United States Spread Of H5N1 HPAI In The News

Reports that the bird flu, or avian influenza, has reached some parts of the US are another sobering reminder of our coexistence with viruses. In January, the US Department of Agriculture confirmed the first case of the bird flu in a wild bird in South Carolina (an American wigeon, or "compact duck").

Now there continue to be reports of bird flu in poultry in some farms and flocks in many states around the country. The USDA announced this week that an outbreak at a commercial poultry farm in Wisconsin will result in the affected birds being "depopulated," resulting in the killing of 2.7 million egg-laying chickens, Reuters reported.

To date, no human cases of the bird flu have been detected in the US.

Though human infections with bird flu are rare and appear to occur in people who work directly with infected birds or poultry, public health officials are closely monitoring bird flu cases in the US, because past infections in humans have caused serious illness and death. As of March 7, the US Centers for Disease Control and Prevention says that the bird flu is an "animal health issue" and that it "poses low risk" to the public. Here's what to know about the current bird flu situation.

What is the bird flu?

The bird flu, aka avian influenza, is the disease caused by infection with avian influenza type A viruses, according to the US Centers for Disease Control and Prevention. These viruses can circulate among birds around the world and have infected humans in rare cases, mostly those who work directly with infected birds. If the viruses mutate enough, the public health fear is that they might make the jump to spread between humans. The bird flu was first detected and controlled in 1997, but reemerged in 2003 and started spreading widely among birds.

The World Health Organization reports four types of influenza viruses: A, B, C and D. But type A viruses, which occur in both humans and different kinds of animals, are the biggest threat to public health, the WHO says. The "swine flu" of 2009's pandemic was caused by a type A virus. Seasonal flu viruses in humans are caused by type A and type B viruses.

Influenza viruses that cause the bird flu are either "low pathogenic" or "highly pathogenic," according to the CDC. Highly pathogenic bird flu can cause severe disease or death in poultry, and it's those cases that the USDA is reporting.

The predominant bird flu virus in the world is called H5N1, according to the CDC.

gettyimages-1326159072-1 — KarraStock/Getty Images

Is bird flu deadly?

More than 800 human cases of the bird flu have been reported to the WHO since 2003, according to a Feb. 18 report from the agency. Although human bird flu cases have remained rare, more than half of people infected with the virus have died.

Because of the serious health threat, the WHO, USDA, CDC and other agencies are closely monitoring outbreaks in the US and in other countries. But, the WHO noted in its February report, the recent bird flu cases do not appear to pose a greater public health threat this year than in previous years.

"The overall pandemic risk associated with A(H5) is considered not significantly changed in comparison to previous years," the report said.

Where in the US is the bird flu? How is it being monitored?

The USDA has reported cases in birds in the following states:

Henry Niman, a biochemist in Pittsburgh, has been tracking the outbreak (as reported by The New York Times) and his map shows outbreaks throughout the Midwest and up the East Coast.

The first case was in a wild bird in South Carolina. Other cases were reported in some backyard flocks (i.e. not part of a commercial poultry farm) as well as some poultry farms, where animals are raised for food. Any birds of the flocks which have cases of avian flu will not enter the food system, the USDA said.

"Wild bird surveillance provides an early warning system for the introduction and distribution of avian influenza viruses of concern in the United States," according to the agency. To monitor outbreaks, the USDA said it is collecting samples in 25 different states, coordinating with State Departments of Wildlife or Natural Resources and more.

getty-images-bird-flu — Karen Moskowitz/Getty Images

How do you get bird flu? Do I need to do anything differently?

The CDC says that the current bird flu cases in animals do not pose a public health threat. But to avoid contamination from poultry of any kind, make sure to properly handle your poultry and eggs, and thoroughly cook them to 165 F, the USDA says, to kill bacteria and viruses. According to the CDC, you should also avoid contact with wild birds, don't touch dead or sick birds you see, and avoid visiting bird markets or farms if you're traveling to another country.

You can also report a dead bird to your local health department or wildlife agency, which can help public health officials track not only the bird flu but also viruses such as West Nile virus. Reporting dead birds to health officials may be especially important if there are more than one of them.

Extra precautions or monitoring may be taken if you work directly with birds, if you hunt birds or if you're a health care worker.

So long as humans eat birds and other animal products, as well as live and work among them, there might be a risk for viruses to jump from species to species. And the threat of bird flu causing an outbreak among people isn't new to 2022.

But with careful monitoring and attention to public health, the hope is that we'll avoid another pandemic with a large loss of life.

The CDC has said it has "produced a candidate vaccine virus," if it's needed, in response to a potential public health threat.

First published on Feb. 25, 2022 at 8:55 a.m. PT.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.