25 June 2018 | Online since 2003

13 April 2017

The risk of H5N8 is not over yet!

Dr Alejandro Thiermann, former president of the Terrestrial Animal Health Standards Commission at the World Organisation for Animal Health (OIE)

The Department for Environment, Food and Rural Affairs (Defra) has lifted the remaining housing orders still in effect in parts of England. The housing orders were originally put in place across the whole of the United Kingdom in early December to try to prevent the spread of highly pathogenic H5N8 avian influenza from continental Europe.

When cases appeared in this country - there have been at least 10 cross England and Wales - the housing orders were extended until the end of February. From the beginning of March orders were lifted across most of the United Kingdom, but they remained in place in areas of England designated higher risk.

Chief veterinary officer Nigel Gibbens has now announced that from April 13 all birds would be allowed out. The emergency labelling on egg boxes, which explained to consumers why birds were temporarily housed, ceases from that date and all free range chickens must now be allowed to range to maintain their free range status.

Ian Brown, head of the virology department at the Animal and Plant Health Agency (APHA)

Nigel Gbbens said, “We continually review our disease control measures in light of new scientific evidence and veterinary advice. Based on the latest evidence on reduced numbers of migratory and resident aquatic wild birds we believe that kept birds in the areas we previously designated as higher risk are now at the same level of risk as the rest of England and may now be let outside.

“However, all keepers must still observe strict disease prevention measures to reduce the risk of contamination from the environment, where the virus can survive for several weeks in bird droppings.

“This does not mean business as usual: the risk from avian flu has not gone away and a prevention zone remains in place, requiring keepers across England to take steps to prevent disease spreading. We continue to keep measures under review and keepers should check GOV.UK for regular updates.”
The decision to lift the orders was taken even though Ian Brown, head of the virology department at the Animal and Plant Health Agency (APHA) told delegates at the International Egg Commission (IEC) conference in April that H5N8 was not yet over in Europe.

"The message at the moment is that the outbreak is not over," he told those attending the IEC conference in Monaco, where the IEC devoted a whole session to the threat of AI. It was revealed during the conference that there had now been 1,629 cases of highly pathogenic H5N8 in 28 countries across Europe. Other strains of bird flu have been confirmed in other parts of the world - H5N1 in Asia and Africa, H5N6 in Asia, H7N9 in China and the United States.

New cases are still arising and Dr Alejandro Thiermann, former president of the Terrestrial Animal Health Standards Commission at the World Organisation for Animal Health (OIE), said the situation could be worse than people thought. "The fact that some countries appear blank is not that they are necessarily free of the disease, but that they are not reported," he said. "Reporting is an obligation for each member country but, unfortunately, it is not always done."

In the UK there have been 10 confirmed cases of H5N8 this winter, although none of the outbreaks have been in commercial layer flocks. Across Europe, only five per cent of the confirmed cases have been in layers.

Ian Brown said, "Every day I get asked the question when do I think the virus s going to stop in Europe," he told IEC delegates. "What's happening in wild birds is relevant because it tells us it's still there. We are still detecting it in wild birds. That's important information, but we need to focus on the poultry outbreaks because it's not just about the presence of virus in wild birds that will dictate when we get outbreaks.

"The message at the moment is that the outbreak is not over. Yes, I think it is declining and there will be a number of reasons for that. Firstly most of the migratory birds that brought the virus into Europe are now departing. But the virus may well be established in your local wild bird populations that don't leave your country for the summer.

"So we can still see some cycling in the local population. The other important piece is that the virus will survive in the environment after the wild birds have disappeared. How quickly it stays in that environment is dictated by a number of factors, not least temperature, humidity, presence of ultraviolet light. In Northern Europe right now the temperatures are still fairly cold. So you have got to add that factor in before you can think about getting into an area where you won't see new cases."

