How Bird Flu is Spreading Among Mammals and Growing Pandemic Fears
Recent studies have revealed the mechanisms by which the H5N1 bird flu virus is spreading among mammals, sparking concerns about the potential for a new pandemic. Originally confined to wild birds and poultry, the highly pathogenic avian influenza (HPAI) H5N1 virus has now been detected in a variety of mammal species across the United States and other parts of the world. This article explores the findings of these studies and the implications for public health.
Spread of H5N1 Among Mammals
Research conducted by the U.S. Geological Survey (USGS) and the Centers for Disease Control and Prevention (CDC) has shown that H5N1 infections in mammals often result from predation or scavenging of infected birds. Between April 2022 and July 2022, the H5N1 virus was found in 67 wild mammals across 10 states, including species such as red foxes, striped skunks, raccoons, and bobcats. The most common symptoms observed in these infected mammals were neurological, including seizures and ataxia.
Globally, sporadic H5N1 infections have been reported in various mammal species, including farmed mink in Spain, sea lions in Peru and Chile, and foxes in Canada and France. The virus tends to infect mammals that consume infected birds or are exposed to environments with a high concentration of the virus.
Genetic Evolution and Transmission Risks
Genetic studies of the H5N1 virus in infected mammals have indicated potential intra-host evolution, which might allow the virus to replicate more efficiently in the respiratory tracts of these animals. However, there is no evidence yet of the virus gaining the ability to easily infect humans or spread between them. The current strains of H5N1 do not bind well to human upper respiratory tract receptors, which reduces the likelihood of human-to-human transmission.
Human Cases and Public Health Concerns
Although H5N1 is widespread among wild birds and poultry, human infections remain relatively rare. From January 2022 to March 2023, there were only 10 human cases reported globally, all linked to direct contact with infected poultry. In the United States, one case was reported in April 2022, where the individual experienced mild symptoms and there was no subsequent human-to-human transmission.
Despite the low number of human cases, the CDC emphasizes the need for continued vigilance and monitoring. The extensive spread of H5N1 among birds raises the possibility of further spillover events to mammals, which could eventually lead to viral mutations that increase the risk of human infections.
The spread of H5N1 bird flu among mammals is a concerning development that requires ongoing surveillance and research. While the immediate risk to human health remains low, the potential for the virus to evolve and adapt highlights the need for preparedness and preventive measures.
I remember back in the early days of bird flu, working in veterinary outreach, we first hand saw the fears build about it spreading to other species. That threat is even more worrying now, however, with animals recently believed to have transmitted it to mammals. Outbreaks of bird flu are common, but the jump to mammals means a potentially higher risk to humans, the WHO says. And cases in mink farms were also highlighted by the CDC that underscores the need for much more stringent biosecurity measures. We have to keep an eye on this, that’s important. How are they tracking or preventing this in your area?