Anew coronavirus, a cousin of the SARS virus, has infected more than 10000people since the outbreak began in Wuhan, China, in December.Scientist Leo Poon, who first decoded the virus, thinks it likelystarted in an animal and spread to humans.

　　"What we know is that it causespneumonia (肺炎)and then doesn't respond to antibiotic(抗生素) treatment, which is not surprising, butthen in terms of mortality (死亡率), SARS kills 10% of the individuals,"Poon, a virologist(病毒学家)at the School of Public Health at The University of Hong Kong, said.

　　The World Health Organization offeredguidance to countries on how they can prepare for it, including how tomonitor for the sick and how to treat patients.

　　Hereare seven things you should know about a coronavirus.

　　Coronaviruses are a large group of virusesthat are common among animals. In rare cases, they are what scientists callzoonotic[zntk](人畜共患病), meaningthey can be transmitted from animals to humans, according to the USCenters for Disease Control and Prevention.

　　The viruses can make people sick, usuallywith a mild to moderate upper respiratory tract illness(上呼吸道疾病), similar to a common cold. Coronavirussymptoms include a runny nose, cough, sore throat, possibly a headache andmaybe a fever, which can last for a couple of days.

　　For those with a weakened immune system,the elderly and the very young, there's a chance the virus could cause alower, and much more serious, respiratory tract illness like a pneumonia orbronchitis [brkats](支气管炎).

　　There are a handful of human coronavirusesthat are known to be deadly.

　　Middle East Respiratory Syndrome(中东呼吸综合征), alsoknown as the MERS virus, was first reported in the Middle East in 2012 and alsocauses respiratory problems, but those symptoms are muchmore severe. Three tofour out of every 10 patients infected with MERS died, according to theCDC.

　　Severe Acute Respiratory Syndrome(严重急性呼吸综合征), alsoknown as SARS, is the other coronavirus that can cause more severe symptoms. Firstidentified in the Guangdong province in southern China, accordingto the WHO, it causes respiratory problems but can also cause diarrhea [dari](腹泻), fatigue (疲劳),shortness of breath, respiratory distress (呼吸窘迫) and kidney failure (肾衰).Depending on the patient's age, the death rate with SARS ranged from0-50% of the cases, with older people being the most vulnerable(易受伤害的).

　　Viruses can spread from human contactwith animals. Scientists think MERS started in camels, according tothe WHO. With SARS, scientists suspected civet cats (狸猫) wereto blame.

　　Whenit comes to human-to-human transmission of theviruses, often it happens when someone comes into contact with theinfected person's secretions [skri()n](分泌物).

　　Depending on how virulent [vrlnt] (有毒的)the virus is, a cough, sneeze or handshake could

　　causeexposure. The virus can also be transmitted bytouching something an infected person has touched and then touching your mouth,nose or eyes. Caregivers (护理人员) can sometimes be exposed byhandling a patient's waste, according to the CDC.