The stinky stuff that dwells underneath the Michigan State University campus is no longer just simply waste. It has become a public health tool. Colleges across the US that are grappling with the coronavirus are testing sewage for the presence of genetic material from the virus. "It's being used on campus as early warning and communication, so to let the students know that in their dorm there's virus excretion, even if they don't have cases," said Joan Rose, the chair of water research at Michigan State.