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Tracking the next pandemic: Avian Flu Talk

H5N1 Testing & Triggers For Culling & Quarantine

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Jhetta View Drop Down
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    Posted: July 13 2006 at 1:36pm

Note from another thread
http://www.avianflutalk.com/forum_posts.asp?TID=10647


Note: This is important comparative info regarding regarding the accuracy and use of "rapid tests" for H5N1 detection in Romania: 
 
"Under the previous strategy, only the birds in the affected premises would be culled until laboratory tests confirmed the presence of the H5N1 form of the virus. To date, in 99 per cent of the cases that were tested using the rapid tests have been confirmed to be H5 by additional laboratory tests.

In order to prevent the virus spread further, the agriculture ministry is culling all birds within a three km area as soon as soon as rapid tests indicate the presence of avian influenza."

DEPARTMENT OF AGRICULTURE 

 

Avian Influenza Response Plan

 

 

AVIAN INFLUENZA

PROTOCOL # 22:  TRIGGERS FOR PLACEMENT OF GENERAL QUARANTINE AND SURVEILLANCE TESTING OF POULTRY FLOCKS

 

{For all subtypes}

 

Following the detection of Avian Influenza, flocks that are located on properties near a positive flock may have been exposed to the virus.  A general quarantine may be placed and surveillance testing of flocks within the quarantine zone may be used to gain information concerning the extent of an infection.

 

§         Triggers for placement of general quarantine and required surveillance (circle) testing:

 

o       H5/H7:

§         Serology or virus detection test positive for H5/H7 in a flock of any size:

·        Please note that if a flock is serology test positive but virus detection test negative for H5/H7, a general quarantine will be placed and surveillance testing initiated.

 

o       NON-H5/H7:

§         Virus detection test positive for NON-H5/H7 in a commercial flock (flock with 3,000 or more birds):

·        Waterfowl excluded.

·        Please note that if a commercial flock or any other flock is serology test positive but virus detection test negative for NON-H5/H7, surveillance testing will not be initiated unless special circumstances arise, at the discretion of PDA.

 

§         Samples:

Blood samples from live birds*:

 

o       Collect blood samples from 30 birds representative of the flock (from all areas of the house or cage banks).  If there are less than 30 birds in the flock, collect samples from all birds.

o       A second collection may be requested several weeks after the initial collection at the discretion of PDA.

o       Refer to the guidelines for collection and submission of samples included in this document.

 

* All samples must be taken by government authorized personnel (PDA, USDA, universities, and laboratory personnel), certified poultry technicians, or accredited veterinarians.

 

*Only birds 3 weeks of age and older will be tested*


 

Guidelines for Collection and Submission of Samples

 

Please Note:  Include the Premise ID number on all submission forms.  Call the Pennsylvania Department of Agriculture for a number if you do not have one.

 

Collection of Samples and Submission of Samples to PADLS Laboratories

 

Blood

·  Collect at least 2.5 milliliters (cc) of blood in tubes available from the PADLS laboratories.

·  Allow blood to stand for 4 to 12 hours at room temperature.

·  Place blood in refrigerator until it can be transported to the laboratory.

·  Complete the submission form and send it with the samples.

·  Write the farm name and Premise ID on the side of the box of samples (not on the lid).

·  Submit a completed submission form which includes Premise ID.

 

Submission

 

§   Samples can be tested at any PADLS laboratory.

§   Call the laboratory in advance to let them know when the samples will arrive:

·    PVL, Harrisburg: 717-787-8808

·    New Bolton Center: 610-444-4282

·    Penn State University Animal Diagnostic Laboratory: 814-863-0837

 

 

Reporting

 

§   Report any signs suggestive of AI in the flock immediately to the Pennsylvania Department of Agriculture at: 717-772-2852.

§   Signs suggestive of AI include the following:

·   Increased mortality;

·   Decreased egg production;

·   Swollen eyelids/sinuses/combs or wattles;

·   Purple or bluish discoloration of wattles and combs;

·   Respiratory snicking; and

·   Generally depressed birds.

·   Commonly, the producer will notice mortality increases and in the case of layers, decreased egg production, which usually trails the mortality by several days.

·   These are general guidelines only.

 

The Pennsylvania Department of Agriculture reserves the right to amend the above mentioned requirements for Avian Influenza with the goal of any changes still being to prevent, contain and eliminate the disease.  Changes to the general guidelines of the protocol may result from information including, but not limited to, virus strain, pathogenicity, morbidity and mortality, movement of birds and products, and additional epidemiological information obtained as a result of avian influenza investigations.

