Researchers have established that the SARS virus emerged from a bat. The virus may have passed through an intermediate species — another animal, perhaps infected by cage-to-cage contact in one of the crowded live-animal markets of the region — before getting into a person. And while SARS hasn’t recurred, we can assume that the virus still abides in southern China within its reservoir hosts: one or more kinds of bat.

Bats, though wondrous and necessary animals, do seem to be disproportionately implicated as reservoir hosts of new zoonotic viruses: Marburg, Hendra, Nipah, Menangle and others. Bats gather in huge, sociable aggregations and have long life spans, circumstances that may be especially hospitable to viruses. And they fly. Traveling nightly to feed, shifting occasionally from one communal roost to another, they carry their infections widely and spread them to one another.

As for the novel coronavirus in Saudi Arabia, its reservoir host is still undiscovered. But you can be confident that scientific sleuths are on the case and that they will look closely at Arabian bats, including those that visit the productive date-palm groves at the oases of Al Ahsa, near the Persian Gulf.

What can we do? The first obligation is informed awareness. Early reports arrive from afar, seeming exotic and peripheral, but don’t be fooled. One emergent virus, sooner or later, will be the Next Big One. It may show up first in China, in Congo or Bangladesh, or maybe on the Arabian Peninsula; but it will globalize. Most people on earth nowadays live within 24 hours’ travel time of Saudi Arabia. And in October, when millions of people journey to Mecca for the hajj, the Muslim pilgrimage, the lines of connections among humans everywhere will be that much shorter.