An outbreak of listeriosis has spread from a few cases in Colorado in August to 35 cases across 10 states with four confirmed deaths, announced the Centers for Disease Control and Prevention on 19 Sept. News of the outbreak was first reported in early September, as the Colorado Department of Health and Environment noted nine cases of listeriosis in Colorado during the month of August, compared to the state’s usual 10 cases per year. Most of those affected in Colorado were older women. Soon, listeriosis cases began to appear in nearby states, such as Texas, Nebraska, and Oklahoma. The CDC then joined the investigation to coordinate between multiple state departments of health.
Outbreak-related deaths have been confirmed in Colorado, Oklahoma and New Mexico, with additional suspected deaths in Missouri, Oklahoma and New Mexico. Illnesses have occurred in California, Colorado, Illinois, Indiana, Montana, Nebraska, New Mexico, Oklahoma, Texas and West Virginia. More cases are expected to emerge, due to the long incubation period of Listeria bacteria and its ability to grow in refrigerated environments. As a precaution, anyone who may have contaminated cantaloupe is advised to dispose of it, especially people who are at high risk of listeriosis. Those at high risk include people over age 60, those with weakened immune systems and pregnant women.
This strain of Listeria has since been traced specifically to Jensen Farms of Holly, Colo. On 14 Sept., Jensen voluntarily recalled nationwide shipments of cantaloupes. Authorities noted that the Listeria strain has not been found in any other Colorado farms that have been tested, and cantaloupe from other producers is safe to eat. Nonetheless, cantaloupe farmers in Colorado are worried about the economic impact of this outbreak, with concern that effects may be felt for the next two or three years.
Listeriosis is caused by eating foods infected with the bacterium Listeria monocytogenes. Historically, the United States experiences three to four outbreaks per year, though the source is generally contaminated deli meats or soft cheeses. However, outbreaks related to produce are on the rise, and the CDC noted that this is the first time Listeria has been found in cantaloupe.