(CNN) -- Federal health officials are expanding efforts to ensure no additional bacteria-tainted cantaloupes get to consumers in what has become the deadliest U.S. outbreak of a food-borne illness in more than a decade.
The Food and Drug Administration said it has teamed up with state officials in the effort.
"FDA and its state partners are conducting checks at retail stores, wholesalers and distributors to make sure they have received notification about the Jensen Farms' whole cantaloupe recall and that they have taken appropriate action to notify their customers and remove the recalled whole cantaloupes from the shelves," the agency said in a statement Wednesday.
Thirteen people have died in what has become the deadliest U.S. outbreak of a food-borne illness since 1998, according to records from the Centers for Disease Control and Prevention.
The outbreak -- blamed on the bacteria Listeria monocytogenes -- was first reported September 12. It was traced to consumption of Rocky Ford cantaloupes grown at Jensen Farms' fields in Granada, Colorado.
As of Monday, it had grown to 18 states, 72 illnesses and 13 deaths, according to the CDC's latest statistics.
"Because some of the wholesalers and distributors may have further distributed the recalled cantaloupes to food processors, it is possible that additional products that contain cantaloupe from Jensen Farms could be recalled," the FDA said. "There is no indication of foreign distribution at this time."
In 1998, 21 people died from consuming tainted hot dogs, according to a CDC database.
In the current outbreak, four people who ate contaminated cantaloupes died in New Mexico, two each in Colorado and Texas, and one each in Kansas, Maryland, Missouri, Nebraska, and Oklahoma.
Public health officials also have reported illnesses in California, Florida, Illinois, Indiana, Montana, North Dakota, Virginia, West Virginia, Wisconsin and Wyoming.
Listeria can grow even at low temperatures and can also can take three weeks or longer to make a person sick, so more cases may emerge in the coming weeks, officials said.
Listeriosis causes fever, muscle aches, diarrhea and other gastrointestinal symptoms. It is rarely a serious concern for healthy children and adults, according to the CDC, but it is particularly dangerous for older adults, people with weakened immune systems. In pregnant women, it can cause miscarriages, stillbirth and premature delivery.
Pregnant women may experience only mild flu-like symptoms, said Dr. David Acheson, a former chief medical officer for the FDA who is now the managing director for food and import safety practice at Leavitt Partners, a firm which advises clients on health care and food safety. Listeria can be devastating to a fetus, he said, particularly in the second or third trimesters, so pregnant women who may have been exposed and have any flu-like symptoms should see a doctor. Symptoms can be more pronounced in the elderly or those with compromised immune systems, he said.
About 1,600 people become seriously ill because of the bacteria each year, the CDC reports, and about 260 die.