Ever since a previously unknown virus killed a Saudi Arabian man last summer, scientists from around the globe have been trying to figure it out.
On Wednesday, two of the researchers who helped identify the virus shared fresh details about recent cases, including some ideas about how people catch it.
The session was part of an annual research meeting on biodefense and emerging diseases put on by the American Society for Microbiology in Washington, D.C.
The new bug is a type of coronavirus and cousin of SARS, which infected about 8,000 people back in 2003.
So far, there have been only 13 known cases tied to this coronavirus. But the urgency to learn more about it was heightened a few weeks ago, when three people in a British family got sick.
The cases markedly changed how health officials view the virus, Alison Bermingham, a virologist from the U.K. Health Protection Agency, said at the meeting. These were the first cases to occur outside the Middle East. After these cases were seen, doctors could say definitively the virus jumped from one to person to another.
"Everything we thought previous to that had been turned on its head," Bermingham said at the meeting. Plus, this was the first time a person recovered from the virus without any medical treatment whatsoever, she said.
The other 12 patients either died or required aggressive treatment in an intensive care unit for severe respiratory problems.
The small U.K. cluster started when a British man caught the virus on his way home from Pakistan. "He had spent a fair bit of time in Pakistan, and then traveled through Saudi Arabia," Dr. Gwen Stevens, from the Saudi Arabia Ministry of Health, said at the meeting. "He was sick on the plane."
None of the other passengers caught the illness, Bermingham tells Shots. But when the the man got back to England, he passed the virus along to his 39-year-old son and a 30-year-old woman in the same family.
Bermingham said the son, who died last week, had cancer and a weakened immune system. But the woman was healthy when she got infected and recovered without seeing a doctor. "She thought it was a seasonal flu," Bermingham says. "She didn't want to see anyone about it."
This experience raises the possibility that the virus is circulating more widely through the Middle East, masquerading as the regular flu.
So where are people catching the new coronavirus? "That's the million-dollar question," Bermingham says.
The virus's genetic code matches most closely to a coronavirus seen in bats, but she says there's no evidence of direct bites from a bat.
She thinks there's an another animal that passes the virus from bats to people. But what that could be is a mystery. One patient from Qatar owns a farm with sheep and camels. "He did go to his farm before he got sick, but he didn't leave his car," Bermingham tells Shots.
The Saudi Arabian health ministry's Stevens says another puzzle is why so few women have been infected. Of the 13 known cases, 11 of them have been men — and the one mild case was woman.
Back in November, the virus infected three men in a large Saudi Arabian family, but never spread to the women and children, Stevens said at the meeting. "The women taking care of the men that were infected never got ill. They were face to face with patients every day but never fell ill."