COVID-19, Ebola, bird flu: What to know about zoonotic diseases

COVID-19 and H5N1 bird flu are both zoonotic, meaning they jumped from animals to humans. How did that happen and how can they infect humans?

The risk to humans from zoonotic diseases like bird flu is low, scientists tell Global News, but they’re still concerned.

The H5N1 avian flu is spreading in the United States. So far there have only been a handful of detections in humans.

The worry is that it could spread further.

It’s a zoonotic disease, meaning it jumped from animals to humans in what’s called a spillover event.

They can, on occasion, pose major risks to humans. Three out of every four new or emerging infectious diseases in people come from animals, according to the U.S. Centers for Disease Control and Prevention.

“SARS-1 was from a civet (an African cat-like creature), MERS was from a camel, H1N1 was likely from a pig farm,” infectious disease specialist Dr. Isaac Bogoch told Global News, referring to severe acute respiratory syndrome first detected in China in 2003 and Middle East respiratory syndrome coronavirus, which was first detected in Saudi Arabia in 2012.

While some infections have jumped to humans and resulted in pandemics and epidemics, Bogoch was careful to point out that there are also “isolated spillover events with one or two other transmission events in humans.”

He also warned that factors like climate change are pushing non-human animals into close contact with people, “where we’re going to see those spillover events becoming increasingly common. And you can’t be surprised if you start to see more zoonotic infections.”