Source of Missouri Bird Flu Case Still Unknown, Could Be a 'One-Off': CDC

FRIDAY, Sept. 13 , 2024 (HealthDay News) -- In a case that continues to confound scientists, U.S. health officials said Thursday that they still don't know how a Missouri patient caught the bird flu and that the case may just be a rare anomaly.

As bird flu continues to spread through dairy cow herds and poultry flocks, the Missouri case has raised the possibility of human-to-human transmission of bird flu. But officials stressed Thursday there is no evidence of other people being infected and the risk to the general public remains low.

“Right now, evidence points to this being a one-off case,” CDC Principal Deputy Director Dr. Nirav Shah told reporters during a media briefing, the Associated Press reported.

Citing patient confidentiality, health officials have shared few details about the Missouri case, which was first announced late last week.

The person had chest pain, nausea, vomiting, diarrhea and weakness and was hospitalized on Aug. 22 “for reasons related to their underlying medical conditions,” Shah said.

The patient was tested for flu, and was positive for influenza A. Follow-up testing found the virus belonged to a category of viruses typically seen in birds.

While the patient had a very low concentration of viral genetic material and officials could not confirm exactly which virus it was, partial genetic sequences were similar to those found in U.S. dairy cows, CDC officials added.

“Ultimately, a full sequence may not be technically feasible,” Shah noted.

The patient had no known contact with dairy cows or other animals associated with the ongoing bird flu outbreak. The person also told Missouri health officials that they didn’t drink unpasteurized milk or other unpasteurized dairy products, Shah added.

"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.

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

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 release, Sept. 6, 2024; Missouri Department of Health and Senior Services, statement, Sept. 6, 2024; Associated Press