BY THE time he had finished his walk through the woods in New York state, Rick Ostfeld was ready to declare a public health emergency. He could read the warning signs in the acorns that littered the forest floor – seeds of a chain of events that will culminate in an unprecedented outbreak of Lyme disease this year. Since that day in 2015, Ostfeld has been publicising the coming outbreak. Thanks to a changing climate it could be one of the worst on record: the ticks that carry

the disease have been found in places where it has never before been a problem – and where most people don’t know how to respond. The danger zone isn’t confined to the US: similar signs are flagging potential outbreaks in Europe. Polish researchers predict a major outbreak there in 2018. In theory, Ostfeld’s early warning system gives public health officials a two-year window to prepare. In many other cases, this would be enough time to roll out a vaccination programme. MORE