When a particularly lethal outbreak of a never-before-seen virus began spreading around Saudi Arabia in 2012, a few researchers in Maryland and around the United States already had a jump on the investigation into its origins.
That's because they'd been studying and working on treatments for a similar bug that surfaced a decade earlier. The new infection, dubbed Middle East respiratory syndrome, or MERS, was in the same family of viruses that produced severe acute respiratory syndrome, or SARS, responsible for an outbreak in Asia in 2002.
The researchers now have promising leads into treatments and even vaccines for these viruses — and whatever comes next.
'We can't promise there will be another such virus in the next 10 years," said Matthew Frieman, an associate professor of microbiology and immunology in the University of Maryland School of Medicine. "But there could be."
Scientists in his lab, along with New York-based Regeneron Pharmaceuticals, are among those who recently identified antibodies that could someday be used to attack MERS, according to a study published in the journal Proceedings of the National Academy of Sciences.
MERS and SARS are part of a big family of coronaviruses that generally cause respiratory infections, including the common cold. They aren't generally deadly in healthy people, but the new bugs can cause really severe cases of pneumonia.
The viruses don't spread easily from human to human, but once people are infected, containment is the key. Quarantining patients and outfitting health care providers in personal protective equipment has been effective, say experts, including Dr. Daniel Lucey, an infectious disease specialist who has been helping health departments and hospitals prepare.
In early July, Lucey headed to South Korea, where a traveler from the Arabian Peninsula had spread MERS. Lucey said such measures have been effective and the virus has been less deadly in Korea, with 20 percent of 180 or so patients dying compared with the 40 percent death rate among the more than 1,000 Saudi patients.
"The response to MERS in South Korea, after initial problems, has been exemplary as evidenced by controlling the outbreak to hospitals and preventing it from spreading in the general population of South Korea," said Lucey, an adjunct professor of microbiology and immunology at Georgetown University Medical Center.
Last week, South Korea officially declared an end to the outbreak.
While containment can help stop the spread of disease, researchers are searching for more potent weapons.
Officials at the National Institutes of Health's National Institute of Allergy and Infectious Diseases convened a meeting of scientists in 2013 to prioritize research. But the officials said there is no simple formula to determine how to allocate limited resources in the face of an outbreak.
In the 2013 and 2014 federal fiscal years, the NIH spent $27.7 million on SARS research and about $27 million on MERS.
In contrast, a much more severe outbreak of Ebola that killed thousands in West Africa last year garnered far more spending in both years: $120 million.
But SARS "galvanized" research into coronaviruses and how the viruses emerge, said Dr. Erik Stemmy, an NIH expert on the bugs. He said it's still not clear how the viruses jump to humans from their longtime animal hosts. Maybe they mutate or maybe there is just increased opportunity as contact with wildlife increases.
Researchers have been stymied in studying the diseases because Muslims in Arab countries don't typically have autopsies, so human specimens aren't available for study. Government cooperation also has been an issue.
Researchers also weren't able to infect rodents normally used to study possible treatments with the viruses. But in a major breakthrough, Frieman and others around the country recently developed genetically altered mice and other animals to allow them to be infected.
Stemmy said he was hopeful about potential therapies that have shown effectiveness in the animal models.
He said new drugs and vaccines likely remain far off because of the time it takes to prove them safe and effective. More likely, researchers will find an existing drug or drug combination that works, he said. Promising candidates include antivirals used to treat hepatitis C.
Since coronaviruses are more likely to spread in health care settings, the focus probably will be on treatments for health workers at higher risk, Stemmy said.
But how coronaviruses emerge and spread remains an open question, he said, which makes it hard to predict if or when there will be another outbreak.
"We still need to understand how these viruses emerge and why they emerge," he said. "If we understand that we'll be in a better position to predict that."
Researchers around the country are exploring different elements of the viruses, including Dr. Stanley Perlman, a professor of microbiology at the University of Iowa, who is looking at why SARS seemed to strike seniors harder than typically vulnerable children.
With MERS, those with diabetes and other diseases seemed more heavily affected, he said.
They are among the many mysteries of coronaviruses, Perlman said. For example, he said officials aren't certain how many people in Saudi Arabia, South Korea or other countries — particularly in the developing world — have been infected with MERS but weren't recognized as having anything but the resulting pneumonia.
"What we've learned many times over the last 50 years is before we can actually address questions of therapies and vaccines, we need to know what we're dealing with," Perlman said. "We've gotten somewhere but we're not where we need to be."
So far, researchers believe they have reconstructed transmission from animals to humans for both SARS and MERS.
Frieman said both likely originated in bats, with SARS taking a turn through civet cats taken to live markets in Asia and MERS moving through camels. It's less clear why the viruses then jumped to people.
Frieman couldn't say whether the viruses mutated or took advantage of an opportunity. He also emphasized that scientists don't know the risks from future outbreaks or new viruses.
"I think there is a high probability something like this will emerge again," he said.