Many of the world’s rivers, namely in Asia and Africa, contain dangerous levels of antibiotics, researchers have found after 66% of 711 sites sampled across 72 countries had tested positive.

“It’s a global problem, and we need global solutions,” says William Gaze, a microbial ecologist at the University of Exeter Medical School in England who was not involved with the research, stressing that even if rich countries restrain antibiotic pollution, drug-resistant microbes can hitch a ride across the globe with people who travel and migrating birds or traded food and livestock.

“I don’t think I was expecting the degree of concentrations that we saw. That was quite eye-opening,” says environmental chemist Alistair Boxall of the University of York in England.

“Ultimately, it would be nice if we could get samples from every country of the world,” he added.