As the death toll rose this week in a devastating listeria outbreak linked to cantaloupes, a national food retailer said that cantaloupe farmers and shippers must confront a history of food safety problems and take steps to make the fruit safe.
On Tuesday federal officials said that there had been at least 19 previous outbreaks involving more than 1,000 illnesses and three deaths resulting from cantaloupe consumption since 1984. The current outbreak, caused by cantaloupes grown in Colorado, has sickened more than 70 people and killed at least 13, making it the deadliest food-borne outbreak in the United States in more than a decade.
“I don’t think the cantaloupe industry can continue on doing the very same thing and expecting a different result,” said Craig Wilson, the head of food safety for Costco, the Seattle-based warehouse retailer, which is regarded as a leader in requiring food safety measures from its suppliers.
“It’s time for companies to get more aggressive. If they know this is going to happen, let’s step up and not let it happen.”
He said that Costco would consider setting standards for how melons are grown and how they are cleaned and handled after they are picked. He said the company would most likely require that suppliers test melons for pathogens before shipping them to Costco.
He called on the industry to finance research into the best way to wash or clean cantaloupes to remove contaminants.
Federal officials said that they were continuing their investigation at Jensen Farms in Granada, Colo., which produced and packed the cantaloupes tied to the outbreak. The company recalled all of its cantaloupes, a type known as Rocky Ford.
The officials said that only the Jensen Farms melons had made people sick and that other cantaloupes were safe to eat.
Dr. Margaret Hamburg, commissioner of the Food and Drug Administration, said that investigators had yet to determine how the melons became contaminated.
Previous outbreaks linked to cantaloupes have typically involved bacteria called salmonellaor a norovirus.
“This is the first outbreak that we’ve seen with listeria and that is a surprise and certainly something that we need to be mindful of,” Dr. Hamburg said.
The outbreak was also unusual because it involved cantaloupe grown in the United States.
Caroline Smith DeWaal, food safety director for the Center for Science in the Public Interest, an advocacy group, said that most previous outbreaks involved imported cantaloupes, frequently from Mexico or Central America.
Melons from Guatemala, imported by Del Monte Fresh Produce, caused a salmonella outbreak that sickened at least 20 people in 10 states earlier this year.
Trevor V. Suslow, an extension specialist at the University of California, Davis, who has done industry-financed research into food safety and cantaloupes, said that the fruit’s rough skin made it more susceptible to harboring unwanted bacteria.
“You have these tremendous hiding places, if you will, nooks and crannies, lots of areas for microbes to get in and attach and hide,” Dr. Suslow said.
It is best to keep cantaloupes dry to reduce the possibility that bacteria will grow on them, he said. In California, growers typically do not immerse melons in water to wash them and use chilled air to cool them.
In other regions, he said, cantaloupes are often washed in a large tank or with a water spray and are cooled with sprays of cold water as well. Those techniques may be more likely to spread bacteria.
Stephen F. Patricio, a melon shipper who is the chairman of the California Cantaloupe Advisory Board, a trade group, said that sales were plummeting, even though only melons from the farm in Colorado were implicated.
He said that California growers had repeatedly been hurt by outbreaks that were a result of lax practices elsewhere. A salmonella outbreak involving Texas cantaloupes in 1991 and a series of outbreaks from Mexican cantaloupes from 2000 to 2002 devastated sales of all cantaloupes. Now, he said, it is happening again.
“The entire melon category needs to look at the best practices and research that’s been done by the California industry and others to best analyze their own risks,” Mr. Patricio said. “Or we’re all going to continue to suffer.”