OP-ED CONTRIBUTORS Hanoi, Vietnam — IMAGINE this situation: A sudden outbreak of a little-understood disease in two European countries kills 41 of the 54 people it is known to have infected. In its wake it leaves 150 million chickens dead, some of them killed by the virus causing the outbreak, others slaughtered to stop its spread. At a zoo in one country, rare tigers suddenly begin dying from the disease. Reports from elsewhere in Europe say the virus, which is normally found only in chickens, is now also infecting pigs, cats and ducks. Scientists sound the alarm. They say that...