In mid-December, some people in the central Chinese city of Wuhan began complaining of flu and pneumonia-like symptoms. Some had a high fever. Doctors were perplexed. To find out what might be causing their illness, geneticists analyzed the DNA of the virus that had infected them. At once, the scientists realized this virus was new to science. As of January 23, experts at the World Health Organization, or WHO, in Geneva, Switzerland, estimated that at least 557 people have contracted the rapidly spreading disease. At least 17 have died.
Tedros Adhanom Ghebreyesus is Director-General of the WHO. At a January 23 news conference he said: “Make no mistake, this [disease outbreak] is an emergency in China.” Although it “has not yet become a global health emergency,” he says, “it may yet become one.”
Exercising caution before declaring an emergency makes sense, says Jennifer Nuzzo. She’s an epidemiologist, or disease detective. She works at the Johns Hopkins Center for Health Security in Baltimore, Md. Researchers are still trying to work out how infectious, and how dangerous, the virus really is, she explains. And, she adds, “I’m glad they’re taking their time.” Right now, she says, “A decision to declare an emergency will signal a level of concern that we don’t have the data to support.”
The new germ appears to be a novel coronavirus (Kuh-RO-nuh-VY-rus). One germ that can cause the common cold comes from that virus family. So do the viruses behind MERS and SARS. Both of those diseases have triggered frightening global outbreaks over the past two decades. Virus experts now worry that the new coronavirus may be poised to do the same.
Chinese researchers used genetic material from one patient to identify the new virus. The World Health Organization has given this germ the uninspired name 2019 novel coronavirus, or 2019-nCoV.
“Anytime there’s a novel virus that appears that’s causing critical illness, it merits concern,” says Amesh Adalja. “Right now, there’s no cause for panic.” An infectious disease physician, he too works at Johns Hopkins Center for Health Security.
Both Nuzzo and Adalja hope this outbreak sparks renewed interest in studying coronaviruses and in creating vaccines and treatments. “It’s been 17 years since SARS, and we still don’t have any coronavirus vaccine. We don’t have any coronavirus antivirals,” Adalja says. “The only way we can take outbreaks like these off the table is to develop countermeasures against them.”
What are the symptoms of 2019-nCoV? Who is most at risk? Who is most likely to die of it? “We don’t know a whole lot at this point,” says Jennifer Nuzzo. “It seems to be a novel coronavirus that can produce viral pneumonia,” she notes. Pneumonia is a lung infection. It can cause coughing, fever and trouble breathing.
“The confirmation that human-to-human spread with this virus is occurring in Asia certainly raises our level of concern,” says Nancy Messonnier. She directs the National Center for Immunization and Respiratory Diseases. That’s part of the U.S. Centers for Disease Control and Prevention, in Atlanta, Ga. Says Messonnier, CDC believes the risk “to the American public at large remains low at this time.”
For now, Chinese authorities are taking big efforts to slow the spread of the virus. On January 23, they locked down the city of Wuhan — home to nearly 11 million people. They halted all air, train and bus travel out of the city. Several other nearby cities also are closed. That’s a big deal as this outbreak emerged at the outset of nationwide travel for weeklong Lunar New Year celebrations, due to begin on January 25. This is when people throughout China traditionally get together with friends and family.
Elsewhere throughout the world, many airports that receive a lot of visitors from China have stepped up their screening of arriving passengers.
Infected patients seen far from Wuhan
Cases of the new disease have been reported in people who had traveled from the Chinese mainland to Singapore, Taiwan, Thailand, Japan and South Korea. On January 21, the CDC also confirmed the first case of the disease in the United States. A man had returned home to the United States from Wuhan six days earlier. When he sought treatment at a hospital in Washington state, the staff collected a sample from the patient. They sent it to the CDC. The agency used PCR technology to analyze DNA from the sample. This confirmed it was the same virus now spreading through China.
Scientists are now trying to understand how dangerous the virus is. How sick most of the infected people become also is unclear. So far, details about the condition of patients in China have not been widely shared, says Adalja. For instance, “Are they requiring oxygen therapy? Intravenous fluids? Those types of questions are really important in helping us know where to place this outbreak in terms of risk.”
Also unclear, Nuzzo says, is exactly how the virus spreads. “Can a sick person easily transmit the disease when they’re out in the community? Or can it only be transmitted in risky situations, for example, when a health care worker is caring for a patient and their personal protective equipment fails?”
And one of the biggest questions: Where did the disease come from? The suspicion is it came from some animal. Many times, animals can harbor a virus without themselves becoming sick. Did that happen here?
The first people reported to have 2019-nCoV became sick after visiting a Wuhan seafood market. But it didn’t just sell fish and shellfish. It also sold a number of wild animals, such as wolves, as food. Might one such animal be the source?
A more provocative suggestion is that the virus came from snakes.
On January 22, the Journal of Medical Virology published a paper suggesting that the germ’s DNA appears to be a mishmash of a known bat coronavirus and another coronavirus that is unknown. In this paper, researchers from four Chinese research centers reported that “snake is the most probable wildlife animal reservoir for the 2019‐nCoV.” They based it on snake genetic material. They conclude, there may have been “cross-species transmission from snake to humans.”
But some virus experts dispute that conclusion. “You should be massively skeptical of a snake” as the source, says Edward Holmes. He’s a virologist in Australia at the University of Sydney. Indeed, he challenges what the authors make of their new analysis. “Their own data doesn’t support their conclusions,” he charges.
“I can’t categorically say it’s never happened” — the transmission of a virus from a snake to humans. After all, he notes, “I don’t know every virus. But the reservoirs for human viruses are mainly mammals and maybe birds.” As such, he suspects, “it’s most likely that the reservoir host of that virus is a bat, given where it [its genome] falls on the evolutionary tree.” Certainly, he says, “It’s close to bat viruses.”