Frequently Asked Questions about Avian Influenza (Bird Flu) (2024)

Wild birds that carry bird flu viruses include waterbirds, like ducks, geese and swans, and shorebirds, like storks. Bird flu viruses can easily spread from wild birds to poultry, like chickens and turkeys. Some wild birds can carry bird flu viruses without appearing sick, but poultry, like chickens and turkeys, can get very sick and die from some bird flu viruses. If you raise backyard poultry or ducks, your birds can get bird flu if they have contact with infected wild birds or share food, sources of water, and environments with them. Most common songbirds or other birds found in the yard, like cardinals, robins, sparrows, blue jays, crows, or pigeons, do not usually carry bird flu viruses that are dangerous to poultry or people.

Human infections with bird flu viruses are rare but can occur, usually after close contact with infected birds. Very rarely, human infections with bird flu have happened after exposure to other infected animals. For example, in 2016, the spread of bird flu from a cat to a person was reported in NYC and in 2024, a person in Texas tested positive for highly pathogenic avian influenza (HPAI) A(H5N1) virus (“H5N1 bird flu”) after exposure to cattle presumably infected with bird flu. The current risk to the general public from bird flu viruses is low; however, it is important to remember that risk depends on exposure, and people with more exposure are at greater risk of infection. There are existing federal recommendationsaround bird flu exposures in birdsor other animals for different groups of people, including people with occupational or recreational exposure, such ashunters[297 KB, 2 pages]andpoultry producers, and also for the general public, including pet owners, as well as health careproviders.

As a general precaution, people should avoid direct contact with wild birds or other animals infected with or suspected to be infected with bird flu and observe them only from a distance, if possible. Wild birds can be infected with bird flu viruses without appearing sick. If possible, avoid contact with sick or dead animals including wild birds, poultry, other domesticated birds, and other wild or domesticated animals. Bird flu viruses have been detected in many other species. Avoid contact with surfaces that appear to be contaminated with animal feces, raw milk, litter, or materials contaminated by birds or other animals with suspected or confirmed bird flu virus infection. CDC has information about precautions to take with wild birds, poultry and other animals. As a reminder, it is safe to eat properly handled and cooked poultry and poultry products in the United States. The proper handling and cooking of poultry and eggs to an internal temperature of 165˚F kills bacteria and viruses, including bird flu viruses. In addition, people should not prepare or eat uncooked or undercooked food or food products, such as unpasteurized (raw) milk, or raw cheeses, from animals (for example, goats or cows) with suspected or confirmed bird flu virus infection.

CDC has guidance for specific groups of people with exposure to poultry and other potentially infected animals, including poultry or dairy workers, for example, and people responding to bird flu outbreaks. If you must handle wild birds or sick or dead poultry, minimize direct contact by wearing gloves and wash your hands with soap and water after touching birds. If available, wear respiratory protection such as a medical facemask. Change your clothing before contact with healthy domestic poultry and birds after handling wild birds, and discard the gloves and facemask, and then wash your hands with soap and water. Additional information is available at Information for People Exposed to Birds Infected with Avian Influenza Viruses of Public Health Concern.

Two human cases of avian influenza A(H5N1) have been reported in the United States. More information about these cases is available: Highly Pathogenic Avian Influenza A(H5N1) Virus Infection Reported in a Person in the U.S. These A(H5N1) virus-positive human cases do not change the human health risk assessment for the general public, which CDC considers to be low. CDC will continue to monitor closely for signs that the risk to human health has changed. Signals that could raise the public health risk include multiple, simultaneous reports of A(H5N1) virus infections in people following exposure to birds or other infected animals or identification of spread from one infected person to another. CDC also is monitoring A(H5N1) viruses for genetic changes that could indicate the virus is adapting and could spread more readily to and among people.

Yes, although H5 bird flu viruses primarily infect different types of wild birds and domestic poultry, H5 bird flu viruses can infect other animals as well. Sporadic A(H5N1) virus infections of mammals have been reported for 20 years in different countries that have experienced A(H5N1) outbreaks in poultry or wild birds. H5 bird flu viruses have previously been known to occasionally infect mammals that eat (presumably infected) birds or poultry and mammals that are exposed to environments with a high concentration of virus. These mammals include, but are not limited to, wild or feral animals such as foxes; stray or domestic animals such as cats and dogs; and zoo animals such as tigersandleopards. However, both wild and domestic animals that have been exposed to H5 viruses can become infected. Recently, sporadic H5 virus infections in mammals, including farmed mink in Spain; sea lions in Peru; and bears,wild foxes, skunks, goats, and dairy cows have been reported inCanada,the United Statesand other countries. The reports of H5 bird flu viruses in these mammals are likely associated with widespread outbreaks of H5 bird flu in wild birds.

