New research has shed light on the detection of Highly Pathogenic Avian Influenza (HPAI) A(H5N1) virus, specifically the Eurasian lineage H5 clade 2.3.4.4b, in various species of wild terrestrial mammals in the United States. This groundbreaking finding, published in the U.S. CDC Emerging Infectious Diseases Volume 29, reveals that North American wildlife is susceptible to natural infections with this strain of avian influenza.
The study highlights the involvement of intrinsic and extrinsic factors in facilitating the transmission of the virus to mammals. Intrinsic factors, such as opportunistic dietary preferences and the likelihood of sharing environments with infected birds, contribute to the elevated risk of exposure and infection. Additionally, the abundance of immunologically naive animals during the onset of avian outbreaks and potentially increased susceptibility in certain species further explain the detection of HPAI H5N1 in wild mammals.
The affected mammals in this study include red foxes, striped skunks, raccoons, bobcats, Virginia opossums, coyotes, fishers, and gray foxes. Interestingly, many red foxes were found in urban or periurban environments, suggesting that human interest in these highly visible animals may have contributed to increased public reporting.
While ingestion of infected birds is believed to be the primary source of infection in wild mammals, evidence of mammal-to-mammal transmission was not apparent in these cases. However, the possibility of horizontal transmission between mammals cannot be ruled out, as it has been documented in other species such as domestic cats and ferrets.
The geographic and temporal distribution of the HPAI virus-infected mammals in this study suggests that these infections are sporadic spillover events into individual animals sharing the landscape with infected wild birds. Sequencing data confirms the presence of different genotypes of the virus, indicating its emergence and circulation among wild birds in the United States.
This research highlights the need for ongoing surveillance of the HPAI virus in wild mammals to better understand its distribution and evolution in free-ranging wildlife. By monitoring the virus in these populations, scientists can contribute to a more comprehensive understanding of the impacts and risks associated with avian influenza.
FAQ:
Q: What species of mammals were affected by the H5N1 avian influenza virus?
A: The affected mammals include red foxes, striped skunks, raccoons, bobcats, Virginia opossums, coyotes, fishers, and gray foxes.
Q: How do mammals become infected with the HPAI H5N1 virus?
A: Mammals are presumed to become infected with the HPAI H5N1 virus through the ingestion of birds infected with the virus.
Q: Is there evidence of mammal-to-mammal transmission of the HPAI H5N1 virus?
A: While not apparent in this study, mammal-to-mammal transmission cannot be ruled out, as it has been documented in other species such as domestic cats and ferrets.
Q: What implications does this research have for understanding the distribution and evolution of avian influenza?
A: By monitoring the HPAI virus in wild mammals, scientists can gain insights into its distribution and evolution in free-ranging wildlife, contributing to a better understanding of the impacts and risks associated with avian influenza.