At least 13 people in eight states have died after eating cantaloupe contaminated with listeria, in the deadliest outbreak of food-borne illness in the United States in more than a decade, public health officials said on Tuesday.
Many of the deaths involved elderly people, who are especially susceptible to the aggressive pathogen.
The cantaloupes were grown by a Colorado company, Jensen Farms, which issued a recall earlier this month. The melons, a type marketed as Rocky Ford cantaloupes, named after a region in Colorado, were sold around the country.
The federal Centers for Disease Control and Prevention reported that since the outbreak began in late July at least 72 people had fallen ill in 18 states.
The agency said that four people had died in New Mexico, two in Colorado, two in Texas, and one each in Kansas, Maryland, Missouri, Nebraska and Oklahoma. The toll could grow as state health officials wait for test results on other deaths suspected of being part of the outbreak.
Officials said that most of those who died were over age 60. At least two were in their 90s.
Listeria is a common but dangerous bacteria that can cause severe illness, especially among the elderly, the very young and people with compromised immune systems. The pathogen can also cause pregnant women to have miscarriages.
Federal officials have so far provided no information about the number of miscarriages or stillbirths associated with the outbreak. Pregnant women are 20 times as likely as other healthy adults to come down with a severe infection, according to the C.D.C.
John N. Sofos, a professor of food safety at Colorado State University, said that many people who were infected might have only mild symptoms, like diarrhea. But in others, especially those in the most vulnerable categories, the bacteria can aggressively move out of the gastrointestinal tract and attack muscle tissue or the spinal cord, leading to much more severe illnesses like meningitis.
For that reason, the death rate in listeria outbreaks is often much higher than with other forms of food-borne bacteria.
William Marler, a Seattle lawyer who represents victims of food-borne illness, said this outbreak might turn out to be especially deadly simply because cantaloupe is a food eaten by many older people.
“Sometimes in outbreaks, it’s the population that’s consuming the food that drives the numbers,” Mr. Marler said. “In this instance, you’ve got a lot of people 60 and older who are consuming cantaloupe.”
The outbreak appeared to be the third worst in the United States attributed to any form of food-borne illness, in terms of the number of deaths, since the C.D.C. began regularly tracking such outbreaks in the early 1970s.
The deadliest outbreak in the United States since then occurred in 1985, when a wave of listeria illness, linked to Mexican-style fresh cheese, swept through California. A federal database says 52 deaths were attributed to the outbreak, but news reports at the time put the number as high as 84.
The second deadliest outbreak was in 1998 and 1999, when there were at least 14 deaths and four miscarriages or stillbirths in a listeria outbreak linked to hot dogs and delicatessen meats. Some sources put the death toll in that outbreak as high as 21.
With the updated death toll on Tuesday, the Rocky Ford cantaloupe outbreak surpassed the 2008 deaths associated with salmonella-tainted peanuts and peanut butter produced by a Georgia company, the Peanut Corporation of America. That outbreak, which drew a large amount of news coverage, killed nine people and sickened more than 700.
The huge outbreak this year in Europe of a rare form of E. coli bacteria attributed to fenugreek sprouts killed at least 50 people.
Listeria is a common bacteria that can be found in soil, water, decaying plant matter and manure. A strain of the organism, called Listeria monocytogenes, was first found to cause illness linked to food in the early 1980s. Since then, only a handful of listeria outbreaks have been associated with fresh fruits and vegetables. The majority were caused by tainted meat or dairy products.
It can take more than two months for a person exposed to the bacteria to fall ill, which means that it is often difficult to identify a food that carried the pathogen.
Unlike some other bacteria, listeria also grows well at low temperatures, meaning it can be difficult to eliminate from refrigerated areas used to process or store foods.
The Food and Drug Administration said it had found the strain of the bacteria on melons and on equipment in the Colorado farm’s packing house. It also found the bacteria on melons in a Denver-area store. Investigators have not said how they believe the contamination occurred.
The F.D.A. recommends that consumers rinse all raw produce, including cantaloupes, under running water. Firm produce, like melons, should be scrubbed with a produce brush. The washed produce should be dried with a clean cloth or unused paper towel, the agency said.