics of and response to the

current outbreak

• Preparedness for a potential return of the

virus during the next flu season

High Path Avian Influenza Outbreak

Canine Influenza Outbreak

Understanding Key Properties of Influenza Viruses

Influenza A Virus

• Enveloped RNA virus: 8 segments, H and

N are coded for by different segments

• 16 hemagglutinins
• Important for attachment to host cell
• 9 neuraminidase
• Important for virus

release from host cell

Influenza Antigenic Drift

• Point mutations in H and/or N
• H and N remain the same numbers but they are

different than the original

• May result in decreased immunity, antibody does

not bind as well

• Antigenic drift is the cause of seasonal epidemics

http://www.youtube.com/watch?v=ug-M1nIhfIA

Influenza Antigenic Shift

• Emergence of a new subtype

(change in H and/or N type)

• Example: H3N2 to H5N1
• No immunity, therefore causes

pandemics

• Mechanisms
• Direct transmission animal to human
• Genetic reassortment in a population
• Re-emergence of virus in a species

http://www.youtube.com/watch?v=DdFCx8jbesQ

Influenza A Reservoir

• Wild waterfowl and migrating birds

are reservoir

• All avian influenza viruses are type A
• All H and N types - low pathogenicity

in waterfowl

Interspecies Transmission

H3N8 H5N1 H7N9, H5N2, etc H3N2 H1N1 H1N2

H3N2 H1N1

H5N1*

H4N5, H13N9 All

Ferrets

H5N1* H7N9*

* Rare occurrences

H3N2

Zoonotic Influenza

• Avian influenza in humans: sporadic infections, some fatal
• H5N1, H7N9, H7N7 – Not in this hemisphere
• Swine influenza in humans
• CDC reported 31 cases from 2005-2011
• Prior to 2005: 1 case every 1-2 years
• H3N2 306 cases mostly in visitors to fairs, 2012
• Ferrets
• Can be infected by humans and vice versa
• Equine
• No reports of clinical cases caused by natural exposure
• Canine
• No reports of clinical cases caused by natural exposure

Center for Food Security and Public Health, Iowa State University CVM, 2011

Risk Factors for Influenza Disease

Risk Factors for Influenza Disease

High Pathogenicity vs Low Pathogenicity Avian Influenza

• LPAI- asymptomatic to

mild infection

• HPAI – can have 100%

morbidity and mortality, many body systems affected

High Pathogenicity vs Low Pathogenicity Avian Influenza

• HPAI:
• An H5 or H7 with specific genetics

and/or high lethality

• Any non H5 or H7 with high

lethality

• LPAI:
• Any H type including H5 or H7
• No or mild clinical signs
• Infection localized

How did the H5N2 avian influenza virus get to Iowa?

H5N1 Avian Influenza

• 2004/5 – H5N1 emerged in Asia, killed

millions of poultry and is zoonotic

• Concern that H5N1 would spread through

migrating waterfowl from flyways in Europe/Asia to the Western hemisphere

• Extensive surveillance programs established

in U.S.

• No detections of this strain of H5N1 in

Western hemisphere

• New strains of H5 avian influenza detected

in Canada and US fall 2014

−Not zoonotic

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H5N3 in wild birds H5N3 in poultry

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H5N2 in poultry H5N2 in wild birds

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H5N8 in wild birds H5N8 in poultry

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H5N1 in wild birds H5N1 in poultry

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H5N6 in wild birds H5N6 in poultry

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H5 HPAI reports from East Asia

September 2014 through April 8, 2015 (OIE)

Eastern Asia

Reports of H5 HPAI subsided in the region during summer 2014. Then in September,

• utbreaks of H5N1, H5N2, H5N6, H5N8

HPAI occurred in China. Original H5N8 outbreak occurred January- April, 2014, most intensely in S. Korea and

• Japan. After 5 months with no reported

cases, H5N8 was detected again, 24 September, in S. Korean commercial poultry. It was detected again in Japan in November. H5N2, H5N3, H5N8 outbreaks occurred in Taiwan in early 2015.

