Listeria monocytogenes

Listeria monocytogenes is a pathogen that has been associated with a number of foodborne illness outbreaks. This pathogen has proven to be very challenging to control and has a higher mortality rate when people become ill than other pathogens. Listeria can survive in environments that are unfavorable to other pathogens.

The incubation period has not been determined for the illness caused by this type of bacteria. With milder cases of this illness symptoms such as fever, muscle aches, nausea, vomiting and even diarrhea can develop within a few hours up to a couple of days. People with the more severe form of the illness have been documented to have symptoms beginning to develop in as little as three days or as long as three months. Healthy people may not have symptoms or may only have mild symptoms when exposed to this pathogen. More severe cases may have fever, muscle aches, nausea, vomiting and possibly even diarrhea. In the most severe cases, the infection can spread to the nervous system and cause symptoms such as headache, stiff neck, a loss of balance, confusion and convulsions. Pregnant women, elderly people and those immuno-compromised, if they become ill from Listeria monocytogenes, are at greater risk of more severe symptoms or death.

Listeria can be found in many places such as soil, water and many animals that may come into contact with food or people. It survives and reproduces at temperatures lower than most pathogens. This pathogen can survive in vacuum packaged products and still be able to make people sick. While this pathogen does not have the largest number of outbreaks associated with it, it does tend to have a higher death rate than other pathogens. Foods that have been connected to Listeriosis outbreaks include unpasteurized milk, seafood, deli meats, cheeses that used unpasteurized milk as an ingredient, raw sprouts, raw fruits and vegetables. In 2011, cantaloupe was connected to a multistate foodborne listeriosis illness outbreak that had 147 people reporting illness and more than thirty deaths attributed to it.

People at higher risk of contracting foodborne illnesses should take extra precautions such as avoiding foods that have been related to listeriosis outbreaks. These foods are noted in the previous paragraph. Besides avoiding these foods, a precaution to take would be cooking deli meats and hotdogs before eating them. Being aware of what has caused companies to recall foods that have a history of being named as a source of Listeriosis can help people know what foods to avoid.

Tips for preventing the spread of this illness can be found on our tips page. To reduce the potential spread of Listeria additional control measures may be required for persons associated with high-risk activities or settings such as food handlers, childcare facility personnel, and health care workers. Specific guidance and recommendations can be found in a manual titled Prevention and Control of Communicable Diseases. Additional guidance for retail food establishment management can be found in Chapter 2 of the food code.

For additional information on HAV, please visit the following references: Centers for Disease and Control and Prevention website and FDA’s Bad Bug Book. For data on reported Listeria cases in Missouri, visit the communicable disease data and statistical reports page for the annual reports listed there.