In South Korea, Singapore and Iran, clusters of infections are leading to a jump in cases of the new viral illness outside China. But it’s not the numbers that are worrying experts: It’s that increasingly they can’t trace where the clusters started.
World Health Organization officials said China’s crackdown on parts of the country bought time for the rest of the world to prepare for the new virus. But as hot spots emerge around the globe, trouble finding each source — the first patient who sparks every new cluster — might signal the disease has begun spreading too widely for tried-and-true public health steps to stamp it out.
“A number of spot fires, occurring around the world is a sign that things are ticking along, and what we are going to have here is probably a pandemic,” said Ian Mackay, who studies viruses at the University of Queensland.