U.S. health officials say 15 people have died and 84 others have become ill after eating listeria-infected cantaloupe from a farm in Colorado.

The Centers for Disease Control and Prevention said in a bulletin Friday that to date, 19 states have reported infections. The CDC has said the outbreak, which began at the end of July, is the worst of its kind in the United States in more than 10 years. Five of the 15 deaths have occurred in New Mexico.

The bad cantaloupes were traced to Jensen Farms of Colorado. The commercial grower issued a voluntary recall of its Rocky Ford-brand cantaloupes about two weeks ago.

Although listeria outbreaks are rare, the pathogen is deadlier than more common and well-known food-borne pathogens such as salmonella and E. coli. People can become ill up to two months after consuming tainted food products. `Pregnant women, the elderly and people with compromised immune systems are the most vulnerable.

Listeria contamination occurs most commonly in seafood, processed meats and unpasteurized cheeses, because the deadly bacteria can withstand the cold temperatures of refrigeration.

Food safety experts say cantaloupes have been involved in nearly 40 outbreaks of food-borne disease over the past 20 years, but this is the first time the melons have been tainted by listeria.