Chinese health authorities have not been able to identify a mysterious strain of pneumonia that has infected dozens of people, although they have ruled out the deadly severe acute respiratory syndrome (SARS) virus.
A total of 59 cases of unknown viral pneumonia have been reported in central China, with seven patients in critical condition.
Authorities in the affected city of Wuhan said they had excluded the possibility of SARS, Middle East respiratory syndrome (MERS), and bird flu. The World Health Organization said it was aware of the reports, is monitoring the situation and is in contact with the Chinese government about it.
The infection appears to have started with employees at a seafood market that also sells other live animals, including birds, rabbits and snakes. Experts are still trying to determine if the virus can be transmitted from human-to-human.
Read the CNN coverage