Bird Flu Virus Spreads in Dairy Cattle, But Human Health Risk Remains Low

According to the CDC, with only 4 known human cases of the virus, risks of the bird flu reaching a mass number of humans remains low despite the virus continuing to spread in 151 herds of dairy cattle across 12 states.¹

“Overall, for the most recent week of data, CDC flu surveillance systems show no indicators of unusual flu activity in people, including avian influenza A(H5N1) viruses,” wrote the CDC in its recent update.

Despite organizations and government entities giving a deeper focus on stopping the spread among US dairy cattle—and despite the ongoing literature stating that a human outbreak is unlikely—efforts to better understand the human version of the virus have been unsuccessful.

“CDC has been unable to sequence or isolate virus from the recent human case in Colorado. Attempts to sequence viral RNA from the Colorado case were unsuccessful most likely due to insufficient virus in the clinical sample. As a result, CDC has not been able to conclusively determine the neuraminidase (NA) subtype of the virus,” they continued.

Instead, CDC is ramping up dairy farm surveillance and monitoring humans who have come into contact with infected animals. Since the start of the outbreak, over 1390 people have been monitored due to exposure and 61 individuals who have experienced flu-like symptoms have been tested for the virus. Since March, over 32,000 specimens have been tested for traces of the bird flu virus.¹

Going forward, CDC has several plans to stunt the spread of the bird flu, including ongoing efforts to discuss assay licensing agreements to develop commercial testing for the virus. CDC is also working to educate the public, especially dairy farm workers and health care practitioners, on collecting and administering testing, as well as a Clinician Outreach and Communication Activity (COCA) call to update the population on the virus.

The Bird Flu came back into the public spotlight in early April when a dairy farmer tested positive after reporting eye redness and conjunctivitis. This was the first known human case since April 2022.²

Shortly after, Andrew Bowman, a veterinary epidemiologist at Ohio State University, conducted his own experiment and collected 150 samples of commercial milk products in the Midwest, where the bird flu outbreak among dairy cattle is the most prominent. They found viral RNA samples of the bird flu in 58 of those products.³

As officials continued to relay messages that a public health crisis was still unlikely, the US Department of Health and Human Services pledged $199 million to the effort. Of the total sum, $101 million was dedicated to prevention, testing, tracking, and treating animals and humans that were potentially infected. The other $98 million was allocated to farms affected by the outbreak to help production and revenue recover from the mass infections across Midwest dairy cattle.⁴

With news about the outbreak seemingly in flux since the second known human case in April, the National Foundation for Infectious Diseases (NFID) recently presented all its current findings about the virus with the public. “There needs to be close communication,” said Ruth Lynfield, MD, NFID secretary, when discussing the ongoing work to track, monitor, and ultimately end the spread in the NFID presentation.² “We monitor what’s going on with the outbreak in general and update the clinical community and the public.”

Whether or not there is uncertainty surrounding the possibilities of where this virus will end up next, the CDC maintains that this is an ongoing issue, and the public should simply stay informed.

“This is an evolving situation, and CDC is committed to providing frequent and timely updates,” they concluded.¹

READ MORE: Everything You Need to Know About the US Bird Flu Outbreak

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References

1. CDC A(H5N1) bird flu response update, July 12, 2024. CDC. Accessed July 15, 2024. https://www.cdc.gov/bird-flu/spotlights/h5n1-response-07122024.html

2. Updates on avian influenza A(H5N1) (NFID Webinar). National Foundation for Infectious Diseases. June 18, 2024. Accessed June 20, 2024. https://www.youtube.com/watch?v=BLz6RJLP13E

3. Molteni M. Early tests of H5N1 prevalence in milk suggest U.S. bird flu outbreak in cows is widespread. STAT News. April 25, 2024. Accessed April 26, 2024. https://www.statnews.com/2024/04/25/h5n1-bird-flu-cows-outbreak-likely-widespread/

4. Aleccia J, Stobbe M. US pledges money and other aid to help track and contain bird flu on dairy farms. AP News. May 10, 2024. Accessed May 13, 2024. https://apnews.com/article/bird-flu-dairy-cattle-h5n1-milk-0b46e7a28a20fe825d7a324a976bac22