Mega-Cities and Animal Agriculture: Coronavirus Signals a New Era of Disease Response

The public health community has gotten better at responding to disease since SARS, but a changing world presents new challenges.



Medical staff members wearing protective suits at the Zhongnan hospital in Wuhan in China's central Hubei province on Jan. 22, 2020. (Photo by STR/AFP via Getty Images)

As a new, deadly outbreak of coronavirus makes clear, fatal epidemics – along with the frantic shutdowns, economic fallout, and media frenzy that go with them – are far from a thing of the past.

More than 900 people have confirmed cases of the respiratory disease, and 26 have died. Although it originated in the Chinese mega-city of Wuhan – population approximately 11 million – cases have cropped up in eight different countries, including the United States.

The current outbreak “seems to be moving quite a bit faster” than the SARS outbreak that began in 2002 and caused 700 deaths, said Gregory Gray, an infectious disease epidemiologist at Duke University.

He’s also concerned about numbers. “The cases that were initially detected in the hospitals are likely the tip of the iceberg,” he said. A more severe coronavirus’s resemblance to an ordinary respiratory infection creates an additional hazard: There are likely “a lot of people who are out there spreading it and they don’t even know it.”

On the other hand, thus far the mortality rate seems to be notably lower than that of SARS, he said.

There’s some indication of similarity between the two viruses. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, said a vaccine he originally developed with colleagues to fight SARS may offer protection against the new virus.

Nonetheless, the outbreak makes one thing clear, according to Gray: “These viruses are not going away.” When they pop up, he said, they’re difficult to contain.

There’s some good news: Since the SARS outbreak, we’ve gotten better at – and more assertive about – controlling the spread of highly contagious infectious disease.

But there are ways in which the response still lags behind. “It’s a mixed picture,” Hotez said.

In addition, both Gray and Hotez outlined ways in which modern existence – in particular, urbanization, conflict, climate change, and drastic changes to agricultural systems – has made it harder to prevent and contain these diseases.

Learning from the Past

Health officials have been accused of responding too slowly or passively to the SARS epidemic when it first broke – of not communicating clearly, of warily trying to avoid panic or economic fallout when the sky was metaphorically falling.

“I think that’s why they’re responding so aggressively to this one,” Hotez said.

And in addition, Hotez said the eventual response to SARS “strengthened a global [mechanism] for disease surveillance and containment.”

The WHO created new guidelines for containing infectious diseases that included checkpoint screening and vaccination certificates. The CDC mentored health agencies in other countries to help them develop laboratories and testing procedures. New initiatives made creating preventive vaccines a higher priority.

Some of that is playing out in the current response.

Although there’s no formally approved commercial protocol for detecting the disease yet, Gray has seen three different improvised – called “home brew” in the world of diagnostic testing – procedures made available to the public health community.

Those protocols are only possible because the new coronavirus was sequenced so quickly – a sharp departure from the SARS response.

“After SARS, it took almost a year for the scientific community to identify the virus, sequence the virus, and start developing a vaccine,” Hotez said. Now, “the scientific community is more poised to get information quicker.”

Still, Hotez said, that doesn’t always translate to a proactive response. Vaccines tend to be developed after a disease has already had a significant impact, often years down the line – a fact he finds frustrating.

“Look at the impact this one coronavirus has had. It’s basically shut down the city of Wuhan, it’s caused a drop in the Dow Jones,” he said. “That’s billions of dollars. A vaccine would have been a fraction of that.”

Looking to the Future

Hotez’s new book-in-progress has a dramatic working title: Vaccines in an Age of War, Political Collapse, Climate Change, Urbanization, and Anti-Science.

“I think these forces have been circulating and brewing for a while and I think it all kind of came to a confluence,” particularly around 2015, he said.

For example, he explained, climate change has driven dramatic changes in agriculture and turned fertile lands into deserts.

Scarcer resources can drive conflict or, as in the case of Syria, worsen existing conditions. They can also drive people toward mega-cities that frequently grow faster than the infrastructure needed to support them, which in turn leads to unsanitary, closely-crowded conditions.

These changing societies make it harder to fight both new threats – like the coronavirus – and well-understood diseases. “These new 21st-century forces…are slowing a lot of progress that we’ve had previously, even reversing progress,” he said.

He cites the example of the Democratic Republic of Congo, where open conflict has allowed measles and the Ebola virus – two diseases for which reliable vaccines exist – to spread unchecked.

And although the Chinese government has announced a quarantine of Wuhan, the epicenter of the disease, there is outside concern that containing a city of 11 million people will simply not be possible.

The world’s growing cities and changing agriculture have led to another issue, according to Gray: animal agriculture.

About 70% of new infectious diseases begin with human-to-animal contact. That includes HIV/AIDS, Ebola, and SARS – all diseases that then spread widely among humans. The new outbreak appears to be tied to animal contact in a Wuhan marketplace.

New, more concentrated ways of raising animals have reduced the cost of protein but led to a “large population of domestic animals that are grown in close proximity to dense populations of humans,” Gray said.

He described industrialized farming systems as “incubators, if you will, for emerging viruses.”

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