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Avian Influenza Continues To Pose Risks To Humans - World Health Organization
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The recent outbreaks of avian influenza, commonly known as "bird flu," have wreaked havoc on animal populations worldwide, causing devastating consequences for poultry, wild birds, and even some mammals. These outbreaks have not only harmed farmers' livelihoods and the food trade but also pose ongoing risks to human health. In response to this global crisis, the Food and Agriculture Organization of the United Nations (FAO), the World Health Organization (WHO), and the World Organisation for Animal Health (WOAH) are urging countries to collaborate across sectors to protect animals and people.
Avian influenza viruses typically spread among birds, but recent findings of H5N1 avian influenza among mammals, which are genetically closer to humans, have raised concerns about the virus potentially adapting to infect humans more easily. Furthermore, certain mammals may serve as mixing vessels for influenza viruses, leading to the emergence of new strains that could be more harmful to both animals and humans.
The H5N1 avian influenza viruses, specifically the goose/Guangdong-lineage, first appeared in 1996 and have been causing outbreaks among birds ever since. However, since 2020, a variant of these viruses belonging to the H5 clade 2.3.4.4b has resulted in an unprecedented number of deaths in wild birds and poultry across Africa, Asia, and Europe. The virus further spread to North America in 2021 and to Central and South America in 2022.
In 2022 alone, 67 countries spanning five continents reported high pathogenicity avian influenza outbreaks in poultry and wild birds to WOAH, resulting in the loss of over 131 million domestic poultry due to death or culling on affected farms and villages. As the disease continues to spread, an additional 14 countries have reported outbreaks in 2023, primarily in the Americas. Numerous mass death incidents have been reported in wild birds, attributable to influenza A(H5N1) clade 2.3.4.4b viruses.
Monitoring the recent surge in outbreaks among mammals has become crucial. Ten countries across three continents have reported influenza A(H5) outbreaks in mammals to WOAH since 2022, but it is likely that there are more undetected or unreported cases. Both land and sea mammals have been affected, including outbreaks in farmed mink in Spain, seals in the United States of America, and sea lions in Peru and Chile. At least 26 different species have been affected by these outbreaks. Additionally, H5N1 viruses have been found in domestic animals such as cats and dogs in several countries, with recent cases in cats reported in Poland.
Dr. Gregorio Torres, Head of the Science Department at WOAH, emphasized the paradigm shift in the ecology and epidemiology of avian influenza, which has caused widespread concern due to the disease's geographical expansion, unusual bird die-offs, and the alarming rise in mammalian cases.
While sporadic human infections with influenza A(H5N1) clade 2.3.4.4b have been reported, they remain exceptionally rare, with only eight cases documented since December 2021. However, these infections can result in severe disease with a high mortality rate. The reported human cases have primarily been linked to close contact with infected birds and contaminated environments.
Dr. Sylvie Briand, Director of Epidemic and Pandemic Preparedness and Prevention at WHO, emphasized the importance of vigilance in monitoring the virus for any potential changes that could enhance human-to-human transmission. She highlighted the collaboration between WHO, FAO, and WOAH, along with laboratory networks, to track the evolution of these viruses and identify any signals indicating heightened danger to humans. Dr. Briand also stressed the need for countries with limited experience in avian flu surveillance to strengthen their monitoring capabilities.
Ongoing studies are investigating potential changes in the virus that may enable easier transmission among mammals, including humans. Keith Sumption, Chief Veterinary Officer at FAO, highlighted the necessity of vigilance and the timely sharing of genetic sequences to assess risks and improve disease control.
To address the unprecedented spread of A(H5N1) avian influenza and the potential risks to human health, FAO, WHO, and WOAH have jointly called on countries to take several critical actions:
• Implement enhanced biosecurity measures in farms and poultry value chains to prevent avian influenza at its source.
• Rapidly detect, report, and respond to animal outbreaks, prioritizing control strategies recommended by WOAH standards.
• Strengthen surveillance for influenza in animals and humans, with a particular emphasis on risk-based surveillance during high-risk periods.
• Animal cases should be reported to WOAH promptly, and periodic genetic sequencing should be conducted.
• Conduct thorough epidemiological and virological investigations around animal outbreaks and human infections.
• 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 risks to healthcare workers, occupationally-exposed individuals, and the general public, providing guidance on protective measures and reporting potential exposures.
• Ensure comprehensive influenza pandemic preparedness at all levels.
