The outbreak of listeriosis that has spread from a cantaloupe farm in Colorado to 19 states has sickened at least 84 people and killed 15, the Centers for Disease Control and Prevention reported Friday.


That’s 12 more illnesses and two more deaths linked to Jensen Farms melons, with Arkansas and Alabama reporting their first patients. The confirmed cases so far since July 31:

Alabama: 1 illness

Arkansas: 1 illness

California: 1 illness

Colorado: 17 illnesses, 3 deaths

Illinois: 1 illness

Indiana: 2 illnesses

Kansas: 5 illnesses, 1 death

Maryland: 1 illness

Missouri: 3 illnesses, 1 death

Montana: 1 illness

Nebraska: 6 illnesses

New Mexico: 13 illnesses, 5 deaths

North Dakota: 1 illnesses

Oklahoma: 11 illnesses, 1 death

Texas: 14 illnesses, 2 deaths

Virginia: 1 illnesses

West Virginia: 1 illness

Wisconsin: 2 illnesses

Wyoming: 2 illnesses

Health departments in these states and others are investigating additional listeriosis cases to determine if they are part of the outbreak, the CDC said. Idaho, Montana and Wyoming each may have an additional suspect case and Kansas awaits lab tests results on two more cases, including another death.

Although the implicated cantaloupes were recalled by Colorado’s Jensen Farms on Sept. 14, more outbreak cases are expected to be reported because of the time lag between diagnosis and lab confirmation of infection. And up to two months can elapse between eating contaminated food and developing listeriosis because of the bacteria’s long incubation.

Listeriosis typically affects older adults and this outbreak follows that pattern. Patients range in age from 35 to 96, with a median age of 78; 88 percent are over 60.  Among 79 with available information about treatment, 78 (99 percent) had symptoms so severe they required hospitalization. Two women were pregnant when they became infected; the CDC said it is following the outcome of each pregnancy.

Listeriosis can cause a healthy, pregnant woman to have mild “flu-like” symptoms but it can be lethal to her baby, resulting in miscarriage, premature labor, stillbirth or neonatal infection.

In the CDC’s Morbidity and Mortality Weekly Report (MMWR), the health authorities who have been helping investigate the outbreak discussed its unusual features:

— This is the first listeriosis outbreak associated with melon.

— Four widely differing pulsed-field gel electrophoresis (PFGE) pattern combinations and two Listeria serotypes are associated with the illnesses.

— The number of illnesses is already unusually high and expected to climb higher. Only two U.S. listeriosis outbreaks, one linked to frankfurters that sickened 108 and one with Mexican-style soft cheese that sickened 142, have been larger.

— More lives have been lost than in any U.S. foodborne outbreak since a listeriosis outbreak in 1998.

There was microbiological proof of the source in this outbreak.  All four outbreak strains of Listeria monocytogenes were found on whole and cut cantaloupes from patients’ homes, on cantaloupes at grocery stores and on melons and equipment at Jensen Farms in Colorado.

But it was shoe-leather epidemiology that led health investigators to the farm.

On Sept. 2, the MMWR report recounted, the Colorado Department of Health, which typically sees about two cases of listeriosis every August, reported seven cases since Aug. 28. By Sept. 6, all seven Colorado patients had been interviewed and reported eating cantaloupe in the month before they became ill.

Three of the seven said the cantaloupes they ate were marketed under the brand “Rocky Ford.”

As other cases were reported from around the country, data from the first 19 outbreak-associated patients were compared with 85 cases of sporadic listeriosis reported in August from 2004 through 2010. Cantaloupe consumption was a common factor in all 19 of the 2011 cases (100 percent) versus 54 or the 85 people (64 percent) in the control group.

Tracebacks from retailers who sold the cantaloupes then converged on a single suppler — Jensen Farms, the CDC said.

CDC director Dr. Thomas Frieden has pointed out that Colorado’s fast work leading to the warning about cantaloupe and the recall of the tainted melons likely saved lives and prevented more illness. Colorado’s state health department is supported by the CDC as part of the federal Foodborne Disease Active Surveillance Network. Called FoodNet, the system tracks lab-confirmed cases of foodborne infection, and plays a vita role in monitoring and protecting the country from foodborne disease, especially at a time when state and local health department budgets are being slashed.

The CDC warned that the contaminated cantaloupes could still be in consumers’ homes and also advised consumers who had Jensen Farms cantaloupe in their homes to take extra precautions, because the pathogen can persist and grow, even after the melon has been discarded. It advised washing refrigerator walls and shelves, cutting boards, and countertops, then sanitizing them with a solution of 1 tablespoon of chlorine bleach in 1 gallon of hot water.

There continues to be confusion about where the contaminated cantaloupes were sold, and the CDC said not all the recalled melons were labeled with Jensen Farms stickers.  Consumers have been advised to ask their retailer, or throw out any cantaloupe of uncertain origin.

On Friday, after further reviewing shipment records, Jensen Farms said its whole cantaloupes were distributed in three more states – Indiana, Louisiana and Wisconsin – than had been previously disclosed. The cantaloupes were also shipped to Arkansas, Arizona, California, Colorado, Idaho, Illinois, Kansas, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Virginia, and Wyoming.

CDC Outbreak Map: