Updated at 2:25 p.m.

For the first time in the U.S., the new virus from China has spread from one person to another, health officials said Thursday.

The latest case — the sixth in the country — is the husband of a Chicago woman who got sick from the virus after she returned from the epicenter of an outbreak in China. There have been previous cases in China and elsewhere of the virus spreading between people in a household or workplace.

The other five U.S. cases were travelers who developed the respiratory illness after returning to the U.S. from China. The latest patient had not been in China.

The Chicago woman came back from the central China city of Wuhan on Jan. 13, then last week went to a hospital with symptoms and was diagnosed with the viral illness. She and her husband, both in their 60s, are hospitalized. Neither have been identified.

Illinois Department of Public Health Director Ngozi Ezike said the man recently reported symptoms, was placed in a hospital isolation room in “stable condition.” The man doesn’t use public transportation and he had not attended any large gatherings. Public health officials are investigating locations where the man visited in the past two weeks for any close contacts that could have led to exposure.

Illinois health officials are investigating 21 possible cases, but “the risk to the general public in Illinois remains low,” Ezike said.

“The virus is not spreading widely across the community at this time,” Ezike said. “We are not recommending people in the general public take additional precautions such as cancelling activities or avoid going out of their homes.”

The virus can cause fever, coughing, wheezing and pneumonia. Health officials think it spreads mainly from droplets when an infected person coughs or sneezes, similar to how the flu spreads.

Chicago Department of Public Health Commissioner Allison Arwady said city residents should remain calm.

“I recognize that this news may raise people’s concern, but I want to state clearly that this development is something we have been prepared for,” Arwady said. “It is related to our first case patient. We do not have sign of spread in the general public at this time. And there is no local emergency.”

Details of the second Chicago case emerged as the World Health Organization declared the outbreak a global emergency as the virus has spread from China to 18 other countries. In China, at least 170 people have died and more than 7,700 cases have been reported.

‘We anticipated this’

National experts have said they expected additional U.S. cases, and that at least some limited spread of the disease in the country was likely.

“We anticipated this,” said Dr. William Schaffner, a Vanderbilt University infectious diseases expert. “The kind of contact that you have in a household is very close and very prolonged. That’s the kind of circumstance where we would anticipate a virus such as this could be transmitted.”

The quick detection and isolation of the new patient shows, “The system is working,” said Schaffner, adding that he does not expect the virus to become widespread in the country.

The new virus is a member of the coronavirus family that’s a close cousin to the SARS and MERS viruses that have caused outbreaks in the past. The new virus has sickened thousands, mostly in China, and killed about 170.

Older people, and those with other health conditions, are believed to be at greater risk for severe illness from the virus. The new patient has a health condition, but health officials did not say what it is.

An international outbreak caused by the virus first emerged last month in China. Doctors there began seeing the new virus in people who got sick after spending time at a wholesale food market in Wuhan. Officials said the virus probably initially spread from animals to people, as did SARS and MERS.

The other U.S. cases are in Arizona, Southern California and Washington state, according to the U.S. Centers for Disease Control and Prevention.