FAO, WHO, and WOAH continue to convene experts, monitor the evolving nature of the virus, update recommendations for controlling its spread, and work closely with countries on preparedness and response efforts. The widespread dispersion of the virus across five continents underscores the urgent need for global cooperation and vigilance to safeguard animals, people, and economies from the devastating impact of avian influenza.
Avian influenza viruses typically spread among birds, but recent findings of H5N1 avian influenza among mammals, which are genetically closer to humans, have raised concerns about the virus potentially adapting to infect humans more easily. Furthermore, certain mammals may serve as mixing vessels for influenza viruses, leading to the emergence of new strains that could be more harmful to both animals and humans.
The H5N1 avian influenza viruses, specifically the goose/Guangdong-lineage, first appeared in 1996 and have been causing outbreaks among birds ever since. However, since 2020, a variant of these viruses belonging to the H5 clade 2.3.4.4b has resulted in an unprecedented number of deaths in wild birds and poultry across Africa, Asia, and Europe. The virus further spread to North America in 2021 and to Central and South America in 2022.
In 2022 alone, 67 countries spanning five continents reported high pathogenicity avian influenza outbreaks in poultry and wild birds to WOAH, resulting in the loss of over 131 million domestic poultry due to death or culling on affected farms and villages. As the disease continues to spread, an additional 14 countries have reported outbreaks in 2023, primarily in the Americas. Numerous mass death incidents have been reported in wild birds, attributable to influenza A(H5N1) clade 2.3.4.4b viruses.
Monitoring the recent surge in outbreaks among mammals has become crucial. Ten countries across three continents have reported influenza A(H5) outbreaks in mammals to WOAH since 2022, but it is likely that there are more undetected or unreported cases. Both land and sea mammals have been affected, including outbreaks in farmed mink in Spain, seals in the United States of America, and sea lions in Peru and Chile. At least 26 different species have been affected by these outbreaks. Additionally, H5N1 viruses have been found in domestic animals such as cats and dogs in several countries, with recent cases in cats reported in Poland.
Dr. Gregorio Torres, Head of the Science Department at WOAH, emphasized the paradigm shift in the ecology and epidemiology of avian influenza, which has caused widespread concern due to the disease's geographical expansion, unusual bird die-offs, and the alarming rise in mammalian cases.
While sporadic human infections with influenza A(H5N1) clade 2.3.4.4b have been reported, they remain exceptionally rare, with only eight cases documented since December 2021. However, these infections can result in severe disease with a high mortality rate. The reported human cases have primarily been linked to close contact with infected birds and contaminated environments.
Dr. Sylvie Briand, Director of Epidemic and Pandemic Preparedness and Prevention at WHO, emphasized the importance of vigilance in monitoring the virus for any potential changes that could enhance human-to-human transmission. She highlighted the collaboration between WHO, FAO, and WOAH, along with laboratory networks, to track the evolution of these viruses and identify any signals indicating heightened danger to humans. Dr. Briand also stressed the need for countries with limited experience in avian flu surveillance to strengthen their monitoring capabilities.
Ongoing studies are investigating potential changes in the virus that may enable easier transmission among mammals, including humans. Keith Sumption, Chief Veterinary Officer at FAO, highlighted the necessity of vigilance and the timely sharing of genetic sequences to assess risks and improve disease control.
To address the unprecedented spread of A(H5N1) avian influenza and the potential risks to human health, FAO, WHO, and WOAH have jointly called on countries to take several critical actions:
• Implement enhanced biosecurity measures in farms and poultry value chains to prevent avian influenza at its source.
• Rapidly detect, report, and respond to animal outbreaks, prioritizing control strategies recommended by WOAH standards.
• Strengthen surveillance for influenza in animals and humans, with a particular emphasis on risk-based surveillance during high-risk periods.
• Animal cases should be reported to WOAH promptly, and periodic genetic sequencing should be conducted.
• Conduct thorough epidemiological and virological investigations around animal outbreaks and human infections.
• 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 risks to healthcare workers, occupationally-exposed individuals, and the general public, providing guidance on protective measures and reporting potential exposures.
• Ensure comprehensive influenza pandemic preparedness at all levels.
FAO, WHO, and WOAH continue to convene experts, monitor the evolving nature of the virus, update recommendations for controlling its spread, and work closely with countries on preparedness and response efforts. The widespread dispersion of the virus across five continents underscores the urgent need for global cooperation and vigilance to safeguard animals, people, and economies from the devastating impact of avian influenza.
Jul 13, 2023
