At least three cases of Guinea worm disease have been recorded in South Sudan for the first time since the government announced a major victory for global health officials working to eliminate the disease.

In March, South Sudan’s health ministry said it had stopped Guinea worm disease within South Sudan borders after the country had gone 15 months without a single reported case.

But health minister Riek Gai Kok told reporters in Juba on Monday that three cases of Guinea worm had been reported in Western Lakes State.

“Today we are informing the public that there is a setback. Three cases have been reported in Western Lakes State,” Dr. Riek Gai Kok said in announcing transmission has been recorded.

Guinea worm — also known as dracunculiasis, or “affliction with little dragons” — is a minuscule parasite found in ponds. Inside anyone who drinks the water, it grows to be a yard long and emerges after a year, usually from a leg or foot, by exuding acid under the skin to form a blister.