April 22, 2015 / 5:01 AM / 4 years ago

U.S. could use vaccines being developed to fight bird flu in poultry

CHICAGO, April 22 (Reuters) - Faced with a deadly bird flu outbreak that has infected millions of chickens and turkeys, the U.S. Agriculture Department could turn to what it has always seen as a last resort: readying and deploying a vaccine to fight the disease.

Up to now, the USDA has said it would prefer not to allow farmers to vaccinate their flocks, as doing so could prompt wider import bans on U.S. poultry and eggs in the $5.7 billion export market. Inoculations produce antibodies that would make it difficult to tell if a bird had actually had the virus or simply been vaccinated.

But the agency’s chief veterinarian, John Clifford, told Reuters on Tuesday that once a vaccine is ready - something likely to take months - circumstances might prompt approving it for targeted use in areas with a high number of cases.

The H5N2 strain first appeared in the United States at the start of the year and is now in 12 states, making it the most wide-reaching outbreak in over three decades. The USDA has been working to develop a vaccine that would protect chickens and turkeys from this highly contagious strain of flu.

An outbreak on an Iowa egg farm that housed 3.8 million birds and had a reputation for tight biosecurity rocked the industry when it was reported on Monday and triggered tougher measures on farms to keep infections at bay.

Three export markets - China, South Korea and South Africa - already have instituted total bans on U.S. poultry costing about $430 million a year, said James Sumner, president of the USA Poultry & Egg Export Council.

The outbreak has dragged on longer than producers and industry leaders expected, with the USDA issuing near daily notifications of new infections in Minnesota, the top turkey producing state. Iowa, the biggest egg producer, has had far fewer cases.

Steve Olson, executive director of the Minnesota Turkey Growers Association, said he would like to see a vaccine available to farmers. Minnesota has been hit hardest by the virus, with 31 farms infected.

“If we’re in a situation where that’s what it takes to protect the flocks and keep them healthy, that’s what we’re going to do,” Olson said about using a vaccine. The USDA would have to give approval for companies to produce the drug once it has been proven effective.

Harrisvaccines, a privately-held company, is also developing a vaccine to fight bird flu that will be tested in four to six weeks in a laboratory setting, said Joel Harris, head of sales and marketing.

Last year, the company was the first to receive a conditional license from the USDA to distribute a vaccine for a deadly hog disease called porcine epidemic diarrhea virus, or PEDv.

Just as hog producers did last year in response to the swine virus, poultry farmers have rushed to bolster biosecurity measures to try to limit contamination on farms.

They are requiring employees to shower before - and after - they enter a farm to remove any trace of the virus, sanitizing vehicles more carefully, tracking the movement of everything from chicks to barn litter, and turning away visiting workers, including electricians and plumbers and even postal employees.

But it is difficult to completely prevent infections being spread by migratory waterfowl, something officials believe is a factor in the current outbreak.

“It’s raining virus in the form of duck and goose poop,” said John Glisson, vice president of research for the U.S. Poultry and Egg Association.

There are likely several ways the virus is moving from waterfowl, who carry it but show no symptoms, into the barns of chickens and turkeys, including being tracked into facilities through contaminated feces on workers’ boots and vehicles.

Even a gust of wind could potentially infect a flock by blowing a contaminated particle of dust or dirt into a barn, Clifford said. Bird flu is not aerosolized.

After Monday’s outbreak in Iowa, the United Egg Producers, a trade group, requested that government agencies suspend regular audits of egg and poultry operations because of the risk of people transmitting the virus.

Such on-farm visits would include tax and payroll audits by the Labor Department, egg safety inspections by the Food and Drug Administration, annual animal welfare audits by the USDA and third-party groups, group president Chad Gregory said.

The suspensions would not stretch to federally-required food safety inspections at food processing plants, he added.

“For the next couple of months, we’re telling our members that every single person who doesn’t need to be on your farm, shouldn’t be on your farm,” he said.

Clifford, the USDA veterinarian, said he would support suspending audits in areas hit hard by the virus.

Commercial flocks infected with the virus are destroyed to prevent the spread of the disease and farms quarantined.

Turkeys are suffocated with a type of foam similar to that used in fighting fires, because it can easily be sprayed on birds that live on the floor of barns.

That will not be used in the Iowa egg farm because the hens are kept in cages stacked to the ceiling. Instead, they are likely to be killed in tanks containing carbon dioxide, Clifford said.

Once they are put into tanks, “the birds just very gradually get sleepy and fall asleep and don’t wake up,” he said. (Additional reporting by Meredith Davis; Editing by Jo Winterbottom and Sue Horton)

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