Coronavirus: Where did it come from and how did we get here?

The new coronavirus is spreading rapidly around the world, curtailing public life and closing the doors on international borders.

Nearly 180,000 people worldwide have been infected and over 7,000 people have died, as of March 16. While the bulk of the cases and fatalities have been confined to China, the virus has its grips on many other countries, including Italy, Spain, France, the United States and Canada.

The pandemic has infiltrated headlines and psyches for months, but how did we get to where we are today?

What is coronavirus?

“Coronavirus” refers to a family of viruses that range from the common cold to more severe illnesses like SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome).

The disease caused by the virus circulating now, formally named COVID-19, is a respiratory illness. It has symptoms very similar to the common cold but is considered the most dangerous for older people and those with pre-existing health conditions.

A recent study out of China has suggested that there are two strains of the virus spreading, one being more aggressive than the other, but it has not been determined definitively.

Where did it come from?

It’s believed the new virus started in a “wet market” in Wuhan, China, where, like many other markets in Asia, farmed and exotic animals are tied up or stacked in cages. Many are killed on-site to ensure freshness.

The markets are considered breeding grounds for new and dangerous infections, health experts say, because the close contact between humans and live exotic animals makes it easier for viruses to jump between species. SARS originated from the same type of market in 2002.

“This virus is closely related to known bat viruses. That’s why it’s believed to have originated from a bat,” said Dr. Jeff Kwong, an epidemiologist and scientist with ICES and Public Health Ontario.

“It then somehow got into another animal and then acquired the ability to infect humans. We call these sorts of infections zoonotic infections — they can infect multiple mammals and cross between species.”

Scientists have not yet determined exactly how the new coronavirus first infected humans, but Stanley Perlman, a coronavirus expert at the University of Iowa, said it likely unfolded in a chain of events.

Since bats were not sold at the Wuhan market where the virus is believed to have originated, it’s likely another animal sold there was infected.

“In this instance, we think that bats infected an intermediary host that served as the immediate source for the human infection,” he said.

“However, we do not know if this is the case or, rather, if an unidentified bat coronavirus nearly identical to the human strain jumped directly to humans.”

However, he acknowledged there’s still a lot unknown about the origin.

“There are several bat coronaviruses that are theoretically able to infect humans and were predicted by some scientists as able to cross species to infect humans,” he said.

“Unfortunately, this could happen again with another one of these bat coronaviruses.”

How did it spread so quickly?

The virus has been spreading since late December. When it first broke out, it was mostly contained to China. Over the past three months, it has touched more than 100 countries and transformed Europe into its newest epicentre.

Kwong said that while it may seem like it caught on quickly, it’s likely its spread in North America that is drawing increased attention.

“It’s been in China for a number of months already. It’s not the most contagious spread of infection — there’s a lot of other diseases that are much more contagious — but because there’s a lack of immunity in the population, we’re seeing a widespread transmission,” he said.

While there is a test to identify the virus, and clinical studies underway for a cure, there is currently no vaccine to prevent an infection or a treatment for those infected.

Kwong believes general global modernization played a role in the spread.

“There’s been an increase in global travel since the last virus that sort of propagates things further and helps it proliferate, just by the fact more people are moving around,” he said.

A study released Monday in conjunction with the American Association for the Advancement of Science (AAAS) suggests that the contagiousness of the virus is likely a result of a large number of undetected infections early on in the outbreak.

Many of the undocumented infections were already circulating long before China and others moved to heighten control and travel measures in late January, the study found.

“These undetected cases seem to have been less contagious than the detected ones,” said Ashleigh Tuite, an epidemiologist at the University of Toronto’s Dalla Lana School of Public Health, who reviewed the study. “But because there were so many, their overall contribution to the spread was substantial.”

Could it get worse?

Without effective measures to slow down the spread, COVID-19 will spread for months, experts believe.

“I think we’re going to see many more cases in the coming months and even years,” said Kwong.

But whether this virus could make way for more severe ones in the future? Kwong isn’t so sure.