How deadly is the bird flu? The US has reported its first death from avian influenza, H5N1. Here's what to know about bird flu mortality rate and who is at risk.

Human cases of bird flu have been detected before in the UK, Russia and China but concern has mounted as the US reported its first-ever death from the virus this week

Humans infected with bird flu display a wide range of symptoms, from pneumonia requiring hospitalization to no symptoms at all. The CDC lists these other possible signs of infection: Less common symptoms include: Bird flu could merge with seasonal flu to make mutated virus that could spread among humans, CDC warns

Bird flu is a disease caused by avian influenza A viruses, according to the CDC. The virus mostly spreads between birds and dairy cows, but there have been 67 human cases of bird flu nationwide and one death tied to the infection since 2024, CDC records show.

Two months shy of the fifth anniversary of COVID-19 being declared a global pandemic, the US has recorded its first human death as a result of avian influenza H5N1 infection. The unidentified Louisiana man contracted the virus through contact with infected wild and domestic birds on his property

NBC News Medical Contributor Dr. Kavita Patel speaks with Gadi Schwartz about the difference in symptoms between a cold and the flu and explains the CDC's urge for faster testing to find human bird flu cases.

People hospitalized for flu should be tested for bird flu within 24 hours, the U.S. Centers for Disease Control and Prevention said on Thursday, in an expansion of the agency's efforts to tackle increasing infections in humans.

CDC officials say they extended the guidance now because they are seeing more H5N1 patients whose illness they cannot track back to an infected bird or cow.