Bird Flu, otherwise known as Avian Influenza or H5N1, has been infecting various herds of dairy cattle across the country. On December 18th, the state of California declared a state of emergency regarding the spread of H5N1 in its dairy cattle.
In the formal announcement of the state of emergency, the Executive Department of California notes that the state has led the nation in milk production since 1993. In 2022 its dairy cattle accounted for 18.2% of the United States’ milk production, highlighting the significance of widespread infections amongst its dairy cattle.
This state of emergency reflects a plan of action to monitor and quarantine infected dairy cattle, and does not reflect a great impact on the public aside from those who work with livestock. The announcement further notes that there have been 61 total reported confirmed cases of H5N1 infections amongst humans across eight states. However, it should also be noted that there has yet to be any evidence of transmission from human to human, and rather only from cattle or birds to human.
This development in California comes in tandem with the news of a human infection in Louisiana, reported by the Centers for Disease Control and Prevention (CDC), also on December 18th. The CDC reports that this infection was confirmed on Friday, December 13th, and that it is the first severe case in a human thus far. Previous confirmed infections have resulted in fairly minimal symptoms like conjunctivitis (eye infection).
The Louisiana individual is reported to have received the infection from “sick and dead birds in backyard flocks,” and that there still has been no human-to-human transmission. Currently, all cases of avian influenza in humans have been received via direct contact with infected birds and livestock. While the spread of avian influenza amongst birds and cattle in the United States continues to develop, there is yet to be any transmissions identified amongst the human population (human to human).
However, on December 26th, 2024, the CDC released an update on this Louisiana patient, after analyzing the virus’ genomic sequences in samples gathered from the patient. The CDC analysis found “low frequency mutations in the hemagglutinin gene of a sample sequenced from the patient,” that were not present in the samples received from the poultry that infected the patient. The potential danger in this occurrence, is that mutations could allow the virus to transmit between humans. However, these specific mutations do not yet mean that human-to-human transmission is likely, and the CDC still considers the risk to the general public to be low. In fact, the CDC does note that the specific virus detected in this patient is similar to existing candidate vaccine viruses (CVVs), suggesting that if need be, vaccines could be easily produced by manufacturers.
On January 6th, 2025, it was reported that the patient in Louisiana, an older adult, had passed due to the severity of their illness. The CDC notes that while tragic, this was not unexpected due to the nature of severe cases of bird flu, and the patient being at greater risk due to their age.
But once again, at this time the CDC maintains that there is little threat to the U.S. general population. At this time there has been transmission from human to human, and the mutations seen in the Louisiana patient are not considered dangerous as of yet. The California State of Emergency is not due any apparent threat of human-to-human transmission, but for the sake of remedying the virus’ impact on dairy herds.
If you or someone you know has had direct contact with birds or livestock, consider the following tips from the CDC:
– Whenever possible, avoid contact with sick or dead animals, particularly wild birds and poultry.
– If direct/close contact with wilds birds, sick or dead poultry, or livestock, wear personal protective equipment (PPE) such as gloves and masks. The CDC further notes that even healthy presenting birds can carry the infection.
– Avoid materials and surfaces that have been contaminated with saliva, mucous, or animal feces from wild or domestic birds, or other animals with confirmed or suspected avian influenza.
References:
– “2024 Bird Flu,” Open State of Emergency Proclamations. California Governor’s Office of Emergency Services. 12/18/2024. https://www.caloes.ca.gov/office-of-the-director/policy-administration/legal-affairs/emergency-proclamations/
– “CDC Confirms First Severe Casse of H5N1 Bird Flu in the United States,” CDC Newsroom. The Centers for Disease Control and Prevention. 12/18/2024. https://www.cdc.gov/media/releases/2024/m1218-h5n1-flu.html
– “Genetic Sequences of Highly Pathogenic Avian Influenza A(H5N1) Viruses Identified in a Person in Louisiana,” Avian Influenza (Bird Flu). The Centers for Disease Control and Prevention. 12/16/2024. https://www.cdc.gov/bird-flu/spotlights/h5n1-response-12232024.html#xd_co_f=YTVkOTA2YmItYjFmZi00ZGQxLWFjZGEtOTM3ZDhmZDExZjQx~
– “First H5 Bird Flu Death Reported in United States,” CDC Newsroom. The Centers for Disease Control and Prevention. 1/6/2025. https://cdc.gov/media/releases/2025/m0106-h5-birdflu-death.html
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