The current outbreaks of avian influenza, commonly known as “bird flu,” have had devastating effects on animal populations, including poultry, wild birds and certain mammals. These outbreaks have not only harmed farmers’ livelihoods and the food trade but also pose ongoing risks to human health.
The Food and Agriculture Organisation of the United Nations (FAO), the World Health Organisation (WHO), and the World Organisation for Animal Health (WOAH) are urging countries to collaborate across sectors to save as many animals as possible and protect human populations.
Avian influenza viruses primarily spread among birds. However, the increasing number of H5N1 avian influenza detections among mammals, which are biologically closer to humans than birds, is cause for concern. There is a heightened worry that the virus may adapt to more easily infect humans. Additionally, some mammals can act as mixing vessels for influenza viruses, leading to the emergence of new, potentially more harmful viruses for animals and humans.
The H5N1 avian influenza viruses of the goose/Guangdong lineage were first identified in 1996 and have caused bird outbreaks since then. A variant of these viruses, belonging to the H5 clade 126.96.36.199b, has been responsible for an unprecedented number of deaths in wild birds and poultry across Africa, Asia, Europe, North America, Central and South America.
In 2022, 67 countries in five continents reported H5N1 avian influenza outbreaks in poultry and wild birds, resulting in more than 131 million domestic poultry loss. In 2023, another 14 countries reported outbreaks, primarily in the Americas. Several mass death events in wild birds have been caused by influenza A(H5N1) clade 188.8.131.52b viruses.
A recent surge in deadly outbreaks among mammals caused by influenza A(H5) viruses, including A(H5N1). Since 2022, 10 countries across three continents have reported outbreaks in mammals to WOAH, but it is likely that there are more countries where outbreaks have yet to be detected or reported. Various land and sea mammals have been affected, including farmed mink in Spain, seals in the United States of America and sea lions in Peru and Chile. At least 26 species have been impacted. H5N1 viruses have also been detected in domestic animals such as cats and dogs in multiple countries, including recent detections in cats in Poland.
The head of the science department at WOAH, Dr. Gregorio Torres stated, “There is a recent paradigm change in the ecology and epidemiology of avian influenza, which has heightened global concern as the disease spreads to new geographical regions, causes unusual wild bird die-offs, and leads to an alarming rise in mammalian cases”.
Although sporadic cases of influenza A(H5N1) clade 184.108.40.206b infections in humans have been reported, they remain rare, with only eight cases reported since December 2021. However, infections in humans can result in severe disease with a high mortality rate. The human cases detected so far have primarily been linked to close contact with infected birds and contaminated environments.
The director of Epidemic and Pandemic Preparedness and Prevention at WHO, Dr. Sylvie Briand emphasised the need for vigilance, stating, “With the information available so far, the virus does not appear to be able to transmit easily from person to person. However, we must remain vigilant to identify any evolution in the virus that could change this.” Briand added that WHO is working closely with FAO and WOAH, as well as laboratory networks, to monitor the evolution of the viruses and detect any changes that could pose greater risks to humans.
Studies are currently underway to identify any changes in the virus that may enhance its ability to spread among mammals, including humans.
Given the unprecedented spread of the A(H5N1) avian influenza virus among birds and mammals and the potential risk to human health, FAO, WHO and WOAH urged countries to take the following actions:
- Prevent avian influenza at its source through enhanced biosecurity measures and good hygiene practices in farms and poultry value chains. Vaccination of poultry may be considered a complementary disease control measure based on surveillance and local factors.
- Rapidly detect, report, and respond to animal outbreaks to serve as the first line of defence. Control strategies should be implemented in accordance with WOAH standards.
- Strengthen influenza surveillance in animals and humans. Enhanced risk-based surveillance in animals, especially during high-risk periods, and timely reporting of avian influenza cases to WOAH are crucial. Surveillance for severe acute respiratory infections and influenza-like illnesses in humans should also be prioritised.
- Conduct epidemiological and virological investigations around animal outbreaks and human infections. Enhanced surveillance should be implemented to detect and investigate suspected cases promptly.
- Share genetic sequence data of viruses from humans, animals, or their environments in publicly accessible databases, even before peer-reviewed publication.
- Encourage collaboration between the animal and human health sectors, including information sharing, joint risk assessment, and response.
- Communicate the risk to healthcare workers and occupationally-exposed individuals, providing them with guidance on protective measures. The general public and animal workers should be advised to avoid contact with sick and dead animals and report any exposure to animal health authorities.
- Ensure preparedness for influenza pandemics at all levels.
FAO, WHO and WOAH continue to convene experts, monitor the evolving nature of the virus, and update recommendations for curbing its spread. They are working with countries to enhance preparedness and response and promote collaboration across sectors and countries. With the virus spreading across five continents, global cooperation and vigilance are essential to protect animals, people and economies.