Infectious Disease Epidemiology Program

Listeriosis summary

Listeriosis is a bacterial illness, caused by Listeria monocytogenes. Symptoms include fever, headache, nausea, fatigue and disorientation. Listeriosis infection may cause sepsis and meningitis. Listeriosis is frequently linked to ready-to-eat meats (pate), deli meats, soft cheeses and raw milk. Pregnant women and neonates are at highest risk as the infection can be acquired during pregnancy and transmitted to the fetus. Listeriosis may cause spontaneous abortion. Also at risk are the elderly and individuals with significant health conditions like cancer, diabetes, liver disease, immune system problems, or multiple medical conditions.

In 2007, five confirmed cases of listeriosis were reported to the Maine CDC. This represents an overall case rate of 0.4 per 100,000 population. Except for 2005, the rates of listeriosis in Maine have been higher than national rates for the last four years. Four (80%) of the cases were males; one case was female. The median age of cases was 74 years, with a range of 56 to 86 years.

Four of the five cases were hospitalized following symptoms of listeriosis. All cases appeared to have been unrelated. There were no outbreaks of listeriosis in Maine or cases matching national outbreaks in 2007. Cases were reported in July, August, October and November. All had at least one medical condition before diagnosis of listeriosis.

Prevention and control measures for listeriosis are the same as for other food borne diseases. Listeria bacteria are able to multiply in contaminated foods even during refrigeration. Poultry or meat (including hot dogs) should not be consumed without following proper cooking instructions. Raw milk or foods made from raw milk should be avoided. Pregnant women and people with weakened immune systems should avoid eating such foods as ready-to-eat meats, hot dogs, soft cheeses, and refrigerated smoked seafood.