SOUTH AFRICA - Quick action and good biosecurity measures are the key to control of highly pathogenic avian influenza, representatives from Europe, the US and China told delegates at the Ceva symposium at the Congress of the World Veterinary Poultry Association (WVPAC 2015) in Cape Town.
Experience in the Netherlands
Dr Andre Steentjies, a member of the Poultry Veterinary Study Group of the EU, said that the Netherlands was quite unprepared for the avian influenza outbreak of 2003.
“The disease had a slow onset and it took a few days before we even suspected it was a strain of highly pathogenic avian influenza,” he admitted.
In the end the disease broke out on 255 farms. Thirty million birds were culled. Eighty-six people were affected (of which one died) and the total management cost mounted to more than 500 million Euros.
Dr Steentjies said that the country was so shocked by the outbreak that it introduced a high surveillance programme through which birds had to be tested within 24 hours to identify future outbreaks.
In addition to more stringent biosecurity measures, the government also introduced zone restrictions and restricted areas and corridors to prevent the disease from spreading. The Netherlands was in effect much better prepared for the recent outbreak.
“When the first outbreak occurred this year, government immediately introduced a three-day standstill by which movement on and off the affected farm was restricted,” Dr Steentjies explained.
The outcome was less severe than the 2003 outbreak with the disease only breaking out on 5 farms, of which one was on a duck farm. Dr Steentjies said that ducks were affected very mildly in comparison with the chickens.
Even so, the industry lost 345,000 birds, while the cost of management amounted to 49 million Euros.
Dr Steentjies said that there was no direct contact between the affected farms that explained the movement of the disease. Further investigations suggested that the disease most likely spread via migrating birds. He said that this posed a huge challenge for the country as European consumers are demanding more free-range chicken.
“The reality, however, is that it is much easier to enforce biosecurity on farms were birds are kept in housing, than on farms where they are allowed to roam outside,” he said.
Largest ever animal disease outbreak in US
Dr Mark Davidson, associated deputy administrator of the National Import Export Services of the United States Department of Agriculture (USDA) and Animal and Plant Health Inspection Service (APHIS) said the outbreak experienced in America which came to an end in June, was the largest animal disease outbreak the country has ever experienced.
The disease broke out in 21 states on a total of 226 premises. About 47.5 million chickens and 7.1 million turkeys were affected and it cost a half a billion dollars to control. The disease also had a huge impact on poultry meat and egg prices.
Dr Davidson said that the US devised a five step plan to spark quick reaction times in the event of future outbreaks, which he suspects might occur in autumn as outbreaks have also been linked to the movement of migrating birds, as was the case in the Netherlands.
- Movement had to be quarantined
- Affected birds had to be eradicated within 24 hours
- The outbreak had to be monitored to detect new outbreaks and show progress of interventions
- A disinfecting regime was needed to remove the virus from farms
- The disease had to be identified as soon as possible through testing
Dr Davidson said that depopulating birds within 24 hours was much easier said than done: “Many of the affected farms had large complex facilities with multiple barns and thousands of birds.
"Procedures were therefore put into place to ensure the availability of supplies and equipment to depopulate as humanely as possible.”
Disposing of the birds was also a challenge. Dr Davidson added that as few as possible birds were incarcerated because it was expensive. Most of the turkey farms had composting facilities and relied on these to dispose of birds with low pathogenic strains.
The problem however was that this required additional carbon sources, which most of the farms did not have access to. Burial was another alternative, but for this farmers could not just use any land and had to consider water laws.
He said that the industry at the moment is in a phase of still cleaning and disinfecting: “Removing the virus from premises is difficult and a highly labour intensive operation in these highly automated poultry facilities. We are using dry cleaning and heat to disinfect the facilities.”
So far the US has not made the decision to vaccinate birds to prevent future outbreaks. “It is a complex issue as it could potential affect trade with other countries. We might however revert to using it to manage future outbreaks.
"The decision will depend on various factors, such as the poultry density in the affected area, the type of birds and what is happening in neighbouring areas,” he said.
Live bird markets a concern in China
Professor Liu Xiufan, researcher and professor at the College of Veterinary Medicine at the Yangzhou University in China said that China was experiencing a very complicated situation.
Before the 1990s the disease was only detected in waterfowl, since then it has become endemic to China and various strains of both the highly and low pathogenic variants are seen.
Prof Xiufan said that one of their greatest concerns were the live poultry markets in China, as these markets are acting as a “mixing vessel for avian influenza.”
While the country is using vaccination to manage the disease, he believes that no control method would be effective without sound biosecurity measures.
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