In July, millions of people will travel to Saudi Arabia to celebrate the Muslim holy month of Ramadan. When they do that, they might be at risk of contracting MERS — Middle Eastern respiratory syndrome — a coronavirus, similar to SARS. They could also be at risk of carrying MERS back to their home countries. Unfortunately, Saudi Arabian authorities have released so little information about MERS that global public health experts don't know how to advise these pilgrims as they prepare for travel. We don't know where MERS came from, we don't know what its infection patterns are or how the disease has changed since it was first identified. It's not even certain that we know the true extent of infections and deaths, given that the Saudi Arabian government has been releasing that information in batches, sometimes months after those infections and deaths actually happened.
Helen Branswell is one of my favorite sources on global public health and pandemic disease. She's got a guest post at Scientific American blogs that explains what we do know about MERS, and why the lack of information is such a big problem.
The new virus was first isolated in June 2012. But its existence came to the world's attention only weeks before last October's hajj, when an Egyptian infectious diseases specialist who had been working in Saudi Arabia's second largest city, Jeddah, reported that he had treated a man who died from an infection caused by a new coronavirus. Whether MERS has or can gain the capacity for sustained person-to-person spread is unknown.
… Infectious disease experts are aghast that this late into MERS's spread the world still has no idea what puts people at risk of infection, how long the incubation period is, when people are contagious or whether there are mild cases that are being missed because surveillance is focused on finding sick people in hospitals. They put the problem squarely at the feet of the Kingdom of Saudi Arabia (KSA), which accounts for 41 of the 55 infections to date.