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Western Europe

H5N8 first isolated 4 November 2014 from commercial poultry in Germany; also isolated in November from a wild duck. By mid-December, H5N8 was isolated from commercial poultry in The Netherlands, United Kingdom, and Italy.

H5 HPAI reports from North America

November 2014 through April 8, 2015 (OIE)

H5N3 in wild birds H5N3 in poultry

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H5N2 in poultry H5N2 in wild birds

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H5N8 in wild birds H5N8 in poultry

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H5N1 in wild birds H5N1 in poultry

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H5N6 in wild birds H5N6 in poultry

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Eastern Asia

Reports of H5 HPAI subsided in the region during summer 2014. Then in September,

• utbreaks of H5N1, H5N2, H5N6, H5N8

HPAI occurred in China. Original H5N8 outbreak occurred January- April, 2014, most intensely in S. Korea and

• Japan. After 5 months with no reported

cases, H5N8 was detected again, 24 September, in S. Korean commercial poultry. It was detected again in Japan in November. H5N2, H5N3, H5N8 outbreaks occurred in Taiwan in early 2015.

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North America

H5N2 first isolated 30 November 2014 from commercial poultry in British Columbia;

• utbreak continues into 2015.

H5N8 first isolated 10 December 2014 from captive wild birds in Washington; later isolated from backyard poultry in Oregon. Similarly, H5N2 identified in US wild birds and backyard poultry. H5N1 first isolated 29 December 2014 from wild duck in Washington. H5N8 isolated 19 January 2015 from commercial turkey farm in California. H5N2 detected in poultry in South Dakota, Minnesota, Missouri, Arkansas, and Kansas in March 2015 and Ontario, Canada in April 2015.

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H5 HPAI reports from North America

November 2014 through April 8, 2015 (OIE)

H5N3 in wild birds H5N3 in poultry

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H5N2 in poultry H5N2 in wild birds

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H5N8 in wild birds H5N8 in poultry

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H5N1 in wild birds H5N1 in poultry

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H5N6 in wild birds H5N6 in poultry

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Migratory aquatic birds – also the likely mode for H5N8 HPAI virus spread to North America

Eurasian (EA) H5N8 was likely carried to Alaska by infected birds migrating on the East Asia / Australia flyway. Within 3 months, HPAI viruses were detected in the Pacific Americas flyway and the Mississippi/Central Americas flyway. EA H5N8 underwent gene reassortment with low pathogenicity avian influenza (LPAI) strains endemic to North American wild birds. This means a bird was co-infected at some point with the H5N8 and an American (AM) LPAI strain, enabling the 8 gene segments to be mixed and matched in new combinations. EA/AM H5N1 and EA/AM H5N2 isolates in the western and central US were reassortants that contained genes of North American and Eurasian origin.

East Atlantic flyway

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Characteristics of the current HPAI

• utbreak

Figure 1. All HPAI Detections As Of May 13, 2015 PM (as reported on www.aphis.usda.gov) *one or more detections may have occurred in county

Figure 7. Premises Detected for ALL STATES Including WILD BIRD detections from 12/8/2015 to 7/2/2015 By WEEK

 Earliest available date indicating clinical signs is used for figure. For most premises, this is the date of clinical signs, a suspect status, or a presumptive positive status. Some premises may only have a confirmed positive status date.  320 detections (4 captive wild bird; 21 backyard flocks; 211 commercial flocks; 84 wild birds).

• Only full weeks (7 days) are pictured; in addition to the dates pictured, there have been no detections after 6/28/2015.
• All captive bird, backyard flock, and commercial flock data are from EMRS.
• Wild bird dates are based on date of collection, from USDA/USGS/National Flyway Council data.
• This represents 80% of the captive bird detections, 100% of all other detections.
• Figures may change slightly as data is added to EMRS (e.g., date of clinical signs).

