In mid-September 2026, Wisconsin's measles outbreak reached Marathon County, carried there by a traveler returning from outside the state, bringing the statewide case count to 164. The virus has found its footing wherever vaccination rates have fallen below the threshold that communities need to protect themselves — most starkly in Lafayette County, where only 60 percent of toddlers have received the MMR vaccine, far short of the 95 percent that stops measles from spreading. What began as a regional health failure is now a regional warning, with neighboring Illinois receiving alerts as officia