Tests confirm cantaloupe link in 10-state Listeria outbreak

Sep 19, 2011 (CIDRAP News) – Listeria monocytogenes found in samples of Jensen Farms cantaloupe from a sick patient's home and from retail outlets have the same genetic fingerprint as the strain that has sickened several patients in the outbreak, Colorado health officials have reported.

In another development, the US Centers for Disease Control and Prevention (CDC) said today that the number of people sickened in the outbreak has risen to 35, with 10 states now reporting cases. Several other state health departments are reporting Listeria cases and deaths that have suspected links to the outbreak, which could push the total even higher.

The number of patients involved in the outbreak so far is 13 more than the CDC reported in its last update on Sep 14, and cases from three more states have been confirmed. Two more deaths have been linked to the outbreak, a patient from Oklahoma and one more patient from New Mexico, raising the total to 4.

Colorado officials said all of the positive product samples came from cantaloupes that appeared to have been grown at Jensen Farms, which on Sep 14 recalled all shipments distributed between Jul 29 and Sep 10. Of 10 samples collected from Jensen Farms cantaloupes, several matched lab results from Colorado's 12 confirmed case-patients, the Colorado Department of Public Health and Environment (CDPHE) reported on Sep 16.

The US Food and Drug Administration (FDA) said last week that no other farms in Colorado's Rocky Ford growing area appeared to have links to the cantaloupe contamination. Chris Urbina, MD, chief medical officer and director of the CDPHE, said in the statement that though the implicated products either had been removed or were being removed from the market, more infections would likely be reported, because Listeria's incubation period is about 3 weeks.

The CDPHE said the number of Colorado patients sickened in the outbreak remained at 12, including 1 death.

States listed as part of the outbreak for the first time today are California, Illinois, and Montana. Additional cases were reported from Nebraska (3), New Mexico (1), Oklahoma (5), and Texas (1).

However, even more states are reporting that they have Listeria cases that may be linked to the outbreak. The CDC has said it and state and local partners are investigating other possibly related illnesses in several other states.

For example, officials at the Kansas Department of Health and Environment (KDHE) said in a Sep 15 statement that they had received reports of six listeriosis cases since Aug 26, none of which have been definitively linked to the outbreak. Tests were under way, and more lab tests were pending.

In Missouri, the Springfield-Greene County Health Department was investigating two Listeria cases that might be linked to the cantaloupe outbreak, according to a Sep 15 statement. The two patients were elderly people, both of whom were hospitalized, according to a Sep 17 Associated Press report. One of the patients died.

Most of the people involved in the outbreak are older than 60 or have underlying health conditions that impair their immune response, the CDC said. Of 28 patients with available information, all were hospitalized. Of 27 patients with available food histories, all but one had consumed cantaloupe.

Though Jensen Farms has recalled its cantaloupes, the CDC said they were distributed widely and may still be in grocery stores. The agency advised people in risk groups for complications, such as older people and pregnant women, to avoid eating Rocky Ford cantaloupes from Jensen Farms.

See also:

Sep 16 CDPHE news release

Sep 15 CIDRAP News story "Seven-state Listeria outbreak prompts cantaloupe recall"

Sep 15 KDHE statement

Sep 17 AP story

Newsletter Sign-up

Get CIDRAP news and other free newsletters.

Sign up now»


Unrestricted financial support provided by

Bentson Foundation 3MAccelerate DiagnosticsGilead 
Grant support for ASP provided by


  Become an underwriter»