Recent finding of ‘bird flu’ in an Oregon pig a cause for vigilance, not panic

The recent discovery of H5N1, or "bird flu," in a pig in Oregon has mainstream news and social media running a gamut of speculation from "nothing to worry about" to predicting the next COVID-19-style pandemic.

But researchers at the University of Calgary's Faculty of Veterinary Medicine (UCVM) say, while the finding is important, there's no need to panic. H5N1 influenza was found in pigs on a small, non-commercial backyard farm. Although the situation is concerning and underlines the need for vigilance, it is neither shocking, nor a sign of impending catastrophe.

"Studies show that it is not easy to infect pigs with this specific virus, therefore the risk remains relatively low that wide-scale circulation of H5N1 in the domestic pig industry will take place," says Dr. Frank van der Meer, PhD, DVM, a virology expert and professor of global health and infectious diseases at UCVM. But, he adds, "Pigs and humans share many influenza viruses, and, in the past, pigs have contributed to the generation of new influenza variants that now circulate in humans; therefore, it is a concern if H5N1 influenza gets into the pig population as we do not know what will happen if H5N1 meets human or pig influenza in the same animal."

H5N1 was detected in both pigs and poultry on the Oregon farm. Initially, only one of the five pigs tested positive, although all were euthanized alongside the infected poultry as a precaution against further spread. Subsequent testing revealed two pigs were negative, one remained positive and results for the other two are pending.

The primary concern is preventing the virus from spreading to more animals. Each time a mammal becomes infected, the virus has the potential to adapt, increasing the risk to humans and other mammals. If a pig concurrently contracts H5N1 and another influenza A virus subtype, there is a possibility of viral reassortment. This could lead to a new strain more transmissible to humans, potentially sparking a pandemic due to a lack of pre-existing immunity.

While the spillover into pigs is noteworthy, it is not unique. Such incidents have occurred in various animal species without causing significant alarms. Notably, the farm's small size and shared resources between pigs and poultry suggest that infection was almost inevitable. It is likely a situation where pigs contracted the virus from birds but did not transmit it further.

Despite the social media buzz, this event is unlikely to have severe repercussions. However, it serves as a reminder of the ongoing risk as long as H5N1 continues to circulate. While we cannot control the virus in wild birds, efforts to manage it in domestic animals, such as dairy cattle, could be improved. H5N1 was found this past spring in numerous dairy cattle herds in the U.S., spanning 14 states and leading to spillover cases in several dozen farm cats and farm workers. While the Centres for Disease Control and Prevention (CDC) in the U.S. believes the current risk to the general public from bird flu viruses is low, proactive measures and readiness to act on spillovers are crucial to mitigating risks.

"While the current H5N1 virus doesn't pose an immediate threat, the potential for it to evolve into something more dangerous cannot be ignored," says Dr. Faizal Careem, PhD, a professor in virology at UCVM and an expert in avian viruses including avian influenza virus. "It's imperative that we remain vigilant and take proactive steps to manage these risks effectively."