U.S. federal health officials have raised the death toll to 18 in an outbreak of Listeria in cantaloupe, the Center for Disease Control and Prevention (CDC) said Tuesday. The CDC said that they have confirmed 100 illnesses in 20 states, including the 18 deaths. The agency said it has confirmed two additional deaths in Colorado and one in Kansas since last week. The death toll may continue to rise, officials said. Wyoming’s state health department said it has confirmed another death in that state linked to the outbreak. CDC officials have said the symptoms of Listeria can take up to two months to show up.