Guinea worm is the favourite, and the clock on it is set by dogs. 2025 closed with 10 human cases worldwide, the lowest ever recorded (Carter Center, provisional, January 2026), down from 15 in 2024. The same surveillance counted 664 animal infections in 2024, 299 of them in dogs in Cameroon and 234 in dogs in Chad, and 550 animal infections in the first half of 2025 alone (CDC MMWR, October 2025); Chad has reported hundreds to over a thousand infected dogs a year since the dog reservoir appeared in 2012, and genomics shows the worms in dogs and people are one population (PLoS Neglected Tropical Diseases, 2020). WHO certification requires zero transmission for three consecutive years under adequate surveillance, and infected dogs count as transmission, so the earliest plausible certification is three years after the last infected dog, which has not happened yet; polio's two endemic countries were still reporting wild-type cases in 2025, and lymphatic filariasis is an elimination target rather than an eradication one. So Guinea worm first, but closer to 2030 than 2027, and the number to watch is the Chad dog count, not the human one.