CDC A(H5N1) Bird Flu Response Update June 28, 2024

The Centers for Disease Control and Prevention (CDC) continues to respond to the public health challenge posed by a multistate outbreak of avian influenza A(H5N1) virus, or “H5N1 bird flu,” in dairy cows and other animals in the United States. CDC is working in collaboration with the U.S. Department of Agriculture (USDA), the U.S. Food and Drug Administration (FDA), state public health and animal health officials, and other partners using a One Health approach. To date, there have been three human cases associated with an ongoing multistate outbreak of A(H5N1) in U.S. dairy cows. Based on the information available at this time, CDC’s current H5N1 bird flu human health risk assessment for the U.S. general public remains low. All three sporadic cases had direct contact with sick cows. On the animal health side, USDA is reporting that 132 dairy cow herds in 12 U.S. states have confirmed cases of avian influenza A(H5N1) virus infections in dairy cows as the number of infected herds continues to grow.

Among other activities previously reported in past spotlights and still ongoing, recent highlights of CDC’s response to this include:

  • Posting the CDC H5N1 Science Agenda that summarizes the key research issues that the agency hopes to address related to the ongoing outbreak of A(H5N1) virus in dairy cows and other animals in the United States.
  • Posting updated recommendations for agricultural fair organizers and people exhibiting animals at agricultural fairs on how to reduce the risk of novel influenza A viruses spreading between animals and people at these events. These recommendations, which previously focused on reducing the risk of spreading swine-origin flu viruses between pigs and people, have been expanded to include cattle, given the ongoing outbreak of H5N1 bird flu in U.S. poultry and cattle. Millions of people in the United States attend agricultural fairs each year, usually in the summer season. When large numbers of animals and people are in close contact with each other, this raises the risk of disease spread. Measures to reduce the risk of infection include avoiding animal exposures, which is especially important for people who are at higher risk of developing serious flu complications, and frequent handwashing.
  • The Michigan Department of Health and Human Services (MDHHS) launched an H5N1 bird flu seroprevalence study of individuals exposed to sick cows. The study aims to determine if there has been asymptomatic infection with H5N1 bird flu among people who have worked with sick cows, if certain jobs might increase risk of exposure, and how personal protective equipment (PPE) can protect against infection. CDC is providing technical assistance.
  • Continuing to support strategies to maximize protection of farm workers, who are at higher risk of infection based on their exposures. This includes outreach to farm workers in affected counties through Meta (Facebook and Instagram), digital display, and audio (Pandora). These resources provide information in English and Spanish about potential risks of A(H5N1) infection, recommended preventive actions, symptoms to be on the look-out for, and what to do if they develop symptoms. Since May 30, when English assets launched, Meta outreach has generated more than 4.5 million impressions. Spanish Meta assets launched on June 6, and since then have garnered 650,000 impressions.
  • Continuing to work with public health laboratories to monitor influenza virus testing. While 53 people have been tested for A(H5N1) virus associated with the dairy cow outbreak, it is important to look at exposure-based testing in the context of CDC’s wider testing for flu in the United States. Since March 3, 2024, 31,223 specimens have been tested by public health laboratories for flu with results being reported to CDC. These were specimens submitted to public health laboratories for flu testing and subtyping as part of regular flu surveillance activities. Public health laboratories report data to CDC each week, and more than 200,000 specimens are tested each year. These laboratories use a testing protocol that would detect A(H5N1) virus and other novel viruses. Among those more than 30,000 specimens tested since March 3, 2024, no cases of H5N1 bird flu were detected.

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