What is MERS?

These days MERS virus is getting much coverage in the newspapers and websites. Hundreds of schools across South Korea are closed, trains are being scrubbed and health officials are threatening to forcibly quarantine some people. The MERS virus is frightening, but is it time to worry? Here are some answers to your questions about MERS: 

What is MERS?

MERS stands for Middle East Respiratory Syndrome virus. You may remember having heard of it last year or the year before. It was first seen in Saudi Arabia in 2012. It's a coronavirus — a family of viruses that usually cause common colds and that can infect both animals and people. It's a relative of SARS, the Severe Acute Respiratory Syndrome virus that swept around the world, infecting more than 8,000 people globally and killing 774 before it was stopped in 2004.

How did MERS get to Korea?

One man appears to have carried the virus to Korea after traveling in Saudi Arabia, Qatar, the United Arab Emirates and Bahrain — all but Bahrain are countries where MERS has spread.

While he's been sick in the hospital, he directly infected other people, including a 69-year-old man and a 73-year-old man who shared his hospital room, a doctor who treated him, an 82-year-old man in the same ward who later died, a 40-year-old man treated in the same hospital who was then sent to three more hospitals, a 45-year-old man who was visiting his father in the same hospital ward, a 59-year-old woman who cared for her husband who'd been in the same ward and a 57-year-old woman who was in that ward, who also died.

Some of these people in turn infected others, something known as tertiary transmission, including a 54-year-old man infected by his mother and a friend of his, who also visited the sick mom.

So far, the World Health Organization says, 36 people have been infected in Korea and four of them have died. It's being called a superspreader event. Sometimes, for reasons that doctors don't fully understand, a single person can infect many other people. WHO says in this case it took a few days for doctors to realize the first patient had MERS and to take precautions.

How do you stop an outbreak like this one?

MERS doesn't usually spread that easily, but it's known that people in hospitals and clinics who have other conditions, such as diabetes, kidney disease or lung disease, are especially vulnerable. MERS has spread in Saudi Arabia this way several times.

It spreads like any respiratory disease -- when people cough or sneeze, and on droplets of saliva or mucus. Medical interventions that generate a lot of these droplets, such as putting a person on a ventilator, can spread these viruses in a hospital.

Controlling it requires isolating known patients and then tracking down everyone they've been in contact with and isolating them, too, until it's clear whether they have been infected. South Korea's asked 1,600 people to stay home, including 1,500 who attended a meeting alongside one of the infected doctors.

One of the men infected in this outbreak traveled against medical advice to Hong Kong and then to the neighboring Chinese mainland. He's been isolated and Chinese authorities are tracking down everyone he was in contact with — not easy, since he rode a bus from Hong Kong to Guangdong.

South Korean authorities said they'll forcibly quarantine anyone who refuses to stay home when asked.

Will it spread more?

Some critics are accusing South Korean authorities of acting too slowly to stop the outbreak. But WHO says it doesn't see evidence that the virus is somehow more infectious than usual in this case. "Given the lack of evidence of sustained human-to-human transmission in the community, WHO does not advise special procedures at points of entry, or travel or trade restrictions with regard to this event," WHO says in its latest advisory.

But it is sending in a team led by Assistant Director-General for Health Security Dr. Keiji Fukuda, an American infectious disease expert who used to work for the Centers for Disease Control and Prevention, to advise on handling the outbreak.

Because MERS looks like a common cold or flu, WHO advises health care workers to wear masks, gloves and to take other precautions with all their patients.

Why not ban travel until it's controlled?

While MERS has been spread to Britain, France, Germany, the U.S. and other countries, it's usually been stopped quickly. Travel bans do little to stop the spread of disease, experts say, and imposing them can discourage countries from openly reporting and asking for help when a new infection shows up. That can allow viruses to circulate and take a hold in the population — something that happened with SARS in Southern China in 2002 and 2003.

Closing schools may help people feel safer but there's no evidence that healthy schoolchildren, especially those who have not been exposed to patients with the virus, will spread MERS. And there's no evidence that public transportation is a source of spread. In Saudi Arabia, measures to disinfect dialysis clinics and hospitals where known cased had occurred did help.

Authorities worry about the Hajj every year, when more than two million pilgrims visit Saudi Arabia, but so far no spread of MERS has been linked to that mass event.

Is there a cure?

There's no specific treatment, no cure and no vaccine for MERS. It's got a fairly high death rate in part because it is more likely to infect people who have other chronic conditions already. "Globally, since September 2012, WHO has been notified of 1,185 laboratory-confirmed cases of infection with MERS, including at least 443 related deaths," WHO says.

Where did MERS come from?

That's not clear, but camels and bats are the top suspects. Camels can carry the virus but many infected people had no direct contact with camels. Bats can also carry it and they often feed on fruit that's harvested by people, so that is another possible route. "People should avoid drinking raw camel milk or camel urine, or eating meat that has not been properly cooked," WHO advises.