Dr. Richard Kock was on duty at London’s Royal Veterinary College in January 2017 when he received an urgent message from international health officials. He was needed for an emergency response mission in the Mongolian countryside, where a deadly viral outbreak was underway.

He packed his things, caught a flight to the capital city of Ulaanbaatar and drove for two days into the arid steppe. He found a disturbing scene: frozen corpses scattered on hillsides, burn pits stacked with bodies and residents addled with anxiety.

But this pandemic was not targeting humans. It was goat plague, a lethal and highly infectious virus that has killed goats, sheep and other small ruminants in huge numbers…