 

TEST DESCRIPTIONS FOR AVIAN INFLUENZA

 

AGID – The Agar gel immunodiffusion test uses positive control antigen obtained from National Veterinary Services Laboratory (NVSL), Ames, Iowa, which when placed in an agar well along with serum samples from birds, can detect the presence of antibodies to avian influenza in birds, indicating that they have been exposed to the virus.  A precipitation line is formed between the well containing the serum (if antibody is present) and the antigen.  The test does not differentiate between the types of influenza viruses or whether it is a recent or past exposure.

 

The Directigen Flu A test® is an enzyme immunoassay test for the rapid detection of influenza A viral antigen from specimens.  Usually cloacal and tracheal swabs are selected as bird samples, although lung tissue and oviduct contents can be used.  The test does yield some false positives when other proteins interfere.  A positive test usually indicates the presence of influenza virus in those tissues or samples and is hence followed up with viral isolation as a confirmation.  The Directigen® is a human test adopted in some situations for avian work.

 

VI- Virus isolation uses 9 to 11 day-old embryonated chicken eggs to which centrifuged or filtered samples of cloacal or tracheal swabs or similar samples from respiratory or intestinal tissues are inoculated.  Death in the embryos after 48 hours often indicates the presence of live virus.  The allantoic fluid harvested from the embryo (which would then contain the virus) is reacted with chicken red blood cells as an additional confirmation, and a panel of antisera is prepared to identify the various subtypes of influenza virus.

 

rRT-PCR- Real-Time, Reverse Transcriptase-Polymerase Chain Reaction, is a rapid molecular test, that can be used for diagnosis of group A influenza viruses. The test detects presence of viral ribo-nucleic acid utilizing matrix (MA) gene specific primers and a flurogenic probe. The assay also helps in sub-typing positive Group A influenza viruses into H5/H7/non-H5/H7 subtypes with use of specific haemagglutinin (HA) gene primers and probes.

 

The test has higher sensitivity for detecting AI in tracheal swab samples than cloacal or fecal swab samples. Overall sensitivity and specificity of the test compared to virus isolation, as determined by National Veterinary Services Laboratory, was found to be 88.2% and 99.5%, respectively. However, this test sensitivity was found to be much higher (95.1%) when using the test on a positive premise.

 

PROTOCOL # 25:  Live bird markets

 

Revocation of ORDER OF SPECIAL QUARANTINE through depopulation of BIRDS AND SWINE at A Live bird market (LBM)

 

{For All Subtypes}

 

Live Bird Markets pose a special biosecurity risk, because it can be difficult to prevent human traffic onto and off of the premises even with a quarantine.  Therefore, all birds and swine in a LBM which has had a positive AI test will be depopulated. 

 

When samples taken from birds or from the environment in a LBM are found positive for Avian Influenza by serology (bird samples) or virus detection testing (birds/environmental samples), the following protocol will be followed:

 

Ø      QUARANTINE:

o       The LBM will immediately be quarantined by the Department.  The regional veterinarian or a designee will post the quarantine.

o       Quarantine prohibits the movement of birds, swine, animal products, litter, and offal into or out of the LBM premises.

 

Ø      INSPECTION OF LBM RECORDS:

Department officials will inspect LBM records to verify that birds have been tested in accordance with Department requirements.

 

Ø      CONDEMNATION OF  BIRDS AND SWINE:

The Department will present a Condemnation Order to the LBM owner for signature before animals are depopulated.

 

Ø      APPRAISAL FOR INDEMNITY:

o       Department personnel will inventory and appraise all birds and swine on the premises, using fair wholesale market value.

o       All birds and swine shall be listed on the inventory by species and approximate weight.

o       The Department may provide indemnity for condemned animals up to 2/3 of the appraised value, plus the entire cost of cleaning and disinfection of the premises after depopulation and disposal has been completed.  The LBM owner must submit an itemized summary of costs for cleaning and disinfection to the Department.

o       Indemnity funds will not be provided or will be returned to the Department if it is proven that animals were illegally moved into the LBM or the Commonwealth.

