Bird Flu Virus Spreading Across US; CDC Warns Doctors to Be Vigilant

Doctors and state health officials should be on the lookout for people infected with the H5N2 bird flu virus, which has spread to at least 20 states this year, the Centers for Disease Control and Prevention said Tuesday.

While no humans have been diagnosed with either H5N2 or H5N8 avian influenza, the virus' expansion across the country has caused more than 200 outbreaks among chickens, turkeys and other birds. It's killed or forced the slaughter of more than 45 million birds, the U.S. Department of Agriculture said.

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"While these recently identified HPAI H5 viruses are not known to have caused disease in humans, their appearance in North American birds may increase the likelihood of human infection in the United States," the CDC said.

A file photo of a poultry farm.
Getty Images
A file photo of a poultry farm.

People can get avian influenza—both H5N1 and H7N9 have infected and killed people. H7N9 avian influenza has infected 622 people since 2013 and killed 227 of them.

H5N1 was the first strain of bird flu to really worry experts—and it still does.

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It's infected 784 people in 16 countries since 2003, and killed 429 of them. "Previous human infections with other avian viruses have most often occurred after unprotected direct physical contact with infected birds or surfaces contaminated by avian influenza viruses, being in close proximity to infected birds, or visiting a live poultry market," the CDC added.

Cooked meat and eggs are not infectious, the CDC stresses, and farms known to be affected must destroy all birds and eggs.

While the risk is low, poultry workers and people who keep birds in small farm or backyard flocks could be at risk.

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"Clinicians should consider the possibility of highly pathogenic avian influenza H5 virus infection in persons showing signs or symptoms of respiratory illness who have relevant exposure history," the CDC said in a health alert issued to doctors.

"This includes persons who have had contact with potentially infected birds (e.g., handling, slaughtering, defeathering, butchering, culling, preparation for consumption); direct contact with surfaces contaminated with feces or parts (carcasses, internal organs, etc.) of potentially-infected birds; and persons who have had prolonged exposure to potentially-infected birds in a confined space."

State health departments should report suspected cases, the CDC added. And if someone who's had close contact with potentially infected birds turns up with flu-like symptoms, doctors shouldn't wait to treat with Tamiflu.

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"Rapid detection and characterization of novel influenza A viruses in humans remain critical components of national efforts to prevent further cases, evaluate clinical illness associated with them, and assess any ability for these viruses to spread among humans," the CDC said.

"People should avoid unprotected exposure to sick or dead birds, bird feces, litter, or materials contaminated with suspected or confirmed highly pathogenic avian influenza H5 viruses," it added.

Federal agriculture officials are looking everywhere they can think of for sources of the H5N2 bird flu.

Highly pathogenic avian influenza has never spread like this before in the United States, and it's flummoxed the U.S. Department of Agriculture, farmers and scientists alike