Novel Middle East virus may take more than a week to sicken victims

The unfolding mysteries of the illness known as Middle East respiratory syndrome coronavirus already have the makings of an epidemiological thriller, and two newly published case reports offer grist for whoever writes the screenplay based on the latest infectious outbreak. Since it was first detected in September 2012 in Saudi Arabia, this strain of coronavirus appears to have sickened at least 49 and killed roughly 26 people in seven countries. But public health sleuths are still scrambling to figure out some essential facts about the virus: how it spreads from person to person, who is most (and least) vulnerable, when a victim is most contagious, and how long the virus incubates before making its victims noticeably ill. Without answers to those questions, public health authorities don’t know how best to stop the virus’ spread. They don’t even know how hard they should be working to do so, since they don’t really know...