 

 

Ø      DEPOPULATION OF BIRDS AND SWINE:

o       Depopulation of birds and swine shall be done within 24 hours of the laboratory notification whenever possible.

o       Under the direction of PDA and/or USDA, all birds and swine on the premises will be humanely depopulated according to AVMA guidelines.

o       AVMA guidelines are available at http://www.avma.org/issues/animal_welfare/euthanasia.pdf

 

Ø      DISPOSAL OF ANIMAL CARCASSES, LITTER, AND OFFAL:

o       Disposal method will be determined by AI subtype:

§         For H5/H7:

·        Preferred options include:

o       Incineration at an approved facility; or

o       Burial at a landfill approved by the Department.

o       Animal carcasses and other materials shall be loaded and transported for incineration or landfill disposal under the supervision of the Department and/or USDA.

 

§         For Non-H5/H7:

·        Preferred options include:

o       Incineration at an approved facility; or

o       Burial at a landfill approved by the Department.

o       Animal carcasses and other materials shall be loaded and transported for incineration or landfill disposal under the supervision of the Department and/or USDA.

 

o       Disposal of animal carcasses and other materials shall be done within 24 hours of the diagnosis whenever possible.

o       If animal carcasses and materials are transported to the laboratory for incineration, all animal carcasses and materials must be placed in red bags and tagged “for incineration” before being placed in the cooler at the laboratory.

o       Armstrong Environmental Services and/or other approved disposal companies may be utilized for loading, transport, and disposal. 

 

Ø      CLEANING AND DISINFECTION:

o       Following depopulation and disposal, the LBM premises must be cleaned and disinfected.  Department and/or USDA officials will supervise the cleaning and disinfection and will inspect the premises after it has been completed.

o       At the Department’s discretion, the Department may require that cleaning and disinfection be repeated.

o       Cleaning and disinfection costs may be included in indemnity from the Department and/or USDA.

 

Ø      RELEASE FROM QUARANTINE:

o       After the Department has approved the cleaning and disinfection of the premises;

§         The LBM must be closed for at least 3 days and must be allowed to dry.

§         When the Department or USDA has determined that the LBM is dry, officials will collect environmental swab samples from the premises.

§         8 to 10 tubes should be collected from the LBM and each tube should contain 5 swabs, for a total of 40 to 50 swabs.  Swab samples should be collected from walls, drains, floors, sinks, slaughter equipment, cages, crates, and any other areas of the LBM which may be considered high risk.

§         The environmental samples will be submitted to a PADLS laboratory for virus isolation testing.  This testing takes approximately 7 days. 

§         If the laboratory reports that all tests are negative, the LBM may be released from quarantine.

§         Total down time may be approximately 10 days in most cases.

§         If any environmental samples test positive, cleaning and disinfection must be repeated, and environmental samples will again be collected and tested. 

§         If environmental samples are positive after 3 cycles of cleaning and disinfection/testing, the Department may require an extended down time.

 

 

The Pennsylvania Department of Agriculture reserves the right to amend the above mentioned requirements for Avian Influenza with the goal of any changes still being to prevent, contain and eliminate the disease.  Changes to the general guidelines of the protocol may result from information including, but not limited to, virus strain, pathogenicity, morbidity and mortality, movement of birds and products, and additional epidemiological information obtained as a result of avian influenza investigations.

 
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AMES, Iowa ~ Agriculture Department prepares for bird flu testing
http://www.avianflutalk.com/forum_posts.asp?TID=8647&PN=1

AMES, Iowa (AP) - The government's elaborate network for diagnosing bird flu will eventually come down to a sprawling 640-acre campus in the Iowa countryside where strict security is the only hint of the crucial role scientists there could play in a national drama that the country hopes will never materialize.

The security and the elaborate protective clothing the Agriculture Department scientists wear - scrubs, coveralls, rubber boots, protective glasses, hairnets and gloves - looks like a made-for-TV disaster movie....."

"Samples will be shipped to a network of laboratories across the country for screening. If a sample contains evidence of the H5 virus, it then gets shipped to Ames, where tests are run over several days to determine if the infected bird carried the H5N1 strain.

First, virus from the sample is injected in bird eggs, which are tested five days later to determine whether it is one of 144 strains of bird flu or whether it is another disease such as Exotic Newcastle, which is harmless to humans but deadly to poultry.

If it contains bird flu, the sample is tested to determine whether it is H5N1 or another of the avian influenzas. Only those testing positive for H5N1 go to the lab with the caged chickens.

Eight of these birds, specially bred and disease-free, are injected with virus from the suspect sample. Perhaps within hours, certainly in two days, the birds will begin moving more slowly, perhaps hunching in the corner of the cage and no longer eating and drinking. Their wattles might turn from bright orange to blue.

