China hunts cause of mysterious pneumonia outbreak in Wuhan

The cause of an outbreak of pneumonia in China that's sickened at least 59 people in the city of Wuhan remains a mystery, although Chinese officials say it is not the deadly SARS virus and doesn't appear to spread quickly between people.

Why it matters: There's no reason for Americans to be concerned at this point, but the source needs to be determined to halt its spread, says Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases. Wuhan, which has a population of 19 million, is the capital of Hubei province, home to 58 million people.

What they're saying: Fauci tells Axios he expects China to complete and announce the results of deep sequencing of the germ's genome soon. "It's obviously a virus," Fauci says, as bacteria would have been found quickly in cultures. "My guess would be that it's a different kind of coronavirus."

The latest: Wuhan health authorities on Monday said they continue seeking the cause but have so far ruled out influenza, avian influenza, adenovirus, and coronaviruses SARS and MERS as the respiratory pathogen that's infected 59 people as of Jan. 5.

• Authorities have quarantined the patients, and close contacts are under medical observation.
• Some cases have been linked to a food market in Wuhan called South China Seafood City, which was closed Jan. 1 for environmental sanitation and disinfection.
• Wuhan health authorities believe this outbreak is caused by a virus that apparently does not transmit easily between humans, with no health workers reporting infection yet. Fauci says they may find it does transmit human-to-human, just not very effectively.

• The World Health Organization issued a statement on Sunday saying that officials are closely monitoring the situation.

Background: Pneumonia is an infection that inflames the air sacs in the lungs and can be caused by a virus, fungi or bacteria.

• Some of the bacteria or viruses that can cause pneumonia have vaccines that can lessen the risk from pneumonia, per CDC, including flu, measles, chickenpox, pneumococcal and whooping cough.

Go deeper: Children worldwide are less likely to die young than ever before