Photo credited to Barend Becker, from the Australian Antarctic Program
The H5N1 avian flu virus has been headlining news recently as cases surge. This strain of the virus, which is known for its extremely high mortality rate in infected humans at 60%, has recently been spreading among wildlife and domesticated birds alike. There has been elevated concern this past week especially, because there were confirmed human cases that were transmitted from infected cows (Cdc Newsroom, 2024).
While infected poultry and livestock is a massive public health concern due to potentially contaminated food and transmission to humans, the spread of this virus is also raising huge concerns for wildlife. At the end of January, there were confirmed cases and deaths of penguins due to H5N1 on the Falkland Islands and Antarctica (Baisas, 2024). The fact that the virus has reached these areas is alarming because they are relatively isolated, so transmission was not previously thought to be a concern. Now that individuals have become infected, the avian flu is likely to heavily impact populations because of the community ecology of penguins (Baisas, 2024).
Penguins breed in large colonies with hundreds of thousands of individuals packed into small areas of land. The close proximity of individuals within colonies coupled with the lack of H5N1 immunity will likely lead to widespread death (Baisas, 2024). Antarctic penguin colonies are already in a fragile state due to climate change, and this disease will only further their perilous position. Several adult Gentoo penguins have been recorded as having died from the avian flu, and over 20 chicks have also perished (Baisas, 2024). If the disease knocks out the vulnerable young of the species, it will be difficult for that population to persist. It was also discovered that the first king penguin to ever contract the avian flu has died (Baisas, 2024).
This virus greatly impacts the respiratory physiology of birds. Specifically, the virus targets the pulmonary epithelial cells of the trachea and lower respiratory tract (Lu & Zhao, 2015). It attacks the delicate capillaries and tissues of the lungs that make gas exchange possible, making it more difficult for birds to obtain the necessary amount of oxygen as the infection worsens (Lu & Zhao, 2015). As oxygen is no longer being efficiently diffused through the capillaries and tissues, flight and normal behavior becomes strenuous, and overall body condition worsens as foraging efficiency decreases. In the end stages of the disease, hemorrhaging of the lungs can occur (Lu & Zhao, 2015).
Although the Antarctic infection was likely introduced naturally by migrating brown skuas, the prevalence of the virus is still very much an anthropogenic issue (Baisas, 2024). Outbreaks and spreads often originate in factory farm settings where unhygienic conditions and close quarters allow disease to spread like wildfire. Even well-meaning homeowners can unintentionally disperse the virus by setting up bird feeders, which causes species that would otherwise be far apart to congregate (Lu & Zhao, 2015). Climate change is causing more disease outbreaks and physiological difficulties for all animals, so it is important to trust and work with epidemiologists and wildlife scientists when treating infected animals and preventing disease.
References
Baisas, L. (2024, January 30). Antarctic penguins are now dying from the H5N1 strain of bird flu. Popular Science. https://www.popsci.com/environment/antarctic-penguins-bird-flu-deaths/
Cdc newsroom. (2024, April 1). CDC. https://www.cdc.gov/media/releases/2024/p0401-avian-flu.html
Lu, P., & Zhao, Q. (2015). Highly pathogenic avian influenza. In H. Li (Ed.), Radiology of Infectious Diseases: Volume 1 (pp. 157–189). Springer Netherlands. https://doi.org/10.1007/978-94-017-9882-2_18