At least a dozen people have died of listeria from eating contaminated cantaloupes, and officials expect the number of contamination cases to rise as effects from the bacterial infection are commonly delayed.
Federal health officials said they are intensifying their efforts to contain the contamination from bacteria-tainted cantaloupes. The bacteria can reportedly cause illness as late as two months after a person has consumed contaminated food.
"We will see more cases likely through October," U.S. Food and Drug Administration (FDA) Commissioner Margaret Hamburg said in telephone briefing Wednesday.
As of Monday, the contamination has spread to 18 states. Seventy-two cases of illnesses were reported, and there were 13 deaths, according to the statistics by the Centers for Disease Control and Prevention (CDC).
Some news agencies have reported that the death toll may actually be as high as 16.
The listeria outbreak linked to tainted cantaloupes may be one of the deadliest in recent history, according to new CDC estimates..
The FDA also announced Wednesday that it has teamed up with state authorities to better fight the deadly outbreak.
"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.
Listeriosis, a serious infection usually caused by eating food contaminated with the bacterium Listeria monocytogenes, primarily affects older adults, pregnant women, newborns, and adults with weakened immune systems.
Listeria is more deadly than well-known pathogens like salmonella and E. coli, although those outbreaks generally cause many more illnesses.
The outbreak has been traced back to Jensen Farms in Holly, Colo., which recalled the tainted cantaloupes earlier this month.
The FDA said at the time that 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.
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 to the fetus.
Symptoms of listeria include fever and muscle aches, often with other gastrointestinal symptoms. Victims often become incapacitated and unable to speak.