Surveillance of Avian Influenza in Animals FETP Avian Influenza - - PowerPoint PPT Presentation

Surveillance of Avian Influenza in Animals

FETP Avian Influenza Training

Photo by Dr. Sue Trock

Learning Objectives

• Describe surveillance methods for

avian influenza in birds and other animals

• Describe the difference in surveillance

methods recommended

– dependent on vaccination status of animals – based on pandemic phase

Surveillance Methods for AI

Animals

Goals of AI Surveillance in Commercial Poultry

• Early detection of AI infections

– Prevent costly outbreaks – Concerns about introduction of foreign poultry disease (unintentional or intentional)

• Assure that commercial poultry is free of AI

infection for trade purposes – Transparency – Assure continued market access

• Instill consumer confidence in poultry and

poultry products as it relates to public health

Goals of AI Surveillance in Commercial Poultry

• Accomplished through…

– Passive and Active Surveillance

Passive Surveillance in Commercial Poultry

• Investigation of clinical cases or flocks

with production drops or respiratory disease

– LPAI – HPAI

• Diagnostic methods

– Antibody detection – Virus/RNA detection

Buffer Zone Surveillance Zone Affected Zone

Outbreak and Surveillance Outbreak and Surveillance Outbreak and Surveillance

Active Surveillance in Commercial Poultry

• Organized random testing to detect infection
• Diagnostic methods

– Antibody detection – Virus/RNA detection

• Source of samples

– Testing at slaughter/processing – serum, eggs – Testing of exhibition birds – Export testing

Diagnostic Tests (Antibody)

• Type-specific tests (type A)

– Agar gel immunodiffusion (AGID) test – Enzyme-linked immunosorbent assay (ELISA) – Detect antibodies to all subtypes of flu virus – Performed at state/university/industry labs

• Subtype-specific tests (H and N subtypes)

– Hemagglutination-inhibition (HI) test – Neuraminidase-inhibition (NI) tests – Performed by reference labs (NVSL)

Diagnostic Tests (Virus)

• Virus isolation (embryonating chicken

eggs)

– Gold standard

• Real-time RT-PCR

– Matrix primers (detects all subtypes) – H5 and H7 specific primers

• Antigen capture ELISA (e.g. Directigen)

– Most useful for clinical or dead birds (acute infection)

Integrating Animal and Human Influenza Surveillance

• Big challenge for almost every country
• Better integration is essential for

preparing for threats to human health

• Need to encourage studies at the

human/animal and wild bird/domestic bird interfaces

• Need to improve global ability to

identify viruses of all subtypes

WHO/OIE Reporting

• Member states of OIE are to report within

24 hours suspected or confirmed cases of HPAI outbreaks in animals

• OIE

– publishes formal communications on

• utbreaks through its website

– issues press releases about established

• utbreaks in animals

OIE Website: http://www.oie.int/

Proposed WHO Animal Influenza Network

• Proposed to be an informal program to

bring together information from various animal influenza surveillance systems

– Clinical outbreaks investigated by diagnostic laboratories – Wildlife outbreaks investigated by wildlife disease groups – Systematic surveillance in lower animals and birds by research-based programmes

Differences Recommended Based on Vaccination Status

Unvaccinated vs. Vaccinated

• Unvaccinated

– Detection is simple in that only infected birds will test positive

• Vaccinated

– Detection is more difficult because vaccinated birds will have some antibodies or reactive proteins from the vaccine

Surveillance in Vaccinated Populations

Haemagglutinin expression-based vaccines

– Antibodies detected to specific HA but not any other of the viral proteins

Inactivitated whole virus

– Low titre of antibodies to NSP; titre in infected birds markedly higher Surveillance strategy dependent on type of vaccine used:

Using Sentinel Birds in Vaccinated Populations

• Sentinel birds should be

– Unvaccinated – AI virus antibody free – Clearly and permanently identified

Vaccinated birds will only have either

– antibodies to one of the specific proteins (but not all) or – low antibodies,

so infection in sentinel birds in a vaccinated population can be detected.

Differences Recommended Based on Pandemic Phase

For Countries Free of Infection

• Implement surveillance in higher risk

sites

– Borders and international entry points (particularly those adjacent to infected countries) – Domestic waterfowl – Unusual mortality in wild birds – Live bird markets

• Vaccine usage has impact

Previously Infected Countries No vaccination

• Surveillance should be targeted to the

following high risk areas and populations :

– Domestic waterfowl – Unusual mortality in wild birds – Live bird markets – Sentinel villages

Previously Infected Countries Practicing Vaccination

• Ensure vaccinated birds achieve

protective levels of immunity

• Field viruses are detected and

characterized

Resources

• FAO Guiding Principles for Highly

Pathogenic AI Surveillance and Diagnostic Networks In Asia

• OIE Guidelines for the Surveillance of AI
• WHO Guidelines for Global Surveillance of

Influenza A/H5

• WHO Manual on Animal Influenza Diagnosis

and Surveillance

Acknowledgements

• United States Department of Agriculture (USDA)

– David Swayne

• U.S. CDC

– Nina Marano – Thomas Gomez

• FAO Guiding Principles for Highly Pathogenic AI

Surveillance and Diagnostic Networks In Asia

• OIE Guidelines for the Surveillance of AI
• WHO Guidelines for Global Surveillance of

Influenza A/H5