Don’t panic!

In recent months, the media has been full of dramatic headlines announcing the latest developments in the spread of the highly pathogenic H5N1 strain of avian influenza, even more so since the disease arrived in Europe. However, despite the vast amount of information on AI, there appear to be some common misunderstandings about the disease, particularly with regard to vaccination and food safety.

Here, Declan O’Brien, Managing Director of IFAH-Europe, the federation representing the European animal health industry, dispels some misunderstandings about avian influenza by explaining some key facts related to food safety and vaccination.

Avian influenza – the clue is in the name!
Highly pathogenic avian influenza is a devastating disease, for birds; it spreads quickly and is fatal, therefore prevention is the order of the day. There are three lines of defence:

• Biosecurity measures – protecting farms against exposure to the virus by restricting poultry movement, hygiene measures, protecting flocks from contact with wild birds etc.
• ‘Stamping out’ – culling of infected birds and appropriate disposal of carcasses.
• Vaccination – as a preventative measure before infections have been detected or as an emergency measure to prevent the further spread of the infection where it has occurred.

These first two lines of defence are generally well understood, but there are a number of misconceptions about the third, vaccination, which is explained later on in this article.

Perception of food safety risk
Although there have been human infections of the H5N1 strain of the virus, some of which have proved fatal, it is important to note that all have occurred in people who have had extremely close contact with infected birds. There have been no cases of human-to-human infection and no cases of infection from eating eggs or poultry products from infected birds. This, however, has not stopped a dramatic fall in the consumption of poultry and poultry related products in some countries. For example, according to the UN News on February 28th, a 70 percent fall in consumption occurred in Italy, following the discovery of the virus.

When looking at food safety concerns, it is necessary to highlight the fact that because of the biosecurity and surveillance measures that must be implemented by any EU Member State where the H5N1 strain has been detected (as laid out in EU Directive 2005/94), the chance of infected eggs or poultry products entering the food supply is exceptionally low. In addition, in the unlikely event that contaminated poultry products reached the food supply, the level of the virus would be extremely low. According to WHO advice, it presents no danger of infection provided that the food is properly cooked as the virus is killed at 70c. A recent EFSA report on avian influenza and food safety concluded that there is no evidence of risk to human health. So, as is often seen with food safety concerns, the perception of risk plays a far greater role than actual risk.

Interestingly enough, in France – which is to date one of only two EU member states to suffer an avian influenza outbreak in domestic poultry – poultry consumption has only experienced a 10 percent slump, much lower than Italy, where the disease was found only in wild birds. As part of its commitment to help the poultry industry through this crisis, the French government, through its French Agency for the Safety of Food (AFFSA), has continuously repeated the message that eating poultry and eggs presents no danger to public health. The message appears to have got through to French consumers.

Vaccination – implementation and implications
Vaccination is a preventative measure that must be carried out alongside biosecurity and ‘stamping out’ measures. The EU avian influenza directive, which IFAH-Europe supports, allows vaccination as a preventative measure in high risk situations as currently in place in the Netherlands or in emergency situations in the face of an outbreak to stop the disease in its tracks as is the policy right now in France.

Entire flocks must be vaccinated, which is done by injection, except that is for a handful of birds, which are legally required by the EU Directive to avoid masking the infection. These are often referred to as ‘sentinel’ birds. Vaccinated birds begin to build up immunity immediately after vaccination and after around three weeks their immunity is fully established. To extend the duration of immunity to one year, re-vaccination is required three to six weeks after initial vaccination.

Vaccinated birds need a greater amount of virus to become infected, and although it is possible during the initial period following vaccination for birds to excrete the virus (sometimes referred to as ‘shedding’), most vaccinated birds do not do so. Those that do, shed at such a low level that it is insufficient to enable the virus to spread to other flocks. Due to the requirement to leave some birds in each flock unvaccinated, there is no danger of vaccination masking the arrival of the disease. This is because in the event of an outbreak the sentinel birds would become infected and die and, as a result, the whole flock would be culled in order to completely eliminate the virus and prevent it spreading to other flocks.

Several animal health companies produce vaccines that protect against the H5N1 form of avian influenza, which are licensed for use in a number of European countries. In recent months, IFAH-Europe has been in close contact with the European Commission and the European Medicines Agency (EMEA) in order to offer the expertise of the animal health industry and to discuss how to obtain centralised licenses (valid throughout the EU) for avian influenza vaccines. Currently, avian influenza vaccines are licensed only nationally, so an animal health company must apply for a license in each country in which it wishes to supply its vaccine.

The key message here is that poultry meat, eggs and other poultry products from vaccinated birds are perfectly safe to eat. In advance of a vaccine being licensed for sale, the relevant animal health company must satisfy independent scientists from the relevant governmental authorities that the product is safe for use in food producing birds.

In conclusion, avian influenza is a devastating disease for birds. The objective is to prevent its arrival into a flock. Biosecurity, stamping out by culling and disposal of carcasses, and vaccination all have roles to play in prevention and eradication. Food from vaccinated animals is perfectly safe to eat and this safety is guaranteed by independent government scientists.

The term ‘H5N1’ refers to the arrangement of proteins on the surface of the virus where ‘H’ refers to the haemagglutinin protein and ‘N’ to the neuraminidase protein. An avian influenza virus is identified by the presence of a combination of H and N subtypes of which there are sixteen H subtypes (H1-H16) and nine N subtypes (N1-N9).