A new virus related to SARS is the culprit in China's mysterious pneumonia outbreak, scientists say

They've found a new coronavirus in 15 of 57 patients with the illness in the central city of Wuhan, saying it has been preliminarily identified as the pathogen for the outbreak, state broadcaster CCTV reported on Thursday.

The report said the whole genome sequence of the virus has been obtained, and a sample isolated from one of the patients showed "typical coronavirus appearance" under an electron microscope.

Coronaviruses are a large family of viruses that cause illnesses ranging from the common cold to SARS, according to the World Health Organization (WHO). Symptoms can range from fever and coughing to kidney failure, and in some cases lead to death.

SARS infected more than 8,000 people and killed 774 in a pandemic that ripped through Asia and spread to 37 countries in 2002 and 2003. A coronavirus is also the culprit for deadly Middle East respiratory syndrome (MERS), first identified in Saudi Arabia in 2012. MERS has since killed 851 people globally, according to the WHO.

But the new coronavirus in Wuhan appears to not be as lethal as SARS. Its symptoms are mainly fever, with a number of patients having difficulty breathing. Eight patients had recovered and been discharged from hospital as of Wednesday, and no deaths have been reported, according to CCTV.

The virus was first detected in Wuhan on December 12. Since then, a total of 59 people have been struck by the illness, with seven patients in critical condition at some stage, Chinese health authorities said on Sunday.

Authorities said there has been no obvious evidence of human-to-human transmission, and no healthcare workers have been infected.

Some of the patients were employed at a seafood market in Wuhan. Local media reported the market also sold other live animals, including birds, rabbits and snakes -- sparking concerns that the virus might have been transmitted to humans from animals.

According to the WHO, coronaviruses can infect both humans and animals. The coronavirus that causes SARS was traced to the civet cat, a wild animal considered a delicacy in parts of southern China, where the epidemic began. And dromedary camels are considered a likely source of MERS.

Across Asia, governments have stepped up preventive measures such as airport temperature screening and notification requirements in the wake of the Wuhan outbreak.

On Wednesday, South Korea reported a suspected case linked to the Wuhan pneumonia, according to the Korea Centers for Disease Control and Prevention. The patient, a Chinese woman who had visited Wuhan in December, has been isolated and is undergoing treatment and further tests.

In Hong Kong, 38 people have been found with fever or respiratory symptoms after traveling from Wuhan, according to the city's Hospital Authority. Among them, 21 have been discharged and so far none has been linked to the cluster of pneumonia in Wuhan.

In Singapore, travelers arriving from Wuhan are also required to go through temperature screening, according to the Ministry of Health. Doctors have been alerted to look out for suspected cases of pneumonia among people who recently returned from there.