Avian Flu Diary: OIE: H7N9 Represents An `Exceptional Situation’

Map Credit ECDC

# 7014

While I was away from my desk Crof posted a statement (see OIE on the "exceptional nature" of H7N9) from the OIE (World Organization For Animal Health) that discusses the difficulties inherent in containing an avian influenza outbreak that doesn’t visibly sicken poultry.

First excerpts from the statement, and OIE FAQ, and then I’ll return with more.

The OIE, World Organisation for Animal Health, highlights the exceptional nature of the influenza A(H7N9) event notified by China

Paris, 11 April 2013 – According to the official reports sent to the OIE by the Chinese Veterinary Authorities, poultry that have tested positive for the presence of influenza virus A(H7N9) and are also suspected of being the source of reported human cases, do not show any visible signs of disease, making it very difficult to detect this virus in poultry.

“Based on the information currently available we are facing a rather exceptional situation, because we are dealing with an influenza virus of very low pathogenicity for poultry which has the potential to cause severe disease when it infects humans”, stated the Director General of the OIE, Dr Bernard Vallat.

(Continue . . . )

The OIE also has a rather extensive FAQ on H7N9 Avian Influenza, portions of which are excerpted below:

Can culling be used as a control measure?

If the infection is detected in animals, generally a culling policy is used in the efforts to control and eradicate the disease.

Requirements include (and are described in the OIE Terrestrial Animal Health Code):

humane destruction of all infected and exposed animals (according to OIE animal welfare standards);

appropriate disposal of carcasses and all animal products;

surveillance and tracing of potentially infected or exposed poultry;

strict quarantine and controls on movement of poultry and any potentially contaminated vehicles and personnel;

thorough decontamination of infected premises ;

a period at least 21 days before restocking.

In the case of low pathogenic avian influenza like the current outbreaks of H7N9 declared by China, stamping out is generally applied at the level of the infected farm or within a short radius around the infected premises.

Does OIE recommend vaccination of animals to control the disease?

When appropriate vaccines are available, vaccination aims to protect the susceptible bird populations from potential infection. Vaccination reduces viral excretions by animals and the virus’ capacity to spread. Vaccination strategies can effectively be used as an emergency effort in the face of an outbreak or as a routine measure in an endemic area. Any decision to use vaccination must include an exit strategy, i.e. conditions to be met to stop vaccination.

Careful consideration must be given prior to implementing a vaccination policy and requires that the recommendations from the World Organisation for Animal Health (OIE) on vaccination and vaccines are closely followed (www.oie.int\downld\AVIAN INFLUENZA\Guidelines on AI vaccination.pdf).

In short, vaccination should be implemented when culling policies cannot be applied either because the disease is endemic and therefore widely present, or the infection in affected animals is too difficult to detect.

What are the OIE recommendations for trade in poultry from a country infected with influenza A(H7N9)?

The risk analysis to be used by importing countries in order to protect their territory from pathogens introduction is very complex and is based on a long list of OIE standards.

In the case of outbreaks of low pathogenic avian influenza of the H7 strain in potential exporting countries, the trade recommendations that apply can be found in the OIE Terrestrial Animal Health Code (Chapter 10.4; 2013). These measures are science-based and should not result in unjustified trade barriers; they include zoning and the testing of the animal populations of origin.

What compensation measures should be applied for the concerned farmers?

Systems for financial compensation of farmers and producers who have lost their animals as a result of mandatory culling requested by national authorities vary around the world; they may not exist at all in some countries. The OIE encourages national authorities to develop and propose compensation schemes because they are a key to early detection and transparency in reporting the occurrence of animal diseases, including avian influenza.

What are the food safety recommendations?

Animals which have been culled as a result of control measures in response to an outbreak of avian influenza, including the A(H7N9) virus, should not enter the food and feed chain as a precautionary and regulatory measure.

There is no evidence to suggest that the consumption of poultry or eggs fit for human consumption could transmit the AI virus to humans.

What is the public health risk associated with avian influenza?

AI viruses are highly species-specific, but have, on rare occasions, crossed the species barrier to infect humans. This disease should not be confused with seasonal human influenza (flu), a very common human disease (generally caused by human H1 and H3 viruses). Transmission of AI viruses to humans has occurred when there is close contact with infected birds or heavily contaminated environments.

Human disease has usually been related to the transmission of a highly pathogenic virus of animal origin. The current influenza A(H7N9) virus notified to the OIE by China is low pathogenic for poultry; investigations are being conducted to demonstrate possible links with the human cases, as the genetic similarity has already been established.

Due to the potential for human infection, it is recommended that people working with, or in contact with poultry suspected of being infected with AI viruses, wear protective clothing including face masks, goggles, gloves and boots.

What prevention measures are recommended at the farm level?

It is essential for poultry producers to maintain biosecurity practices to prevent introduction of the virus in their flock:

keep poultry away from areas frequented by wild fowl;

keep control over access to poultry houses by people and equipment;

do not provide elements on property that may attract wild birds;

maintain sanitation of property, poultry houses and equipment;

avoid the introduction of birds of unknown disease status into flock;

report illness and death of birds;

appropriate disposal of manure and dead poultry;

vaccinate animals when appropriate.

The `exit strategy’ on vaccination mentioned in the second section above has been a largely ignored feature of the OIE avian flu recommendations for years.

In Avian influenza and vaccination: what is the scientific recommendation?, the OIE reiterated their strong recommendation that humane culling be employed to control avian influenza, and advising that vaccines should only be used as a temporary measure.

While the OIE conceded that some nations may require the use of vaccines for `several years', they have consistently urged that countries move away from that program and towards the more conventional culling policy.