At least 25 of those who died were from Hubei, the Chinese province of which Wuhan is the capital. Of those, the youngest was a 48-year-old woman, and the eldest were two 89-year-old men who died on Saturday and Sunday.
What is the source of the outbreak?
Animals are the most likely primary source of the outbreak — but it is still not clear which animals. Past outbreaks of similar illnesses, including SARS, also are believed to have emerged from live animal markets. Another coronavirus, which causes Middle East Respiratory Syndrome, or MERS, is transmitted to humans by camels.
But though the first patients were thought to have contracted the disease at the market, Chinese authorities say the illness can also be transmitted from person to person. A growing number of people, including medical staff caring for patients, have become infected. That makes the virus more difficult to contain.
Has the virus spread to other countries?
Most of the victims are in China, but the virus has spread to several other countries, including Taiwan, Thailand, Japan, Vietnam, South Korea and Singapore — as well as to the United States. Health officials in various countries are currently investigating suspect cases, as are authorities in the United States.
How is it transmitted?
Scientists still don’t know exactly how the virus spreads, but it can be transmitted from person to person, which makes it a bigger risk than if it were carried only from animals to humans, said Dr. Peter Rabinowitz, a director of the University of Washington MetaCenter for Pandemic Preparedness and Global Health Security.
It is most likely transmitted through coughing and sneezing, as is the case with influenza and other respiratory viruses, said Dr. Julie Vaishampayan, chairwoman of the public health committee of the Infectious Diseases Society of America.