W

hen Ebola erupted across West Africa in the spring and summer of 2014, public health officials desperate to halt its deadly spread faced a grim reality. Licensed medical tools to cure the sick and prevent new infections did not exist.

The result: More than 11,000 people died in the largest outbreak of Ebola ever.

This month, public health experts are gathering at the World Health Organization’s Geneva headquarters to try to ensure that that tragedy is not repeated in the case of MERS, or Middle East respiratory syndrome, a virus that many fear the world has largely underestimated so far. The goal is to push for a more active response — to share information on efforts to develop drugs and vaccines and to figure out what still needs to be learned about the virus.

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As with Ebola, there are few, if any, tools currently available to use in the case of a major outbreak of MERS. Experts point to last spring’s crippling outbreak in South Korea — 186 cases, 37 deaths, hospitals closed to new admissions, all stemming from a businessman who came home sick from the Middle East — as evidence of the danger of underestimating the coronavirus.

Because the MERS virus can be transmitted through coughs and sneezes, its spread could be even more difficult to stop than Ebola, which people only catch if they have contact with blood and body fluids.

Zoonoses are diseases or infections that transmit from animals to humans. Here are some examples. Alex Hogan/STAT

You can generally avoid someone else’s bodily fluids, if you know you need to. But breathing is not an optional endeavor.

“I think the outbreak in Seoul was a wakeup call to a lot of people that what has happened on the Arabian Peninsula is not likely to stay there,” said Michael Osterholm, director of the Center for Infectious Diseases Research and Policy at the University of Minnesota. “We are going to see more Seouls happening.”

Given how long the world has known about the MERS virus — its existence was revealed in a posting to the Boston-based online diseases surveillance network ProMED by an infectious disease specialist in September 2012 — the list of things that remain to be learned about how people become infected with this virus and how it works in the human body is unsettling.

“It’s unfortunate that three years after the start of this outbreak and the appearance of this virus in the human population that we still have so little information and that we never seem to have in-depth results of investigations on any of these cases,” said Peter Ben Embarek, the WHO’s point person for MERS. “We [have] never fully [understood] how they appeared and how they spread.”

In general terms it is now assumed that sporadic cases appear to be triggered when the virus passes from camels to people. What kind of contact leads to transmission is still not clear.

Sporadic cases actually make up a minority of infections, however. The majority of cases are spread from person to person, generally in hospitals, after the original infection takes place.

Often a patient who is infected isn’t recognized as a MERS case and isn’t isolated. Health care workers and nearby patients are exposed and infected. Hospital outbreaks can be very large, sometimes involving scores of cases.

A few university laboratories and biotech companies are working on MERS vaccines. But the research is in the early stages and it will take years — and major investments — before any products are ready. If a serious outbreak occurred before then, the medicine cabinet will be be empty.

“You won’t have time to do anything,” warned Malik Peiris, a Hong Kong-based microbiologist who sees the virus as a serious and underappreciated global threat.

Peiris has lots of experience with zoonoses — diseases that jump from animals to people. His lab at the University of Hong Kong was one of two that discovered the cause of the 2003 outbreak of SARS, a coronavirus that probably originated in bats. He has worked for years on dangerous avian influenza viruses such as H5N1 and H7N9. The MERS virus makes Peiris nervous.

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People fear Ebola because of its high death rate and its popular depiction — generally untrue — as a disease that makes victims ooze blood from multiple orifices. But MERS also claims many lives; the World Health Organization estimates about 36 percent of people who become infected die from the disease, which attacks the lungs.

That fact — that this is a respiratory disease spread like colds and flu — makes the MERS virus a threat to be taken seriously, Peiris said. That it is a coronavirus is also concerning.

While SARS was stopped before it could entrench itself as a routinely circulating human virus, two other coronaviruses — one originating in bats, the other in cattle — have succeeded in jumping the species barrier and now regularly infect people.

They only cause colds, fortunately. But they prove animal coronaviruses can establish themselves as human diseases. If its relatives can make the leap, it would be unwise to count out MERS, Peiris said.

Dr. Jeremy Farrar, the director of the Wellcome Trust — a British charity that is a major funder of medical research — agreed. “I think it ticks all the boxes for a potential nasty epidemic-pandemic,” he said.

While 26 countries have reported MERS infections, three-quarters of the estimated 1,618 confirmed cases have been diagnosed in Saudi Arabia. The WHO says it has been alerted to 579 MERS deaths.

The fact that MERS infections to date have mainly occurred on the Arabian Peninsula has thrown up obstacles for those trying to study the virus and develop medicines to counteract it.

The information flow has been and remains limited. The affected countries do not contribute to the scientific literature to the same degree as North America, Europe, and parts of Asia. If MERS had emerged in Japan, for instance, far more would be known at this point. Complaints about the paltry data flow — from the World Health Organization and others — are met with seeming indifference.

“I think it ticks all the boxes for a potential nasty epidemic-pandemic.”

Dr. Jeremy Farrar, the director of the Wellcome Trust

Outside scientists eager to work on the new virus have faced problems forging collaborations and accessing samples. And research funding has been hard to come by, said Matthew Frieman, a coronavirus specialist at the University of Maryland.

Cultural obstacles have also gotten in the way. Autopsies are uncommon in the Arab world. Not a single autopsy has been performed on a MERS patient there; Ben Embarek, the WHO’s expert on the disease, said he believes the same is true for South Korea.

As a result, scientists still don’t have a detailed picture of what happens when the virus attacks the lungs and other organs. Designing a drug to arrest MERS damage in the absence of that information adds layers of complexity to the challenge. “It’s a ridiculously big problem that we don’t have a human [lung] sample from someone infected with MERS,” Frieman said. “It’s a black box.”

Because MERS was limited to the Middle East for so long, there was a sense in some quarters that the virus wasn’t likely to cause widespread problems. The South Korean scare may have changed that.

Still, hopes for progress on MERS have been intermittently raised and dashed since the virus was first discovered.

“The frustration in a way comes from the fact that we all know of the potential of this virus and this disease to create havoc in the future,” Ben Embarek admitted. “And if it happens again, we will have all these review commissions, and reports, and so on saying … ‘Why didn’t we stop it while we could?’ ”

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