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Highly Pathogenic Avian Influenza (HPAI) Basics

Key Points
  • Since March 2024, public health officials have been closely monitoring a multi-state outbreak of HPAI (H5N1 "bird flu") in dairy cows.

  • This is the first time HPAI has been found in dairy cows, which has been widespread in wild birds worldwide and causing outbreaks among U.S. poultry since 2022.

  • Three human cases have been reported in dairy workers in Texas and in Michigan, all following exposures to infected dairy cows. Both cases experienced mild symptoms and have since recovered.

  • The current risk to the general public remains low. Those with direct and prolonged exposure to infected animals are at increased risk.

  • Federal, state, and local agencies continue to work closely to detect, contain, and prevent further HPAI outbreaks and monitor people with animal exposures.

  • Though HPAI currently remains primarily an animal health issue, public health agencies are closely watching this evolving situation and taking routine preparedness and prevention measures in case this virus changes to pose a greater risk to human health.

For the most current information on HPAI, including the Michigan outbreak please visit:

What is HPAI?
Highly Pathogenic Avian Influenza (HPAI), also known as H5N1 bird flu, is a highly contagious and often deadly disease in poultry, caused by avian influenza Type A viruses. HPAI viruses naturally spread among wild birds and can infect domestic poultry and other bird and animal species. While HPAI typically does not infect humans, there have been occasional cases of human infection primarily tied to close contact with infected animals.
How does it spread?
  • In birds, these viruses infect the respiratory and gastrointestinal tracts and are shed in feces. Direct infection of wild birds, poultry, and mammals can occur through exposure to saliva, mucus, or feces of infected birds. The transmission between and from dairy cows is still being investigated and may involve milking equipment.

  • Human infections can happen when enough virus gets into a person's eyes, nose, or mouth, or is inhaled. This can happen if the virus is in the air (in droplets or possibly dust) and a person breathes it in, or if the person touches a contaminated surface and then touches their mouth, eyes, or nose.

  • HPAI infections in people happen most often after close, prolonged, and unprotected (no gloves or other protective wear) contact with infected birds or other animals. People with close or prolonged contact with infected birds or animals or their contaminated environments are at greater risk of infection.

Recommendations for the Public
  • The best prevention is to avoid exposure. Avoid close, long, or unprotected exposures to sick or dead animals, including wild birds, poultry, domesticated birds, and other wild or domesticated animals (including cows), and their feces, contaminated materials, and surfaces. Avoid contact between pets and wild birds.
    • Personal protective equipment (PPE) should be worn when in direct or close contact with sick or dead animals.
    • PPE recommendations
  • Report suspected HPAI infections among animals:
    • For Domestic Animals:
      • Contact the Michigan Department of Agriculture and Rural Development (MDARD) at 1-800-292-3939 (daytime) or 517-373-0440 (after-hours).
    • How to Recognize a Sick Bird
    • For Wildlife
      • Contact Michigan Department of Natural Resources at 517-336-5030
      • Eyes in the Field: Online Form
  • Avoid consuming raw (unpasteurized) milk or raw milk products. Choosing pasteurized milk is the best way to keep you and your family safe.
  • Properly prepare and cook poultry, meat and eggs.
  • Information for hunters: General safety guidelines for hunters
  • Information for People Exposed to Birds or Other Animals Infected with HPAI
HPAI In Poultry, Cattle & Protections For Farm Workers
Raw Milk Safety & Concerns
For Healthcare Providers