Authorities reported on Friday that a resident of Missouri has become the first person in the United States to test positive for bird flu without a known exposure to infected animals.
This case marks a significant development in the understanding of how avian influenza, also known as H5N1 or bird flu, can affect humans.
The adult patient, who has underlying health conditions, was admitted to the hospital on August 22. After receiving antiviral medications for influenza, the patient recovered and was subsequently discharged. Initial tests revealed a suspicious flu strain, prompting further analysis by state and federal laboratories, which confirmed the presence of H5, the strain associated with bird flu.
This patient is the 14th individual to test positive for bird flu in the U.S. this year and the first without a known history of contact with infected animals.
The Missouri Department of Health and Senior Services noted that while there have been reports of H5 cases in commercial or backyard poultry flocks and wild birds, there have been no reported infections in dairy cattle in the state.
Historically, all previous bird flu cases in the U.S. have been linked to farmworkers who had direct contact with infected poultry. The first case in 2022 was among this group.
Bird flu primarily affects wild birds and poultry, but recent detections in mammals, including a notable outbreak in cattle this year, have raised concerns. Human infections typically occur through close contact with infected birds or contaminated environments.
While the Centers for Disease Control and Prevention (CDC) has assessed the public risk as low, the situation is being monitored closely.
The CDC has noted that, although rare cases of bird flu have occurred in humans without a clear animal source, there is no evidence of sustained human-to-human transmission. Such transmission would significantly elevate the threat level.
