MINNEAPOLIS — Federal officials said Wednesday they're taking steps to create a human vaccine for the bird flu virus that's slammed the Midwest poultry industry, though they still consider the danger to be low and the food supply not at risk.
Dr. Alicia Fry, an influenza expert with the federal Centers for Disease Control and Prevention, said officials are hopeful there won't be any human cases of the H5N2 strain — which has cost chicken and turkey producers nearly 6.8 million birds since early March — but the country must be prepared.
"We're really at the beginning of this and so are monitoring very closely. And we're cautiously optimistic that we will not see any human cases," Fry said on a conference call.
Most humans who have come down with other bird flu viruses had close, prolonged contact with infected birds, Fry said, so officials are monitoring at least 100 farm workers who've been exposed to affected flocks. She said signs could be flu-like symptoms or conjunctivitis, also known as pink eye.
It's standard CDC procedure with all new flu viruses to begin looking at creating a human vaccine, Fry said. She said they're preparing a seed strain, essentially a pure sample of the right viruses that could be the foundation for a vaccine.
"We haven't gotten further than that at this point because we don't have a need to go further than that," she said.
Similarly, the U.S. Department of Agriculture is testing a seed strain for a potential poultry vaccine but hasn't decided whether to put it into production, said Dr. David Swayne, director of the USDA's Southeast Poultry Research Laboratory in Athens, Georgia.
Scientists think H5N2 the virus is being spread by droppings from wild waterfowl and is making its way past tight biosecurity at commercial poultry farms. While they think it's most likely being carried accidentally on the few people allowed into the barns, USDA Chief Veterinary Officer Dr. John Clifford said officials also are looking at whether high winds could blow contaminated dust, feathers and other debris for short distances into facilities.
While the virus has quickly killed tens of thousands of birds at the affected farms across eight states, crews are destroying all the rest as a precaution. Clifford estimated about 3.5 million birds have been euthanized already, but it will take time to cull all of them, particularly at an Iowa farm that had 3.8 million egg-laying hens.
In Minnesota, the country's top turkey producer and by far the hardest-hit state, health officials are monitoring 61 people involved in caring for the affected flocks. Many have followed recommendations that they take the antiviral drug Tamiflu as a preventative.
The genetic markers of the H5N2 virus don't seem to be associated with transmissibility to humans, Fry said. Another good sign is that the H5N2 virus and other viruses in the H5 family that have been circulating in parts of North America appear to be different from H5 viruses that have caused severe human illnesses in Asia, she added.
Still, Fly recommended that the public avoid contact with wild birds, domestic poultry and their droppings.
Wisconsin's agriculture department received confirmation Wednesday of an H5 virus outbreak at an egg farm with 800,000 chickens. Spokeswoman Raechelle Cline said that while it's presumed to be H5N2, final test results are pending.