The avian flu is significant, even if it doesn’t spread to humans — yet

Like other viruses, the avian flu has the opportunity to mutate

close up of a chicken on a farm
PHOTO: Finn Mund / Unsplash

By: Victor Tran, Peak Associate

As the world continues to grapple with the COVID-19 pandemic, another virus is quietly spreading among livestock across the globe — the avian flu, or H5N1. While the transmission risk of H5N1 to humans is reportedly low, its case fatality rate is 56%. This should be enough to prompt caution as we watch the current outbreak unfold. H5N1’s significant impact on wild animal populations and livestock farmers cannot be ignored. The potential implications for our food supply are alarming, given the current state of food insecurity and high cost of living. If anything, the frequent and recent mutations of COVID-19 should be a cautionary sign that viruses are unpredictable, and we need to be prepared for the worst. Could H5N1 become the next pandemic? 

H5N1 is a type of avian influenza (bird flu) caused by infection with Highly Pathogenic Avian Influenza (HPAI). These viruses — which include subtypes H5, H7, and more — spread naturally among birds worldwide, and can infect domestic poultry and other animals. There have been several outbreaks of avian flu in the past two decades. The 2004 HPAI outbreak in Canada cost the government $380 million and 17 million birds. As more birds are killed to lessen H5N1’s spread, the poultry supply struggles significantly, driving up the cost of products. The US has seen a 60% increase in egg prices, while Canada saw a 16.5% increase. Furthermore, HPAI viruses have been detected on the outside surface of eggs and inside some egg yolks, which may increase the chance of human transmission. 

This outbreak carries inherent risks of becoming the next pandemic. Since HPAI is notorious for rapid mutation, these mutations affect pathogenicity, resistance to drugs, and the host range of the virus — which means possible adaptation to humans. For now, the human transmission rate remains low. Most cases of human infection result from prolonged, unprotected, and close contact with infected birds or contaminated environments by saliva, mucus, or poop. Fortunately, human-to-human transmissions are rare and have not yet resulted in widespread infection. 

On the other hand, H5N1 raised the alarm bell among scientists as new cases of mammal transmission were recently detected. Between June and July, a case of H5N1 infection resulted in over 150 dead seals in Maine. While it’s possible the seals could have eaten infected birds, close proximity and mass death suggests mammal-to-mammal transmission. Another outbreak on a Spanish mink farm provides more evidence of possible mammal adaptation. Scientists found the strain affecting the minks had a distinct difference — the PB2 T271A mutation. This mutation doesn’t exist in strains affecting birds, and was seen in the swine flu H1N1 virus responsible for up to 575,400 global human deaths in 2009. Transmission from bird to mammal is one thing, but transmission among mammals presents a step closer to potential pandemics.

As more avian flu cases emerge, the chance of pandemic-causing strains increases. One way such virus strains emerge is through reassortment, the mixing of genes from different viruses. For example, if a pig were infected with human influenza and avian influenza, these two strains can reassort and create a new virus that is able to infect humans and capable of human-to-human transmission. 

While the transmission risk of H5N1 to humans may be low right now, its impact on wild animal populations and livestock farmers cannot be ignored. The potential implications for our food supply are alarming, particularly in the context of increasing food insecurity and the high cost of living. Paying close attention to the virus as it spreads might prepare us for potential human transmission, or allow us to avoid it entirely. The government should closely and monitor all cases of H5N1, and strictly require that farmers report any potential infections. This should also include measures like protecting animals through vaccination, rather than killing them off, if possible. Similarly, the WHO should be monitoring the avian flu so that previously approved vaccines for people can be updated and distributed, if needed. The avian flu presents a potential risk of becoming the next human pandemic. It’s essential that we take action to prevent the spread of the virus and limit its impact on our environment, agriculture, and society.