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The World Health Organization has declared the new coronavirus from China a public health emergency. That underlines the increasingly global nature of this epidemic. And here in the U.S., federal health officials have identified a sixth case. It's a Chicago man whose wife fell ill after she traveled to Wuhan, China. This is the first case to arise within the U.S., but NPR's science correspondent Richard Harris reports that health officials say it is not cause for alarm.
RICHARD HARRIS, BYLINE: Health officials in Chicago have been on high alert since a woman who returned from a trip to Wuhan, China, on January 13 fell ill with the novel coronavirus. That vigilance has paid off. Dr. Ngozi Ezike is director of the Illinois Department of Public Health.
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NGOZI EZIKE: This second patient did not travel to China, indicating the first person-to-person transmission of novel coronavirus in the United States.
HARRIS: The man, in his 60s, has been hospitalized and is in stable condition, according to Dr. Jennifer Layden, the Illinois state epidemiologist. His wife has largely bounced back from her disease, Layden says, but remains in isolation while she completes her recovery.
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JENNIFER LAYDEN: We believe that the husband was exposed to his spouse while she was symptomatic.
HARRIS: That's a key point because scientists are trying to figure out if the disease can be spread before people are coughing or showing other symptoms. Dr. Ezike underscored that this case is not a surprise.
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EZIKE: This person-to-person spread was between two very close contacts - a wife and husband. The virus is not spreading widely across the community.
HARRIS: They spoke at a telephone news conference organized by the federal Centers for Disease Control and Prevention. Also on the call was the CDC's Dr. Nancy Messonnier.
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NANCY MESSONNIER: I understand how this may cause people to be worried about the virus and how it could affect them.
HARRIS: This lung infection is a serious disease, she said, but with just six cases in the United States, it does not pose a threat to the general public.
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MESSONNIER: Moving forward, we can expect to see more cases, and more cases mean the potential for more person-to-person spread.
HARRIS: So the CDC is following a tried-and-true approach to preventing these sporadic cases from fueling an epidemic. Disease detectives are keeping watch on those who've come in close contact with known cases, including their health care workers. They are quickly isolating people who get sick. And they're urging people who recently traveled to China to be alert for symptoms, including cough and fever. But Dr. Messonnier says there's no need now for extreme measures, such as wearing face masks in public or canceling events.
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MESSONNIER: We want to lean forward and be aggressive, but we want our actions to be evidence-based and appropriate to the current circumstance.
HARRIS: Those circumstances can change as we learn more about the disease, she says. To that end, the CDC is eager to get more firsthand information from a World Health Organization scientific delegation, which will soon be traveling to the disease's epicenter, China's Hubei province.
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MESSONNIER: It's good news that there will be soon a WHO mission into China. There's much to learn from their more detailed experience that is, by far, where the vast majority of cases are.
HARRIS: Indeed, the case count in China has now surpassed 7,700, including 170 deaths. The novel coronavirus is still a much smaller risk to global health than the annual flu, which kills hundreds of thousands of people every year. But health officials are eager to snuff out the new disease before it can become another chronic killer.
Richard Harris, NPR News.
(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.
