The listeria outbreak that has killed up to 16 people is the deadliest in more than a decade, according to new data from the Centers for Disease Control and Prevention.

There have been 72 cases of listeriosis and 13 confirmed deaths traced to contaminated cantaloupes, and the CDC is investigating three more deaths that are probably connected to the outbreak.

Most of the victims have been in populations with traditionally higher risk: very young children, the elderly or people with compromised immune systems. Other people are only likely to suffer mild symptoms, if any, from exposure to listeria.

The contaminated cantaloupes, which came from Jensen Farms, were recalled on Sept. 14, but some people may still have them in their refrigerator. Officials also expect the death toll to rise substantially in the coming weeks, because listeria has a long incubation period. Some people may not show symptoms until two months after exposure.

CDC Advise: When In Doubt, Throw It Out

The CDC advised people to err on the side of caution when eating any cantaloupes purchased recently.

If you know the cantaloupe you have is not Jensen Farms, then it's OK to eat, CDC Director Thomas Frieden said in a press briefing on Wednesday. But if you can't confirm it's not Jensen Farms, then it's best to throw it out.

If in doubt, throw it out has become the CDC's mantra as the outbreak has escalated. Some Jensen Farms cantaloupes may not be labeled, so consumers are urged to throw out any cantaloupes that cannot be conclusively traced to a different farm.

The CDC said this was the third deadliest food-borne outbreak since it began keeping records. The two deadliest outbreaks were also caused by listeria. Contaminated cheese killed 52 people in 1985, and contaminated hot dogs killed 21 people in 1998.

In this outbreak, there have been confirmed cases in 18 states, mostly in the West and Midwest: California, Colorado, Florida, Illinois, Indiana, Kansas, Maryland, Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, Texas, Virginia, West Virginia, Wisconsin and Wyoming.

Officials say that four different strains of listeria have been linked to the outbreak, which is unusual. They are still investigating how the cantaloupes were contaminated to begin with.

This is the first time there has been a listeria outbreak linked to cantaloupe -- it is more common in processed meats and unpasteurized milk and cheese -- but cantaloupe is a known culprit in outbreaks of other food-borne diseases, such as salmonella.

Listeria is not as common as salmonella or E. coli, but it is more deadly when it does strike. The disease caused by the bacteria is called listeriosis. Early symptoms usually include fever, muscle aches, nausea, vomiting and diarrhea, but if the bacteria spreads to the nervous system, it can also cause headache, stiff neck, confusion, convulsions and, in up to 20 percent of cases, death.