The deadly coronavirus that emerged in China is already adapting and mutating, Chinese officials warned on Wednesday as the number of confirmed cases continued to grow.

Nearly 500 people have been infected nationwide, with total deaths rising to at least 17, as the mystery disease continues to spread.

The latest count was updated at about 7pm Beijing time, with all deaths in Hubei province, where the first illnesses were reported in December.

The outbreak originated in Wuhan, the provincial capital of Hubei, and causes fever and breathing difficulties. Health officials have confirmed human-to-human transmission, and cases have begun spreading to other Chinese cities and abroad.

The major means of transmission is through respiratory tracts, and mutation risks further spread of disease, said Li Bin, deputy director of China’s national health commission.