1 1 5 5 3 2 8 18 37 24 38 30 15 12 26 11 2 6 3 3 7 19 23 12 4 1 1 2 1 5 10 15 20 25 30 35 40 Wild Bird (Pacific) Commercial (Pacific) Captive Wild (Pacific) Backyard (Pacific) Wild Bird (Central/Miss) Commercial (Central/Miss) Backyard (Central/Miss)

First Detection in Commercial Iowa Flock Wild Bird Detections in the Pacific Flyway First Detection in a Commercial Flock in California First Detection in Commercial Minnesota Flock Wild Bird Detections in the Central/ Mississippi Flyways

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In March 2015:

• Iowa had 59.5 million egg layer chickens in

3,821 laying facilities (1st in US egg production)

• 16.5 billion eggs produced annually (17% of

national production)

• Raise over 11 million turkeys (9th in US turkey

production) on about 200 farm sites

Iowa Poultry Production

Highly Pathogenic H5N2 Avian Influenza in Iowa

Total Poultry Affected (6/8/2015) 31,502,052 Layers 24,725,086 Pullets 5,624,336 Turkeys 1,128,729 Hatchery 18,791 Backyard Flocks 5,110

April 13 to June 16, 2015 77 infected sites

−6 “Backyard” sites −71 Commercial sites

http://www.iowaagriculture.gov/AvianInfluenza.asp

Preparedness for Avian Influenza Secure Egg Supply Plan

Biosecurity Vaccination??

Control Area Established Around Each Infected Premises

• Infected Zone = 3 km, Buffer Zone =10

km (6.2 mile radius = 120 sq. miles)

• Quarantine, all poultry inspected
• Movement by permit only

Response to an Infected Premises

• Biosecurity
• Depopulation of all houses on premises
• Euthanasia – Foam, CO2
• Disposal
• Incineration
• Burial
• Composting
• Land Fill
• Cleaning and disinfection
• Remove quarantine and allow re-stocking

Secure Egg Supply Plan

http://www.cfsph.iastate.edu/Secure-Food-Supply/egg-supply.php

Designed to enable movement of eggs from non-infected premises in a Control Area:

• Audited biosecurity steps
• Surveillance: Daily PCR testing of pharyngeal swabs
• Epidemiology questionnaires
• Daily reporting of flock mortality and egg

production

• Movement permits issued by state and federal

authorities

Biosecurity to Control Introduction of Avian Influenza

The structural and operational biosecurity of large caged layer facilities has proven to be effective for control of endemic diseases, has enabled the production of eggs to be profitable for producers, available at a low cost for consumers, and has helped provide an economic engine for communities. However, the current level of biosecurity has failed to protect these facilities from the highly pathogenic H5N2 avian influenza virus.

Google Earth View

Layer facility with approximately 4 million hens Egg breaker for production of liquid eggs (70%

• f eggs produced

in Iowa are liquid eggs)

Biosecurity to Control Introduction of Avian Influenza

Potential sources of avian influenza virus

• Unfiltered air
• Contaminated feed
• Migrating waterfowl and their feces
• Water contaminated by waterfowl feces
• Flies and other insects
• Sparrows, starlings, and other birds
• Rodents
• Contaminated fomites

Vaccination as a Tool for Control of Avian Influenza

Vaccine is specific for the strain of virus in the vaccine and closely related

• strains. The current HPAI virus can

drift so that the vaccine has reduced efficacy, or it can shift so that the vaccine is not effective.

Vaccination as a Tool for Control of Avian Influenza

• Vaccinated flocks can still become

infected.

• Clinical signs may be greatly reduced, but

the virus can still replicate and mutate

• The flock will still need to be depopulated

to destroy the virus.

Vaccination as a Tool for Control of Avian Influenza

• New strains of either high or low

pathogenicity avian influenza virus can be introduced in vaccinated birds resulting in the need to depopulate

• Vaccination for HPAI will result in the

loss of most export markets for all poultry and uncooked products

Vaccination as a Tool for Control of Avian Influenza

• The next strain of avian influenza

virus may be zoonotic (e.g. Asian strains of H5N1, H7N7, or H7N9), greatly complicating the response effort.

• A vaccine for the current H5N2 virus

would not protect against these zoonotic strains of avian influenza

Comments and Questions: jaroth@iastate.edu 515-294-8459

The Gentle Doctor by Christian Petersen, 1938