Scientists in China think they’ve made a break in the case of a mystery disease that’s caused pneumonia in dozens of people. In several patients, they’ve found a virus never before discovered—albeit one related to the viruses responsible for causing SARS and other respiratory illnesses.
On Thursday, the state-run news agency Xinhua reported on the results of a preliminary investigation into the outbreak, which has so far sickened 59 people and left seven in serious condition. In 15 people, scientists say they’ve identified a strong suspect for the illness: a previously unknown type of coronavirus.
Coronaviruses are a family of spiky ball-shaped viruses known to infect a wide variety of birds and mammals, including humans. Most coronaviruses that make people sick cause nothing more than a typical cold. But in recent decades, we’ve come across two more dangerous and sometimes lethal viruses—the virus that causes severe acute respiratory syndrome, or SARS, and the one that causes Middle East respiratory syndrome, or MERS.
Earlier this week, the Chinese government stated that the mystery disease was not SARS, following weeks of accusations by its own residents on social media that the government was once again hiding the truth about a SARS outbreak within its borders. According to the Chinese government, no victims have tested positive for other likely culprits either, such as bird flu, while the mystery virus’s genetics have been completely sequenced, ruling out the possibility it’s SARS, MERS, or any other known coronavirus.
At this point, the research team’s work has yet to be confirmed independently. But on Wednesday, the World Health Organization expressed early confidence that the mystery disease could be caused by a coronavirus, based on reports so far.
The first human outbreaks of a never-before-seen infection, including SARS and MERS, tend to be zoonotic, meaning they’re initially spread from animals to people (for SARS, it was likely rodents or bats; for MERS, camels). That seems to be the case for this new coronavirus, too. The majority of cases have involved people working at the Huanan Seafood Wholesale Market in Wuhan, where many live animals are kept.
Sometimes, these new viruses are already capable of spreading easily from person to person, or can quickly mutate into a more contagious strain. But at least right now, that’s not true for the mystery bug, since no cases of person-to-person transmission have been reported yet. It also doesn’t seem to be as lethal as SARS or MERS, as no patients have died. But there’s still plenty of questions about the virus left to be answered, including where it first emerged.