Story at a glance
- The novel coronavirus in Wuhan, China, has led to more than 500 cases of illness in humans.
- Experts are working to learn more about the virus, and although not much information is currently public, it may have originated in wildlife.
- It is customary in some cultures to consume wild animals as a source of protein, though this may expose people to pathogens like bacteria and viruses.
- Identifying new viruses from wildlife may not necessarily prepare us for future epidemics but could inform us on pathways that viruses can enter humans.
With the entire city of Wuhan, China — with 11 million people — now being quarantined in hopes of containing the growing outbreak of coronavirus, the world watches to see how deadly and how big this particular event will get. Each time there is a new or emerging infectious disease, there’s increased interest in how it happened. How did a new virus get into humans? Where did it come from? What should be done about it?
Basic infectious disease biology would explain that as long as we are in contact with animals, wild or domestic, we are bound to pick up pathogens from them. Not every bug will lead to illness, but considering there are potentially millions of viruses and unknown numbers of bacteria and other microbes out there, eventually some of those will.
Potential sources of the new coronavirus, informally being called 2019-nCoV, are two species of snake: the Chinese krait and the Chinese cobra, according to The Conversation. Researchers in China analyzed the RNA genome of the virus and found evidence that it is a combination of a bat coronavirus and an unknown coronavirus that may be from one of the snake species. Snakes were sold in the animal and seafood market in Wuhan at the center of the outbreak, supporting this hypothesis.
The best way to pinpoint where the virus came from would be to sample the animals sold at the market for viral RNA and to sample wild bats and snakes to confirm. However, the market has been closed down and disinfected, according to the article in The Conversation, making further sampling impossible.
Viruses can mix and mutate in wild and domestic animals, especially in environments like markets where species diversity may be high and live animals are preferred to dead ones. This phenomenon is not limited to Asia either. A study of live animal markets in Minnesota suggests they may be sources for new influenza A viruses. Salmonella is a major concern in meat and poultry markets around the U.S. Researchers have been chronicling the transfer of diseases between animals and humans for a long time, and we’re still not that good at preventing it from happening or from containing it once it does.
When avian flu is a concern, large flocks of chickens are culled to prevent the spread of the disease. This is typically effective because the virus is not passed from person to person, only from bird to person. With the 2019-nCoV, there are reports that it can be transferred from person to person. Even though the original source in the market has been dealt with, quarantining and limiting travel will be the most effective ways to contain the outbreak in this case.
While it may sound drastic to keep millions of people on lockdown by shutting them out from trains and planes, it’s the simplest and most direct way to prevent the disease from spreading geographically. For people who are in Wuhan, their best hope may be to stay away from crowds, wear a mask and wash their hands often.
Experts debate about what’s the best way to prepare for a new disease that jumps over from animals to humans. Should millions get funneled into research programs to discover new pathogens and sequence viruses? How about taking samples from wildlife? Is that worth the effort and if so where and how often should that be done? Should we focus more on domestic animals like pigs and chickens?
One of the largest funded projects focused on emerging diseases was the PREDICT program from USAID that gave funding to several research institutions. The main priorities were to build wildlife disease surveillance capacity in several key countries like China and try to understand why, how and where new diseases emerge. It ran for 10 years and recently was not renewed for another five years of funding.
But even after years of research, it’s still difficult to predict what might go viral, and a lot of those questions about what to do remain unanswered and are rehashed each time a new pathogen comes up like SARS, MERS and now 2019-nCoV. Several experts wrote that although the response to 2019-nCoV has been quicker than for SARS there is still much to do in a statement published in Nature. “Virus genomes from infected people will need to be sequenced continually to understand the extent to which the virus is evolving,” write the authors.
Further laboratory tests may confirm the origin of the coronavirus is in snakes, and we may be able to know which parts of the RNA were combined with other viruses or mutated on its own. Wherever this coronavirus came from, we’ve seen something like it before and we will probably see something like it again.
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