Now, just as Colorado cantaloupes return to store shelves for the new growing season, the foodborne pathogen tracking network known as PulseNet may have connected the cantaloupe outbreak to a listeriosis death in Montana.
The connection was made when PulseNet discovered that a clinical sample of Listeria from a 75-year-old Bozeman, Montana man who died in January was indistinguishable from a rare strain of Listeria found on a cantaloupe from an outbreak victim's home.
A spokeswoman from the U.S. Centers for Disease Control and Prevention, which operates PulseNet, told Food Safety News that the agency has not officially connected this death to the 2011 cantaloupe outbreak that affected people in 28 states, including at least one other Montanan. Questions remain as to whether or not the man had contact with Jensen Farms' cantaloupes around the outbreak onset of August and September 2011.
The Montana man's death had not been linked to the cantaloupe outbreak before now because his specific Listeria infection was not associated with strains from any other outbreak victims or food samples. Following months of investigation, health officials and the public were under the impression that Jensen Farms' cantaloupes had transmitted five different strains of Listeria to victims, and his strain was not one of those.
Now, officials know that the number of outbreak strains is more likely six. This development came to light after a cantaloupe sample taken by the Colorado Department of Health from the home of a Colorado man sickened in the outbreak tested positive for four Listeria strains. Three of these five strains were known to be associated with the outbreak, but the last, sixth strain was not one connected to any other victims or samples. In fact, it didn't match any strains in Colorado's database.
As it turned out, the Montana death resulted from the same sixth strain as was found in the Colorado cantaloupe sample. But while the cantaloupe sample was taken in September and the Montana man died in January, information about the sixth strain found on the cantaloupe sample was not uploaded to PulseNet until June 18.
Food Safety News learned of this potential new cantaloupe Listeria death through epidemiologist Patti Waller, who works for food safety law firm Marler Clark, the underwriter of Food Safety News. The Colorado sample came from the household of a Marler Clark client who is part of a group of victims suing Jensen Farms and its distributors for medical expenses and damages resulting from their illnesses.
Waller assisted the Colorado Department of Health and PulseNet in ensuring that the sixth genetic fingerprint of this sixth Listeria strain was uploaded to the network and compared to other samples.
The fact that the CDC could even potentially connect the cantaloupe sample to an additional listeriosis death in Montana speaks volumes of PulseNet's impact as an epidemiological tool, Waller said.
Food Safety News will continue reporting on this potential link as more information becomes available.
