U.S. Food Safety
A scientist uses a microscope to check cultures. REUTERS

Four people have died from listeria contained in cantaloupes from Colorado, the Centers for Disease Control and Prevention said.

The deaths spread beyond Colorado, with one person killed in Oklahoma and two killed in New Mexico. The CDC said that 35 people in 10 states have fallen ill so far. The illnesses are in California, Colorado, Illinois, Indiana, Montana, Nebraska, New Mexico, Oklahoma, Texas and West Virginia.

Listeria is a dangerous bacteria that flourishes in cool temperatures and is particularly dangerous to the elderly or to people with weakened immune systems. It is common enough that it only creates about 800 reported cases a year in the United States, most of them linked to meat and soft cheese.

Investigators have traced the burgeoning outbreak to Jensen Farms in Holly, Colo. The company recalled its entire crop of Rocky Ford brand canteloupes last week after Colorado health officials identified the problem, but had already distributed 300,000 cases of canteloupes to 17 states.

We know who we sell to and who our customers are, but our customers may resell to another company, Amy Philpott, a company spokeswoman, told The Washington Post.

Listeria can grow in refrigerators or at room temperature, unlike other pathogens, and has an incubation period of about a month. The ease with which it can spread is leading officials to predict more canteloupe cases before the outbreak is over.