WASHINGTON >> Health officials say as many as 16 people have died from possible listeria illnesses traced to Colorado cantaloupes, the deadliest food outbreak in more than a decade.

The Centers for Disease Control and Prevention said Tuesday that 72 illnesses, including 13 deaths, are linked to the tainted fruit. State and local officials say they are investigating three additional deaths that may be connected. 

The death toll released by the CDC Tuesday — including newly confirmed deaths in Kansas, Missouri, Nebraska and Texas — surpassed the number of deaths linked to an outbreak of salmonella in peanuts almost three years ago. Nine people died in that outbreak.

The CDC said Tuesday that they have confirmed two deaths in Texas and one death each in in Kansas, Missouri and Nebraska. Last week the CDC reported two deaths in Colorado, four deaths in New Mexico, one in Oklahoma and one in Maryland.

New Mexico officials said Tuesday they are investigating a fifth death, while health authorities in Kansas and Wyoming said they too are investigating additional deaths possibly linked to the tainted fruit.

Listeria is more deadly than well-known pathogens like salmonella and E. coli, though those outbreaks generally cause many more illnesses. Twenty-one people died in an outbreak of listeria poisoning in 1998 traced to contaminated hot dogs and possibly deli meats made by Bil Mar Foods, a subsidiary of Sara Lee Corp. Another large listeria outbreak in 1985 killed 52 people and was linked to Mexican-style soft cheese.

Listeria generally only sickens the elderly, pregnant women and others with compromised immune systems. The CDC said the median age of those sickened is 78 and that one in five who contract the disease can die.

Dr. Robert Tauxe of the CDC says the number of illnesses and deaths will probably grow in coming weeks because the symptoms of listeria don’t always show up right away. It can take four weeks or more for a person to fall ill after eating food contaminated with listeria.

“That long incubation period is a real problem,” Tauxe said. “People who ate a contaminated food two weeks ago or even a week ago could still be falling sick weeks later.”

CDC reported the 72 illnesses and deaths in 18 states. Cases of listeria were reported in California, Colorado, Florida, Illinois, Indiana, Kansas, Maryland, Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, Texas, Virginia, West Virginia, Wisconsin, and Wyoming. The most illnesses were reported in Colorado, which has seen 15 sickened. Fourteen illnesses were reported in Texas, 10 in New Mexico and eight in Oklahoma.

The outbreak has been traced to Jensen Farms in Holly, Colo., which recalled the tainted cantaloupes earlier this month. The Food and Drug Administration said state health officials had found listeria in cantaloupes taken from grocery stores in the state and from a victim’s home that were grown at Jensen Farms. Matching strains of the disease were found on equipment and cantaloupe samples at Jensen Farms’ packing facility in Granada, Colo.

FDA, which investigates the cause of foodborne outbreaks, has not released any additional details on how the contamination may have happened. The agency says its investigation is ongoing.

The Rocky Ford-brand cantaloupes from Jensen Farms were shipped from July 29 through Sept. 10 to Arkansas, Arizona, California, Colorado, Idaho, Illinois, Kansas, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Virginia, and Wyoming.

The recalled cantaloupe may be labeled “Colorado Grown,” ”Distributed by Frontera Produce,” ”Jensenfarms.com” or “Sweet Rocky Fords.” Not all of the recalled cantaloupes are labeled with a sticker, the FDA said.

Unlike many pathogens, listeria bacteria can grow at room temperatures and even refrigerator temperatures. The FDA and CDC recommend anyone who may have one of the contaminated cantaloupes throw it out immediately and clean and sanitize any surfaces it may have touched.

About 800 cases of listeria are found in the United States each year, according to CDC, and there usually are three or four outbreaks. Most of these are traced to deli meat and soft cheeses, where listeria is most common.

Produce has rarely been the culprit, but federal investigators say they have seen more produce-related listeria illnesses in the past two years. It was found in sprouts in 2009 and celery in 2010.

While most healthy adults can consume listeria with no ill effects, it can kill the elderly and those with compromised immune systems. It is also dangerous to pregnant women because it easily passes through to the fetus. Dr. Tauxe of the CDC said the type of listeria linked to the cantaloupes is not one that is commonly associated with pregnancy-associated illnesses, however. State and federal health authorities have not definitively linked any miscarriages, stillbirths or infant illnesses to the current outbreak.

Symptoms of listeria include fever and muscle aches, often with other gastrointestinal symptoms. Victims often become incapacitated and unable to speak.

Debbie Frederick said her mother knew something was wrong when her father, 87-year-old William Thomas Beach, collapsed at his home in Mustang, Okla. and couldn’t get up. He died a few days later, on Sept. 1. The family later learned his death was linked to eating the cantaloupe and sued Jensen Farms.

“First you just kind of go into shock,” said Frederick. “Then it settles in that he would still be alive if this hadn’t happened. It’s a life, for what?”

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Associated Press writers Jamie Stengle in Dallas, Josh Funk in Omaha, Neb., Maria Sudekum Fisher in Kansas City, Mo., Susan Montoya in Albuquerque, N.M., and Ben Neary in Cheyenne, Wyo,. contributed to this report.

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For more information:
CDC on cantaloupe outbreak: http://www.cdc.gov/nczved/divisions/dfbmd/diseases/listeriosis/092111.html

FDA on cantaloupe recall: http://www.fda.gov/Food/FoodSafety/CORENetwork/ucm272372.htm

Center for Science and the Public Interest, “Super Safe Your Kitchen”: http://www.cspinet.org/new/pdf/safekitchen.pdf