CDC is actively looking into this situation to assess potential human health implications, including looking at H5 viruses found in mammals to see whether these viruses have undergone any changes seen in the past that have been associated with bird flu viruses spreading easily among poultry, infecting people more easily, or causing severe illness in people. The detection of the current predominant H5 bird flu viruses in mammals, includingfarmed mink, sea lions, bears, foxes, skunks, goats, and cows does not change the human health risk assessment for the general public, which CDC currently considers to be low. Right now, the H5 bird flu virus situation is primarily an animal health issue. The U.S. Department of Interior (DOI) and U.S. Department of Agriculture (USDA) are the lead federal departments for H5 virus infections in animals. In general, people should avoid wild birds and animals that appear sick or dead and also keep their pets away from sick or dead birds and animals.

No. The detections of A(H5N1) viruses in dairy cows and the related human infection in the U.S. do not change the A(H5N1) bird flu human health risk assessment for the U.S. general public, which CDC currently considers to be low. However, people with close or prolonged, unprotected exposures to infected birds or other animals (including livestock), or to environments contaminated by infected birds or other animals, are at greater risk of infection. CDC has interim recommendations for prevention, monitoring, and public health investigations of A(H5N1) bird flu viruses.

No. Analyses of the A(H5N1) viruses from farmed mink detected in Spain have not found any indications that would point to increased ability to infect humans. A(H5N1) viruses do not currently have an ability to easily infect the human upper respiratory tract, which would be needed to increase the risk of transmission to people. CDC’s partner agencies have characterized the similarity of A(H5N1) viruses from farmed mink detected in Spain to A(H5N1) candidate vaccine virusesdeveloped at CDC. These data show that vaccine viruses currently available for vaccine manufacturing are expected to provide cross-protection against viruses like the ones detected during the mink outbreak.

No. If there was mink-to-mink spread of A(H5N1) virus, assessment of the risk to public health would depend upon whether there were any genetic changes in the virus, and what those changes were compared with A(H5N1) viruses circulating in birds to date. While there was a genetic change in the A(H5N1) viruses detected during the outbreak in farmed mink in Spain that may have increased the amount of virus in infected mink, this change is unlikely to make it easier for A(H5N1) virus to transmit to humans. The genomic sequences of the A(H5N1) viruses isolated from mink were very similar to A(H5N1) viruses found in birds. Humans lack the type of receptor in the upper respiratory tract that A(H5N1) viruses use to cause infection. Limited mink-to-mink spread of A(H5N1) virus, especially in an environment with close contact among infected animals or following repeated exposure to infected birds, would not be surprising.

The wide geographic spread of A(H5N1) viruses in wild birds, poultry, and some other mammals could create additional opportunities for people to be exposed to these viruses, particularly through direct or close contact with infected birds or animals. Therefore, there could be an increase in sporadic human infections resulting from poultry or other animal exposures, even if the risk of transmission of these viruses from birds or animals to people has not increased.

Seasonal flu vaccines do not provide protection against these viruses. CDC has developed an H5 candidate vaccine virus (CVV) that is nearly identical or, in many samples, identical to the hemagglutinin (HA) protein of recently detected clade 2.3.4.4b A(H5N1) viruses in birds and mammals. This H5 CVV could be used to produce a vaccine for people, if needed, and preliminary analysis indicates that it is expected to provide good protection against the currently circulating H5N1 influenza viruses in birds and other animals.

People with avian influenza A virus infection are recommended to be treated as soon as possible with antiviral drugs that are FDA-approved and recommended for treatment of seasonal influenza. Such antiviral drugs include oseltamivir, zanamivir, peramivir, and baloxavir. Antiviral treatment works best when started as soon as symptoms begin. Patients with suspected or confirmed influenza A(H5N1) virus infection should be treated as soon as possible with the antiviral drug, oseltamivir. In addition to antiviral treatment, clinical management of hospitalized patients is focused on supportive care of complications, including advanced organ support in an intensive care unit for patients with severe pneumonia.