Bird Flu Could be ‘One Pig Away’ From ‘A Big Threat,’ Pathologists Say

By Cami Koons

Pathologists said in a press conference Friday they are encouraged by laboratory preparedness for a potential outbreak of highly pathogenic avian influenza, but are worried about the number of infected animals and the ability of the virus to mutate.  

The College of American Pathologists press conference followed a week of new developments with the virus, H5N1, including the first severe case detected in a human in the U.S. and a state of emergency declared in California, where a large number of dairy cows have been infected.

Ben Bradley, a part of the college’s microbiology committee and an assistant professor in the pathology department at the University of Utah, said this outbreak is a “very different landscape” from the COVID-19 pandemic because laboratories can already detect H5 viruses and labs and government have been “much more proactive” in containing this virus. 

Bradley said the pandemic also made genetic sequencing platforms more available for laboratories, which has allowed them to more closely monitor certain 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. 

The U.S. Centers for Disease Control and Prevention has confirmed 61 cases of the flu in humans, primarily in farm workers who have come into contact with sick livestock or poultry. 

Bradley said a recent blood work survey, however, found more people are being infected on farms than what is actually being detected. Part of that is because the symptoms are fairly mild and people might not always go to the doctor for a slight cough or an itchy eye. 

“We are dealing with marginalized populations here, folks whose livelihood depends on them going to work and not being sick,” Bradley said, noting the survey tested 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, was also on the call and said there are several things about H5N1 that are “worrisome.” 

Pritt, who is also the chair for the CAP council on scientific affairs, explained the H5N1 virus is an RNA virus, so in every infected animal the virus replicates and is prone to mutations, therefore raising the likelihood of a mutation occurring that would make it more transmissible among humans. 

“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. 

Pritt’s other concern is the range of animals being infected with the virus, including domestic cats and, importantly, pigs. Pigs, she explained, can carry both bird and human influenza viruses which creates a “mixing pot” that can lead to the creation of new viruses. 

One pig has been detected with the avian influenza on a small farm in Oregon. Veterinarian experts however, said it was a unique case because it had domestic waterfowl in close proximity with hogs, which is not traditional, especially when compared to commercial hog operations.

Bradley said there is no way to put a timeline or a prediction on what will happen with the avian influenza virus. He said the country might have another year of “minor circulation” in herds and it never becomes something that needs a high degree of testing in humans. 

“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 said. 

He compared it to growing up in a hurricane state, where folks know there is going to be a hurricane, but the question is always about the severity.

“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 said.

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