A new study published in the journal Science has revealed that the avian influenza A H5N1 virus, which has caused outbreaks in poultry and sporadic human infections in Asia and Africa, has also impacted a wide range of wildlife species in the U.S. since 2022. The study, led by researchers from the University of Georgia and the U.S. Geological Survey, found that the virus has caused unprecedented mortality in wild birds and mammals, and has spread across the continent through migratory flyways.
The researchers analyzed the genetic and epidemiological data of the H5N1 virus isolated from wild birds and mammals in the U.S. They found that the virus belongs to a clade 2.3.4.4b lineage that emerged in Asia in 2014 and was introduced into North America by migratory waterfowl in 2021. The virus then reassorted with a North American wild bird influenza virus, resulting in a strain that is better adapted to infect a wider range of hosts, including raptors, songbirds, rodents, and bats.
The researchers also discovered that the virus has acquired mutations that enhance its ability to bind to receptors in the mammalian respiratory tract, which could increase its transmissibility and virulence in humans. Moreover, the virus has shown a departure from the typical seasonal pattern of infection, as it has been detected throughout the year in various regions of the U.S.
H5N1 virus poses a serious conservation challenge
The study highlighted the severe conservation impacts of the H5N1 virus on wildlife populations, especially those that are already threatened by habitat loss, climate change, and other factors. The researchers estimated that the virus has killed more than 10 million wild birds and mammals in the U.S. since 2022, representing a significant loss of biodiversity and ecosystem services.
The researchers also warned that the virus could pose a risk to endangered species, such as the whooping crane, the California condor, and the Hawaiian goose, as well as to important breeding colonies on oceanic islands, such as Hawaii, Alaska, and Puerto Rico. They urged for increased surveillance and monitoring of the virus in wild birds and mammals, as well as for enhanced collaboration and coordination among different sectors and agencies to prevent and manage the outbreaks.
H5N1 virus remains a potential pandemic threat
The study also emphasized the public health implications of the H5N1 virus, as it remains a potential pandemic threat that could cause severe disease and death in humans. The researchers noted that the virus has infected more than 860 people in 16 countries since 2003, with a mortality rate of about 60%. They also pointed out that the virus has shown resistance to some antiviral drugs, and that the current vaccines may not provide adequate protection against the new strain.
The researchers recommended that people who have contact with wild birds or mammals, especially those who are involved in wildlife rehabilitation, research, or management, should follow appropriate biosafety measures and report any signs of illness to their health care providers. They also advised that people should avoid handling sick or dead animals, and that they should report any unusual wildlife mortality events to the local authorities.
