By Cami Koons

Worries Rise as Highly Pathogenic Avian Influenza Spreads

Pathologists expressed both optimism and concern Friday regarding the potential outbreak of highly pathogenic avian influenza (H5N1). While they are heartened by the preparedness of laboratories and government agencies, the sheer number of infected animals and the virus’s potential to mutate are causing serious worries.
 

This week witnessed several alarming developments concerning H5N1. The first severe case in a human in the U.S. was confirmed in Louisiana, as reported by the Iowa Capital Dispatch here. Furthermore, California declared a state of emergency due to the widespread infection of dairy cows, as covered by Calmatters here.

Ben Bradley, a member of the College of American Pathologists’ microbiology committee and an assistant professor at the University of Utah, highlighted the difference between this outbreak and the COVID-19 pandemic. He emphasized that laboratories are already equipped to detect H5 viruses, and proactive measures have been taken to contain the virus.

The COVID-19 pandemic accelerated the accessibility of genetic sequencing platforms for laboratories, allowing them to closely monitor mutations in the virus.

“We haven’t really been seeing those adaptations that make us worry that it’s getting more cozy with humans versus, say, wild birds,” Bradley said.

According to the U.S. Centers for Disease Control and Prevention (CDC), 61 cases of avian influenza in humans have been confirmed, primarily among farm workers exposed to infected livestock or poultry.

However, Bradley noted that surveys indicate more infections are occurring than officially reported. This can be attributed to the relatively mild symptoms, leading some individuals to seek medical attention less frequently.

“We are dealing with marginalized populations here, folks whose livelihood depends on them going to work and not being sick,” Bradley shared, referring to the survey’s focus on dairy workers. “So that also raises challenges for testing this kind of vulnerable population.”

Bobbi Pritt, a pathologist and clinical microbiologist at the Mayo Clinic, expressed additional concerns during the call.

Pritt, also the chair of the CAP council on scientific affairs, highlighted that H5N1 is an RNA virus prone to mutations during replication. This characteristic increases the risk of a mutation facilitating human-to-human transmission, although current strains do not cause widespread concern in this regard.

“But it is true that at this point, there are no mutations that are really … making us worry that this is going to widely spread between humans,” Pritt said.

A more worrisome trend is the growing number of animal species infected by the virus, including domestic cats and pigs. Pigs, as noted by Pritt, have a unique capacity to carry both avian and human influenza viruses, potentially leading to the creation of novel, more dangerous viruses.
 

One pig has been detected with the avian influenza on a small farm in Oregon. Veterinarian experts indicated this case is unusual due to the proximity of domestic waterfowl and hogs, which is uncommon in typical commercial hog operations.
       

While Bradley acknowledged the uncertainties surrounding the future of H5N1, he stressed the unpredictability of viral outbreaks. He suggested this outbreak might be confined to “minor circulation” in herds for another year without escalating into a significant human health threat.

“But at the same time, as Dr. Pritt mentioned, really, it’s just kind of one pig away from becoming maybe a big threat,” Bradley added, emphasizing the gravity of the situation.

He compared this threat to growing up in a hurricane-prone area, where one knows a hurricane is inevitable, but its severity remains unpredictable.

“This pandemic influenza threat is something that will always be with us, so long as there are waterfowl on this earth and so long as there are mammals,” Bradley concluded.