AVIAN influenza has quickly become a serious concern for the commercial poultry industry in the U.S., with more and more affected operations being identified each week.
For pasture-based operations in high-risk areas, the virus has even forced some birds inside despite marketing claims to the contrary.
Since December 2014, two strains of highly pathogenic avian influenza (HPAI) have affected domestic poultry in some 14 states. Most of the cases have been linked to the H5N2 strain and have surfaced in only the past two months. With 70% death loss in birds within 48-72 hours of onset, the results have been devastating for those producers hit.
As of May 4, a total of 122 cases of HPAI have been detected, and nearly 24 million birds have died.
HPAI is a highly contagious disease caused by a type A influenza virus. Infection of domesticated poultry is often the result of exposure to migratory waterfowl, which tend to shed the virus into the environment without showing any outward clinical signs.
The virus has not been deemed a threat to food safety or human health.
When avian influenza gets into a flock, Dr. Carol Cardona of the University of Minnesota explained, birds may become quiet or depressed. Some may have discolored combs or are hot to the touch. Illness may appear concentrated in a small group of birds before the entire operation is affected.
Cardona said the general recommendation is that if anything about the birds is "different," get them tested immediately.
Pathologically, HPAI is a very serious situation, University of Illinois poultry expert Ken Koelkebeck said on an April 30 conference call. He noted that it is hard to know at this point just how long the current outbreak will last. In fact, he said, it could be something the industry has to deal with for another three to five years.
Since the virus doesn't like heat and dry conditions, experts do expect the cases of H5N2 to moderate as summer and warmer temperatures arrive. Still, the general consensus is that the virus will likely be back in the fall as the southern migration of waterfowl gets under way.
As in all disease-related situations, biosecurity is of the utmost importance, noted Koelkebeck, along with colleagues Kyle Cecil and Andrew Larson. They emphasized that biosecurity has no size limitations; it is essential for all operations, big and small.
Iowa State University's Dr. Chris Rademacher said it is important for allied industry and contract personnel, or suppliers, to stay clear of a site that is confirmed positive for HPAI until that site has been depopulated, cleaned and sanitized.
If an emergency requires personnel to be on site, Rademacher said those personnel and their vehicles should be kept away from other poultry facilities for at least three days. In addition, any vehicles and equipment used on site must be thoroughly cleaned and disinfected.
Dr. Rodney Baker of Iowa State University said heat treating vehicles isn't a bad idea, either. Heat, along with dry conditions and sunlight, is very effective in killing the avian influenza virus.
Other biosecurity tips for producers are as follows:
* Make sure domesticated birds are kept completely separated from wild birds that can carry the disease, especially migratory waterfowl. Keep ducks and geese away from pastures and other areas in which chickens day-range, and never allow the birds to use surface water as a drinking source if it is frequented by wild waterfowl.
* Make sure wild birds do not have a way to enter poultry buildings. Keep feed and water sources covered and enclosed to prevent contact by wildlife. In the case of an imminent threat, consider keeping birds penned up in a safe, isolated enclosure or building until the threat subsides. Don't feed materials that were stored outdoors.
* Have dedicated boots and clothes for use inside bird enclosures. Consider a small investment in effective disinfectants, and make a footbath to clean and disinfect boots and tools before and after contact with the flock.
* Do not bring in birds from areas where HPAI has been detected. If outside poultry must be brought in, disinfect footwear and vehicle tires before they enter the farm. Be sure to keep the new birds quarantined for several weeks to ensure that they are disease free.
* Review and update rodent/pest control programs.
Mary Schwarz of Cornell University's Waste Management Institute noted that control of low-pathogenic avian influenza helps in preventing the creation of HPAI.
"Poultry producers should be vigilant for the signs of (low-pathogenic flu) and use excellent biocontrol measures to prevent the occurrence of HPAI in the first place," she said.
The HPAI virus can result from exposure to surfaces that have been contaminated by contact with manure or other secretions of infected birds. There also is some recent evidence that the virus may be able to attach itself to dust or debris and become airborne. This has led to a recommendation for wet cleaning of infected buildings and surfaces.
If HPAI is found in an operation, it must be reported to the proper authorities.
So far, the White House budget office has authorized an additional $330 million in emergency funds for avian flu.
On April 29, leaders of the Senate and House agriculture committees called for the emergency assistance to be issued, and by May 1, funds were released to Agriculture Secretary Tom Vilsack through the Commodity Credit Corp. transfer authority.