Bird Flu (H5N1): Your Questions Answered
By:
Houston Methodist The Woodlands Hospital
| Published 05/17/2024
By: Josh Davis
It hasn't been a good time to be a bird since outbreaks of avian flu began increasing around 2020. Now it may not be fortuitous to be cattle.
Flu, or influenza, is a family of related viruses that can affect both humans and animals. Bird flu, or avian flu, is not the same as the seasonal "flu" that humans transmit but rather a specific type, avian H5N1, which got its name by spreading among wild birds and domesticated poultry, such as chickens, turkeys and ducks.
However, flu viruses have been known to transmit to other species — the current H5N1 bird flu has infected at least 26 wild mammal species, including seals, red foxes, brown bears, skunks, mountain lions and a bottlenose dolphin. Bird flu's latest host? Dairy cows.
The good news: The current risk of humans becoming infected is low. Still, the CDC and FDA are vigilantly monitoring the situation as it develops.
In the meantime, we asked Dr. Wesley Long, medical director of diagnostic microbiology at Houston Methodist, some common questions people have about bird flu and how it might impact Texans and others.
Here are his responses:
Q: What is bird flu?
Dr. Long: Bird flu is a type of influenza virus named after its most common host, birds. It primarily infects birds, both wild and domestic, and has caused outbreaks in poultry from time to time. The most recent outbreak in 2024 in the U.S. is in poultry and dairy cattle. It has also been found in rare cases in other animals.
Q: Can humans get bird flu?
Dr. Long: Bird flu (avian H5N1) does not infect humans very well, and as of April 2024, there have only been two confirmed cases in the U.S. — one in Colorado in 2022 and the other in 2024 in Texas. Bird flu does not transmit well at all from person to person, so infections from person to person are extremely rare and usually very limited to close household contacts.
Human infections with bird flu happen most commonly when there is repeated close contact with an infected animal. People who get infected are most often those who work closely with poultry and livestock. People who work with poultry and cattle in the U.S. are the most at risk at present, but the general population shouldn't be concerned at this point.
Q: What are the symptoms of bird flu?
Dr. Long: They can range from little to no symptoms to symptoms like conjunctivitis or eye redness to flu-like symptoms caused by the human influenza, such as fever, cough, sore throat, body aches and runny nose. In rare cases, there could be more severe symptoms, like shortness of breath or difficulty breathing, that may require hospitalization.
Q: How will I know if my symptoms are bird flu?
Dr. Long: Seasonal influenza (or "flu season") starts in the early fall and peaks in winter and ends in the spring in the U.S., although flu viruses are detected year-round and circulate in the Southern Hemisphere in the summer months. If you or someone you know experiences flu-like symptoms, you can get tested for influenza, which most likely will be the type of influenza A or influenza B that commonly infect people. The two flu viruses that currently circulate among people most commonly are called H1N1 and H3N2 respectively.
At Houston Methodist, the tests we use for influenza will detect and identify these common influenza A and B infections, but our PCR tests will also recognize the avian H5N1 or "bird flu" as a "non-typeable" influenza virus — which means it needs to be followed up on with public health. Working in concert with them, we can determine if it is indeed avian H5N1 or "bird flu" or just a seasonal influenza virus common in humans.
Q: Is there a treatment for bird flu?
Dr. Long: Yes, the same antiviral medication we use to treat human influenza, oseltamivir phosphate, can also treat avian influenza.
Q: Is the current flu shot any effective against bird flu?
Dr. Long: No, the seasonal influenza vaccine is designed to provide protection against the most common human influenza A and B strains that are H1 or H3 viruses. That said, everyone should still get their seasonal flu shot, especially those who work closely with poultry and livestock. You do not want to be infected with two different types of flu at the same time, and seasonal influenza viruses on their own can make even healthy young people very ill.
There is a bird flu vaccine being developed by the CDC, but it's currently not available.
Q: Is cow milk safe to drink right now?
Dr. Long: Yes, drinking pasteurized milk is safe. Pasteurization is when milk gets heated to a high enough temperature for enough time to kill harmful germs, including viruses and bacteria.
When the news says, "bird flu found in milk," what they mean is that scientists detected remnants of inactive and destroyed virus leftover from the pasteurization process, which are not capable of causing infection. It is analogous to finding fragments of a document that have gone through a paper shredder — scientists can identify the document if they find enough fragments, but those fragments cannot become a sheet of paper again.
Q: What about raw milk?
Dr. Long: It's generally not recommended by health professionals to drink raw milk — milk that has not been pasteurized — which can harbor harmful pathogens like Campylobacter, Cryptosporidium, E. coli, Listeria, Brucella and Salmonella. All of these pathogens can cause incredibly unpleasant food poisoning symptoms and can be deadly in some cases.
Now that remnants of bird flu have been found in pasteurized milk, it's just one more reason to avoid raw milk, but it's important for people to know that your risk of catching one of the other pathogens I mention is far more likely. Similar to eating raw hamburger meat or uncooked chicken or eggs, it's just not something that's recommended.
Q: Is it safe to eat poultry and beef?
Dr. Long: Yes, it's unlikely that you will contract bird flu from eating cooked beef and chicken. Most importantly, cooking meats and other food products to the appropriate internal temperatures recommended by the USDA will reduce the risk of contracting food-borne illnesses which are far more common.
Q: What can I do to protect myself from getting bird flu?
Dr. Long: Again, the current public health risk is incredibly low, especially for the general public. People who work with animals like poultry and dairy cattle are at the greatest risk of exposure. There are precautions the CDC recommends, like avoiding direct contact with wild birds, getting the seasonal flu vaccine, and if you work with dairy cattle or poultry to use the recommended personal protective equipment and limit contact with sick animals.
If you find a dead bird and are concerned about bird flu or other viruses that infect bird like West Nile virus, contact your local health department or state wildlife agency, who can assist you further.
