Listeria (Listeriosis)

Multistate Outbreak of Listeriosis Linked to Whole Cantaloupes from Jensen Farms, Colorado

Persons infected with the outbreak-associated strains of Listeria monocytogenes, by date of illness onset*

Chart showing bar graph indicating numbers of persons infected with the outbreak-associated strains of Listeria monocytogenes, by date of illness onset

Onset date not currently available for all persons with reported illness

*n=123 for whom information on illness onset was reported to CDC by 9am EDT on October 17, 2011

Among persons for whom information is available, illnesses began on or after July 31, 2011. Ages range from <1 to 96 years, with a median age of 78 years. Most ill persons are over 60 years old. Fifty-eight percent of ill persons are female. Among the 120 ill persons with available information on whether they were hospitalized, 118 (98%) were hospitalized. Four of the illnesses were related to a pregnancy; one was diagnosed in a newborn and three were diagnosed in pregnant women. One miscarriage has been reported. Other outcomes are being monitored.

The outbreak can be visually described with a chart showing the number of persons who became ill each day. This chart is called an epidemic curve or epi curve. Illnesses that occurred after September 23, 2011, might not be reported yet due to the time it takes between when a person becomes ill and when the illness is reported. Please see the description of the steps in a foodborne outbreak investigation for more details.

About 800 laboratory-confirmed cases of Listeria infection are reported each year in the United States and typically 3 or 4 outbreaks are identified. The foods that typically cause these outbreaks have been deli meats, hot dogs, and Mexican-style soft cheeses made with unpasteurized milk. Produce is not often identified as a source, but sprouts caused an outbreak in 2009, and celery caused an outbreak in 2010.