• Posted September 16, 2024

Missouri Bird Flu Case Raises Possibility of Human Transmission

MONDAY, Sept. 16, 2024 (Healthday News) -- In a disclosure that can't eliminate the possibility that bird flu may have spread from one human to another for the first time, U.S. health officials have reported that a person who lived with a Missouri resident infected with H5N1 became sick the same day.

That close contact "was also ill at the same time, was not tested, and has since recovered," the U.S. Centers for Disease Control and Prevention said in a weekly flu report released Friday.

Still, CDC officials told the New York Times on Friday night that there was “no epidemiological evidence at this time to support person-to-person transmission of H5N1,” although more research is needed.

The close contact did experience gastrointestinal symptoms, which can be a sign of influenza infection, the CDC added.

Before the Friday report was posted, neither the CDC nor Missouri health officials had mentioned the close contact’s illness.

In fact, CDC officials said in a Thursday media briefing that it was unclear how the first patient had become infected and called the case “a one-off.”

And on Thursday evening, Missouri health officials said that “all contacts are known and remained asymptomatic during the observation period,” the Times reported.

But by Friday, CDC officials acknowledged that the household contact’s illness “should have been mentioned in the press briefing, along with the additional context,” the Times reported, though the risk to the public remains low, officials said.

Still, outside experts criticized the omission.

“There are absolutely no circumstances in which it is acceptable to not have disclosed that information yesterday,” Jennifer Nuzzo, director of the Pandemic Center at the Brown University School of Public Health, told the Times on Friday.

Other experts were frustrated with the general lack of information on the case.

“Aside from getting more details on the case, it would be good to get more information on who was included in case investigation and what criteria were used,” Dr. Nahid Bhadelia, director of the Center on Emerging Infectious Diseases at Boston University, told the Times.

In addition to the household contact, a health worker who cared for the hospitalized patient became ill but tested negative for the flu, the CDC said Friday night, the Times reported.

Antibody testing could reveal any exposure to H5N1, and Missouri officials said such tests were “being considered,” the Times reported.

All the previous U.S. bird flu infections were among people who worked around cows and poultry, so this latest case raises concerns about human transmission of the virus.

"This is the 14^th human case of H5 [bird flu] reported in the United States during 2024 and the first case of H5 without a known occupational exposure to sick or infected animals," the CDC noted in a statement it released when the Missouri case first surfaced.

Bird flu has been detected in over 200 dairy herds in 14 states, but not in Missouri, according to the CDC. Bird flu has also been found in commercial and backyard flocks and in wild birds.

This was the first bird flu case detected through routine influenza surveillance, officials noted.

More information

The CDC has more on bird flu.

SOURCES: U.S. Centers for Disease Control and Prevention, news releases, Sept. 6 and Sept. 13, 2024; Missouri Department of Health and Senior Services, statement, Sept. 6, 2024; New York Times