By Stan Deresinski, MD, FACP, FIDSA, FESCMID

Clinical Professor of Medicine, Stanford University

Dr. Deresinski reports no financial relationships relevant to this field of study.

SYNOPSIS: A cluster of cases of pneumonia apparently caused by a novel coronavirus has emerged in China.

SOURCES: CDC Health Advisory Alert. Outbreak of Pneumonia of Unknown Etiology (PUE) in Wuhan, China. Available at: Accessed Jan. 10, 2020.

World Health Organization. WHO Statement Regarding Cluster of Pneumonia Cases in Wuhan, China. Available at: Accessed Jan. 10, 2020.

As of Jan. 5, 2020, public health authorities in China had notified the World Health Organization of 59 cases of pneumonia of unknown etiology (PUE) that had occurred in Wuhan province from Dec. 12-19, 2019. While no deaths were reported, seven (11.9%) patients were critically ill. No healthcare workers have become ill, and human-to-human transmission has not been reported. The patients are being managed in isolation, and contacts are being identified and placed under close observation.

Some of the affected patients worked at Wuhan South China Seafood City, a wholesale market where seafood, chickens, bats, marmots, and a number of wild animals are sold. The market has been closed and is undergoing cleaning and disinfection. Testing of the patients for a wide variety of known respiratory pathogens was negative, but a virus morphologically resembling a coronavirus was observed initially in one patient, and sequencing is reported to have demonstrated that it is a novel coronavirus. Subsequent nucleic acid testing identified the novel virus in 15 patients.


This event obviously elicits memories of the emergence of another coronavirus in China that was linked to markets selling wild animals. Another lethal coronavirus, Middle East respiratory syndrome (MERS), has emerged more recently in the Arabian Peninsula and has been linked to exposure to camels. In addition to often being lethal, both severe acute respiratory syndrome (SARS) and MERS are readily transmitted among humans. Fortunately, the Wuhan coronavirus (so far) appears to have neither of these characteristics, although some human transmission seems possible. Two infections with this virus have been detected in patients outside Wuhan.1 In a case identified in Thailand, the patient had visited a “fresh market” but not the one noted earlier, while a patient identified in Japan had had contact with someone with pneumonia in China.


  1. International Society for Infectious Diseases. Novel coronavirus: China (HU), Japan ex China. ProMed Mail. Jan. 15, 2020. Available at: Accessed Jan. 16, 2020.