The U.S. Centers for Disease Control and Prevention (CDC) has recorded 28 cases of listeriosis among 12 states with all patients hospitalized and with two fatalities.

According to a release on July 26th the source was identified as  the Boar's Head  plant in Jarrett, VA. with liverwurst as the vehicle of infection.  The Company is recalling 103 tons of product including other cold cuts prepared on a common line. It is possible that contamination within the plant is more extensive than the liverwurst equipment and that thorough disinfection will be required, guided by an intensive program of assays.

Since the incubation period of listeriosis may extend to 70 days, and that many cases are mild or not confirmed, the actual incidence rate is probably higher than initially indicated from hospitalizations.

Samples collected from late May through early July showed genetic similarity among patients’ isolates implying a common source. Initially in the absence of a known product or brand responsible for infection the CDC  recommended that those most susceptible to listeriosis including the elderly, pregnant women and the  immunosuppressed to refrain from consuming deli-sliced cold meats.

A contaminated product could result in dissemination of Listeria to other cold cuts or cheeses unless deli slicers are thoroughly decontaminated at regular intervals.  A major outbreak occurred in Canada during 2008, attributed to failure to strip and clean slicers in a major food plant processing and packaging RTE ham and turkey products.