Wild birds that transmit avian influenza viruses include aquatic birds, such as ducks, geese, and swans, and coastal birds, such as storks. Avian influenza viruses can easily spread from wild birds to domestic poultry, such as chickens and turkeys. Some wild birds may carry avian influenza viruses without appearing sick, but poultry like chickens and turkeys can become severely ill and die from certain strains of avian influenza. If you raise ducks or domestic poultry, they can become infected if they come into contact with infected wild birds or share food, water, or environments with them. Common songbirds or other birds often found in gardens, such as cardinals, robins, sparrows, blue jays, crows, or pigeons, generally are not carriers of the avian influenza viruses that pose a risk to poultry or humans.

For birds, the virus can be lethal, potentially causing up to 100% mortality.

To prevent the virus from entering, it is necessary to avoid contact between domestic birds and wild birds. Therefore, the presence of sick birds should be reported to veterinary authorities for timely attention.

Proper surveillance of avian influenza in birds allows us to identify circulating subtypes of avian influenza and, most importantly for public health, helps detect the presence of viruses with significant zoonotic potential—that is, those with the possibility of changing in ways that make them more adaptable to transmission in humans. In addition, early detection allows countries to implement a rapid response to reduce the risk of the virus being transmitted to people.

Culling domestic birds is one of the strategies recommended by the World Organisation for Animal Health (WOAH) and the Food and Agriculture Organization (FAO) to control and eradicate the virus before it spreads. However, this is not the only tool—proper quarantining of infected zones, restricting animal movement, enhancing biosecurity, and intense surveillance near outbreak areas are also important. There is no one-size-fits-all approach; multiple strategies must be used and adapted based on the specific animal population, the epidemiological context, and the availability of other control measures, particularly when dealing with animals of high ecological value.

The widespread geographic spread of A(H5N1) viruses in wild birds, poultry, and some other mammals could provide more opportunities for people to be exposed to these viruses, especially through close or direct contact with infected animals or their environments. As a result, there may be an increase in sporadic human infections due to exposure to infected poultry or other animals, even though the overall risk of transmission from birds or other animals to humans has not increased.

Although H5 avian influenza viruses primarily infect various types of wild birds and domestic poultry, other animals can also become infected. Sporadic infections with the A(H5N1) virus have been reported in mammals for over 20 years in various countries experiencing outbreaks in birds. It is known that H5 avian influenza viruses can occasionally infect mammals that eat infected birds or are exposed to environments with a high viral load. These mammals include wild species such as foxes, domestic and stray animals such as cats and dogs, and zoo animals like tigers and leopards. However, both wild and domestic animals exposed to H5 viruses can become infected.

This is still under study. However, international studies suggest that symptoms of the disease without complications may last between one and two weeks.

• Fever (37.8 °C or higher) or feeling feverish/chills.*

• Cough • Sore throat.

• Difficulty breathing/Shortness of breath.

• Conjunctivitis (watery eyes, redness, irritation, or eye discharge).

• Headache.

• Nasal congestion or runny nose.

• Muscle and body aches. • Diarrhea.

*It may occur without fever.

Although avian influenza A viruses generally do not infect humans, very sporadic cases of human infection have been reported. In humans, illness caused by avian influenza virus infection has varied in severity—from asymptomatic or mild illness to severe cases resulting in death.

As a general precaution, people should avoid direct contact with wild birds or other animals infected or suspected to be infected with avian influenza viruses and observe them from a distance, if possible. Wild birds can be infected without appearing ill. If possible, avoid contact with sick or dead animals, including wild birds, poultry, domestic birds, and other wild or domestic animals. Avoid contact with surfaces contaminated with animal feces, raw milk, animal waste, or materials contaminated by birds or other animals infected or suspected to be infected with avian influenza viruses.

If handling wild birds or sick/dead poultry, wear gloves to reduce direct contact and wash your hands with soap and water afterward. If available, use respiratory protection, such as a medical mask. Change clothes before contacting healthy birds, and if handling wild birds, discard gloves and mask, then wash your hands thoroughly with soap and water.

Seasonal influenza vaccines do not offer protection against these viruses.

The clinical management of hospitalized patients focuses on supportive care for complications, including advanced organ support in intensive care units for patients with severe pneumonia. Patients with suspected or confirmed A(H5N1) infection should receive antiviral treatment with oseltamivir as soon as possible, in addition to standard antiviral treatment.

People should avoid exposure without protection (such as respiratory and eye protection) to sick or dead animals, including wild birds, poultry, domestic birds, and other wild or domestic animals.