On Sept. 30, 2011, the U.S. Centers for Disease Control and Prevention (CDC) responded to a multi-state outbreak of listeriosis, linked to whole cantaloupes.

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.