#USA, #Influenza A #H5N1 in #Humans: #Epidemiology & #Laboratory #Update {as of Feb. 26 '25}

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Epidemiology Updates

As of February 24, CDC has confirmed three human cases of H5 bird flu in people who became ill in 2025: 

-- a dairy worker with exposure to infected dairy cows (Nevada), 

-- a poultry worker with exposure to infected commercial poultry (Ohio), and 

-- the owner of an infected backyard poultry flock (Wyoming). 

These are all considered higher-risk exposures. While the dairy worker was not hospitalized, both people with poultry exposures experienced severe illness and were hospitalized. Both hospitalized cases were confirmed positive from lower respiratory specimens, including a bronchoalveolar lavage and sputum. To date, there has been no evidence of onward spread from any of these people to anyone else.

The dairy worker in Nevada had conjunctivitis (eye redness and irritation) and has recovered. Most infections associated with U.S. dairy cows to date have involved mild respiratory symptoms or conjunctivitis. This person was exposed to infected dairy cows and tested positive for avian influenza A(H5N1) virus.

The poultry worker in Ohio had respiratory symptoms and is home and recovering. This person participated in culling activities on a farm with infected poultry. The initial upper respiratory specimens could not be confirmed as positive for avian influenza A(H5) virus at CDC, so CDC initially reported this as a probable case; a subsequent specimen from the person was confirmed positive for avian influenza A(H5) virus at CDC.

The backyard flock owner in Wyoming had respiratory symptoms and is reported to have underlying health conditions that can make people more vulnerable to severe influenza illness. This person has been discharged from the hospital and is recovering. This person had direct contact with poultry infected with avian influenza A(H5) virus that died on their property. Initial upper respiratory specimens were negative for influenza viruses; a lower respiratory specimen collected several days later in the hospital was positive for avian influenza A(H5N1) virus.

Laboratory Updates

CDC has successfully sequenced the viruses from the Nevada and Wyoming cases. Genetic data have been posted in GISAID (Wyoming: EPI_ISL_19749443, Nevada: EPI_ISL_19726293) and GenBank. Sequencing data are not yet available for the Ohio case.

CDC's analysis of the genetic sequence of the virus isolated from the patient in Nevada identified the virus as an avian influenza A(H5N1) virus from clade 2.3.4.4.b (genotype D1.1). The nucleotide sequence was nearly identical to that of the viruses that USDA reported from dairy cows in Nevada that the person worked with. The virus had a genetic mutation in its polymerase basic 2 (PB2) protein that has previously been associated with more efficient virus replication in mammalian cells (i.e., change of PB2 D701N). This change was previously identified in a human case in Chile in 2023. No other changes associated with mammalian adaption were identified in the sequence data. CDC also did not identify any changes that might impact effectiveness of influenza antiviral medications or existing clade 2.3.4.4b H5 candidate vaccine viruses.

CDC's analysis of the genetic sequence of the virus from the patient in Wyoming identified an avian influenza A(H5N1) virus from clade 2.3.4.4.b (genotype D1.1). The virus had a genetic mutation in its PB2 protein that has previously been associated with more efficient virus replication in people and other mammals (i.e., change of PB2 E627K). This change was previously identified in a human case in Texas during 2024. No other changes associated with mammalian adaption were identified in the sequence data. CDC also did not identify any changes in the sequence data that might impact effectiveness of influenza antiviral medications or existing H5 candidate vaccine viruses. Virus was isolated from the case and will undergo further testing and analysis.

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Source: US Centers for Disease Control and Prevention, https://www.cdc.gov/bird-flu/spotlights/h5n1-response-02262025.html

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#USA, #Situation #summary of confirmed and probable #H5N1 #influenza virus #human cases since 2024 (as of Feb. 19 '25): One New Case in #Wyoming

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[Confirmed Cases: State, Exposure Source: Dairy Herds, Poultry Farms and Culling Operations, Other Animal Exposure, Unknown, State Total]

-- National, 41, 23, 2, 3, 69 {+1}

1) California, 36, 0, 0, 2, 38

2) Colorado, 1, 9, 0, 0, 10

3) Iowa, 0, 1, 0, 0, 1, 1

4) Louisiana, 0, 0, 1,0 , 1

5) Michigan, 2, 0, 0, 0, 2

6) Missouri, 0, 0, 0, 1, 1

7) Nevada, 1, 0, 0, 0, 1

8) Oregon, 0, 1, 0, 0, 1

9) Texas, 1, 0, 0, 0, 1

10) Washington, 0, 11, 0, 0, 11

11) Wisconsin, 0, 1, 0, 0, 1

12) Wyoming, 0, 0, 1, 0, 1 {+1} 

[Probable Cases: State, Exposure Source: Dairy Herds, Poultry Farms and Culling Operations, Other Animal Exposure, Unknown, State Total]

