As of 5 p.m EDT on Sept. 20, 2011, a total of 55 persons infected with the 4 outbreak-associated strains of Listeria monocytogenes have been reported from 14 states. All illnesses started on or after August 4, 2011. The number of infected persons identified in each state is as follows: California (1), Colorado (14), Illinois (1), Indiana (1), Maryland (1), Montana (1), Nebraska (4), New Mexico (10), Oklahoma (8), Texas (9), Virginia (1), West Virginia (1), Wisconsin (2), and Wyoming (1).

Expect those numbers to go up. The U.S. Centers for Disease Control says listeriosis illnesses in several other states are currently being investigated by state and local health departments to determine if they are part of this outbreak.

Among persons for whom information is available, illnesses began on or after August 4, 2011. Ages range from 35 to 96 years, with a median age of 78-years-old. Most ill persons are over 60-years-old or have health conditions that weaken the immune system. Fifty-nine percent of ill persons are female. Among the 43 ill persons with available information on whether they were hospitalized, all were hospitalized. Eight deaths have been reported, 2 in Colorado, 1 in Maryland, 4 in New Mexico, and 1 in Oklahoma.

Collaborative investigations by local, state, and federal public health and regulatory agencies indicate the source of the outbreak is whole cantaloupe grown at Jensen Farms’ production fields in Granada, Colorado.

A table of cantaloupe- (or rock melon) related outbreaks is available at http://bites.ksu.edu/cantaloupe-related-outbreaks.