We're unable to sign you in at this time. Please try again in a few minutes.
We were able to sign you in, but your subscription(s) could not be found. Please try again in a few minutes.
There may be a problem with your account. Please contact the AMA Service Center to resolve this issue.
Contact the AMA Service Center:
Telephone: 1 (800) 262-2350 or 1 (312) 670-7827  *   Email: subscriptions@jamanetwork.com
Error Message ......
From the Centers for Disease Control and Prevention |

Multistate Outbreak of Listeriosis Associated With Jensen Farms Cantaloupe—United States, August—September 2011 FREE

JAMA. 2011;306(21):2321. doi:.
Text Size: A A A
Published online

MMWR. 2011;60:1357-1358

1 figure omitted

On September 30, 2011, this report was posted as an MMWR Early Release on the MMWR website (http://www.cdc.gov/mmwr).

Listeriosis is caused by Listeria monocytogenes, a gram-positive bacillus common in the environment and acquired by humans primarily through consumption of contaminated food. Infection causes a spectrum of illness, ranging from febrile gastroenteritis to invasive disease, including sepsis and meningoencephalitis. Invasive listeriosis occurs predominantly in older adults and persons with impaired immune systems. Listeriosis in pregnant women is typically a mild “flu-like” illness, but can result in fetal loss, premature labor, or neonatal infection. Listeriosis is treated with antibiotics. On September 2, 2011, the Colorado Department of Public Health and Environment (CDPHE) notified CDC of seven cases of listeriosis reported since August 28. On average, Colorado reports two cases of listeriosis annually in August. By September 6, all seven Colorado patients interviewed with the Listeria Initiative* questionnaire reported eating cantaloupe in the month before illness began, and three reported eating cantaloupe marketed as “Rocky Ford.”

A case was defined as illness with one of the outbreak strains isolated on or after August 1. Outbreak strains initially were defined as clinical isolates of L. monocytogenes with (1) specimen collection dates in August, and (2) a two-enzyme, pulsed-field gel electrophoresis (PFGE) pattern combination that occurred in two or more persons and matched any of the three pattern combinations found among Colorado residents in August. Analysis of Listeria Initiative data comparing the first 19 outbreak-associated cases in 2011 with 85 cases among persons aged ≥60 years with sporadic listeriosis identified during August of the years 2004-2010 indicated that cantaloupe consumption was strongly associated with illness caused by the outbreak strains: 19 of 19 (100%) versus 54 of 85 (64%); (odds ratio = 14.9; 95% CI = 2.4–∞). Initial tracebacks of cantaloupe purchased by patients converged on Jensen Farms in Colorado.

After cantaloupe was implicated, PulseNet, the national molecular subtyping network for foodborne bacterial disease surveillance, detected a multistate cluster with a fourth PFGE pattern combination; a sample of cantaloupe collected from the implicated farm yielded L. monocytogenes with this pattern, and interviews with patients revealed that most had consumed cantaloupe. Isolates with this pattern were then also considered to be among the outbreak strains. By September 29, 84 cases with one of the four outbreak PFGE pattern combinations had been reported from 19 states,† including 83 with information on the date of illness onset. Among the patients, 88% were aged ≥60 years (range: 35-96 years); 55% were female, and two were pregnant. Fifteen deaths were reported. Ninety-two percent (57 of 62 with information on food consumption) reported eating cantaloupe in the month before illness began. All four outbreak strains of L. monocytogenes were isolated from whole and cut cantaloupe samples from patients' homes or from samples of Jensen Farms cantaloupe collected from grocery stores and the farm. On September 14, the farm issued a voluntary recall of its cantaloupe.

This outbreak has several unusual features. First, this is the first listeriosis outbreak associated with melon. Second, four widely differing PFGE pattern combinations and two serotypes (1/2a and 1/2b) have been associated with the outbreak. Third, this outbreak is unusually large; only two U.S. listeriosis outbreaks, one associated with frankfurters (108 cases) and one with Mexican-style cheese (142), have had more cases.1,2 Additional cases likely will be reported because of the long incubation period (usually 1-3 weeks, range: 3-70 days) and the time needed for diagnosis and confirmation. Fourth, this outbreak has the highest number of deaths of any U.S. foodborne outbreak since a listeriosis outbreak in 1998.1

CDC recommends that persons do not eat cantaloupes from Jensen Farms. This recommendation is especially important for persons at greater risk for listeriosis, including older adults, persons with weakened immune systems, and pregnant women. Not all of the recalled cantaloupes are individually labeled with stickers to indicate production by Jensen Farms. Consumers should consult the retailer or discard any cantaloupe of uncertain origin. Recommendations for preventing listeriosis from other foods are available at http://www.cdc.gov/listeria.


Shaun Cosgrove, Alicia Cronquist, Colorado Dept of Public Health and Environment. Gail Wright, Boulder County Public Health. Tista Ghosh, Richard Vogt, Tri-County Health Department. Paul Teitell, Investigations Br, Food and Drug Administration (FDA) Denver District. Allen Gelfius, Charlotte Spires, Tracy Duvernoy, Sheila Merriweather, FDA Coordinated Outbreak Response and Evaluation (CORE) Network. Molly Freeman, Patricia M. Griffin, Kelly A. Jackson, Lavin A. Joseph, Barbara E. Mahon, Karen Neil, Benjamin J. Silk, Cheryl Tarr, Robert Tauxe, Eija Trees, Div of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases; Mam Ibraheem, Maho Imanishi, Neena Jain, Jeffrey McCollum, Katherine A. O’Connor, EIS officers, CDC. Corresponding contributor: Kelly A. Jackson, gqv8@cdc.gov, 404-639-4603.


State and local health departments in the 19 states with cases.


2 Available.

*The Listeria Initiative is a CDC-led, enhanced surveillance system that has routinely collected data on food consumption from all patients with listeriosis since 2004. Additional information is available at http://www.cdc.gov/nationalsurveillance/listeria_surveillance.html.

†Colorado (17 cases), Texas (14), New Mexico (13), Oklahoma (11), Nebraska (6), Kansas (5), Missouri (3), Indiana (2), Wisconsin (2), Wyoming (2), Alabama (1), Arkansas (1), California (1), Illinois (1), Maryland (1), Montana (1), North Dakota (1), Virginia (1), and West Virginia (1).




Also Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
Please click the checkbox indicating that you have read the full article in order to submit your answers.
Your answers have been saved for later.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.


Some tools below are only available to our subscribers or users with an online account.

0 Citations

Related Content

Customize your page view by dragging & repositioning the boxes below.

Articles Related By Topic
Related Collections
PubMed Articles