Health officials have confirmed more deaths resulting from listeria-infected cantaloupes in the U.S., raising the outbreak’s death toll to 21. That’s the deadliest American listeria incident since 1985, when some bad Mexican cheese was responsible for 52 deaths. Listeria symptoms, officials warned, can take up to two months to appear, so they expect to learn of more cases throughout October. Including the 21 dead, 109 people have been sickened by the cantaloupes in 23 states. Jensen Farms in Holly, Colo., has recalled the cantaloupes; the last shipments went out in mid-September.