HPAI H5N1 Bird Flu Update as of 4-5-2024
On March 25, HPAI H5N1 bird flu was detected in a herd of dairy cows in Texas and then on April 1 was detected in a human with close contact to the infected herd. Lab testing has shown that H5N1 avian influenza virus is present in milk from the infected cows and therefore raw milk consumption is a concern if this were to become more common.
This is the current risk profile, pulled from this helpful CDC page: H5N1 Bird Flu: Current Situation Summary | Avian Influenza (Flu) (cdc.gov):
Wild birds: widespread HPAI H5N1
Poultry flocks: sporadic outbreaks
Mammals: sporadic outbreaks
People: 2 cases in the United States
Person-to-person spread: none
Current public health risk: low
This HPAI H5N1 bird flu has been circulating worldwide since 2020 and was first detected in the United States in January 2022. The primary reservoir is waterfowl (ducks and geese). This has caused sporadic outbreaks among other wild birds. Waterfowl interactions have also caused outbreaks in domestic poultry (including backyard flocks). In February 2024, a backyard flock in Barnstable County had to be depopulated (MDAR activity here: Avian Influenza | Mass.gov).
HPAI H5N1 bird flu usually does not infect humans or mammals and if it does it usually is through close contact with an infected bird or mammal. However, the constant concern is that the virus will mutate and be able to more easily infect and transmit between mammals and humans. It is a new development that this HPAI H5N1 bird flu has infected dairy cows in Texas as well as 1 human. The human presented with the sole symptom of conjunctivitis and reported close contact with the herd of dairy cows. This suggests that the influenza virus was introduced through their eye rather than their respiratory tract meaning a milder form of illness. While the Texas case was mild, this HPAI H5N1 can cause severe human illness and death. Of the 19 human cases worldwide identified prior to this Texas case, 7 have had severe illness and 5 died (Technical Report: Highly Pathogenic Avian Influenza A(H5N1) Viruses (cdc.gov).
Here are some helpful resources for you going forward:
H5N1 Bird Flu: Current Situation Summary | Avian Influenza (Flu) (cdc.gov) – also has protective action recommendations at the bottom of the page
Barnstable County Avian Influenza blog post, published Apr 4: Avian Bird Flu on Cape Cod - Barnstable County
Avian Influenza | Animal and Plant Health Inspection Service (usda.gov)
USDA HPAI risk to dairy herds fact sheet: hpai-dairy-faqs.pdf (usda.gov)
Massachusetts Dept of Agriculture and Resources Poultry Program: Poultry Program | Mass.gov (great links at bottom of page)
Lea Hamner, MPH
Contract Epidemiologist | Health and Environment
Barnstable County, Regional Government of Cape Cod
Email lea.hamner-contractor@capecod.gov