Skip to main content
Contact Us

An official State of Nevada site. The Office of State Epidemiology works in partnership with:

Circle with an x in the middle

Close

Alert Icon

For information on the recent 2024-25 bird flu outbreak in dairy cows,

Click Here
  • Situational Update
  • Avian Influenza

Avian Influenza – Bird Flu

  • 05.28.2024

Situational Update (Last Updated 2/20/2025)

Bird flu infections are unusual in mammals, including humans. Beginning in the spring of 2024, there have been large outbreaks of bird flu among dairy cattle in several states. Bird flu was first reported in dairy cows in Nevada in December 2024. It was later reported in a human for the first time in Nevada in February 2025.

Confirmed human H5N1 infections in the United States since 2024 include:

  • 41 dairy workers across multiple states who were infected after exposure to infected cows (or to contaminated materials related to dairy farm operations)
  • 23 poultry workers across multiple states who were infected after exposure to infected poultry (or to contaminated materials related to poultry farm operations)
  • 1 person with exposure to a different animal
  • 3 people with unknown exposure sources have also been infected

Louisiana reported the first death due to H5 bird flu (from exposure to an infected backyard flock) in the U.S. on January 6, 2025.

For the most up-to-date case numbers, please see the CDC H5 Bird Flu: Current Situation webpage.

The risk to the public is currently considered low, but people who work with birds, poultry, or dairy cows, or who have recreational exposure to them, are at higher risk of infection.

What is avian influenza A(H5N1)?

  • Avian influenza A (H5N1) is a contagious viral disease that widely affects wild and domestic birds. It is a type of bird flu.
  • There are several viral subtypes of bird flu, one of which is A(H5N1).
    • The “A” means “Influenza A”.
    • The H and N refer to different structures on the surface of the virus.
  • From 1997 through 2023, about 900 people had been infected with H5N1 globally.
    • Thankfully, not a lot of people are infected each year, and the disease doesn’t seem to infect people easily.
    • But of those that were infected during this time period, about 50% died.
  • Of the 68 confirmed cases in the United States from 2024 through the present (2/20/2025), 1 (1.5%) died.
  • We are still learning how infection severity might be affected by factors like virus genetics, transmission route, and pre-existing conditions.

Recent History of Bird Flu in the U.S.

  • In 2022, the A(H5N1) subtype of bird flu was detected in wild birds in the U.S.
  • In 2022 and 2023, H5N1 caused outbreaks in commercial and backyard poultry flocks around the country.
  • In March 2024, H5N1 was detected in goat kids and dairy cows for the first time.
  • In early April 2024, a person who worked on a dairy farm in Texas tested positive for H5N1. In May 2024, two dairy workers from Michigan tested positive and in July 2024 a dairy worker in Colorado tested positive. Since then, California has also reported dairy workers who tested positive for H5N1.
  • Since 2024, the states of Colorado, Iowa, Oregon, Washington, and Wisconsin have reported poultry workers who tested positive for H5N1.  
  • States continue to test dairy and poultry workers with symptoms for H5N1.
  • For the most up-to-date numbers of H5N1 detections in humans and animals, and to see which states have been impacted, please see CDC’s H5 Bird Flu: Current Situation.

Risk to the Public

  • The risk H5N1 poses to the general public is considered low.
  • However, people who have contact with sick or dead animals (especially birds), or with any lactating dairy cows may be at higher risk than the general public.
    • “Contact” includes interacting with a sick/dead animal or with contaminated materials in the animal’s environment like manure, bedding, and tools that have touched raw milk.
  • It is important to note that dairy cows may be infected and able to spread H5N1 but not show symptoms.
    • Testing of dairy cows is increasing, but we still don’t know how often asymptomatic infections happen in dairy cows.
  • Consuming dairy products made with unpasteurized (untreated) milk, also known as raw milk, may be a risk factor. The U.S. Food and Drug Administration is still researching this and the Nevada Office of State Epidemiology (OSE) will update this page as we learn more.
    • Consuming foods made with raw milk is known to increase your risk of gastrointestinal illness from germs like Salmonella and E. coli.
    • Consuming products made with pasteurized dairy is considered safe.

Bird Flu and Nevada

  • The Nevada Department of Agriculture (NDA) first reported H5N1 in dairy cows in Nye County, Nevada on December 6, 2024.
  • NDA reported a detection of H5N1 in dairy cattle in Churchill County on January 24, 2025.
    • On January 31, the U.S. Department of Agriculture (USDA) confirmed that the cattle were infected with H5N1 clade 2.3.4.4b genotype D1.1. This was the first time this genotype was ever detected in dairy cattle.
  • The Central Nevada Health District reported the first confirmed human case of H5N1 in Nevada in a Churchill County dairy worker on February 10, 2025.
    • The individual reported conjunctivitis as their only symptom and has since recovered.
    • Analysis of the virus at the Centers for Disease Control and Prevention (CDC) confirmed that this individual was infected with the same genotype of the virus as was found in the dairy cattle (D1.1).
  • On the U.S. Department of Agriculture’s website, you can see a map of new detections of H5N1 in livestock across the country. 
  • To see a summary of the most recent detections of H5N1 in wild birds in Nevada, click here. To see a map of the most recent detections of H5N1 in domestic poultry across the country, click here.
  • In late April 2024, the U.S. Department of Agriculture issued a Federal Order to test lactating dairy cows for H5N1 prior to any interstate movement.
    • This requires that any lactating dairy cows coming into Nevada are tested before transport.

Symptoms in Humans, Birds, and Cattle

H5N1 infections can vary in severity in animals and humans, from asymptomatic infection with no noticeable symptoms, to severe disease and death.

Humans

  • Symptoms of H5N1 infections in humans may include:
    • Eye redness (conjunctivitis) – this has been the most commonly reported symptom in the human cases so far.
    • Fever (temperature of 100oF [37.8oC] or greater) or feeling feverish
    • Cough
    • Sore Throat
    • Runny or stuffy nose
    • Muscle or body aches
    • Headaches
    • Fatigue
    • Shortness of breath or difficulty breathing
    • Less common symptoms include diarrhea, nausea, vomiting, or seizures

If you develop symptoms in the 10 days after you had contact with an infected or potentially infected animal, contact your healthcare provider and be sure to mention your animal contact.

  • You may also contact the Health Authority for the county you live in and they can help get you information and figure out how to get tested and treated.

Birds and Cattle

You can read more about common symptoms of H5N1 in dairy cattle and in birds on the American Veterinary Medical Association’s website.

Preventative Measures

  • Avoid consuming raw milk or food products made with raw milk.
  • Be sure to cook meat to the proper temperature.
    • For beef: 160°F for ground beef and 145°F for steaks and roasts
    • For chicken: 165°F for all cuts
  • If you find any dead wild birds, do not handle them. Report dead wild birds to the Nevada Department of Wildlife using this form.
  • Report any sick or dead backyard birds to the Nevada Department of Agriculture using this email address: Diseasereporting@agri.nv.gov
    • If you must handle sick or dead backyard birds, make sure to use protective equipment such as disposable gloves, safety goggles, rubber boots, and a mask.
  • Thoroughly wash your hands after interacting with animals.
    • Wash hands vigorously for at least 20 seconds with soap and water. Dry your hands with a disposable paper towel.
  • Stay informed by periodically checking the OSE website and the additional resources listed below!
  • For important tips on safe hunting and harvesting practices, click here.

Additional Resources