Images of people wearing respiratory masks in a Chinese railway station.
Enlarge / Travelers in China are often wearing protective masks in response to the spread of 2019nCoV

Feature China / Barcroft Media via Getty Images

On Tuesday afternoon, the US Centers for Disease Control announced that the coronavirus that’s been spreading within China had made it to the United States. A patient in Washington state is the first confirmed case in the US, although indications are that the disease has already spread to other countries in Asia.

A single patient in Washington had been traveling in Wuhan, the area of China hardest hit by the newly described virus, before returning to the US last week. Shortly after their return, the patient was hospitalized with pneumonia-like symptoms. Based on the travel history and symptoms, the hospital staff suspected that the new virus, called 2019-nCoV, might be at fault and sent samples in to the CDC for testing. Those tests confirmed the virus’ identity.

The initial cases were confined to people who had been in contact with live animals at a seafood market, suggesting that it should be possible to contain the virus. But since then, the news has gotten worse. In addition to spreading to other countries—Thailand and Japan had confirmed cases prior to the US—the virus is now confirmed to be spreading through human contact, which has helped increase the number of cases and enabled its spread to other cities within China. There have also been a number of reported fatalities, although these remain a small percentage of the confirmed infections.

Coronaviruses like 2019-nCoV typically cause respiratory infections, and they appear to be widespread in animal species. A number have previously made the leap to humans, most prominently Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS). While these viruses have caused severe illness and even fatal illnesses in the people infected, they have not end up causing widespread outbreaks. SARS probably infected the most people, but there were only 10,000 confirmed cases, far fewer than a typical flu outbreak.

In announcing the first US case, the Center for Disease Control acknowledged that this is a rapidly evolving and serious situation. But the agency has also indicated that it learned from SARS and MERS and is already developing a management plan for 2019-nCoV and is screening arriving passengers at major international airports. While the Washington hospital had to send samples into the CDC for testing, the organization expects that it will make testing information publicly available shortly, allowing tests to be performed in any lab capable of working with DNA. (China had published the virus’ genome sequence earlier this month.)

As of yet, there’s no indication that the virus is spreading by human contact outside of China. As such, doctors are advised to obtain a travel history from anyone suffering from fever and severe respiratory illnesses. It’s advised that potential and confirmed patients be given their own room and asked to wear a surgical mask in order to limit the prospects of airborne spread.

Further details of the CDC’s advice and the details of the outbreak can be found in links on the organization’s announcement of the Washington case.