"If you lose 75 percent of the chickens, or more, then it's high-path," said Brundaben Panigrahy, head of the lab's avian section, using scientists' shorthand for the lethal strain of Asian bird flu.

Although the test results will be announced publicly, likely by officials in Washington, Granger said this will not be a signal of a threat to humans."

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Americas food inspection system is similar to Canada's...
 
"Which subtypes are routinely tested for ?

The Canadian Food Inspection Agency has the capability to test for all sixteen subtypes of avian influenza.

In the case of an epizootic (animal epidemic), the focus of testing would become the H5 and the H7 and their subtypes, which have caused disease in domestic birds in the past and which have historically been known to change from low to high pathogenic."
 

Canadian Food Inspection Agency

Avian Influenza - Virus Subtypes

What is avian influenza?

Avian influenza (AI) is a contagious viral infection caused by the influenza virus Type "A", which can affect several species of food producing birds (chickens, turkeys, quails, guinea fowl, etc.), as well as pet birds and wild birds. All subtypes of influenza A viruses are naturally hosted by wild waterfowl.

What’s the difference between low and high pathogenicity?

Avian influenza viruses can be classified into two categories: low pathogenic (LPAI) and high pathogenic (HPAI) forms based on the severity of the illness caused in domestic birds. The first causes mild illness, including ruffled feathers or reduced egg production. The second form, known as "high pathogenic avian influenza" is of greater concern. This form is extremely contagious in birds and rapidly fatal.

How many variations of the virus exist?

Influenza A viruses can be divided into subtypes based on two proteins on the surface of the virus - hemagglutinin (HA) and neuraminidase (NA). There are 16 known HA subtypes (H1-H16) and nine NA subtypes (N1-N9). Any number of combinations are possible, as each virus has one HA and one NA antigen.

Are all avian influenza viruses the same?

Most avian influenza viruses are low pathogenic and typically result in little or no clinical signs in infected birds.

Only the H5 and H7 subtypes are of concern in domestic birds. Over the past 30 years only the H5 and H7 subtypes have been known to mutate into high pathogenic forms, therefore affecting birds at a higher rate.
 
All other subtypes (H1 through H4, H6 and H8 through H16) may cause disease and death in domestic birds. However, the illness spreads at a much slower rate than H5 and H7. Depopulation of birds infected with the H5 or H7 virus contributes significantly to reducing the amount of virus in the environment, therefore preventing the spread of the virus.

How many variations have been associated with illness in humans?

Some variations of the H5, H7 and H9 subtypes have also been associated with illness and disease in humans. Specifically H5N1 (most recently in Asia), H7N7 (previously in the Netherlands) and H9N2 (previously in Southern China and Hong Kong) have been known to cause illness in people.

For more information, visit the Public Health Agency of Canada Web site at: http://www.phac-aspc.gc.ca/influenza/avian_e.html

Which subtypes are routinely tested for?

The Canadian Food Inspection Agency has the capability to test for all sixteen subtypes of avian influenza.

In the case of an epizootic (animal epidemic), the focus of testing would become the H5 and the H7 and their subtypes, which have caused disease in domestic birds in the past and which have historically been known to change from low to high pathogenic.

Is there historical data in existence to which we can compare these new survey results?

A number of scientific studies, carried out by American scientists, have been published over the last 30 years. These studies were much narrower in scope than Canada’s wildlife survey. They focussed on two migratory pathways and had only limited sampling in Canada.

The survey undertaken by the Canadian Cooperative Wildlife Health Centre is broader in scope and more comprehensive in nature thereby providing the information necessary to provide a consistent and national benchmark for Avian Influenza in wild birds.

The table below demonstrates that the findings in Quebec at 7 % and in Manitoba at 4 % are both within the literature reported range of 0 to 7.4 %.

North American Findings of Avian Influenza in Wild Birds in the Last 30 Years

The following table outlines the occurrence of Avian Influenza virus subtypes in wild birds that have tested positive for AI.

Most Common Isolates H5 Isolates H7 Isolates H9 Isolates
H3 (32 - 44%)
H4 (5.8 - 28.5%)
H6 (3.3 - 16%)
0 - 7.4%
N types 2, 3, 4, 8, 9
( no N 1 detected )
1.0 - 4.2%
N types 1, 2, 3, 5, 8, 9
0.3 - 7.6%
N types 1-9

 

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