The Missouri Department of Health and Senior Services (MDHSS) announced late Friday that a Missouri resident with no known contact with animals has been confirmed to have contracted the H5 strain of avian influenza.
MDHSS reported that the individual, who had an underlying health condition, was hospitalized on August 22 and tested positive for influenza A virus. Further testing by the state public health laboratory determined that the influenza A virus was H5 avian influenza. The Centers for Disease Control and Prevention has now confirmed this finding and is conducting further testing to confirm that it is the H5N1 strain that is currently causing widespread outbreaks among U.S. dairy cattle.
It is unclear whether the person’s avian influenza infection was the cause of his hospitalization or whether the infection was discovered incidentally. The person has since recovered and been discharged from the hospital. MDHSS said in a statement that no other information about the patient will be released to protect his privacy.
This report marks the 15th human case of H5N1 avian influenza in the United States since 2022. But this case stands out and has quickly raised alarm online because the man reported no contact with animals. The previous 14 cases were all farm workers who had contact with cows or poultry known to be infected with H5N1.
If the virus is found in people without such exposure, it is possible that the H5N1 virus is spreading undetected from person to person or through undetected animals.
But despite the case raising concerns, some infectious disease experts are cautious about letting their guard down, given the lack of more data on the case and potential exposures.
“Until these data are collected and analyzed, my level of concern is only slightly elevated,” Caitlin Rivers, a senior scholar at the Johns Hopkins Center for Health Security and founding associate director of the CDC’s Center for Forecasting and Outbreak Analysis, said online.
“It is encouraging that this case was detected through our existing surveillance system, which bodes well for our ability to identify additional cases in the future,” she added. “Federal, state and local health officials maintained influenza surveillance throughout the summer in response to the H5 situation, and that was certainly the right decision.”
But Rivers, like many of his colleagues, has long been concerned that H5N1 has the potential to jump to humans and cause a pandemic.
To date, H5N1 is known to have infected 197 flocks in 14 states. Missouri has not reported any infected flocks, but has reported an infected poultry farm.
