Six Weeks Into the 2019 Coronavirus Disease Outbreak: It’s Time to Stop Future Zoonotic Infections
Most of us know coronaviruses as the cause of the common cold—annoying, but harmless for healthy people. But since 2003, two deadly coronaviruses have shattered that familiarity: SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome). Now, six weeks into the 2019 coronavirus disease (COVID-19) outbreak, researchers are warning that we need urgent, global action to prevent future “zoonotic” infections—diseases that jump from animals to humans—before they become pandemics.
Vijay Harypursat and Yao-Kai Chen, infectious disease specialists at the Chongqing Public Health Medical Center in China, outline these concerns in a new perspective piece in the Chinese Medical Journal. Their work builds on decades of research into coronaviruses and the devastating outbreaks they cause—offering a clear roadmap for avoiding repeat disasters.
Coronaviruses: From Cold to Crisis
Before 2020, six coronaviruses were known to infect humans. Four are “endemic”—meaning they circulate regularly in people—and cause mild cold symptoms. The other two—SARS-CoV (2003) and MERS-CoV (2012)—are zoonotic: they originated in animals and spread to humans, with fatal results.
COVID-19’s cause, 2019-nCoV, is the seventh human coronavirus—and it’s also zoonotic. The story of how it jumped to people is familiar to anyone who followed SARS or MERS: bats are the natural reservoir.
The Zoonotic Link: Bats, Wet Markets, and Spillover
SARS-CoV likely jumped from bats to masked civets (a wild mammal) sold in Chinese wet markets. MERS-CoV moved from bats to dromedary camels before reaching humans. For 2019-nCoV, the pattern is almost identical.
Genetic studies show 2019-nCoV is nearly identical to SARS-like coronaviruses found in Chinese horseshoe bats. Researchers believe the virus first infected an intermediate animal—possibly a masked civet—sold at a wet market in Wuhan (the outbreak’s epicenter). From there, it mutated and spread to humans.
Wet markets—where live wild animals are sold for food or pets—are a “perfect storm” for zoonotic spillovers. They bring humans into close contact with animals that carry hundreds of viruses, creating opportunities for pathogens to jump species. As Harypursat and Chen write: “The presence of markets trading in wild animals greatly increases the risk of viral infections jumping to humans.”
How Fast Does 2019-nCoV Spread? The Numbers Matter
To understand an outbreak, experts look at two key metrics:
- Basic Reproductive Number (R°): How many people one infected person typically spreads the virus to.
- Doubling Time: How long it takes for the number of cases to double.
For SARS, the R° was about 3—meaning one person infected three others. For 2019-nCoV, early estimates put the R° between 2.2 and 2.7. A study from the University of Hong Kong found a slightly higher R° (2.68) and a shorter doubling time (6.4 days, compared to the initial 7 days). Another model suggested the R° could be as high as 6.47—though that’s still being debated.
But numbers only tell part of the story. For SARS and MERS, 10% of infected people were “super spreaders”—individuals who spread the virus to 10 or more others. Super spreaders drove most of the transmission in those outbreaks. While no 2019-nCoV super spreaders have been found yet, Harypursat and Chen warn: “Clinicians must be ready to identify and isolate these individuals quickly to slow the outbreak.”
The Hidden Cost of Zoonotic Outbreaks
Zoonotic diseases don’t just harm health—they devastate economies. The 2003 SARS outbreak cost the global economy $54 billion. The 2015 MERS outbreak in South Korea wiped out $2.6 billion from the tourism industry alone. The 2014 Ebola outbreak cost Guinea, Liberia, and Sierra Leone $300 million—a crippling blow to their already fragile economies.
The cost of COVID-19 will be far higher. But as Harypursat and Chen note: “Every preventable zoonotic outbreak saves lives and money. If we can limit human exposure to wild animals, we can avoid these disasters.”
The Solution: Ban Wild Game Trade—and Change Culture
China took a critical step on January 26, 2020, when it banned the sale of wild game meat in markets. This will help stop 2019-nCoV transmission and reduce future risks. But more action is needed—globally.
In Asia, wild game consumption is often driven by status or perceived medicinal value, not poverty. Rare animals are served to guests as a sign of wealth; some believe their meat has health benefits. This cultural norm, combined with unregulated wildlife trafficking, creates a constant risk of spillover.
Harypursat and Chen argue: “We need urgent, global action to end the trade in wild game meat and products. If we don’t, regular zoonotic outbreaks could become the norm—with catastrophic human and economic costs.”
Hope for Control, and a Call to Prevent Future Outbreaks
The world is already working tirelessly to control COVID-19. China’s efforts—paired with global cooperation—are starting to show results. But the real lesson of this outbreak is prevention.
As Harypursat and Chen write: “The steadfast work of China and the international community gives us hope for COVID-19 control. But to avoid repeating this crisis, we must end the unregulated trade in wild animals. The cost of inaction is too high.”
doi.org/10.1097/CM9.0000000000000760
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