‘Severe’ Bird Flu in the U.S.: Latest Updates

The Centers for Disease Control and Prevention (CDC) confirmed on Wednesday the United States’ first “severe” human case of H5N1 avian influenza—or bird flu, a zoonotic infection which has stoked fears of becoming the next global pandemic.

The severe case involves a resident of southwestern Louisiana who was reported as presumptively positive for infection last Friday. The infected patient “is experiencing severe respiratory illness related to H5N1 infection and is currently hospitalized in critical condition,” according to Emma Herrock, a spokesperson for the Louisiana Department of Health, who said that the patient is over the age of 65 and has underlying medical conditions but that further updates on their condition will not be given at this time due to patient confidentiality.

It is the 61st case of human H5N1 bird flu infection in the country since April this year. But the CDC said the overall risk of the pathogen to the public remains low, and no related deaths have been reported in the U.S. so far.

Here’s what to know.

What caused the severe infection?

The CDC, in its Dec. 18 announcement, said that while an investigation is underway, the patient was found to have links to sick and dead birds in backyard flocks, making it the first known case of infection in the U.S. to have those origins.

Of the 60 other cases, 58 were linked to commercial agriculture—37 from dairy herds and 21 from poultry farms and culling. The sources of exposure for the two other U.S. human cases remain unknown.

What’s the current state of H5N1 human infections?

Of the human infections recorded in the U.S. this year, 34, or more than half, were in California, with all but one exposed to cattle. In response, Governor Gavin Newsom on Dec. 18 declared a state of emergency.

The CDC said that such a “severe” infection as was found in Louisiana was expected given cases in other countries. In Vietnam, a patient who died in March after a diagnosis of “severe pneumonia, severe sepsis, and acute respiratory distress syndrome” was found with an H5N1 infection, according to the World Health Organization. The U.S. appears to be leading in H5N1 infections across the world this year, according to CDC data on bird flu cases reported to the WHO.

How can infection be prevented?

The CDC issued a number of protective measures, including largely avoiding direct contact with wild birds and other suspected infected animals as well as their bodily excretions. People who work with cattle and poultry on affected farms have a greater risk of infection, and are thus advised to monitor any possible symptoms of infection.

Properly cooked poultry and poultry products are safe, and the CDC says that while unpasteurized (raw) milk from infected cows can pose risks to humans, it’s not yet known if avian influenza viruses can be transmitted through its consumption.