The warnings from public health officials that the deaths and illnesses from listeria-tainted cantaloupes could drag on for a while are proving true.
The death toll from cantaloupes grown by Jensen Farms has hit 18, according to the Centers for Disease Control and Prevention's latest report on the outbreak. A hundred people have been sickened in 20 states, with Colorado and New Mexico the hardest hit.
Even now, weeks after the suspect cantaloupes were recalled, the CDC cautions that there may be more reports of illness to come. The incubation period for listeriosis varies, but it can take as long as two months for symptoms to develop after eating food contaminated with Listeria monocytogenes. It also takes time to diagnose the infection and to confirm the finding with lab tests.
The Associated Press reports that Wyoming's state health department has identified a person whose death was linked to the outbreak and that wasn't included in the CDC's latest update.
Even though the source of the tainted cantaloupes has been identified as Jensen Farms, investigators still don't know exactly what caused the contamination. FDA Commissioner Margaret Hamburg said Tuesday that the investigation is continuing, according to the AP. The farm's water supply and listeria carried by animals are two possibilities.
Listeria bacteria can grow in silage, fodder for cattle and other farm animals, and some research suggests that cows, goats and sheep can serve as reservoirs for the germs. Manure from infected animals can then spread the bacteria.
An outbreak of listeriosis in Canada's Maritime Provinces 20 years ago was traced to a cabbage grown on a farm that used untreated sheep manure as fertilizer. The sheep had a history of listeria infection.