Eleven of those people are in a serious condition, according to the Wuhan city health commission, and more than 100 others are reportedly under medical observation.
Earlier in the week, there had been 27 cases, seven of them critical.
The South China Morning Post reported that two of those in hospital with symptoms of the mystery illness are in Hong Kong, having returned from Wuhan within the past two weeks.
They are both female, aged 12 and 41, and came to hospital with fever and pneumonia-like symptoms.
Wuhan city health commission said fever is the illness’s main symptom but shortness of breath and lung damage have been reported in a “small number” of cases.
It said some of the patients are stallholders of the city’s Huanan Seafood Wholesale Market, but did not go into detail on the other patients.
Scientists are trying to work out the source of the respiratory illness. No link has been established to the SARS epidemic seen in 2002 and 2003.
SARS killed 349 people in mainland China and 299 in Hong Kong.
Wuhan police said they had punished eight people for “publishing or forwarding false information on the internet without verification” regarding possible links to SARS.
There is no confirmation that the disease can be transmitted from human to human.
Common flu, avian flu, adenovirus and other common respiratory diseases have been ruled out, the health commission added.