He was asked by one delegate whether he thought there was a danger of AI becoming endemic in wild bird populations. His response seemed to offer some hope that a virus may die a natural death. "We get cycles of new virus coming in through migratory birds, which then spill over into the local population. What we don't know at the moment is how long it will stay in that local population and continue to cycle. But you will reach a point where you don't have many susceptible birds left or the level of contact is reduced. That, then, goes against the virus maintaining." He said, "That will then go down. How sharply it will go down and whether it could ever become endemic is very early to say for this virus but if we look back to H5N1 and in the Americas with H5N8, those viruses do burn out in wild birds after a while. So whether they are going to become endemic in wild birds is highly debateable. We can't be absolutely sure. They may maintain cycles for a period and it might be more than a year."

United States delegate Chad Gregory of United Egg Producers warned that AI was here to stay. "This is the new world we are living in. It is something we are going to have to live with forever. It is here to stay and is something that is going to dominate IEC conferences going forward." The US egg industry lost 42 million birds in an epidemic that spread across the country in 2015.
The IEC has set up an expert group on avian influenza. Commission chairman Ben Dellaert said this group would be looking at possible new ways of preventing avian influenza. As part of this, the group would look at the pros and cons of vaccination. "It is a very important role we have here trying to tackle this problem," he said.

David Hughes, emeritus professor of food marketing at Imperial College London, and visiting professor at the Royal Agricultural University, said that avian influenza was a threat hanging over the industry. "Bird flu is a prospective very dark cloud. Three weeks ago I was talking in KL (Kuala Lumpur) in Malaysia. It was largely veterinary and technical people there and all the conversation was about AI. And the big, big worry was that there might at some stage be deaths associated with the transfer of the disease, not from bird to human, which is happening - in some countries there have been hundreds of deaths - but from human to human," he said. "If that does happen that would be a big, big, big problem. So there is a dark cloud."

Alejandro Thiermann said it was vital that countries followed international rules and reported outbreaks of bird flu. He said failure to report outbreaks could lead to disruption of trade, with countries shutting down imports to protect themselves. "There's a price to be paid when you want to trade if you don't have very transparent reporting." He said, "Keep that in mind when you have dialogue and discussions about trade. How transparent have you been?"

He said one function of OIE was to promote transparency and understanding of the rules to prevent spread of AI and the rules to prevent unjustified trade restrictions. "At times it's because of ignorance, not quite understanding international standards." He said, "At times they decide it's easier to close the market because somebody reported avian influenza then apologise two or three months later and re-open the market.

"The OIE does not have the power to enforce the implementation of standards or to punish those who don't. The only body that can do that is the World Trade Organisation." He said, "We need to find a mechanism to improve transparency and find a punishment for those who don't report and don't apply the rules."

In the UK concerns have been raised about the time taken and the cost of secondary cleansing and disinfection following an outbreak of bird flu. Ian Brown conceded that the current system had probably been "gold plated, belts and braces." But he said everyone was risk averse. "Nobody wants to come in and sign off cleansing and disinfection and then find several weeks down the stream infection comes back."

He said that APHA was working with the poultry industry to see whether it was possible to reduce the recovery period for a poultry unit hit by an AI outbreak. Those involved in the work had been trying to identify the high risk areas for re-infection following preliminary cleansing. One of these areas for free range producers was the range.

He said that APHA was seeking to find ways to "shorten the window so we can get the business back to usual." However, he said an assessment of risk suggested that, if nothing else was done after preliminary cleansing, there was a one in 23 chance that at least one further outbreak would occur in premises that had undergone preliminary cleansing. Following effective secondary cleansing and disinfection, the chance of re-infection was one in 470. "That gives you an indication of the scale here and the importance of secondary cleansing and disinfection," he said.

The remaining housing orders in England were expected to continue until the end of April. However, the decision was taken to lift the orders early because the majority of migratory wild birds had now left the United Kingdom.

Defra said that the risk of poultry becoming infected from H5N8 remained heightened and countries across Europe continued to experience outbreaks and observe cases in wild birds. Defra said it was stepping up surveillance of wild birds across the United Kingdom. It said that all poultry keepers must continue to take steps to reduce the risk to their birds, including minimising movement in and out of bird enclosures, cleaning footwear, keeping areas where birds lived clean and tidy and feeding birds indoors.


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