Listeriosis Outbreak and Response

The ongoing outbreak of listeriosis secondary to contaminated cantaloupes, and the subsequent recall of cantaloupes from the source farm, have generated questions on the proper handling of patients with potential exposure.  We have attached, for your reference, the current recommendations from the CDC regarding this outbreak.

A few highlights to point out
1) No contaminated cantaloupes were delivered to Iowa.  Any potential exposure would have had to have occurred in a different state (currently: IL, WY, TN, UT, TX, CO, MN, KS, NM, NC, MO, NE, OK, AZ, NJ, NY, PA). 

2) Culture of stool for Listeria has a low yield and has not been evaluated as a screening or diagnostic test (Listeria can be found in the feces of healthy persons, and a negative stool culture for Listeria does not exclude the possibility of Listeria infection or carriage).  The UIHC clinical microbiology laboratory and the State Hygienic Laboratory do not perform stool cultures for ListeriaIf stool is sent for Listeria culture, it will not be performed. There is no reliable screening test for asymptomatic patients.

3) No testing or treatment is indicated for an exposed, asymptomatic person.  Such a person should be instructed to return if he or she develops symptoms of listeriosis within two months of eating the recalled product. Symptoms may include fever and myalgias, often preceded by diarrhea or other gastrointestinal symptoms. In older adults and immunocompromised persons, symptoms of listeriosis can include headache, stiff neck, confusion, loss of balance, and seizures.  Cultures of blood and/or CSF should be performed in symptomatic patients with suspected listeriosis.

For additional information about management of persons at risk for, or with symptoms of, listeriosis, please see the attached CDC document.  The Infectious Diseases consult service is also available to assist in the diagnosis and treatment of patients with suspected listeriosis.

Daniel J. Diekema, M.D.
Director, Division of Infectious Diseases

J. Stacey Klutts, M.D., Ph.D.
Interim Medical Director, Clinical Microbiology