Two recent unusual bird flu infections in humans have sparked concerns about a potential pandemic. One case occurred in Mexico, where a new strain infected a person who subsequently died, and the other in India’s West Bengal, where a known viral strand infected a child who survived. Amid the ongoing COVID-19 pandemic and predictions of future viral outbreaks, these bird flu cases have prompted questions about their potential threat to public health. To understand the risks posed by bird flu viruses, we spoke with Dr. Shahid Jameel, India’s top virologist.
Dr. Jameel explained that consuming poultry products is not a typical way of contracting bird flu because the virus is killed during cooking. However, individuals involved in the poultry industry, including farmers, handlers, and those preparing the birds, are at higher risk due to their close proximity to infected animals. He clarified that while India’s domestic poultry is currently a carrier of the virus, the primary source of the bird flu virus is migratory birds.
The transmission of bird flu to humans is rare and difficult. However, certain influenza viruses, such as those circulating among pigs, can transmit more easily to humans. Pigs can be infected by both human and bird flu viruses, making them potential mixing vessels for these viruses. When a pig is simultaneously infected with both human and bird viruses, genetic exchange can occur, leading to the emergence of hybrid viruses. These hybrid viruses can sometimes transmit efficiently to humans, resulting in significant outbreaks.
Dr. Jameel highlighted the recent cases in West Bengal (H9N2 strain) and Mexico (H2N2 strain), which are distinct from the more common H5N1 strain currently affecting humans. He explained that the differences in how these viruses attach to and enter human cells can lead to different disease presentations. Human flu viruses primarily target the upper respiratory tract, resulting in symptoms like coughs and colds, while bird flu viruses often enter lung cells, leading to more severe pneumonia-like complications.
The immune system’s role in susceptibility to bird flu was also discussed. Dr. Jameel explained that individuals with more exposure to human viruses generally have broader immunity and are less likely to experience severe infections. However, younger children, with limited prior exposure, are more vulnerable to respiratory viruses, including bird flu.
Regarding the emergence of new bird flu strains infecting humans, Dr. Jameel pointed out the constant evolution of viruses. He emphasized that influenza viruses are particularly prone to change due to their genetic structure. The virus’s ability to adapt to new hosts, such as cattle, suggests a potential for easier transmission to humans in the future. While the implications of this adaptation for disease severity in mammals remain unclear, it warrants careful monitoring.
Dr. Jameel addressed the question of vaccines, noting that a vaccine for human flu viruses is already available and administered annually. The development of a bird flu vaccine would follow similar processes. He also highlighted the importance of vaccination against human flu viruses, as it offers significant protection.
Finally, Dr. Jameel dispelled the notion of long-term effects comparable to ‘long COVID’ following bird flu infections. He stated that while individuals may experience varied responses to flu viruses, there is no evidence of lingering effects similar to long COVID.
In conclusion, while the recent bird flu cases raise concerns about a potential pandemic, Dr. Jameel emphasizes the importance of continued surveillance and the availability of vaccines for human flu viruses. He underscores the need for vigilance and further research to understand the evolving threat posed by bird flu viruses.
