For months, the United States has been contending with a steadily growing outbreak of H151, a variant of avian flu. The virus, which was first spotted among commercial and backyard poultry populations, began to spread to dairy cows in March 2024 and then to the humans who work with the animals. Health officials have said that the overall risk to the American population is low, but the Centers for Disease Control and Prevention has confirmed 61 human cases of the bird flu since April 2024. Earlier this month, the U.S. Department of Agriculture ordered the testing of the nation’s milk supply beginning in six states to determine the presence of the virus, a sign of increased vigilance as the virus shows no signs of abating. And on Wednesday, California governor Gavin Newsom, whose state has seen the bulk of the cases confirmed so far, issued a state of emergency in connection with the bird flu.
Although the majority of the reported cases have come with only mild symptoms, this week the agency reported a new severe case of the virus discovered in Louisiana that resulted in hospitalization for the patient. Here’s what we know about this case and what it means for the greater public.
The new case
On Wednesday, the C.D.C. issued a press release confirming the existence of a new case of bird flu in Louisiana and stating that the patient required hospitalization. Per the agency, this is the first instance of “severe illness” connected to the virus in the United States. The Louisiana Department of Health tells CNN that the patient in question is older than 65 and is currently hospitalized in critical condition with “severe respiratory illness,” but also has other underlying health conditions.
The C.D.C. says that the patient’s virus is the D1.1 genotype, which has been detected in wild birds and poultry in the U.S., as well as human cases in Washington state and British Columbia, Canada. It’s different from the B3.13 genotype, which has been observed in “dairy cows, sporadic human cases in multiple states, and some poultry outbreaks in the United States.”
“While an investigation into the source of the infection in Louisiana is ongoing, it has been determined that the patient had exposure to sick and dead birds in backyard flocks,” the agency said, noting that this is also the first bird-flu case to be traced back to backyard flocks.
How does it compare to previous cases?
According to the C.D.C., there have been 61 cases of H151 in the United States since April 2024. In those cases, the patients have largely suffered only mild symptoms. In November, the agency issued an update on the response to the outbreak, writing about the cases that have appeared among farmworkers. In the release, the C.D.C. described some of their symptoms such as “eye redness or discharge (conjunctivitis)” or “mild upper respiratory symptoms.” They noted that none of them were hospitalized.
What does the C.D.C. say about the risk to others?
Despite the emergence of severe symptoms, the C.D.C. says that such a case is “not unexpected,” noting that cases of severe illness stemming from an avian-flu infection have occurred in other countries experiencing outbreaks of the virus in 2024 and years past.
“No person-to-person spread of H5 bird flu has been detected. This case does not change CDC’s overall assessment of the immediate risk to the public’s health from H5N1 bird flu, which remains low,” the agency said.