-- National, 1, 6, 0, 1, 8

- Arizona, 0, 2, 0, 0, 2

-- California, 1, 0, 0, 0, 1

-- Delaware, 0, 0, 0, 1, 1

-- Ohio, 0, 1, 0, 0, 1

-- Washington, 0, 3, 0, 0, 3

NOTE: One additional case was previously detected in a poultry worker in Colorado in 2022. Louisiana reported the first H5 bird flu death in the U.S.

{*} Exposure Associated with Commercial Agriculture and Related Operations

{†} Exposure was related to other animals such as backyard flocks, wild birds, or other mammals

{‡} Exposure source was not able to be identified

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Source: US Centers for Disease Control and Prevention, https://www.cdc.gov/bird-flu/situation-summary/?CDC_AAref_Val=https%3A%2F%2Fwww.cdc.gov%2Fflu%2Favianflu%2Favian-flu-summary.htm&cove-tab=1

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#USA, #Wyoming’s First #Human {#H5N1} #Birdflu Case Confirmed (DoH)

 Wyoming’s First Human Bird Flu Case Confirmed

February 14, 2025

Wyoming’s First Human Bird Flu Case Confirmed

Wyoming’s first case of H5N1 avian influenza in a human has been confirmed in a Platte County older adult, according to the Wyoming Department of Health (WDH). 

The woman represents the third confirmed hospitalization related to H5N1 in the United States.

“While this is a significant development as bird flu activity is monitored in Wyoming and across the country, it is not something we believe requires a high level of concern among most Wyoming residents,” said Dr. Alexia Harrist, state health officer and state epidemiologist with the Wyoming Department of Health.

Harrist said the woman is hospitalized in another state, has health conditions that can make people more vulnerable to illness, and was likely exposed to the virus through direct contact with an infected poultry flock at her home. 

H5N1 has been known to be infecting wild birds in Wyoming for some time now with the currently circulating virus spreading nationally since 2022. Infections among poultry and dairy cattle have also occurred previously in Wyoming.

“Experts continue to track the spread of H5N1 through wild birds, poultry and dairy cattle across the country. A small number of people have also been infected. Most of those confirmed cases involved on-the-job close contact with poultry or cattle and mild symptoms,” Harrist said. “Unfortunately, this patient’s experience has been much more serious.”

“We want to remind people there has been no documented human-to-human virus transmission of this virus in the United States so far,” Harrist said. “Our staff has followed up with other people who had contact with the flock and the patient, and will continue working with state and national experts to monitor the situation carefully for Wyoming.”

Harrist noted the current public health risk is low, but there are some common-sense steps people may consider to help protect themselves and their families:

-- Do not eat uncooked or undercooked food; cook poultry, eggs and other animal products to the proper temperature and avoid cross-contamination between raw and cooked food.

-- Avoid direct contact with wild birds.

-- Avoid contact with wild or domestic birds that appear ill or have died. If symptoms are observed in birds, immediately contact a veterinarian, or report sick domestic birds to the Wyoming Livestock Board at 307-777-8270.  If contact with the sick or dead birds is necessary, use of personal protection clothing and items is strongly recommended.

-- Avoid unprotected direct physical contact or close exposure with cattle and materials potentially infected or confirmed to be infected with bird flu.

-- Do not eat or drink raw milk or products made with raw milk.

-- Sick or dead wild birds may be reported to the Wyoming Game and Fish Department (WGFD) by calling 307-745-5865, reporting online at https://survey123.arcgis.com/share/7d0c547b8fa54eaca73f7eb37d06315a or contacting the nearest WGFD regional office.

The test result was confirmed this afternoon by a Centers for Disease Control and Prevention (CDC) laboratory.

More information about bird flu is available from the CDC at https://www.cdc.gov/bird-flu/index.html. More specific recommendations for people who have poultry are available from CDC at https://www.cdc.gov/bird-flu/groups/index.html.

Source: Department of Health, https://health.wyo.gov/wyomings-first-human-bird-flu-